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Username Post: Saginaw 4 speed swap?        (Topic#357639)
Posts: 26

Age: 55
Loc: Italy
Reg: 07-26-14
08-13-19 08:06 AM - Post#2773128    

I'd like to put a 4 speed saginaw behind my 54' 235. It currently has a torque tube with the original 53' rearend. I plan on changing to an open driveline. The 235 is stock. I saw a rebuilt Saginaw online that comes with a 2.54 or 3.50 1st gear. I guess the 1st gear choice depends on the gears in the rearend. What's the best combination of 1st gear and rearend gear ratio? I want a set-up that gives me the best balance between take off and highway speed. I usually drive no faster than 65 mph.


Posts: 45

Age: 71
Loc: Kentucky
Reg: 04-04-13
08-13-19 10:22 AM - Post#2773131    
    In response to Marche53

Check out this site:

1953 BelAir 2dr Sedan
1953 BelAir 2dr Hardtop

Member #51
Posts: 8900

Loc: Mustang, OK, USA
Reg: 12-25-99
08-13-19 12:09 PM - Post#2773143    
    In response to BAJohnny

Let me provide a little background information and food for thought.
Back in the 50s when 6cyl 3spOD cars were relatively common, they came with a 4.11 rearend and the OD was .70.
Thus, .7 x 4.11=2.877 equivalent final drive.
The 1st gear of a 3spOD was 2.93. So, 2.93 x 4.11=12.04. That's pretty darn low for taking off from a dead stop in a heavy 4dr 6cyl car.
Bottom line, for example a 57 Chevy with a 6cyl 3spOD had the best on both ends ------------- good take off from a dead start and low rpm at hiway speeds.

The 4th gear in a Saginaw is 1:1, which will EASILY work with a 3.08 rear at hiway speeds.

A first gear ot 2.54 x 3.08=7.82, not great.

A 3.50 first gear would be better, 3.50 x 3.08=10.78, for a 6cyl take off from a dead stop. This would be my choice.

Posts: 77
Age: 54
Loc: French Riviera
Reg: 01-16-10
08-13-19 02:02 PM - Post#2773150    
    In response to DZAUTO

I should not have drunk this marvelous old 1964 Armagnac before reading this.....

The story of my 54 Bel Air HT : Clic here


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