SteveW
Senior Member
Posts: 1608
Loc: Shreveport
Reg: 04-24-02
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11-26-23 08:42 PM - Post#2864517
On a Saginaw 4-speed transmission
The front input shaft may have grooves cut around it's diameter. These grooves indicate the ratios of the gears inside.
No grooves 2.84, 2.01, 1.35, 1.00
1 groove 2.54, 1.80, 1.44, 1.00
2 groove 3.11, 2.20, 1.47, 1.00
3 groove 3.50, 2.47, 1.65, 1.00. My question is which one would be the best for highway use. Some cars and trucks seem to have a low low first gear that seems like you could just skip it and take off in second. I would like to have something that feels like in the 60’s. Which should I look for ? A 1 groove 2 groove or a 3 groove. It’s going behind a 1955 235 six cylinder. Also any Idea what would be a good rearend gear to have for highway. Thanks. I am trying to find a good donor car or truck to pull one from that is synchronized. Should I look at late 60’s or mid 60’s  Thanks. I am not a transmission guy . My first car a 47 chevy was slow to shift next was a 67 mustang that would shift as fast as I could move. Just want something that you don’t have to double clutch or come to a full stop to put back into first. Thanks for any Ideas on a model and year chevy to look for.
Edited by SteveW on 11-26-23 08:43 PM. Reason for edit: No reason given.
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 GreatNorthWoods
"9th Year" Silver Supporting Member
Posts: 1608
Age: 82
Loc: Littleton, New Hampshire,...
Reg: 03-31-02
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11-27-23 05:44 AM - Post#2864519
In response to SteveW
That's interesting about the grooves. I never knew that. It sounds like you want a first gear that winds out. I'm no expert but IMHO I think the 2.54 (1 groove) would be best for that. On the other hand, being a six cylinder, I would think you would want a gear that gets you up to speed faster. In that case the 3-groove might be best. As far as the rear end gear, I think something around a 3.55 would work well for a six as a compromise for both town and highway use or a 3.31 or 3.42 for more highway use. 
Vern
1953 Chevy Belair Sport Coupe - 355 Chevy V8, 700-R4, 4-wheel disc brakes, Ididit column, cruise/tilt,'59 Vette Steering Wheel, A/C
1930 DeSoto CK Business Coupe- 350 Chevy Crate V8, 4-wheel disc brakes, TH400, S-10 Rear, Heidt's IFS, A/C |
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bobb
Super Senior Member
Posts: 6686
Loc: paradise
Reg: 09-05-03
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12-03-23 01:42 PM - Post#2864710
In response to SteveW
i would choose rear gear 1st. depends on vehicle weight, desired cruise speed / rpm, tire width / height. then choose trans by 1st gear so you can get it going without smoking the clutch.
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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