Killed the differential yesterday

[PbFut]

Well, it held for 126 hours on track but yesterday went out with a bang. Sounds like a cup of gravel was poured into the case. I sent Jonathan Thayer a message through his website. Hopefully he be able to help. I don't recall seeing him post lately but I've not been around much. Hopefully he can come to the rescue. I see he has a polished set of gears I'll for sure need. (2.74)

[Wertles]

He’s around. I think he’s on vacation this week though. Mindy’s gears lasted about 10,000 miles before it needed a rebuild and I believe he’s harder on that car than anyone else can even dream about.

[PbFut]

I blew off the last few hours of work and pulled the subframe. I Loctite the diff to subframe bolts so it is nearly impossible to remove the four bolts unless I drop the subframe. With the subframe out and diff off the culprit was the pinion gear. It shattered. Lots a bits and pieces in the case and one rather large chunk. The ring gear is toast from picking up the shrapnel and running the junk past the remaining parts of the pinion and ring gear. The shutter wheel is bent. I got an idea the slide and bevel gears are messed up as well. Hopefully the modified ramps that metric mechanic did are ok. So it looks to be a complete rebuild and new gears.
Now the next issue. The mount of the diff to the subframe is cracked badly. I now realize that the reinforcement I did attaching a back plate to the cover bolts and tying that plate to the roll cage was probably too stiff. The subframe bushings are D71 Red but even that is too soft and allowed the frame to move. Since the diff was static, the front ears fatigued and have failed. I am thinking I need to use aluminum subframe bushing and reinforce the ears on the subframe where the front bolts to the diff are located. Hopefully that does not move the stress into the chassis mounts at the subframe connection point.
20180219_184001.jpg20180219_184043.jpg20180219_184129.jpg20180219_184146.jpg

[Z-Thrizzle]

I'm using these reinforcement plates for the subframe. They might help with your setup.

https://store.garagistic.com/bmw-per...l-reinforcment

[Schreier]

I'm using these reinforcement plates for the subframe. They might help with your setup.

https://store.garagistic.com/bmw-per...l-reinforcment

I just had those very same reinforcements welded on to my own axle carrier:

28126642_1622141214532687_301101957_o.jpg

I told the welder "I've never seen it break at those points, but I don't want to be the first one to do that." Well, now I've seen it happen! Sorry to hear about your differential and subframe, Pb.

I also ordered some slightly longer bolts to replace the ones meant to attach to the differential through those points. Those Garagistic reinforcements are about 3mm thick. The original bolts are #07119911694, M12 x 1.5 x 25mm. I have these M12 x 1.5 x 30mm replacements, but I haven't done a test fit yet to see if they are too long: https://www.fastenal.com/products/details/11113402

[z3m.casey]

I'm using these reinforcement plates for the subframe. They might help with your setup.

https://store.garagistic.com/bmw-per...l-reinforcment

Ahh interesting, have a buddy that works a shop here in LA that are in works with these people to support them. He told me about them last week and told me to research these and see how people are responding to them.

I'd assume everything work out ok? Might just end up getting them.

Had my first trackday this past sunday, and had a damn BLAST. So now I'd like to reinforce as much as I can, being it has 45k miles and never was "beat on"...till now.

[325bob]

Those bolts are a PITA to start in car, I drilled access holes through the floor above them,now they come out in 1 second each with an impact.