3 Speed GM overdrive Auto?

[Hot Rod Todd]

I was wondering if it would be possible to build a three speed GM box with an overdrive ratio for the top gear.

As in 1.76 (glide for first) 1:0 for second (glide for second) and say 0.7 (700R4 for top gear) and put it in a T350 case

Can it be done, or if not, why cant it be done?

Just thinking outside the square down here

 

[RPM]

You could use a Powerglide, then couple a Gear Vendor OD unit to it. That would do what you want, but it will be a long unit and I don't see how you could get it in a bucket. .

http://www.gearvendors.com/hrgm3s.html

 

[Screaming Metal]

Yep, might as well go with 700R6 or any auto 3 speed w/Overdrive built in. I've seen what your wanting to do in a older Lenco....

 

[Screaming Metal]

On this one, you replace the tailshaft housing with a adapter, then the actual OD unit. Part #3DG101A . This one is actually 3" longer than a stock powerglide installed!!!! You can get really short powerglides.....was working on a corvair recently that had one......was doing research. It was a mid engined conversion.....

 

[Hot Rod Todd]

Thanks guys,

As Ron said, theres not room for a Gear Vendors overdrive in most buckets. Whats a 700R6? I dont think we saw them down this part of the world. We only get the basic stuff down here

 

[RPM]

Thanks guys,

As Ron said, theres not room for a Gear Vendors overdrive in most buckets. Whats a 700R6? I dont think we saw them down this part of the world. We only get the basic stuff down here

I am betting he meant 700r4

 

[Screaming Metal]

I am betting he meant 700r4

Hahaha.... Thanks Ron! Yes, 700r4! Sorry guys....typo..... As you can see, you can run a OD with your PG but she's expensive!. A good kit though, very well built!
Another option, if you were wanting the challange.....a 2 speed rearend! Ha! Now that would be a conversation piece.....see a old style 'dog button' on the shifter..... You have to back off the throttle all the way to keep from grinding her on the shift from low to high!
That way you could have a turbo 350 in there with a 2 ranges in the rear....hee,hee.
In my younger days, back before rock crawling became super popular, in a 4WD F259 longbed, I mounted 2 4-speed transmissions one right behind each other with the rear having the transfer case. You had a possibility of 16 diff. combos.....but she was hell to shift. In Low range in 1st + 1st.....talk about slooooooooooowww though.....

 

[RPM]

In my younger days, back before rock crawling became super popular, in a 4WD F259 longbed, I mounted 2 4-speed transmissions one right behind each other with the rear having the transfer case. You had a possibility of 16 diff. combos.....but she was hell to shift. In Low range in 1st + 1st.....talk about slooooooooooowww though.....

With gearing like that you could have plowed the back 40 with no problems.

 

[Hotrod46]

Another option, if you were wanting the challange.....a 2 speed rearend! Ha! Now that would be a conversation piece.....see a old style 'dog button' on the shifter..... You have to back off the throttle all the way to keep from grinding her on the shift from low to high!

Ah, the old 2 speed axle! That brings back memories. We had an old International ton and a half wench truck with a 5 speed and a 2 speed axle. By split shifting, you could get 10 forwards. Pretty cool if you like shifting. I've never seen one smaller than 1 1/2 - 2 ton truck size, other than the old Columbia Overdrive unit that was installed in some old Fords. Anyone ever see a car size 2 speed?

Mike

 

[RPM]

You all help me here. Wasn't there a 3 speed manual that had an OD in the tail section with an electric solenoid? Maybe that could be adapted to the auto trans. I know we had a problem with diesel trucks and the gear vendors, of not having enough RPM at lower speed for the tranny pump to have high enough pressure. That was double overdrive.

 

[T-Test]

I think Ford used those electric o/d in some Fairlanes back in the 60s, but also think they wre for manual trans. only. CRS

 

[Screaming Metal]

Ah, the old 2 speed axle! That brings back memories. We had an old International ton and a half wench truck with a 5 speed and a 2 speed axle. By split shifting, you could get 10 forwards. Pretty cool if you like shifting. I've never seen one smaller than 1 1/2 - 2 ton truck size, other than the old Columbia Overdrive unit that was installed in some old Fords. Anyone ever see a car size 2 speed? Mike

I saw one put in a Roadster pickup, had the flathead V8, had custom axles made to run 5 lug....really cool. He could put around a park really slow, or if he was going down really rough roads....
Then I saw one about 4 years ago at a ratrod show in Ca., there was this old 46 dually, had it lowered, all flatblack, had the 2 speed rearand had a powerstrokeV8 with auto in it. Even air.....was really cool. Even had the 1946 wrecker bed on it and all. Sounded mean!

 

[Screaming Metal]

Yea Ron I remember what your talking about. Had a setup on it like the Jeep axles have that go from 2wd to 4wd.....but this gizmo was on the tailshaft with a lever behind that solenoid. The tailshaft housing wasn't skinny either.....looked like it had a drum gear in it.

 

[Hotrod46]

Wasn't there a 3 speed manual that had an OD in the tail section with an electric solenoid?

Ron, those were made by Borg Warner. I'm pretty sure just about all the American car companies used the same basic overdrive unit and adapted it to their transmissions. The coolest setup I ever read about with that OD unit was to install a Saginaw 3 spd OD unit onto a Saginaw 4 speed trans. The Saginaw's shared the same case (3 and 4 speeds), so it was a fairly simple swap. I have the right 3 spd OD trans. If I run across a fairly cheap 4 spd, I think I'll try it.

Mike

 

[Don'tCallMeJimmie]

Getting into the original question - guys correct me if I am wrong here.

The only way you're going to see overdrive with an old-school 3-speed auto is with an external 2-speed or more device of some kind. When in 3rd, the trans is in direct drive, there are no gears involved so the trans ratio can't be modified from 1:1...

Back to your overdrive discussions, folks.

 

[Hotrod46]

The only way you're going to see overdrive with an old-school 3-speed auto is with an external 2-speed or more device of some kind.

Yep. You're correct.

 

[vand]

It seems to me that the Mercury Couger Eliminator came with a 2 speed rear axle in the late 60's or early 70's.

 

[RPM]

It seems to me that the Mercury Couger Eliminator came with a 2 speed rear axle in the late 60's or early 70's.

That was called a Hone O Drive. Here is a link to some info on it. I think Motion used it on some of their cars.
http://www.stangerssite.com/honeodrive.html

 

[Screaming Metal]

That is COOL! Start making one Ron! The way fuel will be going, we'll need those!