87camaroz28.

First time posting, figured id make a account to join the conversations, but i do have a question
I just got a Borg warner 9 bolt posi rear, i want to find out the gearing and im told the p/n tells you all you need to know, well i found a site to look it up, and the p/n wasnt on it, some where close, but no cigar. Anyone have a site i can look it up at or any info

P/n 10046603
Ratio 3·45 sern

big gear head

If the ratio is 3.45 then your gears are 3.45. What is the question?

87camaroz28.

I might of mixed it up. I was told that the p.n will state all infomation (question being gearing) but i was confused cause i thought the ratio ment the gearing. Guy at store said thats not always the case? Idk if hes smoking crack or what, but i had to ask. What does the P/n actually tell you, if anything

sofakingdom

iTrader: (1)

Only need to post this once.

As I posted elsewhere, the part # you posted is the casting # of the housing. doesn't tell anything at all about what's inside it.

"Gearing" is another word for "ratio". If you have a 3.45, then you have a 3.45.

Whatever you saw when you popped the cover off to inspect it BEFORE you bought it, is what it is. Didn't change when you put the cover back on.

87camaroz28.

Well i got into a debate with a fella who claimed that it would tell you more about it, year and production or whatever. it maybe idk. But i wanted to ask to see if thats true, id never heard of it before.
Anyone know best olace to get sone cailbers for this thing, it has the stock ones on it, which its from 87-89 then needs a replacement, trying to search summitt at the moment.

JamesC

iTrader: (5)

Any auto parts store will carry the iron Delco-Moraine calipers (88 and earlier).

JamesC

87camaroz28.

thanks! yeah I found them at a local store (on order only). iv never replaced calibers from OEM to aftermarket, how would I know what can fit on the this rear end? from what iv heard they use to have problems with the stock calibers, I don't know if the replacements would be a "fixed" or if id run into problems later on, but if I can find aftermarket ones that don't cost too much more then why not get them. any thoughts?

sofakingdom

iTrader: (1)

If it's a 88-back rear, it will have the cast-iron Saginaw calipers. (spelled w a "p")

The ones you get in the store aren't "aftermarket"; they're the same as OEM. Remanned, usually.

AFAIK there aren't any "aftermarket" ones "that don't cost too much more" available that will fit in the place of those. You can get the usual stuff (Baer, SSB, Wilwood, etc.) but the price difference is significant.

That system is notoriously crappy in general. There are ways to improve it but it's likely to always be problematic. If that's what you want to put on your car, best to just realize that it's going to be maintenance intensive and troublesome and frequently in need of attention.

The newer system (89-up) with the aluminum calipers, made by PBR out of Australia, is MUCH better. If that's what you've got, then you're in MUCH better shape than if you have the old cast-iron ones. Not as likely though, as that combo (9-bolt w PBRs) was a one-yr-only deal, and there weren't a whole lot of them even in that one year.

What does the inside of the rear look like? Cones still got a ways to go before they bottom out? Most are completely wore out by now.

87camaroz28.

What does the inside of the rear look like? Cones still got a ways to go before they bottom out? Most are completely wore out by now.[/QUOTE]


the inside is great, guy bought it for a back up with less then 20k miles on it, had it sitting for years and his sons firebird never need his (same rear) replaced, so he figured he'd sell it.
as for the calipers they are the "offset" style made of cast. I think I saw the years where (87-89?) don't quote that, I don't know the year of the rear, I cant find a place to look up the casting code, I guess there's allegedly a code on the tubular part, I didn't see one at all, only on the differential housing.
that number being 0578-02590 731
(read that off a picture I took on the phone) could be off, but if anyone has a way to look up the year by this code I can get it again later

sofakingdom

iTrader: (1)

The cast-iron calipers were used 82-88. All the same.

That model of rear appeared in 85 and was used through 89. 85-88 got the cast-iron calipers, 89 got aluminum.

Year of the rear doesn't matter past dividing it into one of the ranges. A total non-issue.

If you have cast-iron calipers then your rear is 85-88. That's all you need to know.

Don't bother with "codes". The parts ARE what they ARE, which you can tell by simply LOOKING at them. Much easier than futzing around with a bunch of that other.

87camaroz28.

[QUOTE=sofakingdom;5887767]The cast-iron calipers were used 82-88. All the same.

That model of rear appeared in 85 and was used through 89. 85-88 got the cast-iron calipers, 89 got aluminum.


Are the aluminum ones better? Is there any vhange between them besides material. Would it be worth buying replacement ones for that style (if i can even find some) or sticking to the cast ones,
Thanks for all the information on this by the way. Very helpful

JamesC

iTrader: (5)

Are the aluminum ones better? Is there any change between them besides material. Would it be worth buying replacement ones for that style (if i can even find some) or sticking to the cast ones.

PRB's aren't a direct replacement for the Delco-Moraines. The following links will provide the info you need:

Fitment:

https://www.thirdgen.org/forums/faq-...iscs-89-a.html

Info about master cylinder, combination valves, and parking brake cables:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

naf

iTrader: (7)

The pbr's will work fine with your existing mc and proportioning valve. The DM's will work 'ok', but factory had a different mc/pv.

If you need to buy new rotors and pads anyway, I'd strongly consider the swap.

JamesC

iTrader: (5)

Personally, for best performance, I'd use the combination valve designed for a particular braking system.

JamesC

naf

iTrader: (7)

Exactly. When I installed a nine bolt with the DMs onto my 87 many years ago, I rebuilt them with the recall kit and swapped MC/PV. I'm now in the process of acquiring the remaining pieces for the PBR swap. Should have gone that way then.

JamesC

iTrader: (5)

Don't you just love hindsight? LOL.

JamesC

Metalizer

I just picked up one of these Australian 9" with the aluminum calipers. The metal tag says it has 3.23 gears and posi seemed to work well.

I bought it to convert to a rear with posi and disc brakes....the guy I got it from said they're extremely rare and solid differentials.

My only concern at this point is where to get the stainless steels brake lines. The OEM steel hard lines probably need to go.

JamesC

iTrader: (5)

Not particularly and not particularly (though a bit stronger than the 10-bolt). A search will provide a ton of info if you're interested.

You should be able to find what you need from Fine Lines, Classic Tube and/or Inline Tube.

Good luck on the swap,

JamesC

Metalizer

I'm sorry, I meant I was looking for stainless steel braided lines. I came across the goodridge kits but want sure if it's a direct fit.