08-23-2004, 06:26 PM
Hey I bought my first MB last year ('85 300cd) and I took it into the shop because the brake caliper needed to be rebuilt but I mentioned to them that the 1st-2nd shift was getting a little too rough. They adjusted the modulator and it started shifting higher and more often jumping to higher RPM's then usual (upto 4500-5000) I drove 250 highway miles and all was fine. thenext titme I drove it though it was slowly started making less and less contact. I'd punch the gas and itcatch at 1900 RPM, shift to 3200 RPM, then again to 4500 without every really providing drive. By the time I parked it you have to gas it to 2500 RPM before the tires moving at all. I towed it home and now it wont drop into any gear except when its really cold( the engine). I'm not sure how proceed except to say that the transmission fluid is in acceptable range.
08-24-2004, 01:26 AM
Here is a good article that might help you:
I am not clear on whether it is just with the 1-2 shifts that you are having trouble with. Could it be that your b-2 piston is going bad? Check this out also:
08-24-2004, 11:22 AM
....And welcome to the forum BTW! :D
08-24-2004, 04:05 PM
hey I appreciate the articles and the suggestion. How does the throttle linkage connect to the transmission? It seems loose now and might explain the lack of connection? the problem I'm now experiencing is a lack of drive. in R,S,L, when the engine is very cold, within 30 secs of startup the car pulls lightly. At all other times the engine simply slips. Theres no movement in the tires until I pass 2500 rpm when the tires begin to turn over. It doesnt seem like a B-2 piston as reverse only works during warm up. Thanks for the time your spending on this.
08-24-2004, 04:34 PM
How many miles on the car?
The throttle linkage connects though a cable called a "pressure control cable" AKA "bowden cable". This is what tells the transmission when you have it floored so that it will stay in the lower gear longer (controls the shift points). Typically when it breaks, the transmission upshifts too soon.
The modulator is a separate device that controls the quality of the shift. You might be able to tighten the shifts with another adjustment (this is on the transmission, driver's side), to the point that the problem goes away, but I am betting that it would only be a temporary fix, if a fix at all.
It is starting to sound like a serious problem. The fact that nothing is happening for you until higher rpms, leads me to suspect a failed torque converter, though other suspects could be the modulator (if you are lucky), the pump, or the clutch pack. In most of those cases, you might as well have it rebuilt. If I recall correctly, my '87 tranny rebuild cost $800. Sorry I don't have any good news for you...
09-16-2004, 08:13 AM
Hello there, I took my car into a indy shop and he said the B2 piston had melted to my core and they couldn't get the b2 piston off. This sounds fishy to me . Have you ever heard of this?
I asked for a written estimate and they wrote down the same price he told me without explination
just new parts $1800
he said I also needed to replace the torque converter and cooling lines
09-16-2004, 09:18 AM
Sounds like you should go with your instinct on this. While I have heard much of the b2 failure, I have not heard of it melting. Just breaking.
The price sounds a bit steep too. You might want to get a second opinion.
09-22-2004, 03:37 PM
Well I replaced the transmission and it appears the new transmission has a b-2 piston failure. At this point I'm going to repair it and my question now is what precautions do I need to take when towing my car. I plan on having all four wheels
09-23-2004, 12:57 PM
all four wheels on the ground and I've heard this can cause transmission problems. Does anybody know anything more about this?
09-23-2004, 09:55 PM
I'm not sure what you mean by towing it with all four wheels on the ground, since tow trucks usually pick it up by the front or rear. I remember my '81 benz being towed by being picked up at the rear and rolling on the front to avoid transmission problems. I guess the fluid pump is driven by the input shaft and extended rolling on the rear without the engine running would burn the bearings. If by "all four wheels on the ground" you mean flat-bed truck, then there is no issue except to be sure that they don't hook the car by the tie rods.
If you mean towing with another car, I would advise against towing for a prolonged period like that, though around the block should be okay.
09-24-2004, 07:29 AM
If you are going to tow it like that, you need to disconnect the driveshaft beforehand.