I have a 9 bolt posi rearend out of an 87 formula with 2.73 gears in my backyard
I have a regular one legger with 3.42 gears under my car right now

I want to put the posi under my car soon but I want gears closer to what in the car now, maybe a little bit better on the highway

what are my options given that its a 9 bolt & posi

PS I want this rear end also because its disc

 

https://www.thirdgen.org/forums/faq-...now-about.html

 

I know about that I just wanted a simpler answer more directly related to my issues

 

do you want to sell that 2.73 in your back yard? I think you have a 2.77
Bob
Palm Bay Fl

 

I don't think I want sell it. Why you think its a 2.77 not that there a big difference

 

9 bolts to the best of my knowledge came in the following ratios. 2.77 series 2 carrier 3.08,3.23,3.27,3.45,3.7,3.9,4.11 all series 3 carriers. Not all were imported in the United States. Borg Warner made these for the Holden. At 100 MPH it is 61 RPM difference all things being equal if you have a 2.73.
Its just I have never heard of one. Of course there are lots of things I have never heard of.
I did get a 2.77 gear set in Orlando and a complete 2.77 rear end in Miami. So I am set
Bob

 

well I use the chart on this site to find out what the Gears were I haven't actually turn it and counted it

 

----Poor method.

2:73 10-bolt ratio only.
2:77 9-bolt ratio only.

Do you really know what rear assebly you do have???

 

I know its a 9 bolt posi, disc brake assembly out of an 87 Formula Firebird thats about it

 

Well I am not going to continue guessing what you hav with the little info you are giving. Let someone else play the guessing game.

 

Definitely 2.77 gears
I took it apart and counted the Gears 36 & 13
plus after I did that, I was cleaning off the cover and lo and behold I found the tag lol it also states its 2.77

 

ok well i think i may be able to help you in your quest for answers.

i just recently swapped out my 1 legger 10 bolt from my camaro.

and dropped in the 9bolt posi rear with disc brakes.

despite the fact that the sell was a complete garbage peice of Cow Dung.

and the fact that i have never repaire one.

i love it!!!

if you are really concerned about the gears you can buy them later on.

now ppl here might start flaming about what is stronger than what..
but unless you are planning to use this as a race car thats putting down 500+hp and tq. then i wouldnt worry about it.

just like anything you take care of it when it happens...

while the rear end is out. i would honestly replace the axle seals along with the wheel bearings.

you need to find some one with a hydraulic press. to press off the old lock ring and wheel bearing and press the new stuff in...
and change the pinion seal while you are at it.

after that freshn her up with some new gear oil..

but i highly recommend doing those things before you install it.

the posi rear helped sooo much as far as traction goes.

well that and i hopped up from a 215 tire to a 265..

but still it hooked up nice. and if you are a fan of 16'' wheels and up. its nice eye candy to see 4 wheel discs..

hope this helped

 

I can't seem to find a place the has the seals. where did you get yours?

 

well it was an extreme pain in the a s s.

i work at an auto parts store.
yeah i work at a REAL one.. not one of those pep boys kids that you ask them for a thermostat gasket and they give you a water pump. with gaskets.

but anywho.. from all my suppliers and then some.

they are on NATIONAL back order...

i managed to find myself both axle seals and pinion seal along with the wheel bearings.

if you give me until tomorrow ill post up the part #'s so you can try and find them.

if worst comes to worst ill get them for you and all you gotta do is pay for shipping and the cost of parts..

but keep the rear end. you will enjoy it.

 

thank you, about how much did it all cost? so I can prepare, and how long ago was it?

 

it was about a week ago..

the seals cost me like 7 dollars each.

the bearings were a little more ill look at my invoice tomorrow. and post the part numbers and brand..

 

if you're taking apart your 9-bolt, you oughta reassemble it with one of those TA alum girdle rear-end covers. I did for mine, and it's a work of art. does require some spot-surfacing of the bearing caps to provide a flat surface for the girdle bearing-cap support bolts. pretty straight forward. get the studs while you're at it, they're 3/8-16.

