I recently rebuilt a C6 and installed a Fairbanks Transaction Shift Kit Part No.51312. The problem is when I put the truck in drive it is supposed to auto shift 1,2,3,. It just stays in first and never upshifts. I can manually shift it from 1st to 2nd but when I shift it into 3rd manually the transmission acts like I shifted it into neutral. If I come to a stop in drive after manually shifting it there it will take off but still not upshift. Another thing that is odd is when I manually shifted from 1st to 2nd the shift was about as firm as a stock shift and nothing like what is should be from a shift kit. Any help or info would be greatly appreciated. One thing that I thought was odd was the instructions said not to use a gasket between the seperator plate and the transfer plate. Then why did the kit come with a gasket?

 

At this point it seems like you are just dealing with a typical no upshift situation regrardless of the shift kit. Start by checking the basics, start with the modulator because its the easyist. Make sure that it installed correctly ( valve first, pin, modulator ). Check to see if the vacuum line has vacuum at the modulator. Next thing to check is the governor, if the valve(s) are stuck or missassembled it wont shift. (hint) With the governor off you can blow air into the hole in the governor support and make the shift valves in the valve body move. Next would be the valve body, make sure the shift valves are free and assembled correctly.

I feel the trans internals are ok because you have reverse, which is the direct drum and the low reverse clutches, and the forward drum works because it moves forward, and the band is ok because it has manual second.

As far as the valve body gasket, the C6 is one of the few that will work fine without it, they probably tell you to loose it because if you are just installing the shift kit without rebuilding it you have a good chance of tearing it and that will cause problems.

 

I have never had any luck omitting a separator plate gasket and I have built thousands of transmissions.

To me that is like not installing a head gaset.

 

I have tried it without and it currently has it installed. Still no worky.

 

Well, I have just about completely lost my mind. I have taken the VB out again and ran air tests on the VB and the tranny. At first the govenor port on the tranny would not activate the govenor but would blow air out the port next to it. I plugged the other port and got the govenor to start making the whoopy cushion sound. Everything else air checked properly then so I thought I had it solved. Well, as you may have figured the tranny is still doing the same thing and will not auto shift or shift into 3rd manually from 2nd. I have P R N (no 3rd) 2 1. Fluid level is correct, modulator is new and appears to work properly when I pull a vaccum on it with a mighty vac setup. The pin modulator pin is installed. The modulator valve is free moving and positioned correctly. The servo is free moving and appears to make a good seal. Someone please help before I go nuts or break down and spend way too much money.

 

Hey, bud. Your problem seems to be similar to mine. If you're still active, what did you do to solve the issue?

 

Last post November '08, and no light shed on his C6 in that one.

Try posting your entire transmission story and history in a new thread.