Gear Ratio


#1

Hi, All,

Could somebody tell me what the gear ratio is for a 1953 Chevy Belair rear end ?

It has the original 235 engine with 3 sp on column.

Thanks in advance


#2

I won’t stake my life on it, but I’m reasonably sure it was in the 3.70, 3.71, or 3.72 range.
Very close to that anyway, but I’m thinking 3.70.
My now deceased uncle owned a '53 BelAir for many years and we had discussed things like this at times, but that was twentyish years or so ago.


#3

Thanks, my son will be in the process of having a 383 stroker, oh lord!!, with a 350 turbo automatic transmission installed by a reputable custom car mechanic. I was wondering if 1) the rear end would be sturdy enought to handle the engine, and 2) be sutable for cruising down the interstate at 70 mph.


#4

Ouch. To be honest, since this car is getting a 383 stroker my opinion is that the rear end, and driveshaft/U-joints, is not going to survive long if he hammers it much.

With a Turbo 350 and 3.70 gears that engine is going to be winding up a bit; probably somewhere in the 3000-3500 RPM range at 60 MPH. The fuel mileage is going to suffer.

Since this car is a custom, hot rod job I would consider changing the rear end and driveshaft out to a heavy duty 12 bolt Chevy rear or as many guys do; use a Ford 9" which has been around forever and can be gotten, usually, pretty cheap.

With a 383 I think the existing rear will get the ring gear and/or axles peeled pretty quickly.
If you change the rear end and are concerned with RPMs and fuel mileage you could use something in the 3.08 or 2.56 category. I did this on a car here a while back (Chevy/350/TH350 trans with 3.42s)by installing a 2.56 axle and it dropped the RPMs down to about 2300 at 60 MPH.

Another possibility is going to a built up 700R4, which is plenty strong when built right. It’s essentially the same trans as the 350 but has the Overdrive in it.
JMHO and hope it helps.


#5

thanks, OK, for the info and suggestions. I will pass this along.


#6

The old reliable way of determining the rear end gear ratio is to raise the back of the car and count how many turns of the driveshaft you must do in order for the rear wheels to rotate one complete revolution.

Joe