Harsh downshifts

[benzonline]

Anyone here expeirence harsh downshifts? No matter at what temp the car is at...downshifts are a bit harsh to my liking...enough to "nudge" my whole body when its shifting down coming to a stop...more harsher when driving slower.

Otherwise tranny is perfect.

[69chevelle]

Yes..when I come to a stop sometimes and with a clunking noise which I thought was the tranny going out. Problem came from a worn flex disc at the front of the tranny. I had it replaced and no more clunking noise.

I dont know about the hard downshift problem u are having. I thought it does that when you drive cold?

[benzonline]

I think its mostly when its cold.

How big of an issue is this?

[kameraguy]

When I recently had this problem, I found my transmission fluid was low. So you might wanna check that too.

But the reason my fluid was low to begin with was due to a slow transmission seal leak. $$$ to fix.

So check and see if this might be the same thing.

Hopefully it is not due to a failing clutch pack. That's even more $$$. I had that problem a long time ago which also caused jerky shifts.

I believe the reason I now have a transmission seal leak is because of the first clutch pack repair. Gotta love out of warranty repairs on the 722.6 transmission :rolleyes:

edit: yes, when I had my problems, they would be more prevalent when the tranny was cold (first operation of the day). After several miles of driving the transmission would work "normally". Once I had teh transmission fluid properly topped off, no more shifting problems. As smooth as butter. Not to say this is the problem you have, but might be something to check.

[davis449]

Then again, if there's no clunking sound and it's just hard shifting here and there and when coming to a complete stop, Merecedes, and German tranny's in general, tend to be like that. What year model do you have? If you have the vacuum controlled tranny (1994-1996), it could be a pressure valve inside it. I had mine adjusted and it fixed my hard shifting problem.

[benzonline]

99 C230K it is.

By the way do you get better mileage if driven in W mode?


Soon I'll get the tranny fluid changed.

[Sulaco]

I read somewhere that if you have your transmission set up to shift smooth and soft that it decreases the lifespan of your engines (causes more wear on the clutch packs). And thus, your tranny should shift a little hard to get more miles out of it.

OR I AM INSANE.

[YYZ]

Generally speaking, that's true.

In order to have velvety-smooth shifts from an auto, the trans must slip the clutch packs or bands (depending on design). More slippage=faster wear.

In colder weather, the engine/trans is programmed to delay upshifts in order to promote faster warmup by putting more load on the engine.

I guess I'm used to it living in the great white north - so far so good on the original trans (fingers crossed) 110,000mi

[jnenad16]

hard downshifts are usually a sign of a defective or failing modulator valve. its the shroom looking part with vacuum line plugged into it on the driver's side of the trans.

nenad

[c55m8o]

jnenad16 knows his stuff. However I hope it's not something serious like that. About 1/2 to 3/4 of a quart of tranni fluid made the difference between my tranni jumping into neutral on hi-G right turns, or getting suck in 2nd @ times ... amazing how slightly low fluid can affect performance lilke that. Worth checking out for this shift issue (if you haven't changed it already).

[benzonline]

now it seems to be ok but does it mostly when cold.

I really dont like MB transmissions...always jerky, nudging, slipping.

[69chevelle]

Yeah.. I hate that delay in the trans shifting when going into reverse.