Weird 2-3 shift.

I just got my C6 ready to go so I could test my burnout potential but ran into an issue. I have it up on jackstands and took it through the gears. 1-2 shift is perfect but 2-3 shifts very hard and almost stops the wheels during the shift. The shift linkage is adjusted correctly and its full of fluid.

Not really sure what parts are in it. He told me they put extra clutches, a superior servo and made it a full manual.

It was built by a local guy that has a good rep with the GM guys. I'm going to call him in the morning but am just wondering if anyone has run into something like this.

zrob90sc wrote:I just got my C6 ready to go so I could test my burnout potential but ran into an issue. I have it up on jackstands and took it through the gears. 1-2 shift is perfect but 2-3 shifts very hard and almost stops the wheels during the shift. The shift linkage is adjusted correctly and its full of fluid.

Not really sure what parts are in it. He told me they put extra clutches, a superior servo and made it a full manual.

It was built by a local guy that has a good rep with the GM guys. I'm going to call him in the morning but am just wondering if anyone has run into something like this.

I think the VB is the problem . Check servo and servo spring and make sure it is releasing and the band adjustment. good luck

It's got to be one of the two, because it's basically trans braking the 2-3 shift. I did some searching and it sounds like a few people have had problems with the superior servo return spring.

the servo must move free in the cast and I bet the supieor senvo is a reboxed sonnax and it will need the large piston sealing ring groove cut .007" deeper and find a stock Ford return spring with .136" to .143" wire and use it
Frank

I am using a Superior Super servo in my C6 with great results. The Sonnax and Superior servos are different in design. I asked many questions prior to and after purchasing my Superior servo, and I received great advice from Mr. Merkl. He advised me to re-use my stock "P" servo spring rather than use the one sent with the aftermarket servo, saying the stock spring would give better results since I was using an "A" servo lever. The stock spring was more robust than the one sent from Superior. I wanted a more positive 1-2 and 2-3 shift and along with my B&M Transpak shift kit installed, the shift quality is exactly what I was looking for. 1-2 shift is very good/almost harsh and the 2-3 is less forceful but very "snappy" and it has absolutely no shift flare. I did not have to modify the Superior servo or my C6's servo bore in any way, the Superior servo slides into the servo bore with just a hint of resistance. I researched both the Sonnax and Superior units and found plenty of info stating that the Sonnax had to be modified to work correctly(again, great info from Mr. Merkl), whereas the Superior servo did not seem to have such problems. Sorry for the long post, just giving my experience with the Superior Servo. I hope this helps in some way. Todd

Thanks for the info guys. I talked to the builder, he told me to check the band adjustment and back it off 1/2 turn to see if that helped. It was adjusted correctly and backing it off did help but theres still something wrong. We're gonna to try a different spring in the servo and if that doesn't do it I'm going to take the car to his shop and he'll go through it.

Odd, I've had the exact opposite experience between the two. Mine is an unmodified superior and it doesn't flare but was very tricky to get in the bore the first time I installed it (10 years ago). I've tried to install news seals when refreshing the trans, but end up resorting to the old ones that will fit. Like I said, no performing issues that I can see with this setup. Also refreshed another with the same deal, and like mine, tight fit.
I have also used the sonnax servo in a few other units, with NO trouble installing into the bore. Also work great. I like the idea of turning down the ring groove, just never have.

I wonder if they have changed designs, I purchased/installed mine about a year and a half ago. I remember looking at an older TCI "badged/branded" servo and it looked like the Superior brand(Fairbanks), now the newer TCI servos look like a Sonnax unit .

I think we have it figured out. Sort of a double whammy problem. I went to take the servo piston out to look at the spring and it wouldn't come out of the transmission. Had to wrap it in electrical tape and pull it out with pliers. I took it to my builders shop, he had another case sitting on a bench and without the o-rings on it didn't move freely in the bore and was a pain to get out. He put it in his lathe and took a little off the OD of the piston and it now fits/moves in the bore like it should. Also the spring that came with the servo looks pretty weak, I can almost make it coil bind with one hand. He gave me a stiffer spring. When I get time I'll test it out.

Told you
Frank

Good call Frank Shifts good now.