Differential Series

[Ray C.]

Could someone please describe the differences in the Corvette positraction differential series? I have read through the archives and read refference to the 3 and 4 series. I am most interested in differentials for the C-1's, but all information welcome.

Thanks for any information!

Ray #36314

[William C.]

Re: Differential Series

The thickness of the ring gear is less on the 4.11 and numerically higher ratios than the 3-series ratios, requiring a thicker flange on the carrier of the "4 series" ring and pinion assembly. A three series carrier can accept a 4-series ring and pinion with a spacer between the ring gear and the carrier, but 3-series gears will not work in a 4-series carrier.

[Bruce B.]

Re: Differential Series

I also believe that the 4 series carrier has a square edge where the ring gear bolts on and the 3 series carriers have a beveled edge on the flange.

[Wayne M.]

2 Pics - 3 series and 4 series carriers & rings

Auto-load pic is of a 3.70 ring bolted to a 3-series "117" carrier

link below is of a 4.56 ring bolted to a 4-series "175" carrier.


Bruce, I think I can detect that (very small) bevel at the thinner 3-series ring/carrier flange interface that you mention.

[Verle R.]

Re: 2 Pics - 3 series and 4 series carriers & ring

I'm not sure the bevel is of any significance.

Normal machine shop procedure will call for a slight bevel on intersecting surfaces, just to remove sharp edges. The machine operator and others had to handle the parts and they didn't want to cut their hands. In the years before CNC machining the bevel could vary considerably in depth.

I would be surprised if any carrier manufactured in those days had absolutely no bevel.

Verle