Hi all,

Been reading through some threads related to clunks when shifting into D or R as well as threads on clunks while in gear and slowing or accelerating. I've troubleshot my vac system pretty well and fixed my transmission shifting issues with the Superior spring kit as well, but I still have not solved this darn thud / clunk issue when shifting from P or N into D or R. Here's some stats:

1987 300D Turbo
245,000 miles

A few Vac Stats
- 20-21" HG from the new vac pump I installed 2 months ago. This reading is after the little plastic filter.

- From the Vac amplifier (aka blue flying saucer), I have 15" going from the VA to the transmission modulator. Modulator cap is intact and was replaced over a year ago as it was torn. On that note, I tapped the line from the VA to the TM and ran a vac gauge to the cabin. At idle, the vac reading was 15". Previously on my old vac pump it was 12" HG. When it's at idle and I shift into D or R, it produces a harsh clunk but the HG doesn't move (which I think is normal).

- When I park on a slight incline and put it into P with my foot on the brake, as soon as i release my foot from the brake, the car will either roll forward or backward. This is the replacement differential I was sold by Enrique at MB Motors, btw.

Regardless, I've had this damn clunk with both vac pumps, but I don't think its a vac issue. My car shifts well, though it does shift a little mushy. As I understand it from Brian Carlton's advice, high HG to the vac modulator produces mushy shifts

I want to run a few things with the group here to see if I may be on the right track to check:

- Is the HG from the vac amp too high? When I moderately floor it, the HG goes from 15" to about 4" before shifting. I haven't floored it yet to see if it goes all the way to 0---should it? I know how to adjust the vac on the VA but I spent alot of time dialing it in to make it smoothly shift, so I'd like to leave this as a last step.

- Would a worn pinion in this replacement differential be a culprit? How to check w/o opening?

- Would a worn flex disc(s) be a culprit?

- Transmission fluid level? I'll check tonight.

Any advice would be greatly appreciated.

Thanks,
Bob