I need some help. I have a chance to get a 9 bolt rear. the onlt thing it has bad gears in it. Where can I get new gears at a resonable price. It has a three series carrier so how low of a gear can I get. I need help fast if it is going to cost too much I am going to pass on buying it.

 

You can get any ratio numerically higher than 3.08.

You can find 3.70 gears for pretty cheap now, but 3.45 and 3.27 are becoming harder to find. Check the classifieds for 3.70 gears.

 

You just have to keep looking at the classifieds and Ebay. I found some good sets there. I just couldn't get them when I had the chance. They are out there. You just have to keep an eye out.

P.S. Just let me know when you want to get that rear

FBird

 

Here are a couple morer sources for 9bolt parts and gears:

http://www.drivetrainspecialists.com/index2.htm

Off and on they have new parts and gears for the 9boltBW.

http://diffsolutions.com/

This fellow is hard to get in touch with as his site is a secondary part time job. He has many parts and gears - some new , and some used.

Hope this helps, Cocacolakidd

 

reider racing has 3.70 gear and the installation kits.

i called them abit ago and they said about 120 for the master overhaul install kit with all the bearings and such, and the 3.70 gears are on back order but cost 299.99. kinda pricey

 

299.00 for gears and all bearings shims? that's a deal

 

Do you have a URL for "reider racing ", sounds like they have some really good deals there. Cocacolakidd

 

www.reiderracing.com You will need to call to get prices though. 734-946-1330 is their #

 

Thanks for the info...3:42's for the 9bolt are hard to find sometimes. Cocacolakidd

 

That is why I have a 10 bolt now

 

Don't know where you guys have been looking, but we have been supplying gears, bearings, seals, etc to fit the "9 bolt" for some time. When replacing your ring and pinion, ALWAYS use new ring gear bolts. The most common cause of having to re-work one of these axles is an uninformed technician, mechanic or enthusiast not replacing all the parts necessary, either through ignorance or some mis-guided attempt to do the job as cheaply as possible. Remember, cheap may be good, but good is never cheap. GM discontinued these bolts years ago, but we have bolts from the original supplier.

The only readily available gearsets are 3.70 ratio because that is the one in demand.

One area to pay particular attention is the axle seals. Use only the O.E style, rubber coated seal. CR was the supplier to BW of Australia, now BTR Engineering, Div of Dana Corp.

Detroit Locker makes a diff for these units also.

A few years back, we made and sold a cast aluminum rear cover/girdle, and it was successful. Demand dropped off so we stopped making it.

As with anything performance related, hook yourself up with a solid reliable supplier and get rid of the Wal-Mart mentality of always chasing the lowest price for your parts.

If you chaps have any further questions about this or other axles and parts please ask away. Incidentally, the 9 bolt article I saw here before the crash was very comprehensive and showed good knowledge of the subject. I noticed some discussion about certain axle ratios, mainly 3.27 and 3.23. 3.27 was the ratio available in this axle at the time it was being installed in F bodies. The current ratio listed is 3.23. Changes such as this are usually made to bring either the ring or pinion gear tooth count into line with another popular ratio.

Hope i haven't been too long winded, and thank you all for your time.

 

Do you have a web site for your buisness? Thanks.

 

Not to hijack a thread but------ Precision Trans, you made a cover for a 9-bolt???? Perhaps you noticed the interest in such a part on this forum? Any chance of resurrecting such a part? We need a supplier for 9-bolt parts. How about your url?

 

Sorry Guys:

Monday morning and all. The e-mail for Precision Transmission is "mail@precisiontransmission.pe.ca" Our URL is"http://www.precisiontransmission.pe.ca"

Regarding "9 Bolt" Parts.

I hate referring to this unit as a "9 Bolt". Yes, there are 9 bolts holding the cover to the carrier, but there are only 8 bolts holding the ring rear to the diff case. The unit is referred to as a Model 78 in the land of OZ, and a 7.75" by GM of North America. A derivative of this unit is used in the new Pontiac GTO, but before you go running there to look for parts, it uses a 10 bolt ring gear, and is a centre section for independent rear suspension. Even the ring gear bolts are only sold with a ring and pinion kit.

Cast cover/girdle

We had 150 castings made and machined them in our shop back in 1997. Initial response was super and the first 75-80 units flew out the door. In the natural order of things, sales slowed as the primary demand was filled. Selling the last five was like trying to give away a disease, with everyone wanting them for nothing, or knowing where "some guy" had one cheaper, and would I be willing to beat some imaginary fire sale price. All in all rather discouraging so no more castings were ordered and the tooling was redirected to other things. I'm certain that another release of this cover would be even better what with the lessons learned from the first go-round. (Ductile iron, anyone?)

