Diff Cover Drain

[centerville]

Ok so I read the "Differentials or differential covers may have a drain plug added" Does this mean I have to add the drain plug to the oem cover?

[Pranav]

Yeah but with our rear ends I would skip that and pill the cover periodically to inspect the gears and diff.

Clean up the rtv and make sure the cover is straight (new ones are cheap), and get some fiber gaskets. I'm able to pull mine and have zero gasket residue to clean up each time, no leaks.

[centerville]

Good point. I will have to look at fiber gaskets. Thanks.

[Pranav]

I got a fresh new diff cover and a stack of gaskets off rockauto for cheap.

I think a new smooth differ cover and a good wire wheel cleaning of the housing will be the trick to get a clean release of the gasket each time, plus about every few race if you pull it to check it shouldn't "set" and harden to where it makes a mess to clean up. I'm liking this a lot better than rtv.

[Al Fernandez]

For clarity, you don’t have to add a drain plug to the cover, you can add it to the housing. The GMs have a nice cavity right at the bottom that is perfect for this.

[Trublu]

For clarity, you don’t have to add a drain plug to the cover, you can add it to the housing. The GMs have a nice cavity right at the bottom that is perfect for this.

Solid evidence it’s a GM biased rule set

[BryanL]

Solid evidence it’s a GM biased rule set

Agreed it's GM biased towards the rearend....of the field.

Had to make a change after the 2016 results in Texas with Fords winning 83% of the podiums, every Toyo race, and every fast lap of the weekend.

2017 got it back in line with 2015's 72% Ford podiums. For 2017 Ford had 75.36% of podiums, every fast lap of weekend, but GM did get a single Toyo win.

2018 so far is right in line (but revisions may need to be reconsidered). Fords have won 73.33% of the podiums, but only 7 out of 8 Toyo races, and they have 3 out of four fast lap of the weekend.

But to keep this on topic are we allowed to run an aftermarket aluminum cover? What if said cover has some bolts to help the carrier bearing in the ultrastrong GM diff? What if the bolts are backed out so they don't provide any support? At least we are allowed to upgraded to the superior Ford 8.8 or Ford 9" with better posi and gearing options. Guess I need to do that swap instead of adding a diff cover with a drain.

[Supercharged111]

That's a negative on the aftermarket cover, this has come up before and gets shot down every time. There's an RCR thread on the national forum about this very topic from a few years back.

[michaelmosty]

Agreed it's GM biased towards the rearend....of the field.

Had to make a change after the 2016 results in Texas with Fords winning 83% of the podiums, every Toyo race, and every fast lap of the weekend.

2017 got it back in line with 2015's 72% Ford podiums. For 2017 Ford had 75.36% of podiums, every fast lap of weekend, but GM did get a single Toyo win.

2018 so far is right in line (but revisions may need to be reconsidered). Fords have won 73.33% of the podiums, but only 7 out of 8 Toyo races, and they have 3 out of four fast lap of the weekend.

But to keep this on topic are we allowed to run an aftermarket aluminum cover? What if said cover has some bolts to help the carrier bearing in the ultrastrong GM diff? What if the bolts are backed out so they don't provide any support? At least we are allowed to upgraded to the superior Ford 8.8 or Ford 9" with better posi and gearing options. Guess I need to do that swap instead of adding a diff cover with a drain.

Haha, I miss those crazy discussions!!!

Everything seemed about as even as could be at Hallett between Ford and GM from my perspective.

[mach1]

Haha, I miss those crazy discussions!!!

Everything seemed about as even as could be at Hallett between Ford and GM from my perspective.
Not even close, it’s obvious that Fords have a massive advantage for the last corner of the last lap of the race.

[Fbody383]

Everything seemed about as even as could be at Hallett between Ford and 1 particular GM from my perspective. Fixed it for you...

I could have done my part and made the first start... not gone off... not overheated and blowed up the transmission.

[Al Fernandez]

lol Brian

[BryanL]

Got it! $150 Aftermarket diff cover is illegal but a $4,000 Ford 9" with aluminum center section is legal.....makes perfect sense.

Well scratch part of that. Rules won't allow a GM car to swap to the optimal rearend which is the Ford 8.8 (even though bolt ins are available and cheaper). Guess instead of helping my diff stay cool or possibly allowing us to strengthen a known weak rear end with a $150 cover we should just throw $4k down on a 9". I know the rules are there to try and help us save a little money but guess they also allow you to spend a lot of money.
I remember some about diff cover debate but think that was so long ago that many who argued for or against are gone but really the fact that we have allowed so many other things to happen that an upgraded diff cover doesn't seem like a big deal.

Glad this came up before Nats so I don't get DQ'd for a diff cover. Guess I'm ordering a Ford 9" for my birthday.

[RichardP]

To be fair, allowing the Ford 9" was a cost saving measure mostly aimed at allowing A Sedan cars a way into CMC without having to spend big money converting their cars back. It had no realistic effect on those building a CMC car because no one would be dumb enough to add the expense, drag, and weight of a 9" when the stock rear ends were bullet proof on cars with 230 HP, 16" rock hard tires, and 12" brakes...


Richard P.

[Pranav]

What is the failure mode for gm rear ends in CMC?

My first one went simply because the ring gear boots were loose, and even then it was fine except for the broken teeth from loose bolts flying around.

