harder shifting after tranny service

[jsmith]

i had posted this before under "transmission shudders". anyway, after my recent tranny service about 800 miles ago, i noticed that the shifts were harder. the 3-4 shift in particular is harsh particularly at lower engine speeds. i would characterize it as a slight shudder. the fluid i used was valvoline semi-synthetic. while i am wary of synthetics and leaks, i decided to give it a try with the thought that the synthetic portion would help "clean out" the tranny. i was planning to drain then refill with dino ATF after 12k or so but i may want to do this sooner if i don't get rid of the shudder. i have checked the fluid level and it is correct. will lowering the pressure on the vacuum modulator help? if so, how much should it be turned?

thanks

[dpetryk]

How many miles on the transmission ??

[jsmith]

the transmission was installed about 20k miles ago. i am assuming it is an MB reman'd unit. it was replaced under warranty by a dealership as the old one was DOA "no forward motion" indicated on the report. i suspect that the new tranny was never set up properly. the car was literally "grandma's ride around town" and i doubt the PO would have complained about anything. i acquired the car almost 2 months ago and have been going through a list of maintenance items. i replaced all the fluids as a matter of course. shift quality was ok prior to the service although i was not happy with shift points (another thread)...

[stevebfl]

Be sure that there is vacuum in the plastic line going to the modulator. Try sucking on the modulator to be sure that has a tight diaphram.

If all is well then I would try adjusting the modulator. I am interpreting your condition to be hard shifting. I get a bit confused because this can actually be the opposite of "shuddering". I describe shuddering as a multiple shift where one gear change appears to be accomplished through multiple steps. For a harsh single shift I would start with a full turn counterclockwise.

If there is a shudder as I described it then you will probably need to make the shift firmer or possibly earlier.

[jsmith]

first, the hard shifting: turns out i don't have to mess with the vacuum modulator, at least for now. by adjusting the bowden cable to make it shift later i seem to have eliminated the problem. the low shift point (~2k rpm) was making the shifts harsh. now the shifts are a lot smoother.

Steve, i will make another thread on shift points as none of the adjustments i made seem to have affected full throttle/kickdown shifting. the shift quality did improve with the bowden adjustments but i am stumped with the max shift point.