igotav8

I'm definitely no computer person so I don't know how it's done. I do know they do it all the time for other makes of cars and trucks. I would imagine you'd need to map what's happening in the transmission now and adjust the inputs from throttle, vehicle speed etc and Change what happens when in the transmission. Like I said, I'm not sure how it's done but I know it can be done.

mattsimis

What confuses me about that mod is its presented as a fix for Thumping (TC Dropout?) yet the update to it only mentions it fixes Hunting:
https://www.audiworld.com/forums/sho...php?p=23905974


I have thumping in 1st to 2nd at car park crawling speeds and at 40mph when I feather the accelerator. Pretty much solved the rest with TPS changes. Is this VB mod worth trying in this case?

Gr8White

I have a "Technicians Diagnostic Manual" which I have attached below. It provides an overview of our ZF 5HP24A along with the technical specifications; my plan at this point is to verify that the resistance though the MV-4 (TC Clutch Solenoid) is within spec before attempting any additional repairs.

If it is within spec, then I will probably attempt the adjustment suggested by TerminA8r. If not, I will find a replacement and hope for the best.

I am just having a hard time understanding what specifically is wearing out and why turning up the pressure will prevent the TC from locking up; part of the picture is missing. . .

Gr8White

Correction; I meant EDS-4 (TC Clutch Solenoid)

tozoM8

By turning that valve you are not turning the pressure up. You make the TCC lock quicker.

mattsimis

Can we buy new Clutch Solenoids seperately? Also where can we get this Vitron O-Rings in the correct size?

I wouldnt mind giving this a shot too.

tozoM8

You can buy the pressure regulator valves separately. The O-ring is part of the rebuild kit. I guess you can get them from the dealer.

mattsimis

I did this yesterday. The little screw wasnt glued like the guide said, it moved fairly easily with a mini ratchet (in situ). I turned it 90% clockwise.

However I didnt get much improvement, still thumps if left in 5th and feathering at 38-42mph. Maybe a shade less of a slam.

Gr8White

A friend just bought a 98' A8 and I thought that this would be the perfect opportunity to do a little extra testing on my 99' before getting more involved with the hunting/thumping/bumping issue that seems to be so prevalent across the board with the ZF 5HP24A.

One of the guys I spoke with at ZF suggested having the TCM re-flashed by Audi. Before spending my money there, I thought I'd try a TCM swap; this would at least confirm/deny the source of my problem. I'm am ECSTATIC to report that by doing so, the hunting has COMPLETELY disappeared! The only glitch right now seems to occur when coasting from highway speeds; around 1200 RPM's, the torque converter decides to lockup, causing a mild bump as the RPM's raise to match the locked-up transmission speed.

I hope this experience helps some of you out there, who are reading this, with the same problem. For those willing to drive to the central Wisconsin area, I may be willing to let someone with the hunting problem swap TCM's and see if this may be the source of your problems too.

Now, has anyone had a TCM flashed by the dealership? If so, did it fix the problems? I'm debating between spending my money at Audi or on a used TCM. . . .