 

what exactly is its use? and where can I pick one up?



EDIT: 160 Bucks? for a cover?

 

http://www.taperformance.com/proddet...prod=TA%5F1802

under hard acceleration, the forces try to spit the differential out the back of the rear end housing. the girdle braces the rear end caps by providing a solid structure, and the load bolts press against the rear end caps to offset some of the force. this provides a more stable, rigid environment for the differential. hope that helps some. read all about it on the TA Performance web site. other companies sell these rear end girdles, but I think TA is the only company that sells one for the 9-bolt.

 

anyone else tried these? any proof to what they claim?

 

I also need help with my 9 bolt rear end. I am the original owner of a 1989 GTA with a 9 bolt rear end with 3.45:1 gear ratio. This rear end was recently inspected and the ring and pinion gears were in good shape; however, the posi was wearing out, the pinion bearing was wearing out and one wheel bearing was gone.

The transmission shop I dealt with suggested installing Eaton limited slip differential in this rear end and I have sent an e-mail to Eaton asking if they make anything for this rear end. The shop I dealt with indicated you can get the cones for these rear ends but not the parts they fit into? I know very little about this so any information would be use full. I read the thread above on “everything you need to know …” and did a search and could not really find what I need.

I would like to stay with this rear end to keep the car reasonably stock as I plan to own the car for another 20 years. Where can I get parts to either completely rebuild the existing posi or is there another posi I can put in it and where can I get bearings and a kit to have this rear end rebuilt. Thanks for your help.

Oh by the way I went to my local Pontiac dealership who indicated there is a guy in the US that has bought up parts for this rear end and that the part number for what I need is 12506812 but that it would cost about $1700 to bring it to where I live. So I need another option.

 

well if everything goes well I should be putting my rear end in this weekend what gear oil would be best? I heard of posi specific gear oil is there any truth in that?
also should I use that lucas stuff?

 

lets see, where to begin:

it's very difficult to find the positraction carriers anymore, they would have to be used, so if you wanted to run more than the 2.77 gears, you will need a new (used) carrier. can't fit the 3.27 or 3.45 and up ring and pinion with the series 2 carrier.

you should be able to get all the 'soft' parts, seals, bearings, shims, etc, from randy's ring and pinion, or ratech maybe? they are yukon brand I beleive, no worries about that.

if the posi is worn, there is a guy that sells posi shims, larry burd or something like that. you need to machine the cones, or apparently you can get new cones.

the girdle/cover is a no-brainer, it adds strength to a rear axle, and since parts are harder to find anymore, it's totally worth it.

lastly, i think that thread linked to above has pretty much all this information already.

 

if im not wrong i dont think the 9 bolt posi's take any lsd additive. i think they take straight gear oil.. none of that friction modifier or anything..

 

Hey Simply, Im having a hell of a time finding the right parts. I mean my checkers and Napa are stock but, they can't give me a clear anwser as to which ones I need.

There telling me I need two different sized seals and ones 15 and the others 30!!!What the hell.... then there computers tell me the rear end supposed to have drum brakes.

I am looking for parts for a 7.75 ring gear, right?...Just to clarify

 

yes 7.75 ring gear.

im not sure if the setup came with drum brakes or not. but yes the driver side and passenger side seals are different.

like i stated before seals are very difficult to find.. whats the confusion about not knowing "which ones to get"?

 

not sure which bearings to get since the ones for 7.75 ring gear say there for drums I don't see how there could be a different in the bearing but meh... maybe drum braked axle bearing are stronger?

so the seals are different, is one bigger than the other? are the bearings different?

 

Go to ratech's website, you can see each and every piece for a 7.75" 9 bolt rear axle. One seal is flat, the other has a flange of sorts, I'm not really sure why, but they are the same disc or drum.

http://www.ratechmfg.com/

I can't make it any easier for you......

 

If I put the LSD addtive in will it hurt anything if the rear doesnt need it?

 

I wouldn't think so.