Has anyone broken a 8.8 IRS? We did...

[Demon]

Started pulling the rear end out to freshen it up/check on it after many hard launches this year (30 or so 1.4 60' times)

Found this:





We have a backup rear end, so we'll switch to that and the aluminum hard bushings, instead of the poly bushing that obviously failed and allowed the diff to break.

[Rayminator]

Interesting breakage.
I would be installing a pinion snubber, or a loop over the top of the housing, anchored at the same mounting points, to keep the ears from flexing.

What makes you think, that solid mounting the ears, would not cause the same damage?

[BeasTT]

And that's why I run the cast iron housings

[Demon]

The shape of the break is exactly the same shape as the break of the poly bushing that's torn, I think it let it give and twist causing it to break where it doesn't have as much surface against the bushing.

[BeasTT]

Gotcha. I'll have to keep an eye on mine, but my bushings are red, so hopefully they're better

[theantirotor]

The shape of the break is exactly the same shape as the break of the poly bushing that's torn, I think it let it give and twist causing it to break where it doesn't have as much surface against the bushing.

The ear breaking could have also caused the bushing to get torn away.

[ablake211]

Iron housing and solid bushings here.

[Rayminator]

"The ear breaking could have also caused the bushing to get torn away".


I just wrote the same exact thing, but my post did not go through.

Yes, it appears that the break may have sheared the bushing, then bent the washer, when the housing raised up.

[Speedfab]

It's the way it was mounted.  The support and structure needs to be ABOVE the nose of the diff, not below it.  A couple of washers on top of the bushings won't f$%king cut it.  Cobras with factory engineered subframes 1000 pounds heavier making twice the power of your car don't have that problem... guess why.

Don't blame the diff housing, it isn't at fault.  If you want a subframe that won't cause that to happen, shoot me a PM.

[largeorangefont]

You may want to make a brace that goes across the top of the 2 front diff mounts for extra support.
That broke because of the poly bushings. Use solid bushings and you will be less likely to have that problem again.

These diff housings as a rule never break in Cobras.
I have an empty Mark VIII/ Cobra aluminium center section if you want it. Shoot me a PM if you are interested.

[mefarri]

It's the way it was mounted.  The support and structure needs to be ABOVE the nose of the diff, not below it.  A couple of washers on top of the bushings won't f$%king cut it.  Cobras with factory engineered subframes 1000 pounds heavier making twice the power of your car don't have that problem... guess why.

Don't blame the diff housing, it isn't at fault.  If you want a subframe that won't cause that to happen, shoot me a PM.

So would Justin's mount be the right way?

[digitalsolo]

That's a negative ghostrider.

[Demon]

It's the way it was mounted.  The support and structure needs to be ABOVE the nose of the diff, not below it.  A couple of washers on top of the bushings won't f$%king cut it.  Cobras with factory engineered subframes 1000 pounds heavier making twice the power of your car don't have that problem... guess why.

Don't blame the diff housing, it isn't at fault.  If you want a subframe that won't cause that to happen, shoot me a PM.

I knew you were good at flipping things over .

I may get in contact with you, thanks!

[theantirotor]

get back to work!

[DeaconBlue]

It's the way it was mounted.  The support and structure needs to be ABOVE the nose of the diff, not below it.  A couple of washers on top of the bushings won't f$%king cut it.  Cobras with factory engineered subframes 1000 pounds heavier making twice the power of your car don't have that problem... guess why.

Don't blame the diff housing, it isn't at fault.  If you want a subframe that won't cause that to happen, shoot me a PM.

Very good point.  Take a look at a photo of a 2003-04 Cobra rear setup out of the car, like here;

http://www.mpsautosalvage.com/sunshop/index.php?l=product_detail&p=2812

Most of the nose weight of the unit maybe carried by the lower mounting bracket, but the twisting motion is controlled by both the lower  and upper brackets, which work in tandum to brace the differential case and share in resisting the twisting motion, during both on and off throttle (acceleration and deceleration) loading.