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View Full Version : Latest GRM Issue CMC Story - Upper PHR Brace Modification Query



NickV
05-11-2011, 12:38 PM
Was reading the CMC2 car writeup in the latest GRM issue, and something caught my eye in one of the pics (see attached). My question is regarding the gussets welded in to the upper brace above the panhard rod.

7.33.2.2 reads: GM vehicles may substitute the OEM panhard bar. The bar may be adjustable for length. The passenger side mounting point must remain OEM stock. The driver side mounting point may be lowered, but only to the point where the panhard bar is parallel to the axle at ride height.

There is never mention of allowing modification/substitution to the PHR upper brace, only to the PHR itself. My question is, does the brace fall under the same rule (is it all considered one piece), or is it considered a separate piece? Anything I'm missing?

BryanL
05-11-2011, 03:19 PM
Nick-where are you finding this article? Is that suppossed to be a CMC legal car? What aboput that axle brace to the phb mount? And is that phb mount legal or the chain?

NickV
05-11-2011, 03:49 PM
It's in the latest Grassroots Motorsports. Has an old 911 on the cover.

Car is stickered for CMC2.

I'm guessing the chain is there to keep the axle from drooping when the car is jacked up so the spring doesn't fall off it's seat.

jdlingle
05-11-2011, 05:48 PM
I think they were running it in another class. The article said they got DQed from CMC2 at Nationals in 2010 but I dont remember what for.

GlennCMC70
05-11-2011, 07:32 PM
That is an OEM upper PHR brace, but it has been modified and is not CMC legal.

The PHR mount shown is legal. Once you extend the mount downward, there is enough leverage to rip the whole mount off the diff. They have been known to do this in OEM form. I've had to reweld mine - and it isn't extended - as well as the one on the #3 car before Love bought it.

While on topic, the proper ride height for a 4th gen will pretty much put the PHR level while in the OEM holes. If we could lower both ends, that would be another issue all together.
The PHR in the above pic has the bar in the OEM hole.

TJ Bain
05-11-2011, 10:51 PM
What about the smaller then stock, non-pigtail springs?

GlennCMC70
05-12-2011, 06:25 AM
What about the smaller then stock, non-pigtail springs?

7.33.4 Springs of any rate, OD, ID and free length may be used. Springs must install in the OEM stock unmodified location using the original system of attachment unless noted elsewhere in these rules.

AllZWay
05-12-2011, 07:58 AM
I sure don't see how welding a bar from the axle to the panhard bar mount should be legal. That is a big modification.

Hood
05-12-2011, 08:20 AM
"The driver side mounting point may be lowered, but only to the point where the panhard bar is parallel to the axle at ride height."

When it specifically allowed, then it must be assumed that it needs to be done safely. Just as Glenn stated, the leverage on the mount is enough to fatigue it even in stock form. Lengthening it is only going to make it more prone to fail.

BryanL
05-12-2011, 09:16 AM
I agree that the welded brace on the axle should be illegal.

So why allow the extended mount if it just creats a weaklink? Is the mount bolted or welded? If its welded then it's possible its not in the correct location. Seems easier just to not allow that mount.

Is the lower spring mount unmodified/stock? To me it looks like their is a taller insert and then a donut.

Would the chain also not limit the upward travel of the rear end?

AllZWay
05-12-2011, 10:23 AM
If that is legal... I am adding a giant...heavy ass bar to the rear for weight purposes and call it a saftey thing.

GlennCMC70
05-12-2011, 04:19 PM
I would never run that chain. It does limit droop. It also will limit body roll if the springs allow the body to roll that far. That would be like increasing the rear roll rate significantly instantaneously.

GlennCMC70
05-12-2011, 04:20 PM
If that is legal... I am adding a giant...heavy ass bar to the rear for weight purposes and call it a saftey thing.

Unsprung weight is a bad thing.

TJ Bain
05-12-2011, 05:51 PM
7.33.4 Springs of any rate, OD, ID and free length may be used. Springs must install in the OEM stock unmodified location using the original system of attachment unless noted elsewhere in these rules.

So it's CMC legal to weld/bolt a plate on the top for an upper spring perch? You can't see from the pics if they have or not, but I know I had to on my AI car to run 2.5" springs. Also, so it would be CMC legal to weld perchs for the front to use smaller springs?

