3 speed with overdrive swap?

[AcampoDave]

Originally Posted by Lugnutz65

Me, being a novice with a lot of truck terminology, I gotta ask.
Is the "3 ring 4 speed" you mentioned the same as what some call a granny gear 4 speed? Paired with a 2.76 rear should be a good match. Any idea what the actual tranny gearing is? 4th would be a 1:1 ratio, but with a 2.76 rear, 70 MPH would be right at 2238 RPMs. Nice!

It's Saginaw car tranny. They had grooves engraved into the input shaft. Basically speaking they ranged from no grooves, or rings, to 3 rings. The more rings they have, the lower the ratios on the first 3 gears.... I'm no expert, sorry to be so vague but most three ring Saginaws seem to be from Chevy Vegas or Pontiac Sunbirds. Much can be found by googling up Saginaw input shaft rings. I would post some links but I don't know how.

[AcampoDave]

Ok..Saginaw 4 speeds stack up like so...
3 rings= 1st 3.50, 2nd 2.48 and 3rd 1.65
2 rings= 1st 3.11, 2nd 2.20 and 3rd 1.47
1 ring= 1st 2.85, 2nd 1.80 and 3rd 1.44
0 rings= 1st 2.54, 2nd 1.80 and 3rd 1.44
4th gear is one to one on all types and replacement input shafts came with no rings. As far as I can ascertain, all of them are basically equal with regard to strength.

[Flthead]

Lugnutz65 , your t5 page is a great source of info

[kieth]

Guys, lots of good ideas here but one must watch out before diving off in 2:76 rear axle ratio land, lots more things must be taken into account before changing rear axle ratios:

Here is what I need to provide each of you with the proper information for the way your truck is set up now :

1. engine

2. transmission

3. rear axle ratio:

4. rear tire diameter: (ground to top of tire)


same information with any changes you want to make;;;;;;;


by looking at your current truck info you can compare it to your new setup and with some other info then you can make a good choice for any transmission, rear axle, tire, engine combos.......

My spreadsheet will provide you the following informatio:

HP/torque information for 230,250, 283, 327, 350 engines

variables: tire diameter

700r4, 350/all standard transmissions, t5, (usable torque to the ground)
(speed in all transmissions at 1500, 2000, 3000, 4000 rpms) variable will be rear axle ratios.....all performance data will be listed for each rear axle ratio.

If you want to change tire diameters and compare the performance to another tire diameter then we can provide you with the information.

By putting torque within a usable range of speed, taking into account all these variables you can combine the correct variables to make your truck perform as you want it to. Send me a PM with your spec's and I will send you back the spreadsheet....... KIETH

[Sumono1]

I have the same set up as ACampoDave. I had installed the same transmission years ago when my budget was tight. Unfortunately, I'm running 4.11 gears in the back. As soon as I get the original 283 restored, I'm going to install taller gears...maybe a 2.76 like you mentioned? I was wondering what ratio to use. Thanks!

[AcampoDave]

Sumono1, I used to run a 308 which was a little better for all around driving and a good burnout now and again. The 308 wore out and I already had the 276 so I put it in expecting to end up with a slug. I didn't get that, but burnouts are pretty much a thing of the past because it's just to abusive on the clutch and drivetrain with the taller gear. The trade off is the freeway is an easy cruise now.

[frankslagoon]

I just put a Saginaw 4 sp. / 3sp. o/d together this winter. it's very cool. I'm not sure how to send a pic. the non-sync. and sync. 3 speeds the o/d 3 speeds also come in non and full sync. and Saginaw 4 speeds are all the same length. 63 shortbed 283 3:73

[jjzepplin]

So you have a Saginaw 4speed that you put the overdrive from a 3speed on?
Pics= You hit the Quote button and look up top for a paperclip symbol-click it and find your pic.

[frankslagoon]

Originally Posted by jjzepplin

So you have a Saginaw 4speed that you put the overdrive from a 3speed on?
Pics= You hit the Quote button and look up top for a paperclip symbol-click it and find your pic.

here are acouple pics I took a bunch cuase I was afraid I'd get lost doin the switch