I chipped a ring tooth on the second one but I had issues with that build with a loose pinion nut, and later running it all setup wrong and super tight when we took my rear end apart for no reason at all at the track.

I think just a properly setup rear end with a crush sleeve eliminator and heavy oil is all that's needed. I run 85w-140.

That fancy diff cover just adds support to the main caps. I don't believe we're drag racer blowing apart rear end housing are we?

[mach1]

I've had good luck with RCR's if you think it's dumb (plain rotors,broken crankshafts) put in a solid RCR and things may happen. I thought a 8.8 was legal in CMC?
Read extreme ownership by Jocko Willink, I take this approach with my team, before passing blame did you do everything you could to "win" (I'm in sales).

I figure a lot of the GM Ford stuff is just for fun, but if it's a real issue, you have the power to do something about it.

I agree, a 4k ford 9" legal but a cover isn't is BS, but that hasn't been an issue for me so I didn't try to change it.

[mach1]

What is the failure mode for gm rear ends in CMC?

My first one went simply because the ring gear boots were loose, and even then it was fine except for the broken teeth from loose bolts flying around.

I chipped a ring tooth on the second one but I had issues with that build with a loose pinion nut, and later running it all setup wrong and super tight when we took my rear end apart for no reason at all at the track.

I think just a properly setup rear end with a crush sleeve eliminator and heavy oil is all that's needed. I run 85w-140.

That fancy diff cover just adds support to the main caps. I don't believe we're drag racer blowing apart rear end housing are we?

Wheel hop killed Paul's 10 bolt, because the torque arm bolts were finger tight, wheel hop is savage on parts.

[Supercharged111]

Mine came with the fancy solid shims and crush sleeve eliminator and hasn't blown up yet. The diff on the other hand seems to unload on right handers.

[Pranav]

Wheel hop killed Paul's 10 bolt, because the torque arm bolts were finger tight, wheel hop is savage on parts.

Oh yeah, I only learned how to start heel toe-ing last summer. My first rear end lived through 5 years of that hop life

[Pranav]

I'm looking at 4th gens in Texas in general, and I'm seeing all kinds of issues that prevent each particular driver/car combo from running up front. Be it breaking things unexpectedly, reliability, or the driver just not doing enough testing/setup time to win.

I'm not trying to put my fellow 4th gen drivers down, but spend an afternoon observing what the Fox guys are doing vs the 4th gen guys in regards to what they're focused on (or even present) on Fridays before the race, and you may see my point. I feel like the combination of new/fresh talent on the Mustang side, the departure of Proctor/Landrum, and the timing of the rule changes all happening at the same time seems to perpetuate the impression that there is an apparent rule bias against 4th gens.

The RMR guys are saying mustangs are getting their butts kicked by Camaros up there.

Yeah the Mustangs have a weight advantage, but they have shit aero and suspension.

Francis has been able to put his car far up there from time to time when it has run right and it (no offense) has the least fanciest gear of the others. Tyler hopped in Sean's car (3rd gen, but still) and was able to put it up there at COTA after working on setup.

My car's been running like a swiss watch and has all of the right parts/numbers to win, but I haven't been put it together as a driver to get it done myself.

At this point performance wise I'm (by choice) weighing 50lbs over post race (I have more than enough extra gas and coolsuit capacity to take it down to zero if needed), and getting closer and closer to 260/310 with the new motor after making tweaks. All that's needed is setup time and a good driver.

We should put Tyler in my car and see how far up he can place vs the big evil Fox mafia.

[Pranav]

Also quick show of hands, who is going to DEs, test days, and other racing events outside of the NASA calendar? How many of you guys are changing alignment settings and spring rates between races?

Is your car showing up to the track Friday completely ready to go?

If you're answering no to some of these, go see if the guys in front of you answered less "NOs" than you, maybe fix that too?

[mach1]

We should put Tyler in my car and see how far up he can place vs the big evil Fox mafia.

I would love to run a 4th gen for nats , thought about building one but don't have time

[centerville]

Well that did not work.

[centerville]

Agreed it's GM biased towards the rearend....of the field.

Had to make a change after the 2016 results in Texas with Fords winning 83% of the podiums, every Toyo race, and every fast lap of the weekend.

2017 got it back in line with 2015's 72% Ford podiums. For 2017 Ford had 75.36% of podiums, every fast lap of weekend, but GM did get a single Toyo win.

2018 so far is right in line (but revisions may need to be reconsidered). Fords have won 73.33% of the podiums, but only 7 out of 8 Toyo races, and they have 3 out of four fast lap of the weekend.

But to keep this on topic are we allowed to run an aftermarket aluminum cover? What if said cover has some bolts to help the carrier bearing in the ultrastrong GM diff? What if the bolts are backed out so they don't provide any support? At least we are allowed to upgraded to the superior Ford 8.8 or Ford 9" with better posi and gearing options. Guess I need to do that swap instead of adding a diff cover with a drain.


There it is, what I have been missing. LOL. Now it feels like every other motorsport I have been involved with. Sorry Brian I get the frustration and I don't even have a gm. Not sure why they would shoot down a simple mod like that. Tyler is right file it again. OK carry on.

