Rear axle rebuild/replacement?

[maupineda]

Stumbled upon this while repacking my inner CVs with the gkn boot kit and it is great news that the Porsche CVs Are a direct fit for the inners, but unless anyone has found a solution for the outers I am questioning what the purpose of just replacing one side of the axle is when obviously the outer do develop play over a lifespan And essentially, you’re just rebuilding half of the axle.

Now after doing this job, I was seriously, considering ordering the inners to do at a waiter time, but if there is no way to rebuild the outer joints, I’m having a hard time justifying doing all the work to only improve the axle maybe 50% instead of a full refresh because greasing alone is not a rebuild. It is just a “repack” which obviously does not reduce any play in the joint it just fills it with grease.

Curious, if anyone can try in if they found a solution to date?

Currently axles are almost $1000 each side from BMW for brand new, which at that price you might as well go aftermarket to some upgraded option like driveshaft shop.

It would just makes sense if your inners have play and outers are fine, that saves you from spending 1000 bucks for a new axle shaft when only one side is bad. If the outers are play free you just repack to make them last longer. If you service the shafts let’s say every 50-60k miles I don’t see why you would need to ever change or rebuild them. Issue with the inners is that the exhaust runs close to them degrading the grease and over time that causes them to develop play.

it makes sense to repack only if you have no play, and to rebuild the inners if those are the bad ones but outers are fine.

lucky e46 m3 owners that only the driver side is exposed to hot exhaust, us Z4 owners have that on bot sides.

[bigjae46]

The outer boot can be replaced. It has been awhile and was a greasy nightmare that I have mostly forgotten. I think you have to angle the CV so that you can get one of the ball bearings out and then work your way around. I just remember it being an exercise of frustration trying to handle greased up balls...lol...and getting the CV back together.

Should do the outers but the inner takes a lot more punishment from the exhaust heat.

[CrookedCommie]

The outer boot can be replaced, but to remove the CV you have to remove the outer cap, you can't get the ball bearings out with it on. The outer cap is a crimp fit with an o ring, so you will have to recrimp it and possibly use epoxy to keep it from leaking when reconstructed. Since they don't sell outer CV's, there's no point removing the cap. If you have a pitted outer CV, grab another used OEM axle and rebuild that instead.

Like has been mentioned, it is the inner CV's that become pitted due to heat and old grease, the outers seem pretty robust. Just inspect and repack with new boots, and put in new inner cv's if needed.

[bigjae46]

The outer boot can be replaced, but to remove the CV you have to remove the outer cap, you can't get the ball bearings out with it on. The outer cap is a crimp fit with an o ring, so you will have to recrimp it and possibly use epoxy to keep it from leaking when reconstructed. Since they don't sell outer CV's, there's no point removing the cap. If you have a pitted outer CV, grab another used OEM axle and rebuild that instead.

Like has been mentioned, it is the inner CV's that become pitted due to heat and old grease, the outers seem pretty robust. Just inspect and repack with new boots and put in new inner cv's if needed.

Did I end up removing the inner and then slide the outer boot over the axle? Crap, I can't recall probably because it was such a shit show...

That might be the case because I didn't want to damage the trigger ring for the wheel speed sensor. I just changed the rear wheel speed sensors yesterday and the trigger rings were goldish/silver which kind of makes the think I replaced them? I can't remember...lol

[Bmulkern325i]

I do not have a 3D printer, but more interested in getting one lately. What type/shape of tool are you imagining?

I wish these were still available, even had orings..

For the love of god someone please make these. Thank you CrookedCommie for the write up. Couldn't have done it without your helpful guide. What a pita....

[CrookedCommie]

For the love of god someone please make these. Thank you CrookedCommie for the write up. Couldn't have done it without your helpful guide. What a pita....

Glad it helped.

I ran the rebuilt axles for a DE event. They did spit out some of the extra grease, talking with my endurance racing buddies, that maybe normal. Next time I do this I think I may try and weight the amount of grease going in so as not to overpack, if memory is right it's 80 grams per CV. I would also reuse the old BMW grease caps, as they seem tighter than the GKN ones that came with the CV kit. I also had the inner CV to diff flange bolts loosen up, BMW has those spec'ed at 56 ft lbs, I tightened them up to 80 ft lbs. I reused those bolts as a set of new ones are $$$.

Regarding that outer Turner kit, this forum member works at ECS and found that they still have the prints for them, but haven't gotten an update yet. Maybe worth reaching out to them again.

https://nam3forum.com/forums/forum/classifieds/members-parts-for-sale-wtb/e46/360628-wtb-turner-outer-cv-rebuild-kit?p=361999#post361999