Diff help with my 65 C20
 

Is there any way of knowing what diff ratio I have when my ring gear is 32 teeth on my 65 C20?Can I upgrade to something better?

Also need some advice on slamming it 5/7,but struggling to find good reading on this as everything is C10 related.

Please help.

Thanks

Re: Diff help with my 65 C20
 

Should be a 4.57 I think, 32 teeth on the ring gear and 7 on the pinion.

I have the same rear in my C30, although in the 7,200lb rated version. They were made by Eaton from 1947-1972 and are known as the HO52 and HO72, yours being the 5,200lb 3/4 ton version. Gears interchange between both ratings, and they are a third member type, meaning if you locate another third member you want to use you can just swap it in and not mess with setting anything up.

A 4.10 gear was made which would make your engine speed 90% of what it is now and the third member will bolt right in place of the 4.57's with no mods. A T-5 5 speed is a common overdrive manual swap, and while I personally hate automagic/tragics in a driver, a 700r4 is another option.

My 65 C30's HO72 is something like 65" WMS-WMS, a later dually 14 bolt rear is 63.5" WMS-WMS (I think) and 3.73's are common in those.

Hope this helps,
Chaz

EDIT: Forgot you have a C20 with the coil springs and trailing arm setup, 14 bolt will require some mods somewhere to work. Also, not sure but driveshaft may not be the same length for the HO72 and HO52 third members, but 4.10 gears will probably be in a HO52 that came in an auto 3/4 ton anyway so you should be good.

Also, the C20 frame (I think) is the same as a C10, so you could also look at swapping to half ton running gear, seeing how you aren't really going to use it as a truck.

Re: Diff help with my 65 C20
 

The tooth count of both the ring and pinion gears is stamped on the outer edge of the ring gear. Divide those two and that is your ratio. As alread mentioned by 66Submarine, 4.10's are the only better ratio you are going to find.

For what you are describing you are wanting to do, I would also suggest converting to C10 running gear. You can lower a C20, but then you are limited to 8 lug wheels.

Re: Diff help with my 65 C20
 

Ok so I will be able to do drop spindles and 5 lugs setup at the front,but what about the rear?Keep the diff?

Re: Diff help with my 65 C20
 

Sorry and maybe a link or supllier where I can buy these?Thanks for the help!

Re: Diff help with my 65 C20
 

If you are going to convert to 5 lugs up front, you do not want to keep the 8 lug Eaton HO52 rear differential. You will need either a truck 12 bolt or a 8.5" truck 10 bolt.


A link to buy what?

Re: Diff help with my 65 C20
 

A link to be the lowering kit and differential.