making open differential a lock.

has anyone ever forced a shim in the rear of a open diff. to force the spider gears to catch each other or something and force it to be positraction ish. a guy i met at a show today that has been building chevys and dragracing for like 56 years was telling me that it can be done and that he has done it a few times himself. and it works until the shim wears down then it just becomes a open diff again.

he said it even lets you lay down two equel tire marks.

real nice guy said he has a 8 second rear engine roadster in his shop along with three other drag cars (forgot which ones he said.) and he has another old i believe he said 28 roadster. that ive actually seen.:cool::cool:

and he told me to swing by his place some time and hell show me his cars and also help me fix up my 75:cool: and the best part he is only like 4 blocks away. with a huge shop.. and tons of sbc parts.

the only thing is he said he hasnt raced em in about 10 years so they are real dusty.
so im gonna have to swing by and check out his rides.

Hmmm....can't say I've ever heard of it...
Can't say I'd want to do it, either!

That being said...lotsa 4x4 guys "lincoln lock" their open diffs...weld the spider gears and the rear end will be locked 100% of the time (think spool).

Not fun on the street, though.

Hmmm....can't say I've ever heard of it...
Can't say I'd want to do it, either!

That being said...lotsa 4x4 guys "lincoln lock" their open diffs...weld the spider gears and the rear end will be locked 100% of the time (think spool).

Not fun on the street, though.

yeah i think it is the same concept cause he said sometimes you have to press the shim in and it forces em together . essentially it is a locker, just a backyard poorboy one he said lots of people did it back then.

sounds like welding the spider gears except you can take it out later instead of being stuck with welded gears

Seems logical, tho fitting the shim could be a pain.

I am not sure I want fine metal particles running around my roller bearings and chewing on my gear teeth. But hey we used to do all kinds of stuff when low funds were a factor.

This would be the best option for what your trying to accomplish for a low budget posi.

http://www.ringpinion.com/ProductDetails.aspx?ProdID=1398

Kieth, if you want posi, then get a posi. You can search ebay, and eventually find a good deal. Actually I think your Nova will a 7.5 rear in it. Posi units for the 7.5 rearends are pretty cheap.

Jamming the gears in the carrier sounds like you would be setting yourself up to have something bad happen. If that shim comes out of the gears, how will you you know that it won't jam up somewhere else, causing your rear tires to lock??? Probably would get real ugly, real fast.

Check out what rearend is in your car, and get the right parts.

Yes shimming the spider gears tighter w/shims make it a little better but no where near a posi. We used to do it for the low budget circle track guys since they were not allowed to run posi's. It heps but only a little. It will also make the spider gears wear out much faster since it takes away the gap for the oil and if you shim it you will feel the gears start to ratchet since the angles of the teeth were no designed to run that close to each other. Not really recommended IMO.

Miles

A spool is cheap too :D



Broken axles anyone??

Kieth, if you want posi, then get a posi. You can search ebay, and eventually find a good deal. Actually I think your Nova will a 7.5 rear in it. Posi units for the 7.5 rearends are pretty cheap.

Jamming the gears in the carrier sounds like you would be setting yourself up to have something bad happen. If that shim comes out of the gears, how will you you know that it won't jam up somewhere else, causing your rear tires to lock??? Probably would get real ugly, real fast.

Check out what rearend is in your car, and get the right parts.

first its a 8.5.:D:D:D

and second i was just curious i dont want a locker for my car cause it is a street car. i want to either go true posi or a lsd like a powertrax or eaton:cool:

i had just never heard of that.

first its a 8.5.:D:D:D

and second i was just curious i dont want a locker for my car cause it is a street car. i want to either go true posi or a lsd like a powertrax or eaton:cool:

i had just never heard of that.

Posi is short for Positrac...which was the term used by GM to describe their limited slip carrier.
In other words posi/limited slip are the same thing ;)

Check around your junkyards for late 70's camaros and firebirds...lots of 'em have limited slip (and I see 3.42 gears frequently as well!).
I bought my GM limited slip unit for $40 at a swap meet...plus another $140 for a rebuild and bearings!

Whatever you do...stay away from ebay. The GM units sell for mega-bucks on ebay--way more than they're worth--and they're usually in need of a rebuilt to boot!
Definitely stay away from the gov-lock!

Cheap cheap cheap if you look around. ;)

Posi is short for Positrac...which was the term used by GM to describe their limited slip carrier.
In other words posi/limited slip are the same thing ;)

Check around your junkyards for late 70's camaros and firebirds...lots of 'em have limited slip (and I see 3.42 gears frequently as well!).
I bought my GM limited slip unit for $40 at a swap meet...plus another $140 for a rebuild and bearings!

Whatever you do...stay away from ebay. The GM units sell for mega-bucks on ebay--way more than they're worth--and they're usually in need of a rebuilt to boot!
Definitely stay away from the gov-lock!

Cheap cheap cheap if you look around. ;)


what about 80's camaros. or are they different size (cause theres quite a few of em at the yards here locally) and two of em are ralley sports

only up t0 81 after 81 they switched to the 7.5 10 bolt. Parts do not interchange. Also make sure the car does not have 2.41 or 2.56 gears in it since that will be a 2 series carrier and wont work with the lower gears without a ring gear spacer which are known for problems.

Miles

You should also check GM 1/2 ton trucks and vans from 73 up as they have the 10 bolt 8.5 in them as well. you will find 3.42 and 3.73. look around the LSD is there too. I think it was 1990 up Pickup that changed to the 30 spline 8.5/8.6. that will work too. but spline count changes and adapter bearing are needed to fit an early case.

An easy one to spot is this one. Look for any 71-81 Trans Am. They all have the 8.5 rear end and they all came with posi. Most Formulas did as well as well as most, but not all, Z-28's. The TA's the easiest to spot though.

only up t0 81 after 81 they switched to the 7.5 10 bolt. Parts do not interchange. Also make sure the car does not have 2.41 or 2.56 gears in it since that will be a 2 series carrier and wont work with the lower gears without a ring gear spacer which are known for problems.

Miles



i have 3.08 in it now and i like them.