jazzdadss

Throw them at me. I finaly found a disc rear to replace the drum rear someone tried to morphedite in my 89 IROC. It was in an 85 trans am at a salvage yard near me. The guy said it was a 10 bolt 3.27 so I went out to go inspect it in the weeds. Of corse there was mud caked all over it so I grabed a stick and started knocking the mud off and sure enough it still had the tags on it. 9 bolt 3.08 posi. Bought it for $250.00 and they will deliver it tomorow.
I tried to use the search function but it took me all over the place! I need to know the bad and the good.
Thanks in advance.

//<86TA>\\

iTrader: (14)

they are stronger than a 10 bolt, parts are harder to find, like the posi cones.

Drew

iTrader: (58)

The aftermarket is virtually non-existent. I've personally seen more broken 9 bolts then broken 10 bolts. It seems to be worse the better the gear ratio... The carrier might be stronger, but the 3.45 gear set seems to have a habit of losing teeth.

Stephen

iTrader: (12)

9-bolts are still used to this day, in Australia, where the 9-bolt originated.

Fewer aftermarket parts, but not "non-existent". But that is because they need less! :rofl: Seriously though...Parts are out there, just not as easy as walking into your corner Joe-Blow mom & pop shop to get the parts.

I want bigger rear brakes, but refuse to sacrifice my 9-bolt for the weaker 10-bolt to get them.

Bullydawg

iTrader: (7)

I dont like mine... Posi went out at 80k miles... then I rebuilt it and it went out again a few thousand miles later... I am looking for a 4th gen 10 bolt when money and time allows...

On a plus side, if I powerbrake it, the posi engages and works great, especially at the track. I just cant get traction.

Some love them some don't. If mine worked better and worked consistently I would be more than happy to keep it. I have looked at 3 9 bolts to purchase and all of their cone to carrier gap was too close and not worth installing. But then again, I haven't had good luck finding the 4th gen rear I want.

P.S... I have a set of machined posi cones I have been trying to sell with no interest. Parts are out there...

jazzdadss

What do you mean by this statement? I have the factory PBR's now on my 10 bolt. Will they not work with a 9 bolt???

I feel I may have just screwed up?????

Stephen

iTrader: (12)

The calipers are the same, but the mounting brackets & backing plates are different.

And I have a pre-89 9-bolt, so I have the smaller rotors & iron calipers, not the aluminum PBRs.

I'm pretty close to how to put LS1 rotors & calipers on my 9-bolt though!

jazzdadss

I guess what I am asking is. Will the caliper mounting plate for the pbr's bolt to this 9 bolt?

jazzdadss

I was reading in the tech articals that losing teeth was a comon problem when too much freeplay occured inside the unit itself?

Stephen

iTrader: (12)

Like I said the 1st time......
"The calipers are the same, but the mounting brackets & backing plates are different."

jazzdadss

I see that the earlier calipers are staggered where as mine are both behind the axle. Can I swap the Staggered mounts ( pre 89 ) for the 89+ rearward mounts like I have? I understand they are different but I need to know if they will swap.

jv9999

iTrader: (1)

As the cones and carrier wears, the spider gear contact gets worse and worse. Eventually something jams and breaks if you put much power through it. Keeping the oil changed helps a lot. Shimming the carrier as it wears also helps. They are strong when new, but at 80-100K most of them are done. The oil gets polluted from the cone/case wear and trashes the bearings. The cones wear to the point where they no longer grab the case and they become one wheel wonders. You can machine the cones and shim them to get more life out of them (most of the time), but all in all, they are cheaply made and designed to fail.

Drew

iTrader: (58)

I knew a guy who killed a 3.45 9-bolt with a LG4... That kinda shoots holes in the 'stronger then a 10-bolt' theory as far as I'm concerned.

Stephen

iTrader: (12)

Yep! ONE single failure makes all the others that have survived over the decades, as PROOF POSITIVE that the 9-bolt is actually weakt.

Bullydawg

iTrader: (7)

I would still get a 10 bolt though, parts are WAY easier to get. If I can find a 9 bolt with great cone clearance I would get it. They both have their good and bads...

Drew

iTrader: (58)

I didn't say that one failure is proof positive of anything. What I alluded to was a personal experience. I find that one failure behind an extremely weak engine to be an indicator that the 9 bolt isn't nearly as strong as it's reputation around here.

Personally I feel the great strength and durability of the 9 bolt that has been so often repeated here on this forum is a myth. A perpetual, unquestionable truth, like the 50 1986 L98 Camaros. Hogwash based on unsubstantiated hypotheses, and speculation. I've yet to see a single reputable source suggest the 9 bolt is some great performance axle. What I do see is GM performance parts pushing the Dana 44 as a substitute for both the 7.5" 10 bolt, and the 9 bolt. Also, if the 9 bolt was so great why would GM drop it in favor of the 7.5" 10 bolt just when TPI hit it's peak with speed density?

From my perspective, the 9 bolt is marginally better then the early 10 bolt, and probably about equal to the 28 spline 10 bolt. My opinion, is the 9 bolt isn't worth messing with due to it's limited aftermarket support. Considering that the newest 9 bolt is now 20 years old, at some point a rebuild is going to be in order. At that point the 10 bolt becomes much more attractive.

jazzdadss

Well ,Thanks for all of your input. I have chosen to stay with a 10 bolt. Servicability is a concern of mine as well as the knowlege base in my area for servicing such an animal as the nine bolt. Slim to none.