Replacement Differentials:

I, personally, was never a big fan of the cone clutch limited slip diff. It is the same design used by Chrysler in the late 8 3/4 "Sure Grip" as a cost saving measure over the previous Dana supplied unit, and by some GM divisions such as Pontiac, Olds, and Buick in the 60's. It was designed, built and supplied by Borg-Warner. Fancy that. Needless to say, we know how it ended up in this Model 78 axle.

During the same time period as the cover project, we looked at utilizing the disc clutch components from other diffs and installing them in a case of our own manufacture to use in the Model 78. A few prototypes were machined from billet steel and rigorously thrashed with stroker motors, slicks, and traction aids. Problems were no worse than expected, but as the factory units were holding up superbly at the time, there was no market. Fast forward a few years and I can personally take you to more than a few cars with bad diffs that aren't driven because the required parts are considered too expensive by the vehicle owners. Seems the "price guide" states that a complete rear axle should never exceed 25% of the price of the stereo in the car. Go figure. ( 5.0 and 4.6 Mustang guys are just as guilty here, but it involves transmissions)


So, now you have the story as to why we now only deal in gears, bearings, bolts, seals, etc for this axle. If demand truly is there, then certainly we would seriously consider re-issuing these parts.


As always, if there are any further questions please do not hesitate to contact us at Precision Transmission.

 

ta performance makes aluminum girdles for them and has for a couple of years now!!!

 

This thread is a over a year old now. It is about time they made one.

 

Yep, TA sure does make them, I got one of the first ones, and here's the proof!




It's a very nicely machined piece and definitely worth the price, I'd recommend getting the stud kit with it also for added strength!

-Paul

 

TA does make them. I have one on my car as well. Now if only someone made gears for the thing. The only ratio available anywhere is 3.73 (I really looked around). My gears howl like no other and it's annoying the hell out of me. Everything's been pulled/reinstalled a few times. Nice tooth pattern, good backlash, etc. There's just a very small blemish on every single tooth in the exact same spot (slightly indented line from a dirty carbide bit). I guess that's enough to make the whole thing whine like no other on part throttle.

 

there are alot of places that sell correct replacment ratio gears for the 9 bolt. here is one right off the top of my head http://www.ring-pinion.com/content/p...sp?vid=4&pid=4
(never bought from them)

now I am not calling anyone a liar but, I can tell you the gto rear diff is night and day from the 9bolt. if you do a search with my name and the gto diff I have a side by side of the two gears and diff..... the only thing they have in common is the part of the world they are from. here is one scroll down https://www.thirdgen.org/techbb2/sho...ng#post1977038


and why we never heard of the rear cover befor??? don't know on that one but, it is possiable since there was alot of aftermarket for these cars at first and due to low sales at the time 90% of these places gave up and went with other cars

 

www.diffsolutions.com has any ratio you want. I recommend him. I put a new set of cones in my posi and replaced the ring gear bolts from him.

 

Yep, I got new cones and a spring pack from him too. He told me he didn't have many sets of cones left though and that when he was out that was basically it because the manufacturer wouldn't make another run unless someone bought a couple thousand or something like that! I think he's pretty much getting out of the 9 bolt stuff so if you want something you should get ahold of him ASAP, he's great to work with and will help you out with as much as he can for sure!! Also keep an eye on eBay. I got a spare 3 series posi carrier with a 3.27 ring gear (would have had the pinion too, but the guy couldn't get it out of the rear) for a little under $100, sometimes they pop up on there and you can get a decent deal!

-Paul

 

Was that carrier off ebay in good shape?? My cones were bottoming out on mine and those new ones have plenty of room!!

 

I can't say for sure since I've never taken it apart. I think it supposedly has like 80k or so miles on it. I just wanted to have a spare in case I broke anything. I figured it'd need a rebuild, but it might be ok. The whole 9 bolt rear that's in my car now was $25 and needs the new cones installed in it before I go drag racing this summer

-Paul

 

Also, for what it's worth these guys have a good selection of small parts (bearings, gaskets, seals, etc.) for the 9 bolt!

-Paul

 

I ordered my rebuild kit from ratech and everything else from diffsolutions. It was cheaper but the shipping was really expensive. Something like 30$. You can usually tell how worn it is. When I rebuilt mine in fall I noticed there was a little window on the side of the carrier. If you see the cone and it pretty much covers up the whole window it is worn. If there is some space and you can see in there somewhat it will probably be in good shape. That carrier comes apart really easy also, just unbolt and separate. I thought it was going to be a big mess but it wasn't at all. Thanks, Mark

 

me and another member made a write up. very very detailed with good pictures.

 

Hey Guys
Where the sorce for that T/A 9 bolt cover.

 

Here ya go! http://www.taperformance.com/rearend.htm