Genesis98

Just recieved this from a guy that works at BW. It is GM number's for BW 9 bolt parts.

DJP87Z28

Nice info if the GM dealers stocked the parts.

FruityOne

Perhaps it can be found on GMPartsdirect.com though.

DJP87Z28

Tried (4) of the P/N's there and NO GO.......... but still good info.

Fast-Tony

It is time to break the myth about the 9 bolt rear axle, it is garbage and my fellow 3rd gen "F" body owners need to pay attention, people have a misunderstanding that it is stronger than the 10 bolt, there is nothing better about an axle that has a cone drive posi carrier that gauls the cone wears surface material into the oil then ruins the bearings, if you want a better axle modify the 10 bolt with an aluminum girdle cover and an
axle "C" clip eliminator setup. there are articles out there that can guide you. Think? If you own a 9 bolt take the carrier apart and take a good look at the wear surfaces?

Fast-Tony

DoBeR

iTrader: (1)

Why would a 10 bolt with a girdle cover a c clip eliminators be stronger than a 9 bolt with a girdle cover and no c clips to begin with??? Even pople that dont like the 9 bolt usually agree that it is a stronger stock unit.

Fast-Tony

The 9 bolt has a cone type carrier that is a design failure from the start, if you have one around that has any mileage at all take the carrier apart and look at the cone wear contact surfaces? you will find that the cones wear badly and bottom out in the carrier in two separate land areas, both the cones and the carrier are made of soft materials, once this happens the clutch preload drops off and the carrier will slip even more, now you will have moly lube for oil and junk bearings. I have 4 carriers for the 9 bolt and they are all junk, GM only services the carrier by replacing the carrier as a unit, separate parts are not available. Another clear indicator is the fact the clutch slip torque is only 35 lbs new not much by any posi standards. There is nothing stronger about a axle that wears out faster than a cheap set of brakes.

fast-tony

884+3

I think some of the problems with the 9 bolts wearing out prematurely is the result of trying to use the standard lube and posi additive. If you read throught your owners manual very carefully theres a tiny paragraph that states the irocs with the 9 bolt require a special lube.
I had a problem with my car wobbling in the back end everytime i slowed down for a stop sign or something. It acted like the brake pads were dragging on a warped rotor. Took me a long time to realize the lube was the problem.
I put over 40,000 miles on the 9 bolt before i switched with a 4th gen 10 bolt a few years ago. The fluid in the 9 bolt looked the same as the day i installed it. And there was no sign of metal flake anywhere in the bottem of the rear.

MillerTime21

what kind of special lube do they need?

Fast-Tony

It would be nice if that were the problem but the truth of the matter is it is a junk design, so the 9 bolts are junk plain and simple. The carrier and cone materials are soft and in the mechanical world soft on soft does not work, there are no aftermarket Companies offering a clutch type replacement carrier. If you want more proof just call any axle parts Company such as Strange or Randy's Ring & Pinion and ask, they will tell you the same. Overall the 10 bolt with a clutch type carrier is better.

Tony

884+3

"...MillerTime21- what kind of special lube do they need? ..."

884+3

Heres a closer look.

884+3

Second try.

jmd

iTrader: (4)

See sig. for related opinionation.

They can't get anything that the dealer can't get.

JA_Formula_89

I will agree with one thing... The parts are more expensive, they are hard to find and are mostly special order. That makes this axle a bit of a curse when you need to repair/replace it.

One example:

AutoZone pinion seal 10-Bolt: $2.99 (in stock)
AutoZone pinion seal 9-Bolt: $15.99 (special order and you better tell them the part number! And that is the best price I found.)

When I was pricing them at the junk yard, the lowest price I found for a 9-bolt with disc was $350. The highest was $650. None of them were low mileage. They all claimed these were "high performance rears".

From what I can tell, GM put these rears in all their higher performance models. I'd guess that was for a reason - especially since I believe the 9-bolt was more expensive for them to install.

As for the additive, I can tell you that it does make a difference. I've tried various additives and only had good results with the real GM additive.

Using limited slip lube with built in additive does not work. The after market addtives are also inferior to the GM additives. I tried many things and only the GM additive got rid of my posi shudder.

- joe

5literTPIterror

i JUST got done replacing the 9 bolt disc rear in my 85 Trans Am, the teeth on the ring and pinion gear both were worn so badly they were almost pointed, and there was alot of fine metallic dust in the gear oil, the axle seals were also in bad shape and i also had multiple problems with the rear calipers(mostly leaking, even after they had been replaced)
i swapped in a 10 bolt out of a V6 firebird and will soon be upgrading to a (most likely) Eaton posi unit and a set of 4.10s

i sold the 9 bolt for 50 bucks and was happy to get that much for the piece of junk.

Fast-Tony

The best lube in the world is not going to make up for a junk design, the GM 12 bolt and Ford 9" never came with a cone type carrier and they are among the most reliable axles out there, they use replaceable clutches and those clutches rarely if ever need replacing, If you have a 9 bolt carrier around take it apart, it is easy and goes right back together, then you will see the junk design for yourself. The good design clutch type carrier was too reliable so the Manufacturer GM Borg/Warner had to come up with something with a limited product life. As I said the 9 bolts are junk.

Tony

DJP87Z28

On the previous Post:
Just another guy that got stuck with a 2:73 10-bolt VENTING.....

bjankuski

I just rebuilt my 9-bolt and I was fairly impressed with the design. The cones were worn but you can get replacement cones from 9-bolt.com along with any other pieces that you need for the rear end. My criteria to determine if a rear end is a quality piece is how much power can the rear end handle before failure. A 9-bolt that is in good shape can handle at least 500 HP and if you do break an axle it is not going to come sailing out and damage your car or someone elses car.

