The Stovebolt Site Forums The Shop Area Driveline 3 speed wt Overdrive options for 1960 Chev Truck?

What Overdrive Transmission options are there, which would be a Bolt-In for a 1960 Chevrolet Truck with Three on the Tree? ( I want to keep the Three on the Tree mode, of course).


Did Chevrolet offer a Truck Tranny in this configuration?


And, if so, if looking at one, how would one tell a Truck version from a Passenger Car version?


Phil
Las Vegas

There's the SM318/RH10 and the later SM326/RH12. Either one would work as a virtual bolt in, though the SM326 is a bit longer, and would require shortening the driveshaft. Shift linkage is the same. On the earlier versions, Truck and Passenger are identical other than shift arms, after '58, the Passenger version has a mounting pad on the taillhousing. Either version will work fine. Look to spend about $100-$200 for one.
BTW, I have an SM318/RH10 from a station wagon in mine, running 3.90 gears and 30" tires, I love it. I can run 75 mph at about 2700 rpm without any problems at all.

Thanks Bill!


I do have a mid 1950s Passenger Car OD Trans I bought a couple years ago for it, which will bolt right in, overall length is identical to my present non OD Trans, but, I was not sure if there was any difference for the Truck version for strength or beefyness or anything.

My Truck is actually a 3/4 Ton Step Van, Tires are 7:50-17, and are about 36 Inches tall ( though originally was 15 inch Factory Split Rims and I gave those away, getting instead, early 1950s Firestone aftermarket Heavy Duty 17 Inch Split Rims, this is really great of course, if having to find anyone to fix-a-flat, Lol...). Rear End is 4-11s.


I hope no one will find fault with me, but, my aim is to rebuild an early 1962 production 327, which I got form a neighbor here shortly after i first got the Van, and, put that in...THEN, I could be able to hold my own on the Interstates!

As it is now, the 235, Love it though I do, is great for around Town, is sweet at 45 MPH, feels strained at 50, and, does not put out enough power to dare get onto any Freeway.

These Vans had the option of coming with the 283, so...I figured, close enough. I got some correct late 195os/early 1960s V-Eight Engine Mounts, and the right Cast Iron Bell Housing, a while back, so, the 327 should go in easily, and, be right at home.


Have to invent some Throttle Linkage, or, get lucky, and find some somewhere.

I am a gentle driver anyway, so, should not strain the Trans too much.


Gets about 9 MPG in Town, with the 235...I am thinking, might get 12 or 14 even, with the 327 and a Two Barrel or right four Barrel?

Lol...

You won't have any trouble using that OD trans with a 327 in a 3/4 ton. I had a 66 C-20 with that combination that I drove for 17 years. I Hauled a camper and everything else. I installed a 350 in my 56 3100 10 years ago and it uses the same OD trans with virtually no problems. I recommend using the relay, govenor, & kick down switch as the factory designed it.
Fred

Hi Fred,



Thanks for that info, that is very good to hear.


I was concerned about that, about how the strain in my application would likely be quite a bit worse, than, say, a 283 Sedan application of the latter 1950s.


My Van is open Drive Line of course, so, all is easy to deal with on that score.


At some point, I will need to refer to some literature or other explainations about how all of this hooks up as far as the Manual "T-Handle" in-and-out, the Solenoid and whatever else, how those all work together or would be used.


Is there a simple explaination for all that?


I can understand the manual "In and Out" control, but, the electrical or Solenoid aspect, and how that fits in to highway use, I do not understand.


Is it an automatic over-ride "out"? In case the driver forgets to dis-engauge once slowing down?



Phil
Las Vegas

The manual control (a pto cable works best for this) only operates the freewheeling clutch in the overdrive unit. When pulled out, it locks the clutch as well as locking out the overdrive. In this mode, it operates the same as the standard 3 speed, with full copression braking available. when pushed in, the freewheeling clutch is unlocked, and withough the overdrive engages, allows the vehicle to coast without using the main clutch. There is a drawback, as there is no compression braking when the freewheel is unlocked at speeds under 28 mph.
The solenoid is what actually engages the overdrive, which is basically a 2 speed planetary style transmission. The solenoid locks the sun gear in the planetary gearset, engaging the overdrive ratio. If setup the way the factory did it, it automatically engages at approximatly 28 mph in any gear (2nd over is a great hillclimber gear).
Here's a shop manual section that explains the operation in depth. The page is from the '55 truck manual, but the operation is the same.

Very nice info there LONGBOX55...thank you!

Phil
Las Vegas

Here is a plethora of info. It will tell you all about it. I put one in my '54 GMC and I love it. I used a DPDT toggle switch in place of the pedal switch. With it I don't have to use the cable.

I never disengage the OD, so the cable's primary use is to hold the lever in place. I just let the OD do it's thing. I also have disc brakes so the freewheel part is not an issue. Your 3/4 ton has plenty of brakes also, so it shouldn't be a problem. You have to remember to shift into reverse when you park and or set the brake or the truck could roll down the street on it's own. There are aftermarket KD switches and relay's available. Send me an email and I can give you some P/Ns and sources.
Fred

Lol...appreciate the tip on Parking...I will remember that!

And or, I will dis-engauge the OD prior to rolling to a Stop to park.

What I have presently, is, the Transmission itself with it's Over Drive..and, the 'T-Handle' and it's little mounting Bracket, but, I have to fit a Cable to it.


I do not have a floor Switch, and, have not read up far enough yet to relate that to the whole.

Been doing long days with Work, so, short on time and shy on presence of mind right now for much of anything but eat-n-sleep and a few house chores.

When things lighten up, I should be able to review the Manuals and get a mental Model of how the whole thing goes together.


I need to open the Tranny up and see how things look in there, see if it is rusty or badly worn or whatever.Outside looks alright, but, guy I got it from did not know wnything as for it's condition internally...he had not run it.

Bear with me..!