GlennCMC70
05-12-2011, 06:45 PM
I didn't say that.

Apparently after TWS, there is a new CMC ruleset that says anyone can do anything as long as it is justified in thier own mind.

Hood
05-13-2011, 10:27 AM
I would never run that chain. It does limit droop. It also will limit body roll if the springs allow the body to roll that far. That would be like increasing the rear roll rate significantly instantaneously.

I would rather limit the travel than lose the spring. Besides, if your body is rolling over that far, you've got way bigger problems than worrying about rear roll rates (lilke what front suspension component has left your car).

rleng1
05-13-2011, 03:01 PM
Remember, illegal parts are allowed as long as they are installled improperly.

chris-CMC#35
05-14-2011, 08:38 PM
Apparently after TWS, there is a new CMC ruleset that says anyone can do anything as long as it is justified in thier own mind.

Are you Texas boys going to be a problem at Hallett? ;-)

-chris

mitchntx
05-14-2011, 08:49 PM
No more than usual.

chris-CMC#35
05-16-2011, 09:06 PM
No more than usual.

That's all I needed to hear. ;-)

nasa-rm
05-17-2011, 09:06 AM
Remember, illegal parts are allowed as long as they are installled improperly.

How about legal parts installed improperly?

I am still bent out of shape over that......

RichardP
05-17-2011, 09:25 AM
How about legal parts installed improperly?


You are silly. The parts were installed legally/properly. They were just made illegal by a wording change years later...


Richard P.

Rob Liebbe
05-17-2011, 12:43 PM
Just as I was getting over the whole Nationals ordeal. :mad:

Adam Ginsberg
05-17-2011, 02:57 PM
Just as I was getting over the whole Nationals ordeal. :mad:

Quit typing, and go finish your car.

Rob Liebbe
05-17-2011, 03:33 PM
You mean start my car.

GlennCMC70
05-17-2011, 05:44 PM
If you can justify them to yourself, then it must be legal. If I'm wrong, help me understand what happened to me at TWS when I asked someone to remove an illegal modification during the time between TWS and Hallett. This after 3 other Directors took a look at it and agreed w/ my initial ruling. Perhaps we should go back to the "under the breath accusations" and rely on the Protest Form and accociated fee to check car legality. God knows having a CMC Official do it carries no weight w/ some.

RichardP
05-17-2011, 06:05 PM
If you can justify them to yourself, then it must be legal. If I'm wrong, help me understand what happened to me at TWS when I asked someone to remove an illegal modification during the time between TWS and Hallett. This after 3 other Directors took a look at it and agreed w/ my initial ruling. Perhaps we should go back to the "under the breath accusations" and rely on the Protest Form and accociated fee to check car legality. God knows having a CMC Official do it carries no weight w/ some.



Wow. You still don't get it. Amazing...


Richard P.

marshall_mosty
05-17-2011, 09:19 PM
What were we talking about anyway???

RichardP
05-17-2011, 09:22 PM
What were we talking about anyway???

How much fun we are going to have at Hallett...


Richard P.

GlennCMC70
05-17-2011, 10:15 PM
I will be fun. I'm sure of it since I'll be at home.

Al Fernandez
05-18-2011, 11:27 AM
This was actually a very entertaining thread! :) Nick Steel began running 2.5" OD springs some time ago. The 4th gen upper perches work fine with no modifications whatsoever, ditto the axle side. I'm not so sure about the 3rd gen upper perches.

Bryan, there are tons of modifications allowed that result in creating weak links, not the least of which is the addition of 40hp over stock and 17" 275 R compound tires.

Alien
05-18-2011, 06:24 PM
The PHR mount shown is legal. Once you extend the mount downward, there is enough leverage to rip the whole mount off the diff.
So the mount is legal, got it. Is the brace to support the mount also legal? (serious question, since Al's reply about weak links makes it seem that the brace is not legal)

This brings an interesting dilema. I decided to look closer at the pictures. Looking at the engine bay picture I noticed a few other things.
First is the radiator upper mount.

7.25.1 Any radiator may be used provided it fits in the stock location and requires no major body or structure modifications to install.
While I wouldn't call it a major modification require to install a legal part, it's not specifically called out in the rules. Similar to the phb mount brace, no?

If these are both legal, it makes sense that if a part is needed to make a legal part work, then that part is also legal.

