Hey Guys,

I have paid the deposit for my Rushforth "Rated-X" wheels. I am also adding Baer SS4 brakes front and rear. What recommendations do you guys have for backspacing? 18x9 fronts and 18x10 rears....

I was thinking 5" front and 5.625" rear. (I believe stock is 4.75" and 5.25")

Thanks for your help. I haven't given Jason the go-ahead yet. I wanted to check with all of you first.

Jim

P.S....engine is complete. Should be on the dyno today or tomorrow. Expecting 470-480 at the crank. The Nitrous Outlet 58mm plate system is on backorder.....

 

front zero offset, or 5" of bs

rear i would do 6 or 5.75

 

Phil is correct - a 5" BS with a 9.0" front wheel would require a 6" BS on the rear to put the tire in the same spot under the fenders. Or 4.75"/5.75".

 

What would you guys do personally? I would like them to be tucked just inside the fenders and would prefer to not have to make any mods...

 

I personally like a touch more BS. Here are some pictures of some test fitting that I did.

This wheels is a 18x9.5" with a +25 offset or 6.25" BS

Rear:

Here is a picture of the wheel bolted on the rear. Remember a 10" wide wheel with the same BS will stick out 1/2" further.



Now these three pictures are the same wheel with a 3/8" spacer. So the outer face of this wheel would simulate a 10" wide wheel with a 6.125" BS.







In this picture, you are looking at 10" wheel with a 285 tire at about 5 5/8" BS. Not my style, to flush for me.

 

Now for the fronts.

In these pictures, you are looking at a 10" wheel with 285 tire and a 6.375" BS. This is with a brake kit that pushes the wheel out 0.3" (same as your Baers). The outer face of this wheel sits the same as a 9" wheel with a 5.375" BS. Right click - view image for larger.





So with all that said. I like the wheels tucked in slightly further than these guys.

I think ideal is.

Front: 5.25" BS on a 18x9" wheel
Rear: 6.25" BS on a 18x10" wheel

Personal preference. You can't really go wrong with what anyone here has suggested.

 

Keep in mind everyone that the 18" (or larger) will tuck the tie rod end into the wheel barrel - 17" cannot. This is the reason for the 5.25" or greater front BS.

 

Agreed. In the original poster's case, that is no issue as he is running 18's.

 

Thanks guys! I think I'm going with 5.25" front and 6.25" rear. I did fail to mention that I have sportlines and tubular LCA's with relocation brackets. Is that going to change anything?

 

and not to change the subject...but have you heard of anyone converting thier 9-bolt to 31-spline? I am trying to stick with the original engine, trans, and rear. No offense to you guys who have 4th gen parts. Just trying to prove the point that our cars have good parts that can built to last and to compete with all the rest.

 

Never heard of any optional (31 spline) posi units for the 9 bolt rears - other than what was OEM from the factory.

You will eventually blow up a 10 bolt or 9 bolt rear with power - whether or not you upgrade it - the parts are not meant for any sort of racing abuse and typically the ring gear lets go, not the posi (unless it is run dry).

Mt advice is to purchase a 12 bolt/9" to fit your car, remove the 9 bolt and leave it until you want to get the car "original" again. I can name 4 of my friends who upgraded their 10 bolt rears, grenaded them anyway, and sold the leftovers for a fraction of what a good unit would go for.

No reason to spend money twice...

 

Or, I think the coolest option to maintain some third gen originality. Find and build a third gen Dana 44.

 

I spoke to Glenn at 9-bolt. He said he can get everything needed to convert to 31-spline. He sent me the following prices:

31 spline side gears (x2) $77 each
31 spline cones (x2) $77 each

The carrier axle bores need to be machined out a little to allow the 31 spline axles to physically fit.

I may just check the bearings, have the posi reshimmed, cones, and girdle. If she blows, I'll go to plan B.

Glenn claims a properly set up 9-bolt should be fine into the 10's. I don't think my car will be that quick. 470-480hp crank...so what 350ish RWHP?? Also have a 150 shot of N20.

 

That is not a bad price. But do you feel the axles are limiting factor in the current setup? Having never blown one up, I really have no idea. It seems like the ring gear would be the weak point.

Also, do you plan to drag race? If not, I wouldn't worry about the 9 bolt. And if you do, the 9 bolt's limited slip is not the best traction aiding device out there. Finally I doubt its the ET that kills the diff, no doubt you can keep them alive in the 10's. Its the 60ft times that really kill them.

 

No...my car will not be raced. When I began this build it was going to be a mild overhaul but has just snowballed into replacing/rebuilding it entirely. I plan to drive it to the golf course and the occasional local show. Of course I'll blow it out every now and then...

I'm worried about losing an axle more than anything else.

 

Good news is the 9 bolt has bolt in axles so at least it will not depart from the car. I think you will be fine with the 9 bolt with your kind of driving. 31 spline or stock.