Drag racing setup
 

So, with the challenge car, im hoping for deep into the 12s or high 11s based on power to weight.

however, i know NOTHING about making an independent rear hook up on the strip. Always been a stick axle and leaf springs guy.

what is the proper setup to make a miata hook for sub 1.8 60 foot times? Other than wrinkle walls and skinnys up front.

Paging @miata2fast Troy. From what I recall, keep the cv shaft straight between the diff and wheel hubs, add spring in the rear to keep it from squatting when it transfers.

Don't use too tall a slick. Diameter is important.

To hook, you want no camber when under load, no deflection from the bushings so whatever the alignment is doesn't vary under load. An LSD that locks helps keep the car going straight if it does spin, so higher bias ratio = better, full locker = best. As mentioned axle's straight under load is best for durability. Depending on your trans/clutch, getting the launch control setup correctly will make a huge difference in your 60' times. Ideally you would leave under high boost and ride the clutch as needed to get the car rolling and not spin, and have enough power on the launch to not bog.

slicks, slicks are the only way you are going to run those 60's and not leave your drivetrain at the light. I have been to the track a few times with my Miata's and have always had shit wheel hop. I ran 24.5x9x13 slicks last time and it was a game changer. 1.8 60's and zero wheel hop, butter smooth 2nd gear burn outs. Those slicks were to big, 23x8x13 M&H's are the way to go.

For the record I ran a 1.8 60' with Hankook rs4's 225/45/15 on craptastic Megan coilovers. A better setup would be faster than a 1.8 60'.

Did you run an 1.800' 60 ft? Or a 1.89? How consistently could you run that time?

There is a big difference between doing a good 60' once, vs every single time you line up. Some yesterday bragged about running a 1.7 60', but they didn't post time slips, or what the actual time was, or how consistently his car ran that time he didn't post.

This wasn't Troy's best 60' but was his best ET of the night back in 2010. Naturally aspirated Miata with wrinkle wall slicks, IDK what size but I think they were 22 or 23 inches by 7 wide. He was launching at 5000+RPM if I recall correctly.

https://cimg5.ibsrv.net/gimg/www.mia...023b2ad26.jpeg
https://cimg6.ibsrv.net/gimg/www.mia...e8aaccb35.jpeg
My car is setup for drifting and has shit Stance AL+ coils from 2008. I ran consistent 1.8's all day with tires way to big, and my alternator failed half after that 12.4 run and I was running 9.5 volts with out knowing for the rest of the day. If I went back with 23" slicks now I think I could run high 1.6's and get 11.9's .

To me the slicks are more about getting that smooth launch, having zero wheel hop is what its all about. I couldn't even do a burn out to warm and clean the tires on street radials.

So, how stiff are we talking about here?

how do you control the wheelhop?

rest makes sense.

since i will be boosted v6, gearing and tire size will probably need to be different, but we wont know that until the first test day.

and 1.8x 60 foot times are my goal. If i can get 1.5x, we should rrally be cooking. But sub 2.00 is my realistically expected results. With this being the challenge and all, we may not have the budget for perfect. But if i can learn what the optimal is, i can shoot for it.

Bushings reduce deflection, which will reduce wheel hop. Control arm bushings, diff bushings, motor mounts all help reduce deflection in the drivetrain.

Bushings and shit only helps to a point, now the last time I went to the track on street tires I had 205 Dunlop dz102. I have yet today run it down the track on my 245 VR-1’s .

but I have V8R control arms with all Polly bushings, Delrin sub frame bushings and I tied my 6pt oem sub frame brace into the diff/ppf mounting point.

I remove the front sway and set the front suspension to max soft. You want the front to lift and transfer weight to the rear.

