Hello all, I have a ? I have a stock 89 9 bolt with 2.77 and have found a 83 10 bolt posi 3.73 w/disc brakes for $100. I want to know of it is worth the swap. I can't seem to find a larger carrier for my 9 bolt or the gears, and I know the 10 bolt parts is more readily available. It is a 26 spline 10 bolt. What are your recommendations? Thanks

 

Welcome to TGO. A search here will generally provide the info you're searching for.

First, should you be interested in upgrading the 9-bolt, check the following link:

http://www.9bolt.com/

The 3.73 rear will give you bang for the buck (you'll think you have a new car). The Delco-Moraine calipers, however, are generally considered poor. Should your 89 have rear discs (PBR's with 11.7" rotors), they'll swap to the 83 rear end with the correct backing plates/brake line. If the 89 has drums, you'll need to consider swapping the combination valve for best braking performance for discs. There's also the e-brake cables and drive/driven gears to consider or the speedo won't read correctly.

The following may provide food for thought:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

Thanks for the info JamesC. I have read the threads on this subject, and I have allot of the info I will need. I was just wondering if it was worth the time/ money to do it. I know the car will run much faster with the gear change. I have seen the prices on 9bolt and think it is best to swap over. I have the 89 with disc brakes, so swap will be pretty simple. Do I have to get different caliper plates to use my 89 disc/calipers of can I just modify them? Thanks for the welcoming to TGO. I really like the site, just makes my computer slow with all the info on here.

Don

 

The plates can be modified, but the idea makes me a bit uneasy as the holes need to be egged/elongated. The 9-bolt is on top, the 10 beneath:

https://www.thirdgen.org/forums/atta...89-bplate1.jpg

The correct plates can be purchased from Ed Miller:

http://www.flynbye.com/catalog/i29.html

JamesC

 

Thanks, I will look into purchasing the bracket.

 

Could I just find a parts car with the brackets from a 10 bolt 89 and up?

 

The 26 spline 10 bolt will be weaker than the 9 bolt. If you are making a lot of power with good traction then the 9 bolt would be the better rear end. Upgrading it to the gear ratio that you want would give you a better rear end. If you have a mostly stock engine with street tires then the 10 bolt will be fine.

 

Sure. The fly in the ointment, however, is that if a rear is sound, most people/bone yards, won't separate the brake components, feeling a complete rear is easier to sell. That said, try the classifieds on site. Who knows what's out there. BTW, I sold a pair of 9-bolt backing plates here for $60.

JamesC

 

Thanks to you all, I think I will just keep the 9 bolt and look for a larger carrier and gear ratio desired.

 

Or you could swap in a 4th gen rear end.

93-97 with have the same brakes as your 89 9-bolt, and 98-02 will have bigger brakes.

Both rear ends are a 100% direct bolt-in. 98+ gives you bigger/better brakes.
Either way, if your still running your stock 16" wheels, they'll fit great under the fenders & not stick out.

 

unless you are planning on increasing the power of the engine by alot anytime soon.. i would swap the rear out for the 3.73.. if it were my car..

but thats just me..

the 7.5" axles dont break often.. unless its already got something wrong with it, or you have a really badass engine maybe,.. and slicks.. and driving it really hard all the time..

ppl run the 7.5" axle under the s-10 trucks with hopped up v8s in them all the time and never any trouble.. so..

same axle as these cars..

and under big cars like the caprice and others..

rarely fail.

out of over 200 different ones ive had only one has sort of failed on me and that was under an 79 caprice classic and it lost the spot weld plugs that hold the axle tube housings to the center housing and so the axle sunk in the middle and when you took turns the drums rubbed the backing plates

but still plenty driveable.

it was 2.41 ratio and stock 305 2bbl in it and 200C trans

the trans eventually failed after i put another axle under it

alot of torque trying ot turn 2.41 ratio alot of stress on the driveline

thats why they will easily sit and spin the right rear instead of hooking up even with a little 305.

because its too tall of a ratio



good luck

 

I like this option better. Ecology juck yards are having a 50% off sale in a couple weeks and I had planned on pulling out the 83 TA but I will now start my search for a late model rear with the 28 spline axles. My plan for the car is to drive it for recreation and use it at the track with my son once in a while, and then give it to him when he turns 16. I have 6 years before that. I currently have a 88 corvette L98 in w/ edelbrock headers and a flowmaster to follow. The car is not running yet. When I get it running and see how it runs, I will then start looking at aftermarket intakes and runners, etc.. Thanks for all the help.

 

Thank for the info. I plan to add more power to the car as time goes on. Gave $200 for the motor w/ 75K and $55 for the headers used. What would be a good ratio to use with current set up?

 

I had a 9 bolt factory in my 87 IROC with 3.27 gears, posi and rear disc brakes. Took it out and sold it. Went and found me a 82 10 bolt rear disc housing out of a T/A. A 28 spline auburn posi out of a 97 T/A, automatic. 3.73 gears out of a 84 Z28 with a 305ho, automatic. 28 spline axles out of a 92 Z28. And finally a set of 98+ Camaro brakes to round out the package. Didn't like the 9 bolt becuase of the lack of parts. Spent about $400 on parts all together. It should hold up fine behind the warmed over 350/6 speed.