Pics of the Alumastars and M/T's mounted

[fastTa]

It started to rain again here today so I was rushed putting on the tires/wheels, but here is how it is going to look.

Keep in mind that the motor is not in it yet, so that is why there is much gap between the front fender and the M/T ET Fronts.

[Black97]

Looking good Kevin.

Brought the hood and the T/A in the other day to be fixed and painted. Will post the pics when it's all done.

[AmericanZ28]

Sweet!!! Whats the status on the engine?

[fastTa]

Just on the callies crank to be knife-edged? Other than that, just wiring the Painless wiring harness and geting the suspension aligned.

[Injuneer]

Do you know how much the rear has been narrowed? That solves a lot of problems with wheel choices. None of the wheels I wanted were made with the ridiculous backspace the 4th Gen stock width requires. Have the fender wells been altered at all?

[fastTa]

Originally posted by Injuneer
Do you know how much the rear has been narrowed? That solves a lot of problems with wheel choices. None of the wheels I wanted were made with the ridiculous backspace the 4th Gen stock width requires. Have the fender wells been altered at all?

It has been narrowed 3" each side, a total of 6" flange to flange. When I first put the 28x10.5W up in the rear fender well, it was about 1 1/2" from the jounce bumper bracket. I thought that would probably be sufficient but I just wanted to play it safe so we did a little can opener work!

I took a cut-off wheel and made an arch type cut about 1 inch above the joince bumper bracket and then removed it, which in turn gave me about an additional 2" of clearance. We also did some mild hammering. I can post a few pics if you want.

Once we get the rear all aligned, it looks like the tread should fit fairly flush with the fenders.

[fastTa]

Fred, what size slicks are you using currently? Did you do any trimming to the fender itself on your car? It looks like I am going to have to on mine.

[Injuneer]

Are the Aluma-Stars 4.5" backspace? I have 15x10 7.5" BS with the stock width on the 12-bolt.

I was running Hoosier QTP 28x11.5-15's, and they fit in the wheel well fine. When trap speeds went over 120mph, they started to rub on the outer fender sheet metal at the front of the wheel well. I moved the axle assembly back about 1/4" to solve that problem - no cutting. The QTP's seemed to be almost exactly 28" diameter.

This year I got a pair of M/T ET Drags 15x10.5-15W. They are supposed to be 28.1" diameter, but I couldn't even get them into the wheel openings. They rubbed on the rubber bumper cover, so I raduised the bumper cover about 1/2" over the bottom 6-inches..... and it still was very close:



So I have taken maybe another 3/4" off the bumper cover, for a total of about 1-1/4". They didn't rub on the chassis dyno, at a speed of about 130mph, so I'm hoping they will be OK if I can push it closer to 140mph on the 275-shot. I don't have a picture of the latest carnage.... but it actually looks OK unless you peak behind the tire. I plan too make an aluminum filler piece to make a very thin "mudflap" that will cover the edge of the bunper cover, and keep some of the rubber off the back of the fender. I saw it on an NHRA "Stock" class 4th Gen, and it looked pretty good.

That's also the reason I got the new LCA's with the rod ends.... I figured the poly ends were compressing at launch and allowing the rear axle to move too much.... figured it would only get worse with the full shot of juice off the line.

[fastTa]

I am using the same rear tire as you. The tire is about 1 1/4 back from the front/bottom of the fender and it is just touching the rear/bottom of the fender.

I am just going to wait until I have the weight of the motor/tranny in the car to begin adjusting the rear and then I will be able to really see how much radiusing I will need to do.

Have you run the 28x10.5W's yet?

[Injuneer]

No passes on the "W"s.

Here's a Camaro with the rear wheel openings modified for a 29.5" ET Drag:



As noted in the PM, it wasn't quite enough.

[fastTa]

The rear alumastars are 4.0" BS which works perfectly with the 3" narrowing.

What exactly do the NHRA rules require as far as the slick protruding from the fender well. Is it just the contact area or the sidewall as well?

[DJ Taso]

Aren't you guys worried about twisting your frames with that much power?

Great pics.

[fastTa]

Well with a un-modified uni-body yes.

However the chassis flex is greatly dampened with a head to toe roll cage that ties together virtually every point of the chassis that receives transferred torque.

[fastTa]

Fred you still here?

[Injuneer]

I'll have to check the NHRA rule book.... Most of the F-Body "events" will require that the tread be under the fender. I think the "North vs. South" event might allow the tire to protrude 1.5". Seems to vary. I like to keep it inside the upper edge of the fender..... but I think that's because I'm still more of a "polisher" than "racer".

These cars will take a huge amount of abuse. Again, I have to go back to George Baxter's convertible. His car still has only a set of MAC tubular SFC's + a roll cage. He even removed the stock convertible stamped-steel X-brace, although there is a tie from each SFC to the TA mount. The cage seems to make a HUGE difference in chassis rigidity. He was running 1,125HP and dropped the car several times from 6-ft wheelstands.... only casualty was a dinged oil pan and a couple cracked welds in the PA tubular K-memeber.

I only have a 6-point roll bar at this point, but it was drilled through into the subframes both front and back, and then the custom chrome moly SFC's were tied to the subframes at the same point. It's pretty rigid, but not completely solid. Last year while the car was in the garage for the winter, I noticed the T-pin in the swingout bar on the driver's side was not going in all the way. When I started poking around, I found the passenger side front tire was soft, and just dropping the corner 2" or so was enough to move the roll bar components. I put air in the tire and the pin slipped in all the way.

But I figure if a convertible can handle that kind of abuse, the T-tops and coupes hsould be even stronger.