Technical The right rear end ratio for 48 ford Car.

I need to change the rear end gears in my 48 Ford. It has been bored and stroked to 265 CID. Stock cam, electronic ignition, stock carb. electric fuel pump. It now has 3.56 but pinion shaft is worn badly. I live in Maine with quite a few hills. Would it be possible to use 3.25 gears ? Thanks

 

Sure. Second gear will come into play more.

Ben

 

My flathead powered 32 has 3.78 gears. I think if you want higher gears you will suffer at lower speed. Especially in hilly country.

 

Forgot to mention I have a C-4 auto trans,

 

The difference between the 3.25 and 3.56 gears is only about 200 RPM so I don't think it will be an issue, unless you're already struggling going up the hills.

 

Thanks I will stick with the 3.56

 

Only 200 R.P.M. !? That’s huge!

I have a 261 Chevy 6 in my 53 Chevy car (57-64 Chevy rear) in changed from a 3:70 to 3:55 it dropped about 200 R.P.M. which is out of the cams power range.

With the 3:55 it has no throttle response, and it endlessly shift gears climbing hills.
If I leave it if 3rd it lugs but if I down shift it winds out to the point I have to shift to 3rd.

I am going back to a 3:70.

 

Wow! I changed my Buick from a 4.1 to a 3.36 and dropped about 650 rpm. The 248 Buick engine must have a much wider power range than the Chevrolet.

Ben

 

I put 3.08’s in a 51 F-1 with a warmed up V8. Yes, use 2nd gear more but very pleased, no regrets