Rear axle ratio

Started by WZ JUNK, January 08, 2016, 01:10:10 PM

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WZ JUNK

The Lincoln rear axle in the 1954 Chevy is a 2.75 to 1 ratio.  It probably came from a car that was not AOD.   My information on the Chevy Caprice donor car, that I used the TBI engine and 200R transmission, says that it probably had a 3.08 to 1 ratio rear axle.  The 54 will use a little bigger diameter rear tires than the Caprice.  So the end result will be a higher ratio than the original Caprice donor.  The Caprice was design for the slower speeds at the end of the gas saving 55 MPH era.  I wonder what this difference from 2.75 to 3.08 will mean.  This is to be a highway car and not built for performance, but just a good travel car with enough zip to climb a steep hill comfortably,  or pass another vehicle easily.  When I get into terrain that is hilly and curvy, I could shift out of OD to D.   Will spending the money to change the ratio justify itself ?  

What do you think?

John
WZ JUNK
Chopped 48 Chevy Truck
Former Crew chief #974 1953 Studebaker   
Past Bonneville record holder B/BGCC 249.9 MPH

enjenjo

I think you will be fine. I built a 48 Ford with the same combination, and it drove fine. The overdrive was pretty much highway only though. The 200R4 has a pretty low first gear, so they are not a dog from a stop. And if you want to change it, 9" gears are still pretty common.
Welcome to hell. Here's your accordion.

chimp koose

I would leave the gears alone ,your 54 chev is likely a fair bit lighter than the caprice the driveline came out of . Drive it as is and if the performance bothers you , then look into a change .

parklane

A friend has a 305/700R4 in his 54 Chev with a lower gear than yours, and it works really well.
If a blind person wears sunglasses, why doesn\'t a deaf person wear earmuffs??

58 Yeoman

I'd bought a rear axle out of a 64 Merc that was supposed to be a 3.00 according to the tag. I've been told that that was a good ratio for the Caddy 425 engine in the 41 Poncho.  IIRC, it turned out to be around 3.55.  You can't always believe those tags.
I survived the Hyfrecator 2000.

"Life is what happens when you're making other plans."
1967 Corvair 500 2dr Hardtop
1967 Corvair 500 4dr Hardtop
Phil

kb426

John, depending on all the factors for calculations, I decide where the engine will be good at 65 mph in od. Most of us have a tire size in mind for stance so the gear ratio is the variable. You have enough info to make the decision. :)
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WZ JUNK

Thanks to all those who responded.  I believe I will leave the existing ratio in the car until I can drive it some.  Changing the ratio later will not be a big problem.

John
WZ JUNK
Chopped 48 Chevy Truck
Former Crew chief #974 1953 Studebaker   
Past Bonneville record holder B/BGCC 249.9 MPH

papastoyss

Quote from: "58 Yeoman"I'd bought a rear axle out of a 64 Merc that was supposed to be a 3.00 according to the tag. I've been told that that was a good ratio for the Caddy 425 engine in the 41 Poncho.  IIRC, it turned out to be around 3.55.  You can't always believe those tags.
That 3:55 is a good choice if you're using a 700R4/4L60 trans.
grandchildren are your reward for not killing your teenagers!

58 Yeoman

Quote from: "papastoyss"
Quote from: "58 Yeoman"I'd bought a rear axle out of a 64 Merc that was supposed to be a 3.00 according to the tag. I've been told that that was a good ratio for the Caddy 425 engine in the 41 Poncho.  IIRC, it turned out to be around 3.55.  You can't always believe those tags.
That 3:55 is a good choice if you're using a 700R4/4L60 trans.

No, it's got the TH400.
I survived the Hyfrecator 2000.

"Life is what happens when you're making other plans."
1967 Corvair 500 2dr Hardtop
1967 Corvair 500 4dr Hardtop
Phil

papastoyss

W/the T400 & that big motor I would look for something in the 2:80 -3:00 range for highway use.
grandchildren are your reward for not killing your teenagers!

58 Yeoman

Quote from: "papastoyss"W/the T400 & that big motor I would look for something in the 2:80 -3:00 range for highway use.

Yeah, that's what someone else had told me, and that's why I picked that particular rear end. But someone must've changed the tag. No big deal for now. I may not be getting that car on the road after all.
I survived the Hyfrecator 2000.

"Life is what happens when you're making other plans."
1967 Corvair 500 2dr Hardtop
1967 Corvair 500 4dr Hardtop
Phil