[BryanL]

Pranav-did someone hack your account? You sound exactly like all the GM guys did 8 years ago when the Fords were complaining but none of them did any testing and they all ran the same spring setup. What's cool is now the Fords did what the GM guys did a long time ago. Now you have say 3 Fords at a given event running the fastest lap times which are basically the same lap times but what's so interesting is that those three normally have all totally different suspension setups, spring rates, etc.
Remember just because it's a coilover doesn't mean it's 10 times better than a traditional shock and spring. Same goes for the torque arm which is so weak and flexes. Sure you have aftermarket setups for Fords that put in a torque arm and aftermarket setups on F body's that add a 4 link type of setup.

I'm not complaining or submitting RCR's. I just enjoy sharing the same data that was used way back when to give the Fords an advantage only now the data is totally reversed.

I also enjoy showing how ridiculous some things are like not being able to run an aluminum diff cover for $150 that gives more strength, fluid capacity, and cooling but I can swap in a Ford 9", GM 12 bolt, or Dana...yet I can't swap in the Mustang 8.8.

Pranav-to answer your questions everyone knows between you and Dan the 4th Gen gets more time time testing away from NASA events and on Friday's. I probably do more than the Summer Shootout Winner but not sure why any of that matters.

[michaelmosty]

Pranav-did someone hack your accoutn? You sound exactly like all the GM guys did 8 years ago when the Fords were complaining but none of them did any testing and they all ran the same spring setup. What's cool is now the Fords did what the GM guys did a long time ago. Now you have say 3 Fords at a given event running the fastest lap times which are basically the same lap times but what's so interesting is that those three normally have all totally different suspension setups, spring rates, etc.
Remember just because it's a coilover doesn't mean it's 10 times better than a traditional shock and spring. Same goes for the torque arm which is so weak and flexes. Sure you have aftermarket setups for Fords that put in a torque arm and aftermarket setups on F body's that add a 4 link type of setup.

I'm not complaining or submitting RCR's. I just enjoy sharing the same data that was used way back when to give the Fords an advantage only now the data is totally reversed.

I also enjoy showing how ridiculous some things are like not being able to run an aluminum diff cover for $150 that gives more strength, fluid capacity, and cooling but I can swap in a Ford 9", GM 12 bolt, or Dana...yet I can't swap in the Mustang 8.8.

Pranav-to answer your questions everyone knows between you and Dan the 4th Gen gets more time time testing away from NASA events and on Friday's. I probably do more than the Summer Shootout Winner but not sure why any of that matters.

I know this is all in good fun but you really need to get your facts in line. 8 years ago Jeremiah and I both had cars prepped to the Max of the rules and were testing our brains out trying to get the leg up on the other. What you are thinking of is 12 years ago when we were all brand new to this and virtually none of the Mustangs did true testing and analysis. The rules changes took place after the 2012 season to change the weights of the platforms and get the track widths closer to being equal.

My car has been setup well for a long time now so my lack of Friday practice is a non-issue.
Also, think about getting the most out of your car when you are racing and have 60% of your focus on hitting all your marks, 20% of focus on your car and any potential issues, and 20% focus on everyone else on track. Car prep and mental prep is vital to getting the most out of your performance.
Now flip that focus to 90% hitting your marks, 5% on your car, and 5% on other drivers on track and tell me who you think is going to be faster.
No offense to Marshall but it is the reason he was running slower in his car at the end of his racing career vs 5 years prior. He was spending so much mental energy focusing on a car that had constant problems, that the driving performance suffered.

[Pranav]

Pranav-did someone hack your account? You sound exactly like all the GM guys did 8 years ago when the Fords were complaining but none of them did any testing and they all ran the same spring setup. What's cool is now the Fords did what the GM guys did a long time ago. Now you have say 3 Fords at a given event running the fastest lap times which are basically the same lap times but what's so interesting is that those three normally have all totally different suspension setups, spring rates, etc.
Remember just because it's a coilover doesn't mean it's 10 times better than a traditional shock and spring. Same goes for the torque arm which is so weak and flexes. Sure you have aftermarket setups for Fords that put in a torque arm and aftermarket setups on F body's that add a 4 link type of setup.

I'm not complaining or submitting RCR's. I just enjoy sharing the same data that was used way back when to give the Fords an advantage only now the data is totally reversed.

I also enjoy showing how ridiculous some things are like not being able to run an aluminum diff cover for $150 that gives more strength, fluid capacity, and cooling but I can swap in a Ford 9", GM 12 bolt, or Dana...yet I can't swap in the Mustang 8.8.

Pranav-to answer your questions everyone knows between you and Dan the 4th Gen gets more time time testing away from NASA events and on Friday's. I probably do more than the Summer Shootout Winner but not sure why any of that matters.

I think 5 years of staying at the Mustang Ranch at Hallett is rubbing off me.

All I'm saying is I'm just not seeing the "Max Effort" push by the 4th gen drivers that I see the Mustang drivers doing right now, or guys are putting in the Max effort but have incidents/failures that hold them back. I'm guilty just as anyone else in the 4th gen camp.

As far as different setups, it is reversed; most of the 4th gens now are running similar rates while the mustangs are all over the place. Go look under Josh's car and see if you can even see any springs up front.

[Fbody383]

One of these days we'll keep threads clean.

