Technical saginaw 4 spd w od

Anyone here ever heard of a 4 spd Saginaw w overdrive, apparently the od is on the tail so it changes all 4 gears and I suppose reverse as well.

 

Google "how to get gone" hot rod deluxe mag article with the basics one needs to know to build one. Garage Motorsports guys are great to deal with to if you need any parts or advice. I built one a few years ago. Flux

 

That's the baby! So will the trans still have the same strength as the original sag 4 spd. And what would the percentage of overdrive be ? I suppose the speedo still comes of the tailshaft . Guess I'll google "How to get gone"

 

http://www.hotrod.com/articles/get-gone-grassroots-overdrive/

 

I see the article was written by my brother. Can't help wondering if it was prompted by the day we rebuilt his Muncie 4 speed on my pool table, his first time inside a manual tranny...

 

You use the tail housing from a Saginaw 3 speed overdrive on a Saginaw 4 speed. The hardest part to me would be the shifter. You gotta avoid the big solenoid. Ive got the parts to make one. But Im really not interested in fuel economy.

 

The overdrive unit will be the new 'weak link' in the finished trans. The R10 will only take light beating. IIRC, Advance Adaptors used to make kits to put the heavier-duty R11 unit behind T10s, Muncies, and Ford toploaders but I haven't seen one in years....

 

I take it that this OD 4 speed conversion will still "freewheel" while in overdrive. Years ago I had a '55 Chevy pickup with the stock 3 speed OD and the "freewheel" feature was always a little unnerving, not having the engine to help slow down.

 

There will not be over drive in reverse there is a rod that takes the unit out of overdrive in in reverse. If not taken out of reverse you will not have reverse the over running clutch that lets it coast in overdrive will not transmit power when turning the opposite direction.

 

Tell your brother many, many thanks for sharing that article ! Flux

 

This is interesting but I imagine the parts would be getting harder to find. Do you shift the overdrive while driving like when driving a 2 speed truck rear end? Or does one start out and stay in either 1:1 or OD? Or can you get 8 forward gears while driving?


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Seems to me , this is an interesting option if you don't drag race.

 

^^ There are many ways to drive it, but mostly depends on how you wire the electronics. Originally the OD could be used from a stop or not, drivers choice. If in OD from a stop, you don't need to use the clutch to shift. The OD is 0.7 : 1 as I recall. Great set up if you like lower gears for the axle.




I had a Muncie four speed in the car before the swap. The crossmember and shifter locations did not change, but...... Only with careful measurement was I able to keep the shifter location. And fabing the mount and shifter was the most difficult part.

I placed the relays behind the right side kick panel. I used a DPDT relay instead of the kickdown switch.

 

You don't 'manually' shift these; the lever on the tailshaft is the mechanical 'enable/disable' OD control, the actual shifting in/out of OD when 'enabled' is done by the large solenoid on the tailshaft housing (and this is controlled by a speed governor on the other side of the housing, not seen in this pic). The governor will allow shifting into OD once you're over about 27 mph, and will automatically shift out of OD while coasting once speed drops below about 23 mph. All OD shifts either in or out of OD MUST be done while the trans is 'unloaded'; either coasting or with power into the trans interrupted. You can install a toggle switch control on the solenoid to 'split' shifts but the gear spread usually ends up so close that there's little point.

 

You can do that, but it's hard on the OD. Eventually the OD will fail. Been there, done that....

 

At least around here the o/d parts are getting like gold, even the old crashboxes. IF you see them they're around $400+ for a unknown condition trans. I have a later 60's 3spd o/d in my panel truck and a late 50's one in the shed (going into my Elco).

 

Well said sir ..... Flux

 

Here's some ideas for shifter mounting. The linkage & fitting it all under our 53 car floor was a bear. I used a hurst comp plus. As one can see I'm not worried about HP capabilities with a 235 mill. I used a 2 ring input to keep rpm's buzzing to meet the best interest of the 235s needs. On another note I've a R11 unit that a local "old" car minded" retired toolist ..... he doesn't like being called a machinist, is going to make me adapter to mount the R11 to a TH400 for an OT car. I know they make all kinds of store bought "brownie" units but I never seem to take the easy path. Plus it's time to use some of this stuff lying around while I'm able. Flux

 

At one time, I was collecting parts for the Saginaw 3 speed with overdrive, to the Saginaw 4 speed with overdrive conversion. I had TWO of the Saginaw 3 speeds with overdrive (hard to find one and I had TWO), and a single Saginaw 4 speed (I don't remember which ratio it was). Like many things, I lost interest, and sold the stuff to fellow
HAMBERS; one was to a Canadian, B.C. Torchmen member, the other to Shaggy. Have't seen either of them post in quite some time. I still have an old Muncie 3 speed with overdrive, the 319 transmission, and a NOS Hurst shifter and kit for that transmission. I guess I should have hung onto the Saginaw's, since I stuck a 4.88 Positaction third member into the Sedan Delivery, and the old Muncie would never stand a chance, not that the Saginaw's may have. Since shifters for these transmissions are near impossible to come by, I thought it would be fairly easy to use the 4 speed shifter from a Chevrolet Monza, the H-body style, not the Corvair, that mounts to the floor instead of to the transmission. Even those are hard to find anymore. Some of the other GM 3 and 4 speed cars came with a floor shifter that mounted to the cross member; those could also probably be adapted. Does anyone know much about the Corvette, 4+3, Borg-Warner 4-speed with overdrive transmissions? The overdrive is sort of an "automatic" transmission attached to a manual 4 speed? I believe the shifter for that transmission also bolts to the floor, and not the transmission. Could probably use one of those shifters also. Good job 57 Heap; how's that overdrive setup holding up? I am Butch/56sedandelivery.

 

For ones wanting an OD like this it could cost as much as a decent T5 for a person who doesn't have parts in hand or an undiscovered vintage junkyard nearby. Neat ingenuity tho for sure. Although I wanted a manual, you can sure pick up an auto OD a lot cheaper. Decisions decisions.....


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^^ You got that right! A quick eBay search shows three speed OD's for $400 and up.

I was lucky to get my three speed OD for $35. The four speed and rebuild kit was another $200. Then the time to create a shifter so that I would not have to cut up my floor. I have to say I'm very happy with the results. I don't use the OD unless I'm on the highway at 55 plus, but it does save the engine.