Originally Posted by FOX-GTA_89

my posi is not that bad...i spin both wheels most of the time 90%...but at the track only one is spinning... should i reshim it or go with a full spool right away???

Originally Posted by TPI-Formula350-

what gear oil are you guys running in your 9 bolts?

Do you guys use the friction additive in your 9 bolt?

Originally Posted by antman89iroc

I used Mobile synthetic 75-90 with the GM additive. I highly recommend the GM additive. After I rebuilt/shimmed my 9-bolt posi it popped and creeked until a used the additive. If you look in the "Product review" section I listed the GM part number. I was amazed how effective it that little bottle of fluid worked. I don't think the brand/type of oil is as important as the GM additive. As long as the oil used is quality stuff.

Originally Posted by FOX-GTA_89

My 9 bolt runs like a charm since i machined it (50$) and use Home Depot Shims 0.49$ X2 !!!!

Originally Posted by TPI-Formula350-

My 9 bolt was total rebuilt last year. I get a light humming on decel. I'm going to change the gear oil soon. I was thinking of using amsoil synthetic with the additive. I got an email from 9 bolt.com a while back and they said the additive wasn't needed but wouldn't hurt eighter.

Originally Posted by drain89

The Borg Warner 9 Bolt Rearend is actually called the M78 Rearend or "78 series". It has been made since the late 60's in Australia by a company called BTR Engineering Ltd. BTR was bought out by Borg-Warner under which company name the rears were produced for our cars. In the last few years Borg-Warner was bought out by Dana Corp. and the rears are still produced by Dana today in the same BTR factory under the "Spicer Axles Australia" name. www.spiceraxle.com.au/products.htm#srd


The rear is offically rated @ 220 kW = 295 HP
@ 435 Nm = 320 lb/ft
It can support a GVW of 2740 kg = 6041 lbs

The above ratings seem to be a bit conservative, as one member I know of has one that has survived the abuse of a 500hp/500+ lb/ft Big Block for a few years now. The 9 bolt offers a few advantages over a 7.625" 10 Bolt: 4 pinion spider gear design, shorter distance between carrier bearing caps, and a 7.75" ring gear diameter adds strength.
All 9 bolt rears for f-bodies use 28 spline axles.
Another advantage over the 10 bolt is it uses pressed on tapered axle bearings allowing the axles to be bolted in instead of using c-clips. I've heard several people say the 9bolt is stronger than the Dana 44. I do not believe this because in my many years of research, I've never seen one shred of FACT to support it. The dana 44 uses bolt in axles and has a larger 8.5" dia. ring gear versus the 9 bolts 7.75" dia. ring gear. Most, if not all Posi Dana 44's built for camaro's were 4 pinion versions also. Dana 44's were used by GM as service/warranty replacements for problematic 9 and 10 bolt rears, then offered them thru GM Performance Parts, and they were then used on the 91-92 firehawks if that tells you anything.

85-90 9 bolt equipped f-bodies were available with either standard open differentials or limited slip versions as well as several different ratios including: 2.77, 3.08, 3.27 (G92 w/auto), 3.45 (G92 w/stick), and a few 3.70 ratio's came in some 85 & 86 Firebird's w/ RPO Option Codes L69 (305 "High Output" Carb Engine), 5 speed trans, & G92 =Very Rare!

3.27 and numerically higher gears will not fit on 3.08 and numerically down carriers. If you have a 2.77 or 3.08 rear and want 3.27 or higher you will have to get a 3 series carrier. www.9bolt.com.

The "Limited Slip" or "posi" rears used on f-bodies used what is called the "Seperated Cone Slip Resistant Differential".
They also make a better version called the Hydratrak SRD but it uses a different spline count on the axles preventing it from being a direct swap into our rears

Vehicles originally equipped with the 9 bolt rear:
Australian made cars: Certain models of Ford Falcons since 1971, Holden Commodores from 1986 thru 1991, Chrysler Valiants since 1971, certain Aussie made Toyota Corrollas & Coronas, Nissan R31 Skylines/Pintaras & certian Datsun's, Mitsubishi Sigmas, Leyland P76s ...1997-up Morgan Plus 8s have the Hydratrak version. In the UK the rears were used on certain Vauxhall models and Jensen-Healey's.

I've also heard that Ford uses the 9 bolt center section in their Escapes and Mazda Tributes, but I haven't verified it yet.

The Nissan Austraila PN for 3.9 gears is 38100-J7100

3.7 gears were used in R31 Skylines with manual trans, the PN for those gears is 38100-J7110

4.1 gears were used in R31 Pintara's (manual or auto) and the PN is 38100-J7000

Holden's and Fords got nothing shorter than 3.45 gears AFAIK.


In 1998 the Australian magazine "Street Machine" did a series of articles on this rear axle, Another member has posted it somewhere in the thread below.

Originally Posted by aussie8

I have never heard of different carriers for different gear sets, maybe someone is trying to rip you off. If the ring gear is thicker or thinner it does not matter, you simply move the carrier across using the correct spacers so you get the correct contact

Originally Posted by chrisvanguitar5

F^^%^&%*($(($))#*$)$*$!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I have to get my car moved in the next two weeks and I have been looking for so long, moms telling me she will crush my gta if I don't move it, of course ill chain myself to the hood if that happenes and they can crush me to but im starting to get desperate here

Originally Posted by chrisvanguitar5

I am desperate to find a 9 bolt posi 3.27 - 3.45 ratio carrier w ring and pinion, my pinion and ring are good but I heard it has to be the same set you can't mix and match?

I am in Canada. does anyone have a good lead?


Thanks

Chris

Originally Posted by gearheadotaku

ok, I machined the cones .030. When fitting the crossshaft, it rocks a tiny bit even without anything under it. I suspect it's bent. Tried different positions and same result from the same arm. I think I'll have to live with it even though it's certainly not ideal.

Whats the typical amount of shims used here? .070 and no difference yet...