Isn't it about time for a nation-wide CMC convention to re-think what CMC needs to be going forward? It's completely against the ideals of the old 230hp rules to allow $$$$$ brakes, but not $ diff cover.


Now flip that focus to 90% hitting your marks, 5% on your car, and 5% on other drivers on track and tell me who you think is going to be faster. I put myself into this camp - my 9.9 effort is equivalent to a 9.0 effort by a trophy queen. I just don't have any processing room left at this point. Some is probably set-up, some is very likely lack of seat time. I think the rules are close though personally I still vacillate between close and not close enough.


All I'm saying is I'm just not seeing the "Max Effort" push by the 4th gen drivers that I see the Mustang drivers doing right now, or guys are putting in the Max effort but have incidents/failures that hold them back. You can say that about me and it doesn't bother me. I struggle whether I should make the investment in the time/cost balance to move up the field a couple of places. OR... keep having a great time with some great folks with a little racing thrown in for good measure.

[BryanL]

I know this is all in good fun but you really need to get your facts in line. 8 years ago Jeremiah and I both had cars prepped to the Max of the rules and were testing our brains out trying to get the leg up on the other. What you are thinking of is 12 years ago when we were all brand new to this and virtually none of the Mustangs did true testing and analysis. The rules changes took place after the 2012 season to change the weights of the platforms and get the track widths closer to being equal.

My car has been setup well for a long time now so my lack of Friday practice is a non-issue.
Also, think about getting the most out of your car when you are racing and have 60% of your focus on hitting all your marks, 20% of focus on your car and any potential issues, and 20% focus on everyone else on track. Car prep and mental prep is vital to getting the most out of your performance.
Now flip that focus to 90% hitting your marks, 5% on your car, and 5% on other drivers on track and tell me who you think is going to be faster.
No offense to Marshall but it is the reason he was running slower in his car at the end of his racing career vs 5 years prior. He was spending so much mental energy focusing on a car that had constant problems, that the driving performance suffered.

Extremely good points in the second paragraph. But I really like this quote from the 39 that sums it up pretty good for me. "You can say that about me and it doesn't bother me. I struggle whether I should make the investment in the time/cost balance to move up the field a couple of places. OR... keep having a great time with some great folks with a little racing thrown in for good measure."

Mosty-I wasn't around 12 years ago as I was still in high school. But yes I'm having fun sharing the same type of data that was used in the past. Sounds like it was 6-8 years ago with what we are talking about when the threads were all about parity. After 2012 the directors took away track width from the 4th gens I think and they specifically threw a bone to the Fords reducing weight by 50 lbs. Of course they used data from you and Procter from one race as well. What has changed on your car since 2012? More power?, Stoptechs?, AST's? etc? Want to test drive my car for a day at Cresson before Nats?

[drecords]

I'm looking at 4th gens in Texas in general, and I'm seeing all kinds of issues that prevent each particular driver/car combo from running up front. Be it breaking things unexpectedly, reliability, or the driver just not doing enough testing/setup time to win.

I'm not trying to put my fellow 4th gen drivers down, but spend an afternoon observing what the Fox guys are doing vs the 4th gen guys in regards to what they're focused on (or even present) on Fridays before the race, and you may see my point. I feel like the combination of new/fresh talent on the Mustang side, the departure of Proctor/Landrum, and the timing of the rule changes all happening at the same time seems to perpetuate the impression that there is an apparent rule bias against 4th gens.

The RMR guys are saying mustangs are getting their butts kicked by Camaros up there.

Yeah the Mustangs have a weight advantage, but they have shit aero and suspension.

Francis has been able to put his car far up there from time to time when it has run right and it (no offense) has the least fanciest gear of the others. Tyler hopped in Sean's car (3rd gen, but still) and was able to put it up there at COTA after working on setup.

My car's been running like a swiss watch and has all of the right parts/numbers to win, but I haven't been put it together as a driver to get it done myself.

At this point performance wise I'm (by choice) weighing 50lbs over post race (I have more than enough extra gas and coolsuit capacity to take it down to zero if needed), and getting closer and closer to 260/310 with the new motor after making tweaks. All that's needed is setup time and a good driver.

We should put Tyler in my car and see how far up he can place vs the big evil Fox mafia.

Honestly I think Bryan Curtis showed all of us at Hallett that a well set up 4th gen is as fast as the foxes. He was absolutely favored to win going into the championship race. As I came out early due to old ass foxbody issues I don't know how the race ended like it did...but his car appeared well sorted and fast all weekend...

[Supercharged111]

Bryan choked on the last lap, he had it locked down otherwise.

[michaelmosty]

Extremely good points in the second paragraph. But I really like this quote from the 39 that sums it up pretty good for me. "You can say that about me and it doesn't bother me. I struggle whether I should make the investment in the time/cost balance to move up the field a couple of places. OR... keep having a great time with some great folks with a little racing thrown in for good measure."

Mosty-I wasn't around 12 years ago as I was still in high school. But yes I'm having fun sharing the same type of data that was used in the past. Sounds like it was 6-8 years ago with what we are talking about when the threads were all about parity. After 2012 the directors took away track width from the 4th gens I think and they specifically threw a bone to the Fords reducing weight by 50 lbs. Of course they used data from you and Procter from one race as well. What has changed on your car since 2012? More power?, Stoptechs?, AST's? etc? Want to test drive my car for a day at Cresson before Nats?
Nothing has changed since 2012. Still the same power / motor setup. I put the AST's on in 2009 and the Stoptechs on in 2010.

