AirCooledRules

It seems like i post alot of threads about parts failures.

Anyways, i picked my car up from the shop on friday night with the new 2bennet coilovers installed and new rear ball joints, tie rods, CV boot, Brake lines, allignment. The car now drives amazing.

Yesterday however i was driving on the highway doing about 70, and my rear Diff light flickered for a moment on the display and all of a sudden the car wouldnt drive, it was as if it was in neutral, i shifted into neutral and back into 5th while coasting and again, revs climb but i wasnt getting anywhere.

All the while i rear a knocking comming from the rear end. so i rolled as far as i could on the shoulder right by the highway offramp. I got out and looked around but couldnt see any obvious damamge so i climbed back in and tried to drive, but nothing.

So i locked both diffs and limped it the 1 block to the gas station and towed her home.

Now if its the diff, which it most likely is, does anyone have an idea as to why it would have failed all of a sudden so quickly like that ?

Also am i better off rebuilding it to stock specs or is there a better option out there ?

Are they the same as a 4kq rear diff ?

Thanks for any imput.

p.s. i just mounted my new 16x10" bbs wheels a few weeks ago and have only done a few days worth of driving on them, could the big wheels contributed to the failure in any way ?

racingiron

I'd suspect anything touched during the recent work. Did they forget to tighten an axle nut or inner CV to flange? Did one of the CVs disintegrate? Don't forget to check the center shaft u-joint and CVs. If it is the diff, it's different from the 4kq (different final drive ratio), but you can use the 4kq piece if you swap the tranny too.

As for the wheels, I doubt they caused the problem. You don't make a habit of driving with the rear diff locked on dry pavement, do you?

AirCooledRules

No i never drive with the diff locked. also, the only CV that was replced was the left outer boot, so i dont believe anyone was in there.

I looked at the shaft and i dont think its the U-joint, however i will have a better look once i can completely crawl under there.

So what are my options as far as repiar if its the diff. Expensive to rebuild ?

I will probably do this one on my own, pull it, send it out and reinstall.

What does a diff rebuild ussually cost?

urcarlos

I'd just put the car in high gear with someone on the brakes of course and check under to see where it stops turning from before checking anything else.

urq20vt

Parts are NLA for the rear diff, so if that is your problem, replacement is about your only option. Unfortunately, the ur quattro rear diff is unique in having that case with 3.89 final drive ratio. Like Eric said, if you use a diff from a 4kq, you would have to also use a 4kq (or '91 200q) transmission as they have 4.11 final drive ratios. Look hard for an ur quattro rear diff if you need one.

Diff failures are VERY uncommon, so let's just hope that isn't your problem here.

AirCooledRules

I was also told Rear tie rods and Rear ball joints were NLA but i got both installed last week. I think it can be rebuilt if need be.

Ill know later today what the problem is.

gmbchef

Seems like it may be the CV joint on the rear of the driveshaft. Like Carlos said, get it off the ground, put it in gear, turn the wheels by hand, maybe even crank the motor over and inspect the driveshaft CV joints.

Katman

I'd go for a broken CV joint (any one of them) causing the problem.

Counting the CV joints at each end of each driveshaft, gets 10 CV joints in the car.

If any one of them breaks (doesn't pass power), then the car won't move unless the diff locks are on.

If you go back to unlocking the diffs, and get your 'no go' situation back, someone looking underneath 9with the brakes on) should easily be able to figure out what IS mvng, and that'll solve where your problem is.

Dropped the transmission to replace the clutch on the 4kq.

Got it all together, but car wouldn't move. Put the diff locks on, and could drive around the block (but with a funny noise).

Got back to the shop, turned off teh diff locks, and tried driving. still no go, so my buddy looked underneath and could see one of the front driveshafts turning, but no car movement.

Seems one of the front outer CV joints cam apart when the driveshaft was hanging loose, when the transmission was out. But didn't see it, because the loose end of the driveshaft was hidden inside the boot.

That won't happen on a urq because the driveshafts are held in with clips, but a CV joint still could fail..

AirCooledRules

Thanks for the imput guys, im already back on the road as of today. The left rear inner cv fell out. It was not torqued tight enough the previous day at the shop and some of the bolts backed off and it tore off.

I dropped it at the shop this morning and picked it up tonight.