The Stovebolt Site Forums The Shop Area Engine Shop Need 3 spd OD help

I would like to install a fully synchronized 3 speed w/OD to my '55 235 engine. I have read through the archives both here and at Inliners and gather that this can be done. Is it correct that 1966 thru 1968 there were 3 speed w/OD that had 1st gear synchronized that will fit the 235 with little modification of the original linkage? If so, how do I identify which ones will work and what vehicles they were in? Any suggestions what to use or not use?

thanksforthehelp,

Nick

68 and newer are the all syncro saginaw 3 spd, some had OD, and case-wise they're much the same as the 55-68 3 spd, but they won't be easy to find

Bill

Thanks for the info Bill. Do you know what vehicles originally came with the all syncro saginaw 3 spd that may have the OD option so I know what donor to start looking for?

Nick

the one you want will be from a Chev truck, 68 to about 1980 I think

Bill

Nick here is the answer to you ID question. The Borg/Worner will have a number on the tail shaft that is R10H-1A this one has the non-syncro. first gear. The one you are serching for is the Saginaw which has the tail shaft # R10Q-1A. The Saginaw will have a tailshaft with a 27 splines while the Borg/Worner has a 16 splined shaft.
Hope this helps and good luck in your search.

Nick another tought is to take a 3speed Saginaw OD trans and remove the tail shaft and it will work on a 4 speed Saginaw trans as they both used the same main shaft. Then you would have a 4 speed OD unit. This is an easy mod.
Just some more info to chew on.

The syncronized trans was an option, could probably find one in any GM car/truck. 1966 and later had the syncro trans, you just have to look. Like fat fenders said the numbers are stamped on the tailshaft housing, there is also a govenor( small round thing) on the passenger side rear tailhousing, and a rather large solenoid(large round thing about 4 inches long) on the right side of tail housing.The shifter arms of the two transmissions are completely different so you will have to get creative to use the original column shifter. Now if you find a non syncronized overdrive trans it will be a bolt in. good luck.

I have a 3spd w/OD behind a 235 in my '62 Belair (all original except some body parts). Unfortunately, I haven't had it on the road yet. I do have the owners manual that explains how to use the OD. The 3spd in the '62 Impala I drove for years never had a problem going into 1st. No double clutching, just had to slow down under 20mph. I used to go to a lot of car shows and I have only seen the OD trans in Belairs (don't know about trucks), not any other trim levels from '57 to '62.
I'll go out later & see what numbers are on my tranny. Right now I need sleep.

I put an o.d. trans in my '54 3100 pickup and it worked great with the stock 235. My highway cruise speed went from 50 to 70 with 2200 RPM. This is the easiest, best method for cruise speed increase. My mileage on highway was always over 24 mpg. Automatic kickdown feature makes for a great passing gear and 70 m.p.h. was easy 2nd o.d. speed. I have had both the synchro and non-synchro versions, the later model is much better you can downshift to low gear without stopping. You will love driving with the o.d. trans. I have had them in 5 or 6 vehicles including a 1973 one ton van with a V-8 engine, mileage and driveability were great.

I finally got under my '62 to check the numbers. They are : R10K-1. I would like to have OD in my trucks, but they all have SM420's. Way too expensive to mess with. Good luck.

Thanks to everyone for the information. This forum has been very valuable over the years in helping build my truck. I wish we could all meet for some bar-b-que, a beer, and a lot of show and tell.

thanks,

Nick

What about the GM new process OD transmission that was used later in the 1980s would that be better then the older one.?

And more easy to find parts for.?