How about we swap cars for a couple sessions at NOLA?

[Storm Trooper]

6.29 Rear axles
6.29.1 Any OEM stock differential housing that was originally offered in an eligible model car is allowed. Updating/Backdating of OEM stock differential housings is allowed.
6.29.2 Both GM and Ford cars may also use a Ford 9”, GM 12 bolt, or Dana 44 rear axle housing, but the housing must maintain both the exact OEM suspension pickup points and OEM rear end geometry as the originally equipped axle assembly.
6.29.3 Any gear ratio equal to or numerically lower than 4.11 that fits the stock/alternate differential case without modification may be used. Differentials may be fully locked (welded) or use any commercially available mechanical limited slip.
6.29.4 Any commercially available replacement type steel or alloy steel axles may be used. Full floater axles are prohibited. Heavy-duty non-”C" Clip style axle ends are allowed and recommended. Competitors should carefully select axle ends. Many of the "C" clip eliminator axle ends are designed for street or drag strip use only and cannot withstand the side loads associated with road racing.
6.29.5 Differentials or differential covers may have a drain plug added.

Can some one explain to my why a aluminum diff. cover in against the rules??

[RichardP]

Can some one explain to my why a aluminum diff. cover in against the rules??

Standard answer. It's not needed. If was made legal, lots of people would think they needed one and lots of money would be wasted. The coolest thing about an aluminum cover is the availability of a drain. As a compromise, they allowed a drain be added to the stock cover.

Richard P.

[Storm Trooper]

Standard answer. It's not needed. If was made legal, lots of people would think they needed one and lots of money would be wasted. The coolest thing about an aluminum cover is the availability of a drain. As a compromise, they allowed a drain be added to the stock cover.

Richard P.
(The coolest thing about an aluminum cover is the availability of a drain.) not to mention increasing the capacity of the oil, cooling the oil, supporting the bearing caps.

Big brakes were not needed, 260 hp was not needed! But people wanted them so.....the rules are telling us where not to waste our money?

[RichardP]

not to mention increasing the capacity of the oil, cooling the oil, supporting the bearing caps.

Again, all that crap is overkill and a waste of money (on a 230 hp car with shit tires). At the current state of things, does this need to be revisited? Probably.




Big brakes were not needed, 260 hp was not needed! But people wanted them so.....the rules are telling us where not to waste our money?


NASA, not the CMC management, mandated the S197 Mustang and the LS Camaro. Neither one of them could realistically get to the 230 hp number. Once you've gone there, along with wider and stickier rubber, big brakes actually save money over the old crap that had to be replaced often if you do enough events. Do I like where the whole thing has gotten to? No, and I don't believe many people do. If crap tires were mandated way back when, we wouldn't have needed big brakes and we wouldn't be hurting transmissions, rear ends, etc. at the rate that we are. We are literally tearing the tubs apart on these ancient cars. And we are spending a lot of money doing it. The whole thing doesn't make much sense...


Richard P.

[marshall_mosty]

No offense to Marshall but it is the reason he was running slower in his car at the end of his racing career vs 5 years prior. He was spending so much mental energy focusing on a car that had constant problems, that the driving performance suffered.

No offense taken, but it is 100% accurate.. I had no clue if the next shift would break a transmission, diff, shell a lifter, break a crank, or some other ungodly evil that would put my car on the side of the track...

[drecords]

No offense taken, but it is 100% accurate.. I had no clue if the next shift would break a transmission, diff, shell a lifter, break a crank, or some other ungodly evil that would put my car on the side of the track...

I completely understand this sentiment. It's one of the biggest things mentally I've had to get over transitioning to this series. In my endurance days it was all about finishing the stint to hand the car back off to the next guy to stay in the race... No risks, no dumb decisions, no risky moves.

One of the best things I've done to my car is not put another $4k machine shop built engine back in it. Mentally it's been great knowing that if I pop the explorer engine I'm out way less money. So I'll hit the limiter occasionally trying to make a pass, etc. Never did that on the old one and it blew up fantastically for my trouble... currently considering picking another one up from the junkyard and having it ready to go in the trailer....

[Supercharged111]

In 2015 my car dynoed 70hp low. Turns out I'd lost a rod bearing the last race of the year prior. I forgot how weird the car had felt the last lap or 2 and how I'd just cruised there because we were really spread out by that point. I grabbed a crank off of CL and had it polished, pistons and rods used off of Fleabay, new bearings and gaskets, honed in my garage, all in for about $800. That motor is still in and healthy, has been good and made good numbers. It's getting replaced by an LS. While the rest of the crap is an asspain to hunt down cheap, the motor itself was $220 from the pull and pay for an aluminum LM4. Gotta find another for a spare. 170k and I'm not doing anything to the bottom end. Got a late LS1 cam for free fiddy to pop in there and that's it. I don't believe in machine shop engines for these cars when stock seems to last just fine.

[Pranav]

Leave the ls1 cam alone.

An lm4/lm7 as is with some work on intake exhaust restriction is all you need.

If you throw the ls cam in there you may have trouble getting the torque you need after choking the power down to get under the HP limit.

