I have an 85 camaro with a crate 350 with around 330-350 horsepower at the flywheel. I also have a turbo 350 tranny with a 2200-2700 stall. I need a rear end and I would like a strong 12 bolt limited slip for an occasional sight at the track just to play around a little. I would like 3.73 gears, so just tell me what you think. I thought that I would get a junkyard rear end and put in a new ring and pinion.

 

You won't find a junkyard differential to fit into a third gen other than from another 7.5" 10 bolt from another third or fourth gen.

The problem is the width and that a third gen uses a torque arm suspension. You can easily swap over spring, shock mounts etc but there's no easy way to attach the torque arm onto any other differential. You could change out the rear suspension to something like ladder bars to eliminate the torque arm but there is fabrication involved.

A complete aftermarket bolt in 12 bolt or 9" for a third gen will set you back about $2500

The 7.5" 10 bolts are stronger than most people realize. Some people have broken them on the street with nothing more than a factory engine while other have made them survive on the dragstrip with a BBC. I ran one into the 11's before finally swapping it out for a 9".

 

Mine is a 3.42 out of a 1989 v6 camaro. I just added a locker. No problems at all..... yet

 

so pushing no more than 375 horsepower at the fly wheel can I use the stock rear end I have and put in a new ring and pinion add a locker and be good with the stall (2200-2700) I have?

 

All new stuff

upgrade 28 spline axles
ring & pinion
posi
TA girdle

and pray that you dont hook hard

 

I ran a well used 9 bolt posi in an high 12 sec 86 Z28 before breaking a pinion. I think if I had used anything stickier than ancient drag radials I would have broken sooner.
I'm hoping that a set of quality gears ( read that made in the USA ) and a thorough rebuild/set up will let it live for a few seasons.
Seems a few people here have made them live.

 

i was wanting to know if these are good brands to buy from especially the locker and gear set. I also was wondering which rear end is the strongest in the stock 3rd gen 4th gen camaro firebird so i can start with the strongest one

i have a stock 10 bolt 7.5"


moser 28 spline axles

YUKON GEAR - 3.73 RATIO RING & PINION GEARSET - THICK GEARSET

TA gurdle

Powertrax Lock-Right locker; GM 10-bolt w/ any ratio, 28-spline

 

Actually, it isn't difficult at all to put a 9" into a thirdgen, i am currently searching for one for mine. You just need to weld a bracket on the 9" for the torque arm, and shorten an axle. You can buy a shortened axle, or take one that is too long and have it shortened and re-splined. Don't tell me it's impossible or unreasonable to do, I've seen this exact thing done before, and it's WAY cheaper than buying a 9" made specifically for a thirdgen.

 

For some people, it's not impossible. I installed my first 9" under my car by converting it to ladder bars. I narrowed another 9" to put it under my car after doing a back half on it.

Most people however don't have the tools or skills to do this kind of fabrication and expect a diff swap to be a simple task. This makes it impossible and unreasonable. With lots of trial and error, they may get it right but if they've never attempted something like this before, it can be a lot cheaper to just buy an aftermarket diff and do a simple swap.

I mentioned a 9" but the original poster wanted a 12 bolt. I could have also mentioned the aftermarket Dana 60 but for a street car, that's overkill. You can't just "weld a bracket" onto the 12 bolt case and expect it to be strong enough to hold a torque arm. That makes swapping in a junkyard 12 bolt very impractical. That is if you can even find a 12 bolt the correct width. First and second gen 12 bolts are very close but difficult or expensive to find. Truck 12 bolts are too wide and are not the same as a car 12 bolt.

Cutting and narrowing a differential should have a jig put through it to keep it straight. Not a lot of axles shafts can be cut and resplined.

 

My point is that it isn't too difficult or expensive to modify an existing diff to put in your car. If you don't have the tools or skills to do it yourself, paying someone to do it for you is still going to be cheaper than buying an aftermarket diff. Taking any 12-bolt from a jy car and having it modified to your specifications is usually going to be cheaper, not necessarily easier.

Anyways, he might as well use his original axle until it breaks, because it could be fine.

 

I would be very careful with that recommendation. I have seen axle failures cause some serious and deadly accidents. Nothing like having ring and pinions seize at 80 mph or more.

 

That's true, I should have thought about before I spoke. But, if he does upgrade his axle, similar as he specified to, he should be fine. Personally, i'm not going to put my money into stock axle.

 

back to this are these reliable parts?

will it be strong enough to handle 425 ft. lbs. at the flywheel?

also what year or model was the strongest rear end put in 3rd gens so i can start with that.

 

yes, thats true, but i was just generalizing a strong rear end

 

Never heard of yukon gear. Stick with a good name like Ricmond or Motive. You also want to change out the crush sleeve to a solid piece. All the 3rd gen rears suck so it really dosent matter. The parts you put in them will help.

 

what is a crush sleeve

 

It's a special piece of tubing that fits between the pinion bearings. When you torque down the pinion nut, it crushes and provides tension between the bearings to provide preload. It takes a lot of torque to crush the sleeve properly.

The solid crush sleeve is a metal tube with some thin shims that allows you to set the preload. The solid crush sleeve won't crush is over torqued.

The way a ring and pinion work, under acceleration as the pinion is trying to climb the ring gear, the ring gear is trying to go out the back of the diff. The pinion at the same time is trying to go out the front. If there's enough force and the pinion teeth don't break off, there can be enough force to crush the factory style crush sleeve which will then change the preload which can cause the diff to fail.

Using a solid crush sleeve, you eliminate this problem. The solid crush sleeve kit is sold by Raytek and is cheap. If for any reason your preload has loosened off, you can simply take out a shim to tighten it back up.