Hi
Recently picked up an 85 Z28 that I plan to overhaul.

The one area I'm not familiar with is the rear end on these cars.

How tough are the 3rd gen rear ends?

What can be done to beef one up to handle up to 450HP?

Are their certain 3rd gen rears that are better than others?


Thanks
REJ

 

The only stock rears that will be close to holding with that kind of power would be the 9 bolts.The gears range from 2.77 to 4.11 but 3.45 and shorter gears are very hard to get.The 89 and up 9 bolt features the bigger brakes

 

Thanks

Would that be 89-92 rear ends? Are they a direct or a fairly close bolt in with a few mods?

9 bolt is the number of ring gear bolts or cover bolts?

What is the ring gear diameter for the 9 bolt?

Sorry for all the questions. I know my first and second gens pretty well. Just getting started on the 3rds.

Thanks for the help.

 

9 bolt is the number of diff. cover bolts.
It's a 7.75" rear. And there supposed to be pretty tough.
They'll bolt right in from 82-92(I'm pretty sure anyways)

 

With 450 horse and traction your going to roast any stock rear made for 82 and newer F bodies with the only exception being the dana 44 GM service replacement rear which is long out of production and harder to find than a winning lotto ticket.

The 9 bolt is fairly tough as far as the gears go and it uses 28 spline bolt on axles so its safe but the cone posi's suck and parts for the 9 bolt are very scarce and pricey as all get out.

The only biatch in building a diff up from a Ford or whatever is the torque arm mount. Moser and Strange make bolt in 12 bolts for third and fourth gens. Fourth gen rears bolt right in as the suspension is the same but the axles are a few inches wider in fourth gens so stock wheels dont jive.

If your looking to spend dough dont put a nickel of coin into a 7.5" ten bolt. Take your chances and if(when) it blows step up to an aftermarket replacement. Same goes for the 9 bolt in my opinion its not much better.

 

Go for the new S60 Just spend some change.$$$