BrazenStang

So about 6 months ago I was showing off and slapped my car sideways into a curb. I hit hard on the driver's side and had to replace both wheels and get a realignment. Since that day there was a squeaking/rubbing noise that came from the back and the car was just not right. I changed the rear brake pads and rotors and used silicone grease to lube all moving parts and guide pins. The car needed brakes anyways, but I hoped that the silicone lube might clear up any squeaks. The noise still would not go away.

I then learned that I could have a slightly bent rear axle, which seemed weird because I had the car aligned. I jacked up the car and found that the rear driver's side wheel was not spinning true. It was so slight, maybe only 0.005" of runout. So I changed out both rear axles. I inspected the bearings at that time and they were fine. So I greased them up and put everything back together.

After this I had a horrible vibration at highway speeds, and I still had the squeal that I tried to fix! The vibration was only when I let off the gas. When I was on the throttle the car ran smooth. So my mechanic told me that I probably inserted one of the bearings wrong when I put them back in during the axle switch. He also told me to check the U-joints.

On the last attempted repair I changed the rear driver's side caliper bracket and guide pins (I know, I should have done this before the axles). SQUEAL/RUBBING FIXED! WOO HOO! Now I was getting somewhere. Then I slid under the car and pushed up on the axle, THE WHOLE AXLE MOVED. In the rear where the U-joint bolts to the carrier, all 4 bolts had backed out ~1/4". I put Loctite on the threads and tightened them up and the car runs like new!

What a relief! Hopefully some DIYers can learn from this and get to the root cause of the problem faster then it took me. Has anyone ever heard of the driveshaft bolts backing out? I have never done any work on this part of my car. And I don't think I have any enemies who would sabotage my car. lol.

uberstang1

What do you mean when the u joint bolts to the carrier, are you talking about a bearing cap? If the bolts backed out of a bearing cap its amazing lucky that the rear didn't blow up or at the least cause dammage to the gears.

BrazenStang

My terminology may not be correct. The 4 loose bolts were on the rear portion of the driveshaft and they bolt the rear U-joint to a piece that comes out of the differential. I believe this is the end of the pinion gear in the diff. I have never done a gear switch or u-joint work, so I am not familiar with how the whole set-up is held together and what could have been damaged. I did take the whole driveshaft down to make sure that u-joints were not worn or damaged before I loctited the bolts back in place. Everything in the differential was in place and OK. Do you have a link to a diagram of the differential set-up so that I could maybe be a little more specific about the bolts that were coming out?

BrazenStang

I found a diagram. It was the 4 torx head bolts that hold the u-joint flange to the pinion flange. The pinion flange bolt was bolted snug and had not been loosened.

uberstang1

I gotcha now, I thought u were talking about inside the differntial.