Next item is the box infront of the radiator. I don't see any rule that allows this. Not trying to pick on the Life's Good guys; I know I've seen this type of setup on a few cars in our region.

I'm now looking at my car in a different light. Things I would do, for what I believe the intent of this series is, need to be reevaluated. I boxed my radiator to solve an over heating issue. I had my door locks and hole for the antennae shaved for aerodyn... looks, pure looks to make it appear more professional to all the fans. I also added a wire mesh screen infront of my radiator to keep out big rocks. None of that explicitly legal.

My biggest take away from all this is to never get published in a magazine :D

GlennCMC70
05-18-2011, 08:40 PM
Al's comment to Bryan was in regards to not allowing the mount all together (Bryans POV) if it was a self inflicted weak link. Al commented on other things we allow that creat a weak link.

The extended mount is legal. The brace added to keep it from breaking is legal. This is not a home brew part - it is all part of a kit sold by a CMC vendor.

The box you mentioned in front of the rad is an airbox to direct air into the rad. Legal. I've searched the rules and found no verbage allowing it. It has been allowed in every region since I've been racing in CMC. Perhaps it should be added to the list of rules changes/clarifications for the 2012 rule set.

GlennCMC70
05-18-2011, 10:17 PM
I got word today that the car in question does not currently race w/in CMC.

Adam Ginsberg
05-19-2011, 04:08 PM
I will be fun. I'm sure of it since I'll be at home.

Well, that also means it will be fun for everyone else, too.

;)

Al Fernandez
05-19-2011, 04:44 PM
Good points Gary. I havent seen the pictures Gary, but you and Glenn are right that boxing radiators has been an accepted and strongly recommended practice from day one! Its funny that after all this time it comes up now as not being specifically allowed.

To me this just highlights the fact that the rules are a living, breathing document that we all need to collaborate on to ensure it results in a series we all want to compete in. We have a formal rules revision at the end of each year, but the reality is the directors are discussing issues and items brought up by the racers all year long. Sometimes this results in a tech bulletin, sometimes we realize we need an immediate change, etc.

Personally, I see it as every driver's responsibility to point out opportunities for improvement to the series. We all know the intent: safe, fun, close competition. I think finding competitive advantage via a modification that nobody else knows is allowed is outside of that intent. I would hope you agree and are confident that when those items that appear "grey" or easily overlooked are discovered they can be openly discussed and either laid to rest as not legal, or opened up as legal so everyone can benefit.

BryanL
05-20-2011, 08:25 AM
So even though boxing the radiators, the lower panhard mount, and brace aren't specifically allowed in the rules they are all legal? Would that hold up in a protest? Please try to clarify all of this in the rules silly season. Don't look at it from your POV of being in the series since it started or for 5 years. Look at it from a rookies perspective building a car. They should be able to get more info. out of the rules. I have been in this awhile and still don't see how that PHB mount and brace are legal. I have never heard of a CMC approved vendor and don't know where to find one? Could you please explain this to me and clarify this in the rules.

Al-I totally agree with you that the rules will always need clarifications and there should be plenty this year. Not everyone has the same "Intent" as you or I do. So since there will always be someone looking at the grey area of the rules as an opportunity to exploit it and gain an advantage the rules have to be amended to clarify the grey area.

GlennCMC70
05-20-2011, 09:29 AM
The lowered PHB mount is in the rules. The brace is not spelled out, but is allowed.

7.33.2 Panhard bars:
1. Ford vehicles may add a panhard bar. The bar may be adjustable for length. One panhard bar mounting point may be height adjustable to allow for leveling of the bar, but the other mounting point must be of fixed height.
2. GM vehicles may substitute the OEM panhard bar. The bar may be adjustable for length. The passenger side mounting point must remain OEM stock. The driver side mounting point may be lowered, but only to the point where the panhard bar is parallel to the axle at ride height.

michaelmosty
05-20-2011, 10:15 AM
How is the brace allowed if there is clearly nothing AT ALL in the rules about it?

Wirtz
05-20-2011, 11:14 AM
The lowered PHB mount is in the rules. The brace is not spelled out, but is allowed.


