th-400 swap

[PrimerGMC]

Im swapping a long shaft th-400 into my truck, 1976 GMC, it had a th-350 in it but for the higher hp application I've decided on the swap. I've heard the th-400's had an electric kickdown switch but how would that work if I decided not to get the kickdown, just to shift it like a manual valve-body in a sense. Also what about the cross-member, would that be in the same place or would it be moved, and if it had to be moved, would I have to drill holes in the frame or would there be holes there for it already. The driveshaft is a two-piece, I know it has to be shortened, but should I stay with the two-piece or get a custom one-piece?
Thanks for all the help.

 

[eugene68]

electric kickdown?????? are you sure? I thought it was a vacumn kickdown. your crossmember should be o.k. If you have access to a reputable driveline shop, I would just cut it down or check your play in the two-piece driveline, you MIGHT be able to adjust it out that way. I REPEAT, MIGHT. Sometimes there is enough room to move it back, but you don't want it to bind.
anyone else out there have any info?
I think the "kickdowns" function is not just limited to passing gear,it has something to do with all the shift points. I have always read that if it is mis-adjusted it could burn up your tranny faster
I might be mis informed, can any one else shed some light on this?

eugene

 

[oldpickup]

Jason Richardson
1975 K20 BB454
1976 K20 BB454
1980 K30 soon to be BB502


the crossmember schould be good to go. as for the elec. kickdown just get a kickdown switch for your truck with a 400, it mounts down on the gas pedal, run a hotline to it and the trans. and you are good to go. just remember to hook up the vac. modulator or you can burn it up real fast.