Hillclimb Ascutney I 2014

[drummingpariah]

I had originally planned to have my Datsun 280z ready by now, but with only one weekend remaining I decided to pick up a stock NA Miata as my daily driver and toss it up a mountain this month. I brought the car home this week, registered it, and have been taking note of everything that might be an issue to fix this weekend. Forgive me if I missed it, but I didn't see a 'prep your miata for the track' thread in here, and was hoping to get a little feedback on my current plan of attack.

My main goal is to flush all the fluids, which are well documented. While I'm in there, I'm going to replace the brake pads since they've been making some noise and feeling soft (it could be air in the system, but I like knowing I have fresh pads). I don't want race pads, as there are only one or two turns on Ascutney that will require a Miata to touch the brakes. What I want is immediate response out of the brakes, and I'm not getting that right now. Open to recommendations!

There's a slight whine around 55mph coming from the rear end. I'm guessing it's either a wheel bearing (which may explain the wobble, below) or the differential. I'm hoping it's just old differential fluid, and a flush will solve it, but nothing ever seems to go that easily.

I've also noticed a rear end wobble under load changes that I assume is a differential or subframe bushing that's on its way out. Based on my reading, it could also be a bad axle or stub? I'm going to look around for the source of the wobble this weekend, but I'm not going to kill myself over it. It may be solved by the normal maintenance I'm planning anyway.

Because the Miata is a convertible, I'm required to have a roll bar to go up the hill. The tech specifications don't define exactly what a 'roll bar' is, but the car came with a Hard Dog Hard Bar, which is more of a 'lol bar' than a roll bar. There's no bracing whatsoever, it's just the main hoop. I picked up some DOM tubing last night, and am going to spend my weekend sorting out a decent bracing solution (two rear braces and either one or two diagonals should do it). No harness bar, as I'm not putting a race seat or harnesses in this car. I just want it safe to take out for the occasional weekend of track duty.

Finally, I'm ordering new tires. Ideally, I'd love to get some 15x7 or 15x8 wheels and slap some 225-width tires on and call it god. Unfortunately, everything else is quickly consuming my budget and I'm left with a very modest budget for tires. The catch is that I need dual-purpose tires which are street legal and safe, but I also want enough grip to have fun at Ascutney. The current tires are around 2 billion treadwear, the rears are dryrotted, and they won't pass race tech or state safety inspection. I'm looking at 205-50-15 Kumho Ecsta XS, as they're the stickiest tires I can get that will still be street legal. Delivered, mounted, and balanced, I think I can get away with a new set from tirerack for around $600.

To put a fine point on it, I'm asking for your experience here:

1. Am I missing anything important?
2. How much alignment adjustment is possible on a 92/93? Any recommendations on a good 'sane default' starting point? I'm happy to explain what a hillclimb is to anyone who's interested, but a Google search should answer any questions you may have as well.

For anyone who wants all the gorey details, I document my projects in a project management suite:
https://trello.com/b/TXbNrCDC/na

As always, thanks for being a part of such a solid community. I'm really looking forward to my first hillclimb and my first race event in a Miata.

[— Phatmiata —]

please post some photos of your event!! Good to hear from you again!!

[drummingpariah]

It's going to be rainy this weekend. It'll make photography a bit difficult.

[Bummer]

Wish I had seen this sooner. I'm prepping my Miata for hillclimb (I have a build thread on here, somewhere). With so little time left, I suppose it's a bit late for suggestions. But, I'd go with Carbotech AX6 pads. You can get plenty of alignment adjustment. Toe at zero front and rear, probably something around -2.0 camber in front, and -1.7 rear with the tires you mentioned.

Good luck and have fun!

[drummingpariah]

I didn't have much time to sort out camera mounting solutions, and had my hands full trying to remember all the turns (Ascutney long is REALLY long) but I did manage to get video of one run, at least.



My target for the weekend was 5:00, and ended up with a best time of 4:48. I didn't crash my car, didn't interrupt anybody else's run, learned the car a bit, learned the course a bit, and had an absolute blast. Okemo is right around the corner, June 6th. I really need to source a hardtop for that - the soft top has a metal bar right where the top of my helmet should be and I really don't like having to wear arm restraints. I also need to sort out my steering wheel spacing. As for pads, this is the longest hillclimb we have other than Mt Washington, and I didn't have any brake fade issues, so I don't see much value in upgrading them. The Kumho XS tires offer more grip than I could use, and stock suspension was definitely the right setup for this hill. My alignment was 1/8 degrees toe front/rear, ~4.1 degrees caster (that was the most I could get - one of the eccentric bolts is bent and should be replaced soon), and 1.5 degrees of camber in the front and 1 degree in the rear. It felt extremely forgiving, but I didn't carry enough speed through corner exits to load up the suspension properly. With a shorter hill that's easier to learn, that shouldn't be an issue.

If I can't get the Datsun together and ready to race in time for Okemo, the Miata will make another appearance. There isn't much that needs to be fixed, but Okemo is definitely a power hill, and that's not the strong suit of the 1.6 - I'd definitely prefer to have the Datsun ready to go.

[etikoner]

205's on the 8" wheel should be faster than 225s on it.

Good thing you're getting the sorted out, and congrats on beating your goal!

[drummingpariah]

205's on the 8" wheel should be faster than 225s on it.

Good thing you're getting the sorted out, and congrats on beating your goal!

Thanks! I'm not traction limited at this point, but I'm curious as to why a narrower traction patch would be faster than a wider traction patch on the same wheel.

[etikoner]

Stiffer side wall due to tire stretch will cut out tire deflection. It will respond quicker to inputs and a sticky tire is a sticky tire.

Also it 949 recommended

[— Grip Driver —]

Sweet video, thanks for sharing!