I know the part I am having trouble with is the whole "is it doesn't say you can, than you can't" thing. This comment seems to be counter to that. I was under the impression that the axle side mounting hole can be elongated to make the PHB level without the need to extend the whole bracket. Maybe I'm wrong. But no mater, I don't see the rules as written allowing the axle side mount to be reinforced or triangulated. Now if we think it is a good modification to allow, I'm all for that. I'm thinking of the rule for the rear control arm repair, it is clearly spelled out what you can do to repair that region. I would think something like that would work for this case. Explicitly say you may lengthen (or replace??) the OEM bracket. And that it may be triangulated with some limit on the length of the brace that may be used?

AllZWay
05-20-2011, 11:32 AM
The rules don't say you can so you can't is what I have been told for years. I don't see that bracing even remotely legal ... And don't see the need for it either.

One broken mount doesnt equal epidemic.

Hood
05-20-2011, 10:14 PM
Well... maybe, maybe not. I've welded quite a few street car PHB mounts that were cracked and/or broken back in the day on the third gen cars. These weren't abused in the sense of auto-x or road racing either. So the jury may be out on the epidemic.

GlennCMC70
05-20-2011, 10:56 PM
Mine is not lowered and it was breaking. I can only wonder how much more leverage is there once it gets a longer lever arm.
I've fixed the one on CMC#3 and it too was not extended. I've seen them completely ripped from the housing. I check every 3rd/4th gen I look under now to see if it is failing.
If it makes you feel any better (likely not), I wouldn't allow a OEM PHB mount to be braced.

My personal opinoin - I would be more interested in the allowance of the Fords and the fact that they can install a PHB in ANY position and any hieght off of the ground that will result in a desired rear roll center. Where as the GM's can only make it level. Its overall hieght is dictated by ride hieght (and therefore rear roll center hieght). Not so for the Fords.

michaelmosty
05-21-2011, 11:56 AM
My personal opinoin - I would be more interested in the allowance of the Fords and the fact that they can install a PHB in ANY position and any hieght off of the ground that will result in a desired rear roll center. Where as the GM's can only make it level. Its overall hieght is dictated by ride hieght (and therefore rear roll center hieght). Not so for the Fords.

Your right, the Fords have such a huge advantage over the Camaros. (rolls eyes smiley)
Lower min weight and rear PHB geometry. Grow that list from 2 to double digits and then we can compare.

marshall_mosty
05-21-2011, 05:29 PM
I've fixed the one on CMC#3 and it too was not extended. I've seen them completely ripped from the housing. I check every 3rd/4th gen I look under now to see if it is failing.
If it makes you feel any better (likely not), I wouldn't allow a OEM PHB mount to be braced.
Failing = unsafe... Why would not it be okay to make parts safer... I don't think anyone in their right mind would say that the bracing in the picture was a performance advantage. Just my opinion as a racer...

GlennCMC70
05-21-2011, 06:44 PM
Failing = unsafe... Why would not it be okay to make parts safer... I don't think anyone in their right mind would say that the bracing in the picture was a performance advantage. Just my opinion as a racer...

A LEGAL modification should be allowed to be implimented safely. Read that agian.... a legal modification - that is what the extended PHB mount is.
The OEM unmodified mount generaly only requires re-welding to fix the issue for good.

GlennCMC70
05-21-2011, 07:02 PM
Failing = unsafe... Why would not it be okay to make parts safer... I don't think anyone in their right mind would say that the bracing in the picture was a performance advantage. Just my opinion as a racer...

Also - a Sprint Cup NASCAR chassis is way safer than a legal CMC car. We don't allow that now do we. Obviously the answer lies somewhere between a OEM stock car off the street and the Cup car. CMC is currently where the CMC rules limit us.


The rules have moved so much in just the 6 years I've been involved w/ CMC. If we asked someone who was a Director from back in 1990 if they thought CMC would ever creap this far, the likely answer would be hell no. From my POV, CMC hasn't changed alot. More than I would like, but not by alot. From that 1990 Director's pespective, it has moved a ton. Each year a new CMC Director is added/replaced. Each willing to let CMC creap a little. After 2-4-10 generations CMC could end up where none of us want it. Where none of us ever thought it would go.
The old addage "How do you boil a frog?" comes to mind. Very slowly is the answer. Each generation of Directors is turning up the heat one tick mark at a time. Next thing you know, we got frog soup.
Do you want to be the one who add's that last degree of heat that boils the frog (kill's CMC)?

GlennCMC70
05-21-2011, 07:11 PM
Your right, the Fords have such a huge advantage over the Camaros. (rolls eyes smiley)
Lower min weight and rear PHB geometry. Grow that list from 2 to double digits and then we can compare.