[Al Fernandez]

I'm pretty confident the reason for Gm having worse rear end reliability than the Fords is all due to axle hop and no diff cover is going to fix that. I've never blown a rear end, and only rebuilt mine recently because the 13 or so yr old T2R was feeling like it wasn't working well any more.

[liquidroam]

a little late to the party on this one.... but what an entertaining read. A bit off the wall at points but good entertainment value! Ya mine was in the early days before I did any sort of mechanical prep to the car and was running HPDE. Do much more these days but Hallett will show that my experience is about the same. Looking forward to getting that part of my racing career behind me. Well to the extent that is reasonable.

[Pranav]

I'm pretty confident the reason for Gm having worse rear end reliability than the Fords is all due to axle hop and no diff cover is going to fix that. I've never blown a rear end, and only rebuilt mine recently because the 13 or so yr old T2R was feeling like it wasn't working well any more.

So what can we do about eliminating axle hop?

If there's one major platform disparity, it's that fact that F-bodies have to drive and brake bias around rear axle hop while the ford guys can actually use their rear brakes and go fully aggressive with brake compound.

If I understand correctly it can be as simple as converting the nose end of the torque arm to be a sliding type instead if a fixed bushing with no other geometry changes.

[Sook]

So what can we do about eliminating axle hop?

If there's one major platform disparity, it's that fact that F-bodies have to drive and brake bias around rear axle hop while the ford guys can actually use their rear brakes and go fully aggressive with brake compound.

If I understand correctly it can be as simple as converting the nose end of the torque arm to be a sliding type instead if a fixed bushing with no other geometry changes.

As an alternative, we could allow torque arms on mustangs to induce wheel hop.

[Fbody383]

6.33.7 Suspension bushing material is unrestricted. Does this include the torque arm bushing?

[RichardP]

So what can we do about eliminating axle hop?

If there's one major platform disparity, it's that fact that F-bodies have to drive and brake bias around rear axle hop while the ford guys can actually use their rear brakes and go fully aggressive with brake compound.

If I understand correctly it can be as simple as converting the nose end of the torque arm to be a sliding type instead if a fixed bushing with no other geometry changes.


Apparently one of the best fixes for axle hop is a stiffer, aftermarket torque arm that doesn't attach to the transmission. Other than that, you are playing with spring/damping/tire pressures to make the car less likely to hop. When that inevitably doesn't work, you crank the rear bias to almost turn the rear brakes off...


Richard P.

[Pranav]

Apparently one of the best fixes for axle hop is a stiffer, aftermarket torque arm that doesn't attach to the transmission. Other than that, you are playing with spring/damping/tire pressures to make the car less likely to hop. When that inevitably doesn't work, you crank the rear bias to almost turn the rear brakes off...


Richard P.

Fixed that for you. I know the the Mustangs have a shitty rear suspension, but are at least able to run ideal rear brake compounds and spring rates. We, not so much...

[Pranav]

Gary's street 3rd gen has a nice sliding type bushing that uses an otherwise stock torque arm setup, will see if he can send pics.

It involved modifying a stock torque arm.

[Pranav]

As my own data point, I've tried two seperate times to run XP8 carbotechs in the rear (XP10 in the front).

Each time I've had to pull them and go back to parts store ceramics to cut the bite out of the rear, so I can actually go deep into my brakes without upsetting the rear. Using a brake bias adjuster creates more problems in that the ability to modulate and control pressure spikes to the front brakes is further reduced (more likely to lockup).

We're all driving around a glaring issue and it would be nice, as a group, to be able to engineer a cheap, effective solution that doesn't give us a huge advantage like a decoupled torque arm or any other major geometry changes.

I'll see if I can get a picture of this front bushing thing. It looked neat/simple.

[Pranav]

Here's a setup I'm willing to test.

Replace the torque arm with a tubular unit and heim joint front.

No changes in geometry and I'm replacing a stock piece with a heavier one.

http://www.superchevy.com/how-to/0410htp-2002-pontiac-trans-am-lg-suspension-upgrades

[Sook]

Here's a setup I'm willing to test.

Replace the torque arm with a tubular unit and heim joint front.

No changes in geometry and I'm replacing a stock piece with a heavier one.

http://www.superchevy.com/how-to/0410htp-2002-pontiac-trans-am-lg-suspension-upgrades

Interesting concept. Worth a try to see if it solves your problem. I think the torque arm shaft going through the center of the heim joint might gall over time. It would also be better if the heim joint was held into a bore with snap rings or the like. Welding the outside of the bearing isn't going to be good for the life of the joint.

I think the factory torque arms arm free to move fore and aft, albeit with some friction in the bushing. The factory setup probably doesn't allow for angular changes as well. Has anyone tried a squishy rubber bushing to see if the issue is better or worse? We have urethane torque arm bushings on the Red Shift cars.

- Josh

[Pranav]

I lube the shit out of mine before sticking it in.

I don't even unbolt the clamshell anymore I just tug on it to get it out.

[marshall_mosty]

I lube the shit out of mine before sticking it in.... I just tug on it to get it out.
Sounds like a MAJOR personal issue, especially considering the time of the post. Wrong website and forum??
LOL

[Pranav]

We're talking about sliding our torque arms in/out smoothly and making sure we avoid our rear ends from bouncing while doing it. Not sure what you're referring to?

