[rusty duck]

what is the best way to determine what the gears are in a '57 chevy rearend? Do you take off the cover and count the teeth on the gears? what were the gear ratios on the '57 chevy rearend? Thanks

[64 elky]

Yeah you can do that but normally it's kinda hard to see the piñon gear cause it's blocked by the carrier. You should be able to find a stamp tooth count somewhere on the outside of the ring gear and normally the stamp on the piñon gear is on the flat part rear facing in the vehicle toward the ring gear and divid the two to get the ratio. Such as I originally wanted to know what my car had so I took the big number(ring gear) and divided it by the piñon gear and I had 3.23 gears. But I had a two speed power glide in my car and that ratio was common in alot of el camino's in 64.

[vinniekq2]

what cover?

[vinniekq2]

usually the ring gear has a stamp on it somewhere,like,,,, 41/10= 4.1 gear ratio. 57s were 3rd member rear ends, so if its posi then turn the tire 1 revolution and count the drive shaft revs

[AutoGear]

Aren't '57 Chev rears 'front-loaded'?

[SSedan64]

Both 57 Car & Truck were Drop out 3rd members but, 57 Truck "55T" Rear also had a 12-Bolt rear cover.
Differentials: GM 55T - Drops out the front of the housing in attition to having a 12 bolt rear cover. Uses c clip axles. Ring Gear Bolts: (12) 3 8 x 24 RH

[anglia427]

alot of them got swapped out for olds/pontiac rears they were stronger make shure what you have first

[rusty duck]

didn't know that. thanks for the tip.

[Cape Cod Bob]

Turning the drivers side hub one turn while watching the pinion yoke to see how many turns that makes will give you a pretty good idea of the ratio. For instance ,one turn on the hub may give about 2 3/4ths turns on the pinion = 2.73 gears etc.


The rearend gear ratio refers to the relationship between the ring gear and the pinion gear. By simply dividing the ring gear tooth count by the pinion gear tooth count, the ratio is determined. For example, if we divide a ring gear with 41 teeth by a pinion gear with 10 teeth we find that the gear ratio is 4.10:1 (41/10 = 4.10).

Read more: Gear Ratio Calculating - Tech Article - Chevy High Performance Magazine

[timothale]

both wheels have to make one turn, on a non posi rear if only one wheel wants to turn, then One Wheel has to turn over TWO times and count the pinion-drive shaft turns and do the math.

[rusty duck]

Thanks fellas. I'll do what you suggest and see what I have asap. I'll post what I find out.