Help w initial set up for autox

[SallyFinney]

Hey all-
Thanks again to all of you who gave me the awesome feedback and suggestions. Thanks for helping me shop, too Luckily, after 14 cars or so I found my match.

Here's my starting point:

99 5spd 110k mi
excellently maintained- all synthetic fluids, timing belt/water pump/belts/gaskets all changed recently
double hoop roll bar (i believe that's what they're called?)
suspension is solid
LSD (read the VIN to the Mazda folks and they confirmed)
14" rims w 185/60's on it - "sailun atrezzo" tires - per google "third tier tires" (aren't even carried on Tire Rack site)
top leaks a little, but it can wait til next year- if i carry a towel
clutch in great shape- i can make the tires bark going from 1st to 2nd

So- since i'm hungry for wisdom, i'll open the floor to your venerable feedback:

Tires/Rims: Not wanting to get race tires yet. I've read about some 99's having 15" rims- are they better/worth investing in/appropriate?
Suggestions for autox friendly street tires? Tire Rack options and the Miata forums were overwhelming.

Shocks: Bilsteins? Koni? Was looking at Bilsteins... they come in a few options- sport vs HD I think?? Adjustable, non adjustable? HELP!

Sway bar: I can have *one* and it not count as a mod, right? They're only about a hundred bucks I've read.

Radiator: not urgent, but plastic looking it's age. i'll pick an aluminum one up if there's an opportunity (Rumor has it Joe might have one? If so, let's make a deal! )

Other suggestions?

Thx guys, I love learning about all this stuff. Autox has captured my heart, and I'm loving every minute of it, even if I'm a dense student and am more tortoise than hare right now.

[jev61]

I started a Q & A for you earlier today hoping you would see it; however, this will do just as well. Here is what I posted about BILSTEIN shocks.

BILSTEIN HD = BILSTEIN B6 Performance, normal length replacement Monotube shock.

BILSTEIN Sport = BILSTEIN B8 Performance Plus, shorter length Monotube shock for lowered suspensions.

Two additional notes: Most people have reported that the valving in the