Just out of curiosity.......I've heard enough about 9 & 10 bolt rears and could literally have an ongoing war between the ya and na sayers as to which one is stronger. I understand they were only offered on 3rd gens from 87-89, my question is.....If the 9 bolt rears where really that good, then why were they discontinued? Just wondering cuz my 9 bolt is on its last leg and I need a new rear, and am currently tryin to figure out which way to go.

 

If you knew enough to debate the pros and cons of both, you'd know why the 9-bolt is stronger and which way to go. The 9-bolt was installed on 3rd gens from 1985 to 1989. Due to cost (for GM), it was discontinued. It was imported from Australia ($$$), still used down there. It is the "equivalnet" to Aussies as the 10-bolt is to US.

 

Everything you need to know is at www.9bolt.com

Miles

 

The 9-bolt is both stronger and more costly than the 10-bolt. it was used in the IROCs because GM was afraid the higher torque output of the TPI350 would break 10-bolts, but then they decided it wasn't worth the extra money to import the 9-bolts so they stopped using them.

Note that even during the 9-bolt years (85-89), GM put 10-bolts in cars with auto tranny 305's and all V6's (except the TTA).

 

Exactly.

 

AFAIK, it would be hard to purchase a 9 bolt right now. I'd go to a Ford 9 in custom made for our cars before I did that. 10 bolt is weaker than the 9 bolt, both of which are weaker than the Ford 9 in

 

You can get a used 9 bolt for about $350.
I sold mine for $200 and a set of extra T-Tops. I didn't realize I had the 9 bolt until my friend that I sold it to told me.
He wanted the posi unit and his friend wanted the gears. I told him it was a 10 bolt and that is what we assumed it was.

I'd go 9 bolt if I were you. Stronger than the 10 bolt and cheaper than the 12 bolt. You pay a little more for the gears though so get one with the gears you need already installed.

 

Everyone is so quick to jump and say FORD 9's are the strongest.. ok.. well they may be the easiest rear to swap gears in.. and have heavy duty parts.. but any TRUE gearhead knows your rear is only as strong as the parts you put inside of it. A built 10 bolt can handle the power. Ive seen 1200HP go through a 12bolt NUMEROUS times.. this car does wheelstands on the bumper and has never broke! IMO FORD 9s are overrated. Besides.. who wants FORD parts on their Chevy.. ICK!

 

How built can you get? You could get aftermarket gears, diff, diff cover with support and axels. My axels are not the problem. I am experiencing cap walk according to my driveline guy. Currently the carrier bearing on the driver side will slip onto the carrier. That should not be. You should have to press it on. We had to put dimples on the carrier and something to stick the bearings on it just to make it work. This was done with the understanding that next time, I will need a new carrier. Also the caps are not perfectly aligned anymore. How much for a built 12 bolt that fits into a 3rd gen with disc brakes and will it stand as much abuse as the 9 in?

 

You can find 2.77 9-bolt rears all day long for under $400. I know because I've been hunting for that oh-so-rare 3.45...



And both of which are cheaper than a 9 inch. IMHO 9 inch rears are overkill in anything thats street driven. When you're running 800 hp at the track, sure.....but back and forth to work? It's not worth it.

 

I do drive my car on the street and a few times at the track. However, I tend to do WOT launches every chance I get on a ramp which is about a couple times a day.

 

hey greatj, u can have my busted oh-so-rare 3.45 9-bolt
I'll tell ya, this car hauled pretty good *** b4 it broke for a 16 year old car ('87 IROC, LB9, T-5, 3.45:1 rear [RPO code GM3]). However, I've yet to experince an '87 IROC with the L98, or any other 3rd gen L98 for that matter.

 

Hey Smoothie, exactly what is broken in there...the posi or the gears?

I picked up a 2.77 '89 9 bolt complete with the big brake setup for $100 to put in my Iroc. That's a deal IMO...the brakes alone were worth that. I then sold my '88 2.77 complete for $200, so you can expect those rears around that price, and they are pretty plentiful.

Ed

 

I,ve got a 9 bolt in the wharehouse at work that's out of my 1le with about 10,000 mile on it.

 

What ratio willis?

---lookin for a non-busted 3.45