rear u joint keeps going out

[jw 325ic]

What would cause the rear u joint on the driveshaft to keep going out? I've replaced it like 4 times...I would get one rebuilt but I'm afraid to waste my money if it's something like the diff mount bushing.

So far I have new motor mounts, trans mounts, flex disc, and CSB. They all look fine. Could it be the diff mount? Maybe (hopefully not) rear subframe mounts?

Thanks.

[bloodshot-e30]

do u have the CSB in the right way?

[shiboujin]

How did you replace it 4 times? You replaced the Ujoint or the drive shaft?

Define "Went out"

[jw 325ic]

the csb is on correctly, trust me, i've done this a few times now. i always pre-load it but have tried it without doing so (last year), and same thing happens.

by went out, i mean it starts to shake at 40mph+ and when removing the driveshaft, inspecting the joint. It moves freely...

on one of my other driveshafts, the rear ujoint is starting to tear apart. on my original shaft, it snapped the rear joint.

by replace, i mean i went the junkyard and replaced the whole rear driveshaft with a known good one and on occasion the whole driveshaft.

hope this helps.

[shiboujin]

Never replace just part of a drive shaft. they are balanced as a whole. Did you make sure to align them correctly when you reconnected the whole drive shafts?

IMO you just unbalanced all your drive shaft. Get one, have it balanced, replace the U joint, never worry about it again.

[jw 325ic]

i figured that was probably the case, but wanted to see if a diff bushing or rear subframe mount bush would cause this. If i mix and match the shafts I line up the u joints as a ghetto balance method. But even with complete shafts the rear will go out and the shaft will be lined up with the white dots.

[shiboujin]

you can try your subframe/diff bushings but I doubt it. usually the subframe bushings will manifest as a "clunking" sound on hard accel or burnouts. You can easily inspect the diff bushing.

[scottinAZ]

remember you are still replacing your driveshaft with a used unit. Luck of the draw in getting a good one that will go the distance. Chances are it is just their time to go, and you are teh unlucky SOB who gets to change them out

[jw 325ic]

Yea youre probly right. Guess ill suck it up and pay the $400 and hopefully just have it done for good. Thanks guys.

['e30love']

i agree with what everyone is saying,
they are balanced, thats probably why yours is going out.

[jlevie]

You absolutely cannot mix-n-match driveshaft halves. They must be balanced as a unit. Furthermore, the odds of finding a good drive shaft at a salvage yard are pretty slim. Get a reman from DriveLine Services.

[Wanganstyle]

You absolutely cannot mix-n-match driveshaft halves. They must be balanced as a unit. Furthermore, the odds of finding a good drive shaft at a salvage yard are pretty slim. Get a reman from DriveLine Services.

100%. this is the truth.



drop off one of your bad units for rebuilding? get a local driveline shop to warranty the work?

OR buy a quality reman unit or a NEWER e36M unit? they are a decade newer..... I have not had problems with any E36M driveshaft U joints yet, even when destroying the center bearing via right foot fun.

if you have a ETA G260 with big size guibo the e36m guibo is pnp size, shaft is also pretty much the same length. That is what I will be doing when the e30 longshaft takes a poop, mine seems pretty decent shape though.

[bloodshot-e30]

Never replace just part of a drive shaft. they are balanced as a whole. Did you make sure to align them correctly when you reconnected the whole drive shafts?

IMO you just unbalanced all your drive shaft. Get one, have it balanced, replace the U joint, never worry about it again.

i do it all the time doesnt hurt a thing as long as u put it back the right way. both front and rear have weights and if you line the u joints up there are no vibrations



if the joints KEEP going out theres something else wrong IE not lined up rear diff could be lose subframe bushings could be worn out diff bushing it could be a lot of things. or u just have bad luck with driveshafts lol

[Wanganstyle]

i do it all the time doesnt hurt a thing as long as u put it back the right way. both front and rear have weights and if you line the u joints up there are no vibrations



if the joints KEEP going out theres something else wrong IE not lined up rear diff could be lose subframe bushings could be worn out diff bushing it could be a lot of things. or u just have bad luck with driveshafts lol

Diff will break it's cover if bushing is worn, or fall out of car bc the mounting bolts loose.

If diff k member support bushes dead the pitch may increase to unacceptable angle for driveshaft durability but that would be extreme and probably kill the diff pinion bearing first.

Does your diff have good front bearings?

[Brandon12V]

if you've gone through 4 u-joints, you better check the pinion shaft on your diff.