Factory 12 bolt posi question
 

Just converted my 3 speed to a turbo 350. As I was wrapping everything up and and the truck was on the lift, I put the truck in gear and pressed the brake firmly but the right rear wheel was spinning.


Question, how would only one whee spin on a posi?

I’m hoping it’s just a brake issue (cylinder, adjustment, leak…) in that back rear wheel. I will say the brakes don’t feel right, like they did before I did all the work. The pedal is almost bottoming out when I’m completely stopped.


TIA

Re: Factory 12 bolt posi question
 

I can't comment on your possible brake issue, but one reason for a posi to behave like a non posi is if there is an issue with the clutches. I did not know I had a posi until I pulled the cover and chunks of clutch plates fell out. I had used the spin the wheel test prior to finding/fixing that and I thought I had a one legged axle.

Re: Factory 12 bolt posi question
 

FWIW: Did you decode the rear end? Not all 12 bolts are posi.

Re: Factory 12 bolt posi question
 

Sounds like you have a brake problem first. Pull the right wheel and drum and inspect the shoes and hardware. I would pull the left also. It may be worn out if it’s the only one working.

Re: Factory 12 bolt posi question
 

The factory "posi" is a limited slip, not locker(NO-SPIN 20-30 series) unless stated as such on the SPID. There will be slippage under certain conditions.

Re: Factory 12 bolt posi question
 

Thanks everyone. I changed t he gear oil yesterday and it looked great inside. Drove it home on the freeway and it cruised great.

Up in the air I spun one and both spun the correct direction.

I used maps 80-90 gear oil and added the additive they told me.

I’ll start with checking the brakes

Thanks

Re: Factory 12 bolt posi question
 

Great news! Brakes much easier and cheaper LOL