Help: rear clunk on acceleration
So I just recently finished a full suspension rebuild: Meyle hd control arm kit up front and replaced all bushings in the rear with poly ones, 034 rear adjustable control arms, and added rear aluminum subframe mounts. All bushings/subframe mounts in the rear were removed and pressed by a machine shop and install was done by a friend (former VW tech) and myself helping with what I could. To add, prior to all of this I had already replaced all sway bars and linkage, engine mounts, trans mount, and rear diff mount and carrier. Most of it was 034 parts. Car drove fine other than the suspension was beat up and the car could never be 100% perfectly aligned bc of the beaten up suspension system. Have been running. E85 stage 1+ motoza time and beating on it fairly regularly with no drivetrain issues.
In order to do the install we found it easiest to remove the whole rear end (subframe, diff, control arms, axels, etc) and then rebuild before putting back into the car. I even took the time to use some heavy duty rust proof paint after a good cleaning with a wire brush drill attachment. Upon closer inspection my rear diff was confirmed to have been leaky primarily on one side. Can?t remember which I?d have to look at a diagram to better say. Considering that I am going to be doing a BT build and 01E swap in the next 6 months we opted to leave it as is. Kicking myself for not servicing it/replacing while out but recently i installed 034 rear diff and trans mounts and have really been thrashing on the car with no issues. So I decided it was an added expense that I would avoid.
Flash forward to today. Had the car towed to get a proper alignment. Also had the shop torque any suspension related bolts after the car had a chance to rest on its own weight for a little and double check our work. I work late and the shop took payment and locked keys in the car and I came by and pick it up with a spare. Immediately, I noticed upon releasing the clutch to reverse and then drive forward that there was a clunk in the rear. Seemed to be towards the center of the rear end and was only noticeable whenever I would shift gears or add throttle after behind off throttle. Moreso noticeable at lower speeds. It feels as if something back in the rear has a bit of play and because of it there is this thud/clunk upon connection.
On the plus side, suspension feels great and solved a lot of issues with that. Minnesota car for most of its life so things were pretty rough when it came time to break apart bolts etc. My point being, this problem seemed to be directly connected to the drivetrain and not from a control arm, strut, etc. Somewhere from the driveshaft back. Now I?m going to go ahead and assume the rear diff is the culprit, but I know there are various other connection points that could possibly be the source of the problem. I plan on getting the car up on jack stands here very soon, most likely with the intentions of replacing this rear diff (facepalm).
Has anyone else on here dealt with similar issues? If so, what areas did you check and what was the cause in the end? Looking to get some ideas before I tear into it again. Would like to have a plan, maybe even a few suggestions of where to look before I start unbolting the driveshaft and removing the diff. Any tests of methods to diagnose would be appreciated. I hope this description helps. I will do my best to stay aware of posts so feel free to ask questions for clarification.
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