(See pics!)

Hey guys, new here. Picked up a 150k mile 01 1500 4wd and it drives great. Trans was rebuilt by reputable local trans shop about 5yrs/7k miles ago and drives very good.

Received my new to me corvette servo today hoping to tidy up the shifts a bit more and attempt to address a hard to downshift issue (have to really burry foot into accelerator to get it to drop a gear or two when merging onto highway or passing) and hopefully add some life to the trans but ended up finding a corvette servo has already been installed ! Waste of $50….

installed new Vette servo w/ much healthier looking seals etc anyway, exactly how it is supposed to be installed however, ran into some strange issues …

shifts much more precise and quicker 1-3 however I was having an issue with it holding 3rd that I actually liked.. as it would normally almost always downshift into 4/overdrive too early… at least I thought. Although day 2 and 3 I started noticing shifting issues where it felt like it wouldn’t shift into 4 until 3krpm accelerating onto highway.. and feeling like the converter wasn’t fully engaged in OD on the highway. Gave me a feeling of slipping.. backed off and got to town, noticed somewhat harsher part throttle 2-3… and hunting for gears…


pulled servo slowly and everything was as it was supposed to be…. Lined up and installed perfect…. I began to investigate the original Vette servo and noticed drilled slots in the 2nd apply piston… opened it up and found 3 springs.. ranging from large medium & small. One appeared to possibly be white at one point in time. Also noticed a different 3-4 spring. It’s a shorter but stiffer 3-4 spring where the washer and C-clip attach, can also be seen in pics. The new Corvette servo was claiming to be a “Peformance” upgraded version with a new “spring” and seals as well as a new pin and completely assembled/drop in ready.

can anyone help me identify this modified servo and maybe enlighten me as to why it has been modified this way ?? Could it be a shift kit or maybe a name brand rebuild kit ?

planning on installing a Sonnax billet 2nd and 4th and so I’d like to potentially understand my trans a little bit better.

New Corvette servo left / modified corvette servo that came w/truck on the right

 

Grinding those slots is a common modification. Changes the degree to which the servo acts as an accumulator for shifts into and out of 3rd gear, therefore the timing of those shifts (clunking from too much overlap for example). Works together with certain combos of other mods esp to the 2-3 shift valve.