Help- 71 granny 4 speed to saginaw 4 speed
 

What would I have to do to go from the stock 4 speed (with granny low) to a saginaw 4 speed in a 71 truck. Would saginaw bolt up to the bell housing?

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

I think you would need a pass car bell housing due to the pilot hole size

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Thanks for the reply, I'll check into that. I got the trans for cheap and I'm wondering if it's worth the trouble.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

There is a spacer ring available to use to make the holes match.
george

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Do you know where I can get the spacer ring

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

If you need one.

https://www.advanceadapters.com/prod...-down-to-4686/

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Thanks for the info. Ken

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Why the change?
The sag might be much weaker in first gear.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Are there rings etched into the input shaft of the Saginaw? If so how many? That will tell you the gear spread

No lines on the input shaft- First 2.84, Second 2.01, Third 1.34, Fourth, 1.00

1 Line- First 2.54, Second 1.84, Third 1.44, Fourth, 1.00

Much less common 2 Line- First 3.11, Second 2.20, Third 1.47, Fourth, 1.00

3 Line- First 3.50, Second 2.46, Third 1.65, Fourth, 1.00

I used to run a 3 line and the spread was so wide that I could roll a 2.76 rear end gear with no problems. It made 4th a bit like an overdrive however, with freeway speeds coming in around 2000-2200 rpm. Be great if you had one that suits your diff gears.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

I have a 3 line sag.,so what your telling me sounds good. The reason I'm going to the sag is because the original needs a rebuild and I don't want to spend that kind of money on that trans. Like I said I got the sag for a swap of some old parts I had after my build. Thanks for the info. Ken

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

The 3 line sag is the weakest one of them all.
Driven very gently it might last awhile.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

The engine is stock. I'm just planning on it being a driver and not pounding it.I really appreciate all the info. In the mean time maybe I'll start looking for a 1 ring sag or a muncie.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

The first gear on the 3 line is very deep. Its designed for a highway friendly rear gear ratio like a 2.76 or to a lesser degree a 3.08. On your more high winding rearends you'll essentially be skipping 1st gear most of the time, or doing the ol' first, third, fourth..
After I switched from a 2.76 to a 3.08 with my 3 ring, I felt like I was driving a bus. You know, shifting to second halfway across an intersection. I put the 2.76 back in. As near as I could tell the 3 ring was used in light duty gas mileage cars like the Chevy Vega and the Pontiac Sunbird. The internals themselves aren't inferior to the other versions with different ring counts, but the Geez is right about them being weaker because the lower ratios exert more force against the components.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Before dropping too much cash on a manual tranny it it a good idea to determine what your rear axle ratio is going to be and then select a model of a given tranny based on that. Most trannys have different available ratios. A highway axle requires a wider spread because each step or gear change needs to be bigger to get up to speed. A hot rod rear end is already kinda low (numerically high) so the gears are closer together. Thats why old school muscle cars ran "close ratio" trannys. They simply didn't need big changes to get from 1st to 4th when their final freeway rpm was already at 3000 rpm. That in turn kept the motor in its sweet spot for haulin' arse.
Edit: notice in the ratio chart I posted above how a 1 ring 1st gear is only marginally deeper than a 3 ring 2nd gear.

Re: Help- 71 granny 4 speed to saginaw 4 speed
 

Again ,thanks for info. A lot to think about.