I'm looking to put a set of 15x10s on a '71 with 9x30 slicks. I need to keep the tire as tucked under the fender as possible, what backspace do I need look for?

Should I assume I'll need to use notched control arms and massage some of the inner fenderwell? Any other pitfalls?

Thanks for the advive,
Dave

 

I have 15x10's with a 5 inch backspace. I needed off-set trailing arms and needed to remove the rear sway bar. You might be ok with a 8 inch rim for a 9 inch slick.

 

Thanks big_G,

Nearly every good working NHRA/IHRA stock eliminator car I've seen lately has been running 10" rims with the above tire combo. Just trying to see if anyone on the forum has gotten this package to fit.

Dave

 

I have 10X28 goodyears. Vette's have two problems when trying to run a stock frame rear even if you have the IRS up to the task.

#1 to much rear squat. To correct the problem I installed Smart struts and Zero toe on my HD trailing arms with good shocks sway bar and 420 inch pound steel custom spring.

#2 Now it got rid of rear squat, but you don't have the weight transfer. Your even taller 30 inch slicks - which lift the rear end because of tire diameter will cause additional problems. So I had a car that as I had motors with more power I had rear hook up problems. My solution was to severly lighten the front end. I went to extreeme levels of even the Datona nose just to loose another 150 pounds by having such thin fiberglass hood and body panels.

For drag racing you really need to to look at 90/10 drag shocks, lite long springs with drag skinnies. I even considered the battery box relocated behind the passenger rear tire.

In the end I figured out that running a Drag bike was much more adrenilan (SP?) and much cheaper on parts. Without a doubt. Just get on a 7.60 turbo lay down drag bike with an air shifter. Then don't even wait for the shift light to come on and just keep it hammer down. Your on the wheely bars to just under the 660 foot light. Cars are very boring and way to safe!

 

My 10X15 wheels with slicks mounted are 4.5 BS The max without offset trailing arms is about 5 inches

 

Thanks gkull,

Do you know of anyone using the offset trailing arms?

Dave

 

I have offset trailing arms and 1/2" shortened 290 lb spring on the back (1/2" shorter on EACH side of the spring). I currently have 15 X 9 wheels with 4" Backspace just cause that is what I had before I used the offset trailing arms. I have about 1.5" extra space and will buy 5" bs wheels next time. I don't think I can go anymore.

I have an article on Vette 17" and 18" wheels and they did a bunch of testing and the MOST Backspace they could get on a 17" wheel with 285 40 17 wheels was 5". This with offset trailing arms. Don't think they had a shortened spring and they said this combo would run on the rear sway bar.

Personally, I wish I had gone with double offset trailing arms and the heavy duty halfshaft/spindel kit from Vansteel, but it is expensive.

I am certain that you could NOT run 5" bs wheels with 15 X 10 rims with stock trailing arms, so don't even try. I think 4.5" bs is the most you could go.

 

Clarification. The above combo with 285 40 17 wheels with 5" bs and 10" wide wheels, WOULD NOT run with a rear sway bar. I wasn't very clear with that.

 

Wanna buy a 2005 ZX10R? Just Like New

 

I just went with a custom 550 lbs/inch spring (shortened by 1.5 inches).
The spring eliminated all squatting.. I don't get more than 1/2 inch travel in the rear...
I use 28 x 13.5 - 15 ET Street tires (11 inch tread) on 15 x 10 Convo Pro wheels.. In front, I use '65 Corvette Small block springs and Competition Engineering adjustable Drag Shocks (set to 80/20).
On a well prepped track, I don't have traction issues with my setup, however, my front bounces.. (wheels come off the ground by about 2 - 3 inches, then come down and then they come off the ground again by about 2 inches... Other than the bounce, the suspension works great!

As I told you in the PM, in order for the rear tires to fit, I had to

1) remove the rear sway bar
2) use the narrowed rear spring
3) cut a small piece of the frame (where it comes down to the trailing arm

 

Just got my Mark Williams billet wheel spacers to get a little more clearance for my rear tires...

 

Thanks for all the info guys

This C3 project was back burner but it's warming up fast. I picked up a lot of missing parts lately so now I've got the itch to start putting it together. Are you automatic guys running TH400s or 350s? I'd prefer a 350 if it's not to much of a PITA to swap in.

I'm in need of a lot of the grill/front end mounting hardware, if anyone knows of a stash out behind a garage or barn for cheap please let me know.

Keep 'em racin',
Dave

 

I'd go with a TH350.. The TH400 just eats up too much power and TH350's can be built to hold up to over 1000 HP.. We have a local builder that guarantees his TH350's to over 1200 HP.. Lot's of guys at the local track use his trannies...

 

In fact I helped my trans builder do a low drag 350 for a F/SA that picked him up .2's over the previous 400 setup with no other changes.

 

350 vs 400 Yes, there is a hp change loss. I had a hot rodded th350. I had busted chunkes of metal in the pan.

When ever you use a "A" tranny You might talk about 25-50 hp in comparision to full man stick shift. 400's can take on 1200 hp

I used power glides in a dragster.

The real key like my 850 hp Art Carr tranny is such grade high steel make them last a long time.

My wimpy motor never hurts it.

 

It all depends on who builds the TH350's... Most of them aren't any good if you use serious power, but there are builders that can make them almost as strong as TH400's with less drivetrain loss and less weight... If I'll ever change my tranny, I'll go with a TH350....unless I'm going with A LOT more power, then I'll switch to a Glide... TH400 is not an option for me..