Don Zeller

Looking to change my 62 Vet from 4:11 to 3:55 or 3:70. Having hard time finding all the parts including carrier. Any ideas will be appreciated.

Thanks

GTOguy

Much easier to locate a complete third member and just bolt it in. No set-up of gears and bearings and lash required. Put a wanted ad in the parts for sale section. You can even use the center section from the full size Chevrolets up to and including the 1964 model year.

CaptainEgg

Don
You don't say which parts are hard to find. Summit Racing carries everything you need except the carrier. Those are not that hard to find, not cheap but they are around. Have you tried Craigs List, E-Bay, your local drag racers, your local club? Are you looking for numbers correct or just an extra rear end? What part of the country are you in? I know a guy in Northern Ohio that has a few old carriers laying around, if all else fails PM me and we can talk. Hope this helps.

Factoid

4.11 to 3.70 is not a huge change unless you are also installing an overdrive tranny. Anyway, here is a 3.36 posi on eBay. You can change the gears to your desired ratio as part of disassembly and inspection.

https://rover.ebay.com/rover/0/0/0?m...2F223434546332

DZAUTO

Are you wanting a posi or a non-posi rear???? AND, AND, AND, are correct numbers a requrement???
If you simply want to change the gear ratio, with no concern for numbers, then ANY 57-64 (DO NOT use a 55-56) Chevy pass car (or 57-62 Vette) is a pure, 100% bolt-in swap.
If you want a posi rear------------------BUT HAVING THE BIG P ON THE CASE IS NOT MANDATORY-------------------------then, again, ANY 57-64 Chevy non-posi case (WHICH WILL BE CHEAPER) can be converted to posi. The BEST BUY that I have found on gears and a rebuild kit is from Rock Auto. Both Eaton and Nitro Power Lock posi units are available from various sources for about $500.
I've been rebuilding these early rears and converting non-posi rears to posi for about 50yrs.

Here is an article I put together a few years ago.

Dreaming60’s

Glad you chimed in Tom! I've already forgotten many items I learned last year, but isn't it true changing from 4:11 to 3:70 doesn't require a new carrier, but if you want a smaller ratio 3:55/3:36/3:08, it requires a new carrier? Also, if you're trying to tame the engine rpm's at highway speeds, dropping to a 3:70 won't do much.....which has been my dilemma. I want the acceleration of a 4:11 at slower speeds, but a highway cruiser too.....and this is where a Tremec 5 speed comes in handy with its overdrive 5th gear. Best of both worlds, but not cheap.

IIRC Tom has a FI 400 SB with tons of torque and HP and runs a 3:08. He doesn't need an overdrive with that set-up.

BH

GTOguy

This unit is grossly overpriced since it is in need of gear repair/replacement and a rebuild. The $850 price is typical of an overhauled or good-to-go positraction unit. A 3.36 open rear would be less than $500.

DZAUTO

WITH THIS OLDER STYLE REAREND, ONLY a 4-series ring gear will fit a 4-series posi unit, and a 3-series ring gear will only fit a 3-series posi unit.
Now, with that said, a 4-series ring gear can be used on a 3-series posi unit---------------------WITH A SPACER------------------- but NOT the other way around. Thus, to change a 4-series rearend to a 3-series, a 3-series posi unit MUST be used!!!

The OUTER case (CORRECTLY called carrier, but not by most people)-------------------------REGARDLESS of posi or non-posi is the same and can be used with ANY ratio from 3.08 to 5.38. ONLY the differential (posi or non-posi) is different.

DZAUTO

I think it is priced high. Also, that particular rear was built at the Buffalo, NY plant (Corvette rears ONLY came from the Detroit plant) and it came out of a 63 PASS CAR. From the pictures, it looks OK, but for sure will need a total dear down and inspection. At one time, these early posi rears were bring premium prices. But since NEW posi units from Eaton or Nitro are now available, and the original posi units are 50-60yrs old, it may be severely stressed and worn, or may have some cracks (you CANNOT see the condition of what the internal gears/parts are like until it is disassembled!!!!!), It's better to just build a posi rear with a new aftermarket posi unit (yes, it may cost a little more, but everything------------except the outer case-------------will be new).

This is Aubrey Bruneau's 62 409 4sp car (yes, it has a 60-64 style rear in it). Lots of hard use here!



If that rear came out of a 63 409 car, it is possible that it may have suffered some severe abuse in its early days.

Personally, I have ZERO interest in a 3.36 or 3.55 ratio. I either want a 3.08 or a 3.70 ratio.

GTOguy

The ad said rust on the gears and gear damage/pitting that would need to be addressed. NO THANK YOU.

DZAUTO

I am so sorry, I forgot to expand on my comments about the posi on Ebay.
First of all, the rust on the ring and pinion gears is so bad that they are JUNK!
So it sells for $825, new ring and pinion (best deal I've seen is Rock Auto) for $215+shipping + rebuild kit (+labor if you don't do it yourself), and you're easily over $1200-1500 and end up with a posi unit 55+yrs old, AND, AND, AND a case for a 63 pass car (NOT for a Vette).
It's not that the total is all that bad, but me personally, I'd prefer to round up a CHEAP, NON-posi case ($25-100), convert it to posi and put in new parts (gears, posi unit, rebuild kit) for the same (or less) money, .

ryan22

6T2Vette

This is not a recommendation or opinion. This is what I did because I didn't want the 4.11 either. I removed the numbers correct third member and I bought the third member with the long P of a '64 Chevy station wagon. It cost me 100 bucks. I cleaned it and dropped an Eaton 3.55 posi in it. I boxed up the numbers correct third member and put it away. It doesn't have the first gear bite of the 4.11 but rides very comfortable at 65-75mph. My tach isn't working, but speed was taken with a iPhone App (Speedometer). If better acceleration is more important to you than highway comfort, perhaps the 3.70 might be better, and it's only a .15 jump from the 3.55, but it is a considerable drop (.41) from the 4.11.
Good luck
Bob

GTOguy

Depends what engine you are running. A high strung Hi RPM small block with a lot of camshaft will want the steeper gears. The 383 stroker in my '61 would be fine if I stuck a 3.08 gear out back. Low end torque doesn't need much gear. My '67 Pontiac has over 430 foot pounds of torque and pulls its 2.56 rear gear just fine.

vettsplit 63

Aubrey sells a billet strap that goes over the stock cap on the power side that prevents the ring gear from getting spit out of the back of the housing. He runs larger diameter axles, with a special oversized axle bearing that requires machining the stock housing tube. And, he also runs a very soft clutch.