The posi is about gone on my 88 IROC. I may be able to get a cheap (maybe free!), unused 9-bolt posi unit off of a "friend of a friend's brother". The friend lives in Florida and the friend's brother lives in Pennsylvania. You probably know how these things can go...

I want to make sure that it is a 9-bolt posi before I enter into any negotiation.

I am NOT an expert on rear ends and quite honestly have never seen a posi unit beyond pictures in catalogs, so be kind please.

What could I look for on the posi unit to be sure that it is a 9-bolt posi unit? Will it have Borg-Warner stamped on it? Is there a specific feature (or group of features) that distinguishes it as a 9-bolt?

My funds are limited these days and getting this right could really help me out.

Thanks.

 

My 9-bolt has Borg-Warner stamped on the bottom of the differntial case.. it has a tag saying "Limited Slip Unit", and also a tag/stamp with the serial number and gear ratio.

Hope this helps.

 

the 9 bolt will say aust . patent and the patent # will follow. the pat # on mine is 222888
HTH

 

Are you guys referring to the case or the actual posi unit itself? I know that the axle assmbly is stamped with "Borg-Warner" and logo, but am not sure about the posi unit. The posi unit in question is a new piece just sitting on a shelf. No gear, no cover no axles, etc.

Is there something mechanical about the design of the 9-bolt posi unit that would identify it as the correct one? I know that the standard 10-bolt is a clutch-type posi and the 9-bolt is a cone type. What is the visual difference between te two?

Thanks.

 

wht i said was on the carrier(posi) . i was looking at my old carrier as i wrote it.

 

Sorry, I was referring to the casing itself. I've never taken my rear diff apart. (So far it's the only thing that hasn't given me problems. *knock on wood*)

 

Well, it looks like I need to look for a stamp referring to an australian patent. Thanks.

 

Here is what is should look like.

http://www.geocities.com/mek88427/te...i_series_3.jpg

It should have a cone style posi unit and have 8 holes in the ring gear mounting flange. It probably also has Borg Warner markings on it somewhere.

Miles
www.9bolt.com

PS What series is it and what series do you need?

 

Thanks for the picture, Miles. As I'm sure you've noticed, I've been torturing myself with this for months. I keep believing I'm going to tear the motor up and the rear won't matter... The L98 is pretty tough!

As for your question, I think that this unit is for a 3.27 rear, therefore this would be a series 3 (I assume that the 2.77 is the series 2, which I have today). ...don't know much about the "series" question so I'm speculating. The reason that I say this is that this is an old spare from a now non-existent IMSA Firehawk team (Joe Varde was the driver, if you've ever heard of him). This posi unit should be from an 88 or 89 Trans Am. This unit has been passed around multiple states by guys who didn't know that they couldn't use the 9-bolt stuff on 10 bolts, so they passed it on. This apparently started around 7 years ago...

Anyway, what I plan to do is chase down the next guy (I am already 4 guys deep) and get the posi, then decide if it is compatible with a 3.27 gear (which I would like to put in when the posi goes in), then buy the appropriate install parts from you. This has been a painfuly slow process.

If you like, please educate me on the differences between the series 2 and 3 carriers.

Thanks.

 

Keith,

Quite the adventure If the carrier is for a 3.27 (ie series 3), you can run any of the gear ratios listed below.

Series 2 carrier is for 3.08 & 2.77 gear ratios.
Series 3 carrier is for 3.27, 3.45, 3.70, 3.73, 3.9 & 4.10 ratios
and if someone really wants (and has money to burn) I can set up a 9 bolt with 4.56, 4.88 or 5.13 gears, but again, it's not cheap.

Miles
www.9bolt.com

 

Miles, thanks again for the information and your patience. Yes, this has been quite the adventure. I hope there is a reward at the end of this long, dark tunnel...

From your post, I suppose that I need to keep my fingers crossed for a series 3 carrier. I am trying to stay in SCCA Solo II stock. Since the 88 IROC came with 2.77 or 3.27 ratios, that is all I can (technically) run and I would prefer to stay stock. The 3.27 would be better for me in competition. If it turns out to be a series 2 carrier, they I suppose I'll need to stay with the 2.77. Either that or (series 2), I can ask my competitors if they are going to protest me if I go with the 3.08. If not, then I may go this way.

I gotta get this done. I'm planning on putting the 'ROC on Watkins Glen (full course - 3.4 miles!) May 6th and/or 7th.