The Stovebolt Site Forums The Shop Area Engine Shop chevy 3speed w/overdrive

Can anyone tell me the easiest way to wire a 55-57 chevy car 3speed w/overdrive. When going into overdrive do I activate the overdrive solenoid first or the manual kickdown switch? When I am cruising at any speed and let off the accelerator the engine goes back to idle and then when I press down the accelerator the tranny won't kick back in right away. What's up with that? I am using a 235ci+ 3speed w/od+ 3.90 rearend. Is this a good combo? Thanks Joe

Joe, this is the combination I have: '49 3100, '56 235 (.30 over) with "848 head" (the last 3 #'s of the head ID casting indicating a slightly higher compression), '55 3 sp+od, '57 truck 3.90 rear. My former torque tube set-up-as-is when I purchased the truck imploded one day on the way to work, a 3 mile in town commute, so I did the changeover to the open driveline set-up by burning off the old pivot-mounted spring perch assemblies and replacing them with Buffalo spring perches and tube shock mounts for the rear and front (bye-bye knee action shocks). The '57 3.90 rear is from a truck, I pulled the pumpkin from a bone yard and after having it rebuilt by a man who had done "100's of these" with new bearings and crush sleeve, I measured the length of open driveshaft needed and I was good to go. The pumpkin is one of those plug-ins that fit the 10 bolt '49 axle perfectly. The overdrive for '55 is .70, so .7 X 3.9= 2.73; your final drive ratio in overdrive. I now can drive at 65mph @ around 2000rpm's in OD with my 215 85R 16 Michelin TRUCK TIRES,(30" tall). I don't have or seem to need any of that 'kick-down stuff' for the OD, I wired my solenoid to a two pole, push-pull switch in the never used throttle hole, complete with the "T" knob, also a light wired into my on-off switch from radio shack located in the left radio blank out hole to remind me NOT to start out in 1st OD! This is a note to self: NEVER start out in 1st OD, if you've ever been inside this tranny the reason is self evident. I've rebuilt one and am presently rebuilding another so I know of what I speak. I'm still 3-on-the-tree for a strange reason...people always ask me how I can shift from Park to Drive without the letters on the column, they think it's an automatic and many don't know what you're talking about when you say that "...it's a three speed pattern, it's just on it's side." Some would think this is a great combination, just as many are "living in 1949" which is cool but your're wound out with that 4.11 rear at 50, she'll be shouting at you at 55mph. Then there's the other side of the coin for those who desire chirping a little rubber in all four gears...for any of us that want to go that way we have to think about decreasing the weight of rotating mass (Aluminum flywheel, maybe Al driveshaft, lightweight wheels with low profile car tires,etc.) You have to consider a vee ate (misspelling intentional) and so on. I see this is your first post so may I extend a welcome to you from all of us with all kinds of goals for our vehicles. I've got a lot of info on the old od's if you want to contact me, right now my email carrier is all afoul. .....I got ten forward gears and a georgia overdrive, I'm taking little white pills and my eyes are open wide, There's a speed zone ahead allright, I been passin' everything in site, Six days on the road and I'm gonna make it home tonight... Cosmo

Am I understanding you right? The larger electric solenoid on the left side you have wired to a toggle switch and a 12volt power supply. The manual kickdown switch farther back on the same side you do not mess with. Do you leave it activated in the forward or back position? How about the little governor solenoid on the passenger side tranny tail housing? Do you need to do anything with this also? Why is the engine returning to an idle when I let off the accelerator and then not picking back up right away? Will this problem go away once I wire the solenoid? Why do you not want to start off in 1st gear in overdrive?

Uhhh! OK! on that last post! Is he answering someone elses post? Anyway, whole idea of OD is that it freewheels when used and no backpressure from engine for braking. Your engine can idle down. Don't know the recovery time when you reaccelerate, bet there's some gear/operation lag there, shouldn't Bang into drive again tho. I think you can bypass the switches for carb/kickdown and such and use toggles or pushbuttons or something if you don't have all the parts. Not aware of all the tricks, just from what I've read on them here.

Joe, yes that's correct, I only use the solenoid as my ON/OFF, I don't have the kick-down or the governor wired. The switch is Off when the switch is In and the light I have hooked up is Off. The OD is engaged when I pull the switch Out, the light is now On. The manual lock-out that enables the engine to run in overdrive is a friction cable like you find on your choke or throttle cable only I bought a real long one and have it under the dash running out through the engine compartment and then secured to the lock-out on the driver's side of the tranny. This lock-out cable 'IN' enables the engine to run 'freewheeling', without the ability to engine brake. This lock-out cable pulled 'OUT' enables you to use your transmission like any three speed transmission exclusively (no OD capability). I occasionally take a full stacked load of firewood to a friend's in hilly central Virginia; for this occasion I pull the LOCK-OUT CABLE to the Out position so I have constant engine braking for a heavy load. With me so far? O.K.?? Now this is how I drive with my truck using OD which is 90% of the time. The LOCKOUT cable is IN on the dash. I start out in 1st, let off the gas, shift to 2nd, apply gas to normal 2nd gear speed, let off the gas, pull my OD switch ON, apply gas, I am now in 2 OVER (this gear can easily push the truck to 55+mph), I let off the gas, shift into 3rd, I am now in 3rd OVER, with the 3.90 rear I've hit 75-80mph no strain. You can also 'split the gears' and go 1st, 1st od, 2nd, 2nd od, 3rd, 3rd od giving you six forward gears but I tend to use variations. I hope I haven't scared you off, it's really a great little transmission. The idea behind freewheeling and of course overdrive is fuel economy. This transmission is a joke for those of us that prefer an automat*c which in my humble opinion is not a real truck transmission. Joe if you have more questions you can email me privately through the use of the Icon above my name (the two guys shaking hands in front of the letter) so that we don't use valuable board space. Sorry that you weren't able to follow my first post GL, how are you doing on this one?

[ 01-04-2002: Message edited by: Cosmo ]

Cosmo, thanks for the info. I just need to set the tranny up this way now that I know how. If I have more trouble or questions I will contact you, thanks again Joe!

A really helpful site for these OD's is www.classictruckshop.com/club/earlyburbs/ or search on yahoo for Early Suburban Owners Club. Look in the tech section under T85 Tranny. It was really helpful to me.

Cosmo, Yeah, I'm the "dummy" here! Last post was more my level. :rolleyes: A high school buddie had an old V-8 OD in a 63 Chev we rode to school in. It's my only real Driving experience with one, maybe I don't qualify to give advise here on OD's. :p
Hey! I'm from "Huntucky" if you noticed my address!