The nine bolt is the best rear end GM ever put into the third or fourth gen F-bodies and if is properly maintained it will perform well for years,

Fast-Tony

If you replaced the cones how about the carrier surfaces?
where did the metal go that wore off? and how do the bearings look now? also the outer axle bearings run in the same lube? All 4 of the carriers I took apart had thick gray metal inside the carrier, crap looking bearings and thick lumpy oil. A "C" clip eliminator kit for the 10 bolt would stop the axles from comming out should one break. The 9 bolt would have been a great axle if it had not had a cone carrier. The 9 bolt is still a garbage design.

Tony

Dr G

I wish I could get a hold of products from 9-bolt.com but he has never responded to my emails! I wish the guy would though.... so Miles if you see this - please reply!!!

Bjankuski:- How did you manage to get a hold of him? Could you forward an email to on behalf of me?

Fast-Tony

Save your money? the 9 bolt is only good for bench racing where you can sit and brag about what is in you car, not how well they hold up? Go 10 bolting and be happy!

Tony

jmd

iTrader: (4)

specifically, what sucks about them besides the cones?

Have you ever run one with the correct lube as 884+3 has alluded to here in this thread?

If it "would have been a great axle" then it's still a "garbage design" ? Contradict much?

Done whining yet?

Fast-Tony

What sucks is that the cones and carrier are soft, they gaul badly regardless of lube type (85-140 with additive) when the cones wear they move deeper into the carrier as that happens the distance between the cones opens up lessening the cone spring preload causing the differential to slip even more, then the cones and carrier bottom out on each other on two different lands (raised area at minor end of the cones and a raised ring extending into the carrier from the axle thru hole) all this metal goes into the lube for the bearings to run on. Replacing just the cones or just the carrier won't work for long because both mating surfaces cone and carrier gaul together. If you have one take a look. All other aspects of the 9 bolt are better than the 10 bolt. The ring diameter is .125" larger, the ring is closer to the center in the housing, the axles are .100" larger in diameter at the spline end, and the non "C" clip design. Those who think the cone type posi is a good design don't have enough experience with a good clutch posi. I have 32+ years building drivetrains.

Tony

jmd

iTrader: (4)

That's what I was looking for.


I don't remember anyone here saying that cones were better. Goodness knows, I know that clutches > cones

Settle down there, killer.

Fast-Tony

The idea here is to inform people of the pros-cons of the 9 bolt, what I have explained to you in long is that what happens with the 9 bolt is that the positive traction performance fails and takes the rest of the axle with it. This was intentional from the start with the design. I have spent a grand on 9 bolts and parts to upgrade my two IROCs then found the design flaw. I will take a different route 12 bolt, 9" ? If I had know before what I know now I would have a grand more in my pocket. As for the 2 complete 9 bolts, 2 spare posi carriers, spare axles, extra 3:45, and 3:27 gears that now take up space in my garage I may hang them out and watch them rust away?

Tony

bjankuski

To contact Miles at 9-bolt.com I just sent him an e-mail that I needed parts ASAP and he responded with the prices and parts.

Brian

DoBeR

iTrader: (1)

Ive got the stock 9 bolt in my car with almost 175k miles now and it still runs perfectly and launches good and hard. I just picked up another one with a better ratio and around 80k miles on it. The oil looked fine and I found no traces of metal in it. Ill have to see what my current rearend looks like when I open it up this weekend hopefully. Either way im happy with it and it has not yet given me any trouble.

Dr G

Thanks Brian, I'll give him another try and hopefully might get somewhere this time. I'll let you guys know how I get on.

Fast-Tony

Reply for DoBer

When you take apart your 9 bolt can you take apart the carrier and take some pictures of the cones? carrier mating contact surfaces tapered bores? than attach them here? I invite any others to do the same.

Tony

JA_Formula_89

Hah! Fast Tony has got us on that one! :-) I have not seen ANY pictures of good or bad cones yet!

Someone please do this, I want to see for myself!

I don't like the fact that its "wear" by design. Fast Tony is right about that. However, my rear made it 170K w/o any service at all. Maybe I was lucky???

In a way, this is sort of like saying... Hah, I dare you.. Anyone out there take pictures of your brakes and show me that you don't have wear on your pads! :-)

FastTony's view (and maybe rightly so) is, -- Hey, if they designed it right there would be no wear at all. In that sense, I'll agree. There was a compromise made.

If I do a POSI-TEST and pass, does that mean my cones are still good enough???

In the service manual - I thought I saw they mention that if you fail the POSI TEST that you need service. At the time, they probably thought changing the cones would be like going to get a brake job. Instead, its only the guys in 3rdGen.Org that would ever even consider it!

In my opinion the worst thing about the 9-Bolt is that its so rare. They only made them for a few years. They were only used on a few models of cars. That makes finding parts, getting service, etc all more difficult and more expensive.

DoBeR

iTrader: (1)

I think the 9 bolt is quite a bit more popular in austrailia. I know the new GTO has an IRS version of a 9 bolt. Im not sure how different the new rearend is but the holden monaros and stuff seem to have 9 bolts, even the older ones.

Fast-Tony

I compare the problem to having metal debris or shavings in engine oil, no matter how good the parts used the engine will still run but what is happening to the friction parts? Its just a matter of time and the harder it is used the worse the problem gets. The cones and carrier would be ok if they were not soft, I consider this a light duty posi, this to me has turned the 9 bolt into a no go. I have a relative who bought a 87' IROC new and within the first year the GM Dealer had to replace the differential carrier assembly, the relative said all he did was light them up while turning a corner and after that he had a single trac?

Tony