Thinking about an D-Prepared Miata

But what kind of spring rates are suitable for a Miata that weighs 500-600lbs less than stock?

Aeromoto picked up a 93 Miata that was a victim of the Baton Rouge floods, thus leaving it with a certificate-of-destruction and no(easy or legal) way of getting plates for it.

The top & a few other parts have already been scavenged, but the damn thing still runs & drives great, and seems to have a functioning VLSD. So we've been pondering how to put it to good use & figure a budget-DP build could be fun, without going full ghettocet/Miatakart on it.

Does it happen to be red? (Curious as there was a famous water rescue of a driver and their dog in a red miata from those floods).

Stiff. Miatas have to be treated like go karts. 700/450 is what my gut tells me. Stiffest front bar you can get your hands on (look at Small Fortune Racing). Prepare to spend money for wheels and tires.

In reply to captdownshift:

Sadly no. I'd seen that vid too.

In reply to KyAllroad:

That's about what I had on my STS-prepped 96(IIRC), which is good. I'm hoping to find a used Koni/Ground Control setup and save some $$.

We're hoping to find some road-race takeoff tires. I'm not sure that we'll take advantage of the 10" wide wheel allowance at the start, but that will probably depend on what we can find used vs. a new set from Diamond, etc.

Why not 6ULs for the wheels?

VLSD and wide sticky tires....it won't be functioning for long.

codrus wrote: Why not 6ULs for the wheels?

I've not priced them, and honestly at this point not yet sure what size to get. I'm just familiar with Diamond for being cheap, though I've never owned any of their wheels personally.

kevlarcorolla wrote: VLSD and wide sticky tires....it won't be functioning for long.

Very true. It wouldn't be hanging around for long, but at least it wouldn't be the first thing on the list to spend money on.

petegossett wrote:

codrus wrote: Why not 6ULs for the wheels?

I've not priced them, and honestly at this point not yet sure what size to get. I'm just familiar with Diamond for being cheap, though I've never owned any of their wheels personally.

949 Racing's 6ULs are pretty much purpose-designed for this. 15x10, +25, 4x100 bolt pattern, 13.5 pounds, and about $200 each. It looks like Diamond are cheaper, but almost double the weight.

Tire Rack sells a TRM 15x9 that's cheaper than the 6UL, but a few pounds heavier. I don't think they have a 15x10 though.

In reply to codrus:

I had the TRM 15x9's on my 96, they were good for the money. At this point I'm not even sure if 15" is our best diameter for finding wide used race rubber, or if we should look at 13"...or maybe something in between?

I'd run 13's,doesn't sound like a big bucks effort to build an engine to the max so light,short and wide wheel/tire combo would get my vote.Also tough to ignore the cg advantage for free compared to trying to lower that extra inch to get the same with taller tires.

CSP guys have moved to 15x11" wheels now, still running A7 275/35 tires.

In DP do the tires have to be DOT approved? There are sticky take offs available in a variety of sizes in non-DOT tires. I'd call John Berget tires and see what is available.

The 255/40/13 purple crack seem like the best option for the FSP crowd which is reasonably similar in weight and requirements to "The Answer. I'm currently running 13x7 and ancient 235/45/13 khumo's. Currently running very well loved diamonds but hunting lighter options like the Team Dynamics or Panasport 3 peice.

In reply to 84FSP:

I was running 13 inch bias ply purple crack on the 323 and it was faster on that than it was on 225/40/15 V710s.

I ran the 255-13's on 9's on my miata and another guy in my area with a nearly identical prepped miata ran the 275's on 9's.

We were essentially dead even,I didn't realize it but the alignment guy didn't go king kong on the new accentrics like I asked and they slowly slipped thru the season,I thought the hoosiers were just doing the thing that hoosiers did.

Didn't figure it out until the end of the season,I think if the alignment had of stayed put I'd have been quicker than him with his big boy wheels and tires.

In reply to KyAllroad:

No, DP allows true race slicks. I just need to figure out what common sizes are available for as cheaply as possible(including shipping or travel to pick them up, for example), then find some cheap(ish) wheels to mount them to.

From what I've seen, the 15" 275 Hoosiers are significantly faster on Miatas than the 13" 255s. That's all new-DOT-legal-rubber though, which doesn't have a lot of bearing on a cheap DP build.

Last I heard, the best answer in non-DOT slicks is 15" Avons, but I have no idea what the right size for takeoffs is.

In reply to codrus:

All I've found so far is this blog post about using Avon A11 240/600R15 slicks, and that they may be a Formula Atlantic fitment.

In reply to kevlarcorolla: man I'm starting to feel like a shill on this thread, but here's one more. Pace Motorsports (the guy who came up with the offroadster) developed and sells an alignment locking system. I'm installing it this winter on mine. Seems like a good way to keep an alignment from getting jacked by cornering loads and E36 M3ty roads (thanks Ohio).

petegossett wrote: In reply to codrus: All I've found so far is this blog post about using Avon A11 240/600R15 slicks, and that they may be a Formula Atlantic fitment.

Miata.net thread

In recent years, CSP Miatas have been turning in faster times at nationals than DP Miatas. I think that points to the competition in CSP being harder and people building the CSP cars closer to the limits, because the rules should clearly favor DP.

I drove this DP car a couple of times:

It was on Hoosier A6s at the time (A7s didn't exist yet), but the owner was planning switching to Avons. I think he wound up selling the car before that happened, though.

In reply to codrus:

Wow, I didn't realize the CSP cars were faster than DP. I looked through the national's results and noticed the participation levels in Prepared seem pretty low - or maybe it's just that the numbers are up in all the Street/Touring classes?

petegossett wrote: In reply to codrus: Wow, I didn't realize the CSP cars were faster than DP. I looked through the national's results and noticed the participation levels in Prepared seem pretty low - or maybe it's just that the numbers are up in all the Street/Touring classes?

The fast drivers were all congregating in CSP for a while, so the level of competition (and thus car prep) in that class was very intense.

Resurecting this thread since it popped up on a google search for "Avon A11 autocross".  Here are my ready-to-go A-11s for the Zoomboni.

Just in a thumbnail test these things are SOFT.

Where did you buy these?

In reply to 84FSP :

John Burget race tires.  He sells take offs in a bunch of sizes.