Hey fellow Buick lovers. I will be starting a conversion on a 3/4 ton chevy 4x4 very soon. Need to do a little homework first though. I can get an adapter plate to mate the Nailhead to the Cheby tranny, but it's over $250. So, I have a 1966 T400 SP from a Riv. that I could use. I would need to get it built. Are all parts easily bought? Also, would the Chevy 4x4 tail shaft bolt up to this old SP? How would I hook up the SP without the original carb. switch? Maybe I need to buy the adapter plate and build the Cheby tranny. What do you think?
John, I think the VP in the 4x4 is a great idea. You'll love the low stall for constant speeds & the high only when you need it. The stock converter should do just fine with a good auxiliary cooler. I'm not sure about the 1966 output housing compatibility, so I can't say one way or the other on that one. If you can make the 4x4 output housing work, might as well stick with the '66 trans as it's modern enough that it has almost everything in common with the later TH 400's. I'd purchase a good rebuild kit & reprogramming kit which will firm up shifts & increase line pressure. I'd also use torrington bearings throughout instead of phenolic thrust washers, and install the good 34 element sprag. Stick in a later filter & pan and you're good to go. As far as actuation goes, use the stock chevy kickdown switch for detent, and wire a momentary switch somewhere in reach for the VP converter. I have my momentary switch at the end of the column shift. Devon
Thanks Devon. I don't have the Chevy drivetrain out yet, so does anyone know if the 66 T400 has the same case as a 1979 T400? Or will the tailshaft not interchange? Devon, explain the momentart switch please. What will be the exact use?
The momentary switch will energize the variable pitch solenoid in the trans. Whenever you have your finger on the switch, you'll be in high-stall mode. Buick originally handled this with a switch on the throttle linkage so that high stall always occurred at 2/3 throttle (or so). I like having control with a switch on the gearshift instead. Here are some various articles you might like: http://www.buickperformance.com/switchpitch.htm http://buickperformance.com/SPTrans.htm http://www.442.com/oldsfaq/oftsp.htm http://www.bdub.net/tranny/SwitchPitch-StreetRodder-5-77-text.pdf http://www.california.com/~eagle/SWITCH.html http://www.bdub.net/tranny/TwoTimer-CarCraft-11-77-text.pdf http://www.webrodder.com/article.php?AID=85&SID=6&PHPSESSID=6166d046a3c6fc2ca75d28a450167fef Devon
switch-pitch or not pooods You may need to change tailshaft and housing as I think they are to long. Use the shorter tailshaft and housing, or does your trans bolt to the tranfer case, in which case you will that tailshaft and housing. Use the SP, you like it, that extra low gears are handy. I had a nailhead in a 66 Chevy pickup, it would shake up the cheby & ford crowd when I put the pedal down. Diver
sw pitch The best trans for such use. You can just put a toggle sw. and then it will have hi stall in all foreards and reverse. [ 6 forward speeds and 2 reverse] :laugh:
