I have a 9-bolt under my 89 gta and I was wondering how strong the rear is or if I will need to go to a 9". I plan on running 10s on the juce.

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97 formula w/6speed,cags skipshift eleminator, hurst billet pro shifter, 30#injectors,adjustiable fuel presure regulator,Moroso cold air induction,ported mass air sensor,accell300+ ignition box, accell 9000 wires, bosch platnum4 plugs,flomaster crossflow muffler,Lingenfiter 52mm throttle body,TPIS L98 SuperProfile cam,Crane 1:6 full roller rockers,Edelbrock subframe connectors,Edelbrock strut tower brace.

Other car is a 89 GTA w/700r4w/stage 2 shift kit,2800 converter, corvette servo, B&M mega shifter, TPIS bigmouth intake, TPIS large tube runners, TPIS 52mm throttle body,Edelbrock ported centerbolt heads,LT1 24# injectors,holly afpr,GMPP LT4 hotcam,CompCams Pro magnum roller rockers,Edelbrock headers, flowmaster crossflow muffler,MSD 6A, accell coil,150 shot NO2. This car is currently under rebuild and restoration.

 

I also plan on putting 3.73s in the rear. also is there anything that I can use to beef up the rear?

 

I'm no expert but from what I've read the stock 9-bolts are only good for 200-250 hp. I would say look into a different rear-end, but thats just my opinion.

 

The 9-bolts are really very strong. Much stronger than 10 bolts. They were the heavy duty option on these cars. They have thicker axle shaft, and the axle shafts are bolted in, which means no C-clips.

As to how strong they are, I can't give you an exact number because I don't know for sure, but I know that there are people on this board running at least in the 11.8-12.1 range on 9-bolts. Surely one of them will see your thread before long and give you a closer range than I can. Hope this helps.

Willie C.

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86 Trans Am WS6

It takes some ***** to do your quarter-miling on foot.
Recent ET's:
@Atlanta 50.80
@Southeastern 50.62
@Mtn Laurel 50.04
Future mods: More endurance workouts and some 300 meter repeats. Projected E.T., 49.8

 

Yes, the 9 bolt rears are really strong. Like WillDC7 said, the 9 bolt is stronger than the 10 bolt rear ends are. But... if you're planning on putting 3.73s in the rear then you might as well get the Ford 9" rear because you're going to pay just as much for the 3.73s for the 9 bolt (since you can't get them aftermarket, only through GM) as you would for the 9" rear and it's MUCH easier to change the gears with the 9" ... so you could set up a carrier with 3.73s for the track and a carrier with 3.23s (for instance) for every day driving.

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1986 Trans AM
305 TPI
Well over 200,000+ miles (speedo/odometer non-funtional! Odometer reads 142,000)
4 Wheel Discs
9 bolt Borg Warner Rear (2.77's....oh joy) :P
Completely Stock
Current Project: upgrade to a 355 TPI, 6" rods, 9.7:1 Compression, Stock TPI ported, 24#/hr LTI injectors (cleaned and flowmatched), Hedman Shorty Headers, 3" cat back exhaust with flowmater, SBC 993 heads completely redone and modified for 1.6 RR, Comp Cams XE262-14 TPI Cam, Ed Wright Fast Chip, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Box, Hypertech hot coil!!

 

I found gears for the rear for $500 with the install kit with berrings. That is much cheeper than a 9" and put gears in it.

 

I ran 11.8's with factory 3.27 gears and 26" slicks when I still used a 9 bolt. I still have the diff. I built up a strong 10 bolt just because I needed a deeper gear. I'm going to be using a 9" soon because I need even deeper gears.

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87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

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You can't get 3.73's from GM, only 3.70's, BUT, I can (and currently have in my car) 3.73's. I currently have new carriers and 4.10 gears (both for 9 bolts) in stock - COPY & PASTE to see new carrier and 4.10 gear set www.koolmeister.com/set2.jpg

How strong is the 9 bolt? Much stronger than the 10 bolt, that's why it was the high performance option. I have been running mine for 3 years now with 500hp/520lbft(first with 3.27 gears, then with 3.73 gears). With slicks, it sees low 1.7x 60 ft times.

Miles

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88 427 Camaro
12.18 @ 113mph 1.75 60ft
Currently installing 3.73's into my 9 bolt (YES, it is a 9 bolt & YES they are 3.73's, not 3.70. I currently have 4.10 gear sets and new series 3 carriers in stock for 9 bolts )
www.koolmeister.com

 

Miles, the 9 bolt is good enough to lauch from slicks? WOW That has made my day, I'm going to get me some sticky rubber right now! Also were most 9 bolts 3.27? Was that like the common ratio?

 

that is what I was wondering I plan on having 425hp and 465fptq and I have seen too many guys blow out rears at the tree and I don't want to be towed home for twenty miles from the strip and getting raped by the tow truck driver.

 

I don't think it will hold up to 1.5x trans brake or clutch dump launches for long (get a 9 inch), but I think it will take foot braked 1.7 and high 1.6x. Atleast mine has . Regardless, it's still much stronger than the 10 bolt (2 extra spyder gears), it doesn't have c-clips and it's lighter and cheaper than a 9 inch. It fills the void well between 10 bolt and a 9 inch.

Miles

PS I don't know what the most common ratio was. Try checking the tech database.

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88 427 Camaro
12.18 @ 113mph 1.75 60ft
Currently installing 3.73's into my 9 bolt (YES, it is a 9 bolt & YES they are 3.73's, not 3.70. I currently have 4.10 gear sets and new series 3 carriers in stock for 9 bolts )
www.koolmeister.com

 

just as a matter of interest to you guys in usa
GM-Holden still uses the 9 bolt ring and pinion on our cars in aus ...just in case you dont know we have LS1 powered cars running them

 

Try adding 200 to those numbers. I've got over 400 TQ to the rear wheels thru a T5 and a 3.70 9-bolt, and so far, no problems.

9-bolts are very strong rear ends. They just get a bad rap because GM only used them for a few years, and only in f-bodies. (In the USA) They never caught on with the aftermarket like 10-bolts did.

I dont know if a 9-bolt will hold up to 10 second runs, however. I do know several 11 second Turbo Trans Ams using the stock 3.27 9-bolt.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
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