But it so far nothing has calmed the wheel hop except drag slicks. I used to go around the water box and launch the car at like 3500-4000 and pussy foot it out of the hole. Only could get high 2.1 60’s

Wrinkle wall slicks will prevent hop and absorb power pulses like a rubber band and release them smoothly. Practice higher and higher rpm launches until you reach the point where it doesn't bog at launch. That's what I remember. Slicks will still spin a little, but it is needed to avoid bogging to do it right.

exactly, I was launching at 8k

First time at dragstrip and only ran 4 times, ran a 2.009, 2.015, 2.109, and a best of 1.854. So yea, was a fluke to get down to a "1.8" but I wasn't happy with any of my launches really, bogged twice, and 1 time I thought I slipped clutch too much, and the worst run my clutch ended up slipping in first and second. Was hot lapping it pretty good. Maybe was a well prepped track IDK, it never spun, no wheel hop. Car made 240 at 15PSI and I have it turned up a little for the drag.

Wrinkle wall slicks that fit on stock 15 x 6 rims are easily available and cheap insurance on drive train. The question I have is what to safely run in the front. Bias ply skinnies want 4" rims. So it is either street radials on stock rims, or skinnies on some special purpose rims Like These?

Any recommendations for that?

I had thought about using two donut spares for skinnies. However, i can't put my finger on why it may be a bad idea.

Because they're totally meant to do 110 mph and then come to a stop very well.

You'll want to use soft walled slicks. Ask me how i know.

Soft wall slicks for the front? And how do you know.

It's obvious i was talking about the rear.

Just run your normal wheels up front. I ran skinnies because my friend let me use them, but I don’t think they are gonna make much difference.

Don't quote me, but 30 seconds of Google says that the factory Mazda spare is often a 4" wide wheel.

Too heavy?

Heavy and not rated for more than 65mph in the quarter.

Between this discussion, many internet searches, and some comments from Sonofthehill, I think wrinkle wall slicks, which I understand also means a driveshaft hoop, and my 195-50 Dunlops on the front. We're talking 105mph in a straight line. Slicks will be M&H 23 x 7.5, Part Number MHR-021.

So, say i have a 14x6 rear wheel. And the need for wrinkle wall slicks.

what size? Again, planning 325rwhp/325 torque.

and yes, both halfshafts and driveshaft need safety loops per nhra

Pick up a couple of 15 x 6 NB1 rims and use what I quoted above. I don't see anything available for 14's, except Mickey Thompson in a 26" diameter. 13's or 15's.

Where are you located?

Crap... and halfshafts? That might change my approach. No hop, no care.

my track never checked for a loop, but yeah you should have a driveshaft loop. I think If you just made a loop to enclose a section of the PPF it would be ok. 23x8x13 MH is what you want. the 13's will fit over stock 1.8l brakes.

The 15x6 will be have my sm7 autocross slicks.

im outside Charlotte nc

Someone needs to do a drag car with 15 x 6 6UL's in front and 15 x 12's in the rear. I'm not normally a "drag race" guy but when I do, I'd do 6UL's.......

15" wheels

This article is (slightly) relevant to this thread:
https://blog.caranddriver.com/how-mu...-ford-mustang/

That's unfortunate. You will fail.

Dead weight. 10's are enough for 1000 hp. Bp's don't make 1000 hp.

The key to success on a mildly built Miata is use the smallest slick money can buy. My best 60’ was 1.719 on a set of 20”x8”x14” on stock wheels way back in the day when I was running nitrous. At the time the car was mostly stock with an open diff. My car is a base model.

Those tires aren’t available anymore. Today I run 22x8x15.

Lots of local sources for the 15 x 6's for you. I have a pair here you could drive down for.

Is that for the extra sidewall height, more flex?

Yes I would run the 23’s over the 22’s personally for more side wall flex and to match a normal street tire diameter better

I don’t think the extra sidewalk is any benefit at all. If anything, for lower powered cars it may hurt. You get the benefit of less rolling resistance with less sidewall, and in my experience you can 60’ exceptionally well with a very small tire. I have very little wheel hop with the lower profile tires.

In a much higher powered car it’s another matter.

What qualifies as "much higher powered"?

Asking for a friend :party:

In your ‘friends’ case, 24.5x8x15 Mickey Thompson and 4.10 gear ;)

I did some more looking. Donut TIRES are not NHRA legal. Donut rims are not discussed, that I could find. They will fit Front Runners from about anyone.

In Australia, the rims are not legal.

I have ordered the Rule Book.