[Supercharged111]

Here's a setup I'm willing to test.

Replace the torque arm with a tubular unit and heim joint front.

No changes in geometry and I'm replacing a stock piece with a heavier one.

http://www.superchevy.com/how-to/0410htp-2002-pontiac-trans-am-lg-suspension-upgrades

That dude shelled out all that cash to LG to make an automatic car turn.

[Pranav]

The f-body aftermarket was built on one Jean shorts dad shoes gold chain wearing guy's wallet at a time.

[Pranav]

But yeah I spent a solid minute trying to figure out why the trans mountt was going next to the oil pan lol

[liquidroam]

We're talking about sliding our torque arms in/out smoothly and making sure we avoid our rear ends from bouncing while doing it. Not sure what you're referring to?

I mean sometimes it is a torque arm. Just depends on the position of the rear end...:eek:

[Al Fernandez]

The OE rubber bushings are preferable than the urethane IMHO. The urethane just adds friction fore/aft and bind bump/droop. Neither is good.

[DAlgozine]

Not making eye contact.............or sounding off too loudly
But, bumps also tear up rear ends. Freeze thaw cycles north of the mason dixon cause ripples in tracks.
So, in this case...."bouncing rear ends", is not good.
Its is widely accepted that the 8.8 holds up to abuse better then the 10 bolt.

[JJKJ]

Adding to the discussion regarding an aftermarket diff cover, I tried unsuccessfully to get an RCR up for review twice. Second time I provided not only justification, but also evidence that they should be legal based on the fact they were an option on SLP cars. If all the other SLP factory options are legal, why not the diff cover?

I have a hard time rationalizing the arguments I've read against the covers. They are a durability mod, not a performance mod. No one is going to feel they "have" to buy one just because someone else has one. No one is going to feel they lost a race because their competitor crossed the finish line ahead of them due to the overwhelming performance advantage of their aftermarket diff cover.

This is the most ridiculous rule we have in CMC. As pointed out, aftermarket rear axles costing thousands of dollars are ok but a $150 cover is not. Regardless of the original intent of the rule (AS homogenization) the fact is the rule still stands and makes no sense.

Those who feel it is a waste of money don't have to do the mod. Allow those of us who feel there is a benefit the opportunity. I challenge anyone to say with a straight face that a $150 durability mod is going to push this class into spending whirlwind.

Bottom line though, as I brought up in my second RCR, why isn't a mod that was an option on the factory order form for SS Camaros not legal?

[DAlgozine]

Bottom line though, as I brought up in my second RCR, why isn't a mod that was an option on the factory order form for SS Camaros not legal?

I erased my smart a$$ answer, that I initially typed. It was difficult for me to do, but I'm turning over a new leaf.

[JJKJ]

I erased my smart a$$ answer, that I initially typed. It was difficult for me to do, but I'm turning over a new leaf.

How will I even know you? :D

[MHISSTC]

As one of the original rabble-rousers who brought up the topic of differential covers, I clearly still remember the exchanges on the national CMC forum when it was still an active place to hang out.

I never proposed any of the preload type aluminum diff covers, as I think those could be portrayed as having a potential performance advantage. Instead, my recommendation was a modified junkyard Explorer differential cover for the Ford 8.8 that would have added both a drain and a fill plug to the cover that had magnets on both of them, and included cooling fins and ribs for strength and lower temps to increase component longevity and make fluid changes easier. I wasn't suggesting one of those "expensive" GT500 kind of finned covers either. Check out the following link to learn all about modifying this cheap OEM Ford cover. https://www.svtperformance.com/forums/threads/modifying-an-explorer-aluminum-cover-to-fit-any-8-8.653880/

[BryanL]

As one of the original rabble-rousers who brought up the topic of differential covers, I clearly still remember the exchanges on the national CMC forum when it was still an active place to hang out.

I never proposed any of the preload type aluminum diff covers, as I think those could be portrayed as having a potential performance advantage. Instead, my recommendation was a modified junkyard Explorer differential cover for the Ford 8.8 that would have added both a drain and a fill plug to the cover that had magnets on both of them, and included cooling fins and ribs for strength and lower temps to increase component longevity and make fluid changes easier. I wasn't suggesting one of those "expensive" GT500 kind of finned covers either. Check out the following link to learn all about modifying this cheap OEM Ford cover. https://www.svtperformance.com/forums/threads/modifying-an-explorer-aluminum-cover-to-fit-any-8-8.653880/

So you recommend a cover that has ribs for strength, cooling fins for lower temps but are you against one that has preload which potentially strengthens the weak GM rearend?

The aftermarket cover for the GM isn't a performance advantage-unless you count potentially being more durable as an advantage. If you want to say it is a cooling advantage then whats the big deal since we allow radiators, coolers everywhere else.

JJKJ-send it it for another try. But not everything on an SS or SLP car is legal in CMC anyway.

It doesn't make sense.

[Supercharged111]

Haha, I miss those crazy discussions!!!

Everything seemed about as even as could be at Hallett between Ford and GM from my perspective.

