have you guys done anything else suspension wise to help your 60ft ?

 

I have stiffer rear springs, poly bushings, zero camber, zero toe, welded subframe mounts so they don't tear off, ford 8.8 diff bolted in with poly bushings (no PPF to flex), solid motor mounts, rigid trans crossmember, trans brake, air down mickey thompson drag radials. Setup has cut 1.67 60' times with a conservative launch and 2 yr old tires. I expect with launch control setup it would dip into the 1.5X range without any other changes.

 

Wheel & tire sizes pat?

 

stock 15x6 wheels, 225 size mickey thompson drag radials.

 

What kind of harness is required, and what will work with stock seats? 5-point / 6-point? Pictures?

I'm reading rules that if Convertible, then Roll bar is needed, and if Roll bar, then harness.

Seems to me a 6 point might be easier to install than a 5 point.

Thoughts?

 

Do you prefer radials over bias plies?

 

I run radials, they work well so I never tried anything else.

 

At this point, Pat has an automatic. Drag radials are normal with an auto.

 

For reference, here is what a 23x8x13 M+H slick looks like on a 7.5" 25offset Lenso wheel.
The wheel clears the brakes, and I can probably go 1.5" higher on the xidas if the tires rub.

 

That sidewall is drool.

Does it look like a 24.5 tall tire would fit?

 

 

Not comfortably with my setup. Clearance from top of tire to fender is currently 1-1/8"(stock fenders 2.5camber) and double checking,
I have closer to 1" more of height adjustment. So call it a comfortable 2" of clearance.

A 24.5" tire will be .75" closer to the fender and you will probably see about .50" of tire stretch at speed.

YMMV depending on your fender modifications, wheel offset, camber, spring rates etc.

BTW, the stock wheel/tire weighs ~33lb while this weighs ~23lb.

 

This is 13x8 +20 with 13x8x24.5 hoosier bias ply slicks.

No diff in the car and these are 1.5" taller than my standard setup so I have quite the monster truck look going on. Ill post final picture once ride height is lowered and car is in 4 wheels.

This confirms 13" wheels fit standard NB brakes. Cant wait to start replacing axles now

 

Question 1: Fuel lines.
Got the new NHRA rule book. Says no rubber lines and no clamps.

I am running the stock nylon line from steel supply to the rail. I think this is OK as stock. However, I have a rubber hose from the FPR to the steel return line. Both ends use fuel line clamps. Will this be a problem?

Question 2: Harness. Seems like without hardtop, I am required to use roll bar - OK - and Harness. Is that correct? I will need to install harness? Not all that expensive. Just checking.

I understand that Commerce is pretty much By the Book.

I plan to run True Street class and hope to break into 12's, and should realistically beat 13.5, which is a transition point, IIRC.

 

1) Check rules - I believe you're allowed 12" of cumulative rubber hose in the fuel system.

2) Any bar or cage that's not OEM installed requires an in date 3" SFI harness.

 

Thx. Yes, there was / is something about a length.

Fortunately, I do plan to install seats that will be compatible with a 5 point harness.

Also, though I don't know how they would know... is stock flywheel OK? There was something about not using a cast iron "stock type" flywheel. EDIT: Ordered a steel Flywheel: ACT 13-pound unit. Will go in with my SM Organic Clutch.

 

11.49 and quicker would need SFI flywheel/clutch and bellhousing or shield.

 

Non DOT slicks might require this stuff too. I believe 13.49 is a big deal without a hard top, and 11.49 is a big deal with a hard top, loops, shields, cages, ect... It's also interesting to note that it's 11.49 or 135.

 

So, on stick axle cars a rear sway bar helps them launch straighter. Is this true on the miata as well? I have mine removed for autocross, but can reinstall if it will help 60ft times.

 

My understanding is you want the biggest rear sway money can buy.