is my diff shot ?

[bigtow]

hi i have a 93 formula which i have been giveing some stick on the road and at the track but now i think the diff is playing about. before when i nailed it out of a juction it would light both rear tyres now it just spins the in side wheel but once i get the car straight it snaches from side to side and is no where a pridctible as it useto be plz help. the car has got 86k on the clock do you think a gear oil change will help or is the diff shot? .if so what is my best option for a new diff unit as i do drive the car hard on the street and track

[bigtow]

re diff oil

oh i forgot to say i have some royal purple gear oil that i got last time i was in the states is this any good ?

[N20LT4Bird]

Sounds like the clutches in the differential are worn. This would be a good time to change the rear gear ratio, but you dont have to. You can go in and just replace the clutches. Its a job probably left to a professional or get some help if you have never had one apart.

Oh and I have heard that the Royal purple is good stuff, but I have never used it.

[bigtow]

thanks

as i use the car every day as well as race it what type of diff unit do you sugest . i pall of mine has just fitted 3.73s to his 97 formula which has also got a zex nos system on it and he suffers from very bad traction of the line to the point that i can beet him to the 8 th mile. i am thinking of nos or a blower for mine so i think i will need a upratied lsd unit

[SteveH95Formula]

I would put in the GM limited slip differential oil in first to see if it runs better before rebuilding. Even with synthetic fluid you might need the additive. I use mobil1 synth. gear lube with an additive and my gears are fairly quiet.

[Squat13]

Dont even bother with the 10 bolt man... you will only break it again if you drive that car hard. That would be almost a 1000 dollers down the tube if you rebult that thing. save the extra 800$ and get a ford 9" and some slicks. YOU WILL NEVER BREAK A MOSER FORD 9". Our 85 Monte carlo runs with a Trans Break and 4500 Stall and I snaped all five lugs on the drivers side and the rear was fine.

[fastTa]

YOU WILL NEVER BREAK A MOSER FORD 9"

That is a very, very bold statement!

[bigtow]

lack of funds

thanks for that but a lack of funds and the cost of importing a 9" to the uk put that option way out of reach. i saw a mag showing a replacement locker fitted to a 10" unit that had all the pros of a spool but non of the cons it looked like a set of dog gears does this sound right or am i barking up the wrong tree

[N20LT4Bird]

as i use the car every day as well as race it what type of diff unit do you sugest . i pall of mine has just fitted 3.73s to his 97 formula which has also got a zex nos system on it and he suffers from very bad traction of the line to the point that i can beet him to the 8 th mile. i am thinking of nos or a blower for mine so i think i will need a upratied lsd unit

If you arent going to upgrade to a 9 inch or 12 bolt, I would just put new clutches in your current differential. Buy a girdle for the rear and hope for the best with the blower or N2O. It should survive as long as your only using street tires. Mine did for 2 years on Nittos.

[bigtow]

re diff

hi just had a look around and found that mag withe the diff install in it and the unit i was on about is called powertrax does any one have any thoughts on this unit or the eaton posi as both units are avalible from year one which is best ?

[bobsflyinz]

I DONT KNOW WHAT THAT BIRD DUDE IS TALKIN ABOUT WHEN HE IS SAYIN THAT THERE IS CLUTCHES IN THE DIFF I NEVER HEARD OF CLUTCHES IS THE DIFF OF A F-BODY BUT I THINK U WILL NEED THE WHOLE UNIT IN THE DIFF CARRIER AND ALL BUT THERE IS NO CLUCHES IN THERE

[gimp19]

Posi-trac use's clutches

[fastTa]

I DONT KNOW WHAT THAT BIRD DUDE IS TALKIN ABOUT WHEN HE IS SAYIN THAT THERE IS CLUTCHES IN THE DIFF I NEVER HEARD OF CLUTCHES IS THE DIFF OF A F-BODY BUT I THINK U WILL NEED THE WHOLE UNIT IN THE DIFF CARRIER AND ALL BUT THERE IS NO CLUCHES IN THERE

Posi-Trac rearends do utilize clutches and they are not specific to the f-body. The clutches are what allow the center section to differentiate the torque being applied to the axles. Hence a differential.

BTW lose the caps please.

[DeWynter]

I DONT KNOW WHAT THAT BIRD DUDE IS TALKIN ABOUT WHEN HE IS SAYIN THAT THERE IS CLUTCHES IN THE DIFF I NEVER HEARD OF CLUTCHES IS THE DIFF OF A F-BODY BUT I THINK U WILL NEED THE WHOLE UNIT IN THE DIFF CARRIER AND ALL BUT THERE IS NO CLUCHES IN THERE

I think you should read a little more about Diffs before you rant about the subject as there are two conical Cluches in my Diff.

[DeWynter]

Best way to see if you diff is shot is lift one side of the car and put a torque wrench on one lugnut and it should take about 65#lb of torque to spin the wheel. If not the clutches are toast. This is strait from davinport preformance Calgary Alberta. They mostly do f-bods and Corvettes. Trucks on the other hand are a whole nother story...