Rear-end Binding Issue

[hemifan1]

Hi All,

I was cruising down the highway yesterday afternoon when the car began to feel wierd. It slowed down and felt like the throttle wasn't responding. I pulled over and had the car towed home.
When I got home I took a quick look and realized that something in the rear-end was binding causing a lot of friction (which is what slowed the car down).

I jacked up the rear of the car and spun the wheels. The car has an open diff so when I spun one wheel, the other would spin in reverse and everything felt fine. Then I blocked one wheel so it wouldn't spin and tried again. I could feel something bind when I spun the wheel. I got underneath to take a look and could see the driveshaft U-joint flexing when it would bind. I tried to wriggle the U-joint itself but it seemed fairly tight. When I wriggled the driveshaft it was loose in the diff housing. I'm not sure if this is normal or not but it struck me as not right. When I spun the wheel in reverse however, everything seemed to turn smoothly.

Unfortunately I had to drive home so now the car is 250 miles away from me so I can't investigate further. I need to order parts this week so I can repair it next week and be back on the road in time for the new year so I can get to work.

I looked online and couldn't find U-Joints for E36's, are these replaceable? I'm also looking at getting a LSD for the car in case the diff is the issue. Has anyone had an issue similar to mine? Any ideas what it might be?

Also, where can I find information on what rear-end ratio my car has and what LSD diffs will fit? The car is a 1999 323is 5-speed.

Thanks,
-Matt

[slocar]

Gonna leave the majority of your question to the diff experts, but the 323is uses a 2.93 rear end ... might be a good time to get a 3.15 LSD from a 325i.

[Eric93se]

You might want to raise the rear end off the ground (but do it more securely than usual, not just jack stands, maybe cinder blocks instead with something soft on top) and then start it and put it into drive and slowly run it till you see whats going on.

If your lucky the problem is in the diff.

[hemifan1]

I think the problem is in the diff since the few videos I saw of U-Joint failures had quite a bit of play but the cars still seemed driveable (although with heavy vibrations). The car did not have any vibration in the drivetrain before the issue. It felt like someone was intermittently applying the rear brakes while I was driving.

When I tried to move the U-Joint the input shaft that goes into the diff had play but the cross in the U-joint didn't seem to have any. It seems like the input into the diff is the issue but I have never heard of a failure like that before so it had me confused. Either way, I think I'm going to look at getting a 3.15 LSD and half a driveshaft from a 325 by next week if I can find one. Better to replace everything than not be able to make it to work and have to rent a car for a week.

[Eric93se]

Open the diff, you might see chunks of metal :)