AT shudder before gear change - PeachParts Mercedes-Benz Forum

JHZR2 · #1 07-13-2004, 12:28 PM

Hi,

What are the signs of a bad transmission mount?

My symptom: Especially when warm, I notice a shudder or shake just before the trans gets to the point where it will change gears. Once the change begins to occur, all is fine and the actual gear change is fine, clean, quick and smooth. Its just that fraction of a second leading up to the gear change, when there is almost always a noticable shudder. It seems to be more noticable in the 1-2 and 2-3 changes.

Transmission actually performs shifts fine, 100%, although sometimes does an immediate 2-3-4 shift. Fluid stays nice and clean red, changed regularly, allmost entirely highway driving.

Fluid used is quaker state, as they claim to have MB acceptance as a correct Dexron fluid for MB auto transmissions. It has maybe 20k, probably a bit less on it at the current time. Filled to the correct level, nice bright red.

Any ideas?

I just got a case of castrol dexron III as it has been certified and licensed by GM (originators of the Dexron standard) as a dexron III fluid with 100% compatibility as dexron IIE, II and standard dexron fluid for all cars made 1983 or later. The first line on the back of the bottle says its specially formulated to meet the new GM Anti-shudder specifications of Dexron III - Thus my temptation to try it.

But would you think this to be a fluid issue or a mechanical/mounting issue. Hopefully its just a trans mount, but I sure dont knwo how to tell.

Any help would be great.

Thanks,

JMH

dieseldiehard · #2 07-13-2004, 01:31 PM

You possibly have a flex disc about to give out. The driveline bearing support is also worth changing at the same time as it is often a culprit in cases where there is vibration. If either of these items have not been changed then they should be checked, especially the flex discs because if one fails it can (and will) tear up things pretty badly on the bottom side of the car. The rear transmission mount can be checked out at the same time and is possibly involved but I'd place my bets on the front flex disc.
DDH

turbodiesel · #3 07-13-2004, 01:40 PM

Torque converter slipping?

JHZR2 · #4 07-13-2004, 02:23 PM

I had my indy shop check the flex discs just recently, and he said they were fine. i look at them from time to time as well to see that they havent cracked or anything. They appear OK. Might be worth a change anyway though, along with the center bearing.

So long as its not cracked, is it safe to say that I'M ok to drive on it, at least for another month or so? (Ill be taking the car to the dealer for the usual citric acid flush, and could get the other stuff done then - I understand guibos, flex discs and center bearings are kind of tough to do). I dont mind doing preventative or excessive maintenance, but I would just assume get as much life from those parts as I could, and keep from a panic.

If a torque converter was slipping, wouldnt I notice it at other times besides right before a shift? times like when Im really heavy on the throtle, starting to move up a steep incline, etc?

Thanks very much,

JMH