I was talking to a guy who said he ran a bw 9 bolt with 3.70 gears and a set of Moser axles in the mid 9's for 2 years.

If you have (or know of someone) broken a 9 bolt, what was the part that broke? I am leaning towards picking up a 3.70 gear set and install kit next month when I am in Australia for ~$300 USD and then a set of Moser axles for ~$300. That's a whole lot cheaper than a 9 inch, but I am not sure how long it will last. Hence, the question of what is the weak link in a 9 bolt?

Thanks
Miles

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88 427 Camaro
12.18 @ 113mph 1.75 60ft

www.koolmeister.com

 

Wow that sounds promising. I wish there was a set lower than 3.70. Right now I need 4.10 and possibly 4.56 in the future.

I really can't think of any weak part. With aftermarket axles about the only thing I can think of is the actual gear size.

The axles are bolted in, not held in by c-clips. 4 spider gears. Both pluses.

I suppose a weak link would be the stamped steel cover not allowing for bearing cap support.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
454 Big Block almost ready for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857 altitude corrected to 11.163
Best MPH on a time slip: 117.87 altitude corrected to 126.10
Altitude corrected rear wheel HP based on power to weight ratio: 476.5
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

ok which one? (weak link) the fact that you can only have 2 diiferent gears or that the price for them is 700$ through gm only! as for the rear end its not as tough a ford 9" or chevy 12 bolt but definitely better than a 7 3/4 rearend most f-bodies have!

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1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 heads,350 horse cam,bored.40 over, Edlebrock torker2 and a 600 edlebrock manual choke.

Future mods performer rpm air gap intake (polished) comp roller cam, and way better headsa 400 defintely in the works!

 

Stephen - I don't know of anything lower, but will ask when I am there.

Burnoutrpm - read the question again

Miles

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88 427 Camaro
12.18 @ 113mph 1.75 60ft

www.koolmeister.com

 

I broke 3 teeth off the ring gear (2.77s) when I had my 9 bolt...so IMO that's the weak link. The cause of it though, not too sure of but I believe one of the bearings was toast as it would make strange howling noises driving down the road. I wasn't even racing when I broke it, just driving down the highway.

I picked up a USED 9 bolt diff w/2.77s for over $300! I had them installed for another $300 w/ new bearings, etc. This was back in 1993 when parts were nearly IMPOSSIBLE to find. Then about a year and a half later it was making those same funny noises again. Not wanting to risk get stuck somewhere again because I sheared the ring gear, I tossed the 9 bolt and got a Moser 9" instead. Haven't had any problems since.

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1989 IROC-Z, ZZ3 shortblock with some bolt-ons.
13.20 @ 108.69, 2.2 60'

 

I have heard about people using 9-bolts in extremely fast cars with no problems at all. However, I have also heard of people who have fried them in cars with no modifactions at all. I run them in both of my cars with no problems. I have one with SLP 3.70 gears in my '82 Firebird that puts out roughly 500 horses and it has never given me a problem. I also have one in my '85 Trans Am that put out roughly 275 horses. This car has about 180,000 miles on it and the rearend is still going strong. I get these rearends in parts cars all the time so if you're in the Chicago area and want to pick one up let me know.

 

LFN AT U,

I already have one in my car (3.27 gear). It's been in there for 2 years and has been living with 500hp/520lbft (crank) so far. I'm going to australia next week and ausrs can get some 3.70 gears and install kit for ~$300USD. Plus another 300 for moser axles. $600 is a lot cheaper than ~2300 for a 9 inch. But, 600 is alot if it doesn't last.

Miles

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88 427 Camaro
12.18 @ 113mph 1.75 60ft

www.koolmeister.com

 

I don't have a 500 HP vehicle, and i may not have a 300 HP vehicle. But i sure as heck give my 9 bolt a good beatin and it responds back with a kick in the *** and a slide from left to right

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Problems every other day with the car (probably not a mod, but to me it sure makes a difference)

 

I sheared my 2.77s, broke one axle and bent the other...screw that 9 bolt crap. Just installed a used 10 bolt and fries the POSI already....what can i say, I'm hard on rears. I'm goin with a Moser 12 bolt ASAP, seeins how I work in the place that machines them, I might be able to hook up a good deal.

Lata,

Kelly

 

The 9-bolt is 7 3/4". The 10-bolt is 7 1/2" or 7 5/8" after 1985.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

listen to you guys you all throw out the GM g92 (heavy duty rear end .....read stronger than the 10 bolt)
geesh
you can get the 9 bolt up to 4.11 rear ratio
there are no real large problems with this rear apart from you guys cant get parts for it easily
i am trying to get someone to post on here that is willing to ship to usa
88427 will meet him when he is out here so maybe just maybe these cars can remain with the stronger GM option
one other thing 9 bolt has common carrier with the same posi fitting ALL ratios from 2.77 to 4.11