I think the clutches in my posi finally wore out or whatever they do when they stop working properly. Ironicly enough, it happened soon after putting the GM additive in about 6 months after changing the fluid with Mobil 1 syn ... worked fine until about when i put the additive in. (or perhaps it has something to do with the 6 speed, right after i installed that is when i notice it) but with 219K miles im sure its time was coming.. so now im getting that crappy one tire burnout (which i do more often since im not getting any good traction when trying to accelerate)... and going aroudn corners while accelerating suck alot more now..

so i want to know how much $ or how hard it would be just to replace what needs to be fixed? i mean if its just the clutches then it shouldn't cost as much as a total rebuild right? and its a 9 bolt..

 

oops. ment to post this in tranny\drivetrain forum. oh well

 

get rid of the synth and get rid of the GM additive. go with conventional GL5 fluid no additive. works for my 9 bolt.

if that doesn't help, I sell shims to tighten the posi.

 

whats wrong with the gm posi aditive??
dont you need that regardless of a 9 or 10 bolt, if its a posi you need to use that posi aditive? i am confused now..

 

well, 2 things...

1) the GL-5 gear oil is limited slip ready.

2) the GM additive listed in my 89 owners manual has been discontinued by GM and not replaced.

3) there are no clutches to chatter in the 9 bolt.

4) the additive is only to reduce friction, and if you disassemble
a 9bolt, you'll see you need friction for the cones to grab the inside of the carrier case. otherwise no posi action.

5) I've been running without the additive for 8 months and my posi works great

6) WTF do I know? I'm just a mechanically inclined guy who was a GM mechanic for 5 years

you have to pull apart a nine bolt and decide for yourself.

 

hmm. my posi was working fine without the additive also.. the only reason i put it in was because i noticed that like in the rain, when my tires would spin, i would hear a whirling type noise coming from the rear end. and everyone told me it was cause i needed the additive.. so could it be that because im using syn. and gm additive that there isn't enough friction for the posi to work properly? I think i am going to change the fluid and just go with GL-5 gear oil like u suggested..

Now how difficult is it to pull the 9 bolt out and check it. I really don't know much about rear ends. and my car is a daily driver (for now) so i can't go too long without it. but i am very mechanicaly inclined so as long as there are instructions and not to expensive special tools and it doesn't take too much talent\experence with rear ends, i can do it..

or is there any way to tell just by looking inside? or at least get some sort of idea?

also what is this about the shims, how would i know if i need them. Sorry for the ignorance.

thanks alot Larry Burd

 

there is an article around here somewhere about 9bolts. and there is a copy of the GM manaul on the 9bolt.com web site.

other than that you need a weekend (cause I'm a slow a$$), and a lot of patience.

I never played with too many rears before I did mine. you just need to put it back together exactly how it came apart plus a few shims.

I know there is a guy around here that just rebuilt his last week with my shims, and he is very happy.

 

:: Beavis and Butthead laugh ::

Stupid question... how do I know what kind of rear I have? As far as if it's a 9-bolt or whatever. What do I look at and where do I look at it?

 

hey larry, how do i go about ordering shims

i'm thinking
2x.020
2x.005
2x.003

doews that sound like enough to get the job done/
i plan on milling the cones .020 but i'll measure first.

 

if your milling the cones, then you need to make up the difference with thicker shims.

one guy here milled his .020, and I sold him .036 shims. he was very happy with the results.

but you should really measure with a good calipers to see where your at. I'd venture to say, every rear is worn a different amount.

 

if i take it apart first, how soon after payment can you get me shims?? how do you want to be paid??
if i send you a check ahead of time will you overnight the next day?

do you have a number i can call so i don't have to keep typing to you?

 

How exactly do you shim a posi. I hear alot about it and mine is going out. I can spin two on slicker surfaces but only one on most. I don't know it shimming would help me or not. I haven't really messed with rearends too much. Am I going to need a rearend spreader to preload the bearings. I have a nine bolt and I am even more in the dark on that. If anyone has any ideas or info on how to shim, or what to look for, or how much it should be shimmed please let me now.

 

read the tech article located on this board somewhere.

the amount of shimming depends on the amount of wear (of the cones and carrier case) and how tight you want to posi to be.

 

What is the GL-5 oil, and where do I get it? Is this a brand of oil or what? Also, what weight do you guys think I should put in my 9-bolt? And do I just keep filling it up with oil until I can feel the oil level off when I stick my finger in the fill hole (about how many quarts would that be, assuming gear oil is sold in a quart)? Most of you think the posi-additive should not be used so I guess I won't use it. Anyways, most gear oils say they are for limited slip rears, so I don't see the point of the additive. Suggestions? Thanks. -89IRO

 

I recently put a new 9 bolt posi in my car. I just started taking things apart and it was a lot easier than i thought. all u have to do is pull the axels, take the cover off, and theres 4 bolts that hold the posi in place.

I used penzoil(sp?) 80W90 (i think) gear oil that said that it didnt need the posi additive, it works fine.

if u need help just ask and i'll type more

 

i have a 1991 z28 with a 10 bolt...as alot of the other guys said get rid of the synthetic right off the bat...i dont believe its reccomended in our rears...another thing u gotta do is find out if you have a cone type or clutch type posi...the cone type(which mine was) DOES NOT NEED THE ADDITIVE...all it will do is make the cones slip their asses off....the clutch type does need the additive....i eventually got tired of my "part time" posi...so i said f*ck it and bout an EATON unit...all i gotta say is bad ***!!

 

Does my 9 bolt BW with a 2.77 gear have the cone-type posi like is discribed? I hope so because I just put in 2 quarts of 80W-90 Valvoline w/out the additive and it works fine. -89IRO

 

yes i believed the 9 bolt rears were the cone types 2...even if it wasnt u wouldnt hurt anything...u would just feel ur rear shuddering around turns and stuff...thats all the additive does...which is by the way WHALES OIL...lol...its just extremely slippery for the clutch type rears to function properly...but i brought my old posi back 2 life PLENTY of times by frequent fluid changes...its cheap enough 2 do it every other oil change...u should b ok just keep usin 80 90 weight...its hard 2 kick a 9 bolt rear's ***...trust me their tough!