It's been quite a while since I have posted anything but have been enjoying my MK4 roadster for the past several years and working on some other projects. All was fine until I recently noticed a strange noise in the drivetrain. I guess it would be best described as a "clunking" sound which I first noticed going around a sharp curve in the road but it didn't happen all the time. When I got home, I checked the rear end for any loose bolts and/or nuts but didn't see anything that was obviously wrong.
The next time I took the car out, I pulled out of the garage and was slowly going down the driveway in first when I let off the gas and heard an even louder clunk. I parked the car back in the garage and again looked for any signs of what was wrong. Again, nothing obvious.
This morning I jacked the rear end of the car up with the intention of not stopping until I found out what was wrong. I checked the engine mounts, transmission mount, lower rear control arms and upper arm (3 link setup). I grabbed the driveshaft and gave it a twist to check the u-joints and they looked fine. With the transmission in neutral, I turned the driveshaft to check for any play before the rear tires started turning. Looks to be about 1/8" - 3/16" of play which I don't think is abnormal. The bolts holding the driveshaft to the differential are tight. I then checked the lug nuts on the rear wheels and the ones on the right side could be tighten just a little more. Thinking this might be the problem, I drove the car but the clunking was still there and is now more frequent. Even when I let off the gas/get back on the gas when I shift gears, I can hear the clunking noise which is definitely coming from the rear end drivetrain area.
Really not sure what to check for next. Note that the pre-98 Mustang 8.8 rear end was completely rebuilt with new axles, bearings, seals, 3.31 gears and Ford traction-lok unit. Unfortunately the person who rebuilt the rear end is no longer at the shop where I had it done and he was their "expert". I live in a rural area so its probably at least a 100 mile trip to a competent shop plus I don't like the idea of leaving my car with someone I've never done business with. If I knew for sure it was the differential, I could take it out of the car and just take it for repair.
I guess there is a chance that it's something wrong with the output shaft on the TKO 600 transmission but it was a new unit so my first guess is the differential. I'm thinking it just wasn't put together properly. If the pinion bearing nut wasn't properly torqued would this eventually cause the clunking?
Any ideas, recommendations or suggestions as to how to narrow down the problem?????
As always, thanks for your help and advice.
Ron