I know some seem to think Bryan is the only one who can hustle a 4th gen, but he's not completely ruling the roost back here. I'm not seeing any disparity in the platforms based on my observations in RM, TX, and Nats. I am faster than I drove at Hallett this year. My weaknesses are launching, learning a new track quickly, and managing traffic to the extent that Michael and Bryan do. The latter 2 hurt me at Hallett and, quite frankly, getting all the way to my 10/10ths really takes a lot. I have to be pretty relaxed to get that last little bit on some tracks and that isn't exactly easy when there's 20 cars breathing down your ass (or 1 Mosty). I think some people believe they are at the limit and they're not realizing what's still on the table. I haven't touched my setup in years, I just drive. If it feels pushy, I change my driving and if it feels loose, again, I change my driving. Next event car usually feels fine. Typically when my car is off, so is everyone else's so it's relative.

[MHISSTC]

So you recommend a cover that has ribs for strength, cooling fins for lower temps but are you against one that has preload which potentially strengthens the weak GM rearend?

The aftermarket cover for the GM isn't a performance advantage-unless you count potentially being more durable as an advantage. If you want to say it is a cooling advantage then whats the big deal since we allow radiators, coolers everywhere else.

Maybe I worded my post poorly.

I am in not against alternate diff covers for GM axles, or any platform for that matter, because I don't think durability is a performance advantage that can be measured in faster lap times. I think we should let diff covers be wide open. It also doesn't make sense to me that we can't do covers, but we can camber an axle which CAN lower lap times, but also introduces potential reliability issues by introducing a slight angle at the splines that increase wear. I would also venture to guess cambering a solid axle isn't something that should be attempted by your average CMC driver and that only those who are hiring expensive race shops to prep their cars are doing it. How much does it cost to have a shop camber a solid axle? Maybe we can get rid of that one along with the long overdue removal of the Ford 9" allowance?

What about being able to do C-clip eliminators? All the information and discussions I've seen say even though we CAN do that, we don't need to because all but one company builds them for drag racing and not road racing and that they really aren't needed anyway and are a waste of money. Can we get rid of this one along with the Ford 9" too?

Anyway, what I was trying to point out was that my recommendation to a rule change way back when didn't include diff covers with the preload feature that is commonly perceived as a potential performance advantage, even if it offers no such benefit in reality... ...and that got shot down back then. Has reliable information been shared widely enough to have changed perceptions since then?

Earlier in this topic the subject of wheel hop in the GM being the main culprit of reduced axle reliability was brought up. Will a different diff cover successfully combat this? I see there was a rule change request made to allow the Ford 8.8 in the GM chassis to supposedly bring about increased reliability to the GMs. Is the Ford 8.8 rear really that much better? If a different diff cover will do the job of making the rear end more reliable for the GM drivers, wouldn't that be a more cost effective solution to increase reliability than to allow a modified Ford axle in a GM? I'm thinking out loud here because I don't know.

[centerville]

Does this mean aftermarket diff covers?

6.29.4 Differentials or differential covers may have a drain plug added. "Differential covers may be
substituted".

[Supercharged111]

Yes, they're open now.

[BryanL]

Yes, they're open now.

So the rules are out. Guess I missed that. Where are the cliffs notes for changes.

[Supercharged111]

Changes are in red in the rules. Most were clarification changes. Big diffs also axed, years corrected for 5.3 swaps, aftermarket accessory mounts allowed for LS, ram air defined, angle iron can be welded to our k member to protect oil pan, and a couple others that escape me.

[Fbody383]

So $3k brakes, just not $3k rear ends... got it.

Sorry couldn't resist...

[Supercharged111]

So $3k brakes, just not $3k rear ends... got it.

Sorry couldn't resist...

Good point, but killing the diff rule doesn't impact people the way that killing the brake rule would.

[Storm Trooper]

Good point, but killing the diff rule doesn't impact people the way that killing the brake rule would.

Unfortunately both are not the intent of what the race series was supposed to be!

[AllZWay]

Unfortunately both are not the intent of what the race series was supposed to be!

I need a like button. :D

[blk96gt]

I'll take my $2k StopTech kit over having to replace rotors and pads every 2-3 weekends. Now I get 5-8 weekends on pads and 4 years on rotors.

[t500hps]

I'll take my $2k StopTech kit over having to replace rotors and pads every 2-3 weekends. Now I get 5-8 weekends on pads and 4 years on rotors.

I was down to pads and rotors EVERY WEEKEND (well, I could get 3 days out of them but not 4 days). NOTE: most of our tracks have 130-140 mph straights that end in 40-45mph corners.

[drecords]

I've not had the Girodisc rotors with the same pad compound long enough to say how long I'm getting out of cobra calipers and those rotors, but the same pads have been on the car since hallett and will make MSR-H (I didn't do nats). That's 3 weekends...seems like good life.

[AI#97]

I'll take my $2k StopTech kit over having to replace rotors and pads every 2-3 weekends. Now I get 5-8 weekends on pads and 4 years on rotors.

Stoptechs are not the end all. Think $38 rotors and FAR better pad life at half the cost for the kit and pads.

[ShadowBolt]

Stoptechs are not the end all. Think $38 rotors and FAR better pad life at half the cost for the kit and pads.

$38.00 rotors that last four years of racing?

JJ

[blk96gt]

Stoptechs are not the end all. Think $38 rotors and FAR better pad life at half the cost for the kit and pads.

Ok.