Diff Cover Drain

[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.

[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

[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.