You also can't run a sub 13 second pass without a roll bar. I've been talked to about it.

id be more than willing to take you up on that offer.

as far as power and et go, im shooting for low 12s to mid 11s, and 325 rwhp/350tq

boosted v6 swap.....

PM me.

I also spoke with MandH and John -(661) 889-5221‬ said he would support import owners with coupons. He gave me the “you have to run bias plies in the front with slicks” song.

Another interesting thing about Australia, they only require bias up front with slicks at a certain speed (which I don’t remember, but faster than I will be going).

I wish that 949 had produced a 4” instead of the 6”.

I had Bogart Racing Wheels build me a set of front skinnies that are 4” wide. I got the entry level version and were reasonable in price.

They are pictured in my signature.

I think it is sub 13.5, an ET I hope to obtain.

I've got the roll bar, but not the harness to go with it. However 16.1 harnesses seem mighty reasonable in price.

I thought this would be simple, much less complicated than a reliable track car, but the details of not breaking the car, and me wanting to "do it right" is getting difficult. Likely I'm over-thinking and should just try with what I have and see if I can even shift well under duress.

mata2fast: And matching rear? I can't tell. Thanks.

I think that is the best choice on the market for us right now, and plan on trying them.

M&H makes an 24.5x8.5 as well. I assume the 24.5s are going to work differently off the line than a 23? Is that all dependent on power or is there something more complex to consider?

You want just enough tire to get the job done. Too much tire will slow you down on every part of the track. Keep in mind manual shifted turbo cars don’t hit as hard off the line as nitrous, so you will not need as much tire.

Also, it is important to have the lowest gear ratio you can to get through the traps without going into overdrive gears. If you don’t plan to change from a road race final gear, go to the shorter tire.

Awesome, thanks. It seems insane to me but all the online calcs claim the car will go 130mph in the quarter, so I'm planning on needing ~140mph worth of wheelspeed to get there. Assuming 415whp/2700lbs with driver. With my 3.63s, that is 7000rpm on 24.5s or 7500rpm on 23s. Will that 23x8.5 hook that kind of power in 2nd, or will the 24.5 do it, or will neither tire do that so I'm better off staying shorter?

You always want to go through the traps in your one-to-one gear right at redline from what Troy tells me.

Both will hook in 2nd it’s hard to say if you will overpower the smaller tire off the line. I haven’t tried at that power in a Miata.

The bigger tire should hook in 1st.

This is a 24" mickey Thompson, launching at 5K @ 20 PSI, it dead hooks.

Holy lol :rofl:

The soft suspension was helping that car a lot as well. I think 24.5"x9 is plenty big for anything we will ever do in a Miata. A SFWD Honda is limited to 24.5x9.5 and they are putting 1200+ whp down and running 1.4 60's (7.9 @189). Thats with the weight transfer working against them.

I had to launch at 8000 to get the 24.5 to not bog thats with 280whp K24.

with that tire and 3.636 gears and a 6spd I was going through the traps in 4th well off my 9k limit. 23" tires on 4.10 gears would work perfect for me and like posted above the smaller tire probably would help me pick up everywhere. I could launch lower and more in the torque and have less resistance. I would expect my car to run high 11's with those changes.

Re: suspension
afaik pat is on a DIY coilover setup on base suspension

So, I got the NHRA rule book. Indeed, under Tires, compact spares are out, but under Wheels, they are not mentioned.

Seems that it is OK to run those rims with proper Front Runner skinnies.

You might have a hard time finding a tire that will fit the spare wheel that is rated for speed.

3.5/22.0-15 (Skinnies) D.O.T. Certified

? Spare is a 15x4 wheel, aren't most frontrunners set up for 15x4s?

I have the non DOT version from Mickey Thompson. You are right, a race tire in 14” not happening. If you are on a tight budget, a 15” skinny spare from another vehicle?

Factory NB spares are 15"

Just make sure that your skinny spare setups don't weigh more than a 185/60/14 or what not on a factory wheel.
Reduced rolling resistance is great and all but not at the expense of more weight.

Learned this decades ago when I would spent Wednesday night's at Sears Point.