Add two more:
Easier to get well below minimum weight. My car is 2925 at best w/ no fuel and no diver. My quick math tells me your car w/ no fuel, no driver, no cool suit, no ballast is well below 2900. My bet is it is like 2800-2850.
Peak power in the RPM band normally used while racing.

mitchntx
05-21-2011, 07:25 PM
Just my opinion as a racer...

You lost that when you took that first sip of Kool-Aid.

You post an opinion and it's as a director in the eyes of readers regardless of what disclaimer you quantify.

Nature of the beast ...
Your opinion is your opinion and it influences your vote, your rule interpretation, etc.

marshall_mosty
05-21-2011, 09:23 PM
You post an opinion and it's as a director in the eyes of readers regardless of what disclaimer you quantify.
Then I am no longer allowed to have a public opinion since everything is black/white from the director's eyes.... okay, fine.

GlennCMC70
05-21-2011, 09:35 PM
Then I am no longer allowed to have a public opinion since everything is black/white from the director's eyes.... okay, fine.

Don't let Mitch bait you. That is his opinion. Me and him have been round and round over that. My opinion is my opinion and not necessarily my position as a Director.

BlueFirePony
05-21-2011, 10:08 PM
so what'd I miss?

mitchntx
05-22-2011, 12:40 AM
Don't let Mitch bait you. That is his opinion. Me and him have been round and round over that. My opinion is my opinion and not necessarily my position as a Director.

No baiting taking place. It somes with the turf.

How are the common folk supposed to know which hat you have on, especially while posting on the net?

This time Marshall had a disclaimer. Next time he doesn't. So is that him as a director or him as a dude, just forgetting the disclaimer?

GlennCMC70
05-22-2011, 07:05 AM
Perhaps you could ask.

mitchntx
05-22-2011, 07:24 AM
Perhaps you could ask.

OK ... did you say that as a racer or as a director?
This will get old pretty quick.

GlennCMC70
05-22-2011, 07:46 AM
See, you got it. Didn't take long at all.

michaelmosty
05-22-2011, 11:34 AM
Add two more:
Easier to get well below minimum weight. My car is 2925 at best w/ no fuel and no diver. My quick math tells me your car w/ no fuel, no driver, no cool suit, no ballast is well below 2900. My bet is it is like 2800-2850.
Peak power in the RPM band normally used while racing.
Last I checked James was at minimum weight and I think Steve is also. (I know y'all had to add alot of ballast when Patterson drove it in 06).
Regarding power, I'd love to do some calculations for power under the curve and see how the various motors stack up. I know nothing about how to get the numbers but I'm sure some of the Engineer brains in the group could help.

FWIW, I'd love for the cars to be apples to apples. Right now it is apples to oranges of the same size but different flavor.
I'll be the first in line for every car to be 3250 lbs, all same exact track width, and same suspension components. The reality is this would cost way too much time and money for competitors and the end result would still be people thinking the other platform still has an advantage.

The current system isn't perfect but works very well. It is just fun to bitch every now and then.

GlennCMC70
05-22-2011, 06:39 PM
Yes it is.

mitchntx
05-22-2011, 08:10 PM
Yes it is.

As a director or a regular schmoe?

marshall_mosty
05-22-2011, 10:43 PM
No baiting taking place. It somes with the turf.

How are the common folk supposed to know which hat you have on, especially while posting on the net?

This time Marshall had a disclaimer. Next time he doesn't. So is that him as a director or him as a dude, just forgetting the disclaimer?

I will ALWAYS have a disclaimer, if it's not posted as "his royal highness"... Believe me, I've been around for 7 years now and know that some just LOVE to tear people apart for small slip-ups. That's what so wonderful about the internet warrior behind a keyboard. Some come across all tough and weathered, but they are nothing more than a pussy cat in person... :)

**Posted as Marshall "A Dude" Mosty**

marshall_mosty
05-22-2011, 10:45 PM
As a director or a regular schmoe?
I think I prefer "Dude"...

mitchntx
05-23-2011, 06:17 AM
Dud ... got it



Edit:
Dude ... sorry, typo

RichardP
05-23-2011, 07:54 AM
I think I prefer "Dudes"...


This isn't really the place for that... :)



Richard P.