[GreshamRoss]

I just picked up a Saginaw 4 speed for my 70' Chevelle and am having a tough time trying to figure out what it came out of and how many grooves are on the input shaft (I believe this is how you determine the gear ratio?)

Here are some #'s I was able to pull off the unit:

GM 4 K 338935
F20
F186
GM6261886(or 8)
352254
R5K02 (stamped on the plate below the cover)

Also, what bellhousing and flywheel should I be looking for?

I have this posted on the Chevelle site but am not getting much help on it. Plus a lot of guys over there bag on Saginaw so I dont think there is much interest. I realize they are not as strong as a muncie, but I am running a mild 350 and the Chevelle will be a cruiser with the occasional romps.

Thanks!

[anglia427]

gm started making saginaw 4 speeds in 1966,they came in 3.11 and2.54 ratios.in 1968 they stopped making 3.11 boxes and were replaced by a 2.85 low gear.by the numbers you posted i think it is a 2.54 but you should put it in low and count how many times the input turns vs one turn of the output shaft.as far as the bellhousing any chevy housing will do the bolt patterns are the same for v8,and small block flywheels(internal balance)it uses coarse spline clutch disc and come in 10/12 or 11 in. clutch.i ran these transmissions in 2 different street cars a 55 chevy and a65 chevelle both were small blocks and they held up fine and i drove them hard.hope this helps paul

[Centerline]

Originally Posted by anglia427

gm started making saginaw 4 speeds in 1966...

Actually I believe they showed up in some Buicks in 1964.

Centerline
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[mmerlinn]

Externally, Saginaw 4-speeds are all essentially the same with a very few variations in the tail housing. They used the standard bolt pattern to the bell which allows them to bolt up to almost any standard bell, with one major caveat - Saginaw used two different bearing retainers differentiated by the diameter.

Basically, the internals are the only major difference and mostly just ratio changes. About half of the 3-speed Saginaw internals are the same as the 4-speed internals of the same ratio.

I see only one groove on your input.

Flywheel, clutch, etc are more dependent on your bell housing and motor than on the transmission.

[GreshamRoss]

Hmmmm...

Well I am bell housing and flywheel hunting so I am not sure what I should be looking for. Not sure on the bearing retainer? I am just learning on these transmissions.

So one groove? I've got some telling me its a 2 groove and I have heard 3 groove, but I am not sure where that one came from. I am trying to get it nailed down as I may attempt a rebuild before putting her in place.

Thanks for the replies and lets keep em' coming. As you can see in one of the pics she is currently in paint prison so I am trying to get it figured out when she brakes out.

So I paid $200 for the tranny and it came with the Hurst Comp plus shifter and ball. Did I do okay? Also, I believe it is a bench seat shifter which is the route I am going.

[regguy1]

Put the trans in first gear / mark the input shaft and output shaft / count the number of turns it takes to make the output go around exactly once /that give you an idea of the ratio in first gear. Low tech but it works

[Truckedup]

Generally speaking the grooves on the clutch shaft tell the ratio story,no groove,2.85 first gear,one groove is 2.54,2 grooves 3.11 and 3 grooves is 3.50.There might be an exception to this on GM replacement clutch gears.Usually the 3.50 gear version has a lump on the bottom of the tailhousing for the Vega type car torque rod .I Believe the 3.11 first gear versions were used in the V6 Vega chassis cars with BOP nameplates.
The strongest is the 2.54 gear ratio due to the "head gear" ratio with the 3.50 being the weakest.

[GreshamRoss]

Originally Posted by Truckedup

Generally speaking the grooves on the clutch shaft tell the ratio story,no groove,2.85 first gear,one groove is 2.54,2 grooves 3.11 and 3 grooves is 3.50.There might be an exception to this on GM replacement clutch gears.Usually the 3.50 gear version has a lump on the bottom of the tailhousing for the Vega type car torque rod .I Believe the 3.11 first gear versions were used in the V6 Vega chassis cars with BOP nameplates.
The strongest is the 2.54 gear ratio due to the "head gear" ratio with the 3.50 being the weakest.

Can you tell how many grooves my has based on the pics? It doesnt appear to be real obvious like it should be. Let me know if additional pics would help.

[tjoy427]

You needn't be concerned about the grooves. Do what the other fellas told you. Put it in first and calculate the way they said. A rebuild on that trans will probably require very few parts. First you have to look inside. Blocker rings,maybe a bearing or two, unless its rusty inside, which I doubt. Good buy for 2 bills. May need a bushing kit for the shifter as they are possibly worn, and that's cheap. It's a decent "crusier" trans if you don't beat on it and that is definitely a bench-seat shifter. I had one in a 55 210, but I beat on mine and broke it. Barnetts 4 speeds has any parts you may need. Make sure your pilot bearing is in good shape or, if there's none present, put one in the crank. I can't remember the number of times guys would bring in their cars that wouldn't shift, or wore out their input bearings, or other crap, and upon removing the trans, oops...no pilot bearing. "I didn't know it needed one" is no excuse. Good luck with it and mainly, try to have fun. Money is tight these days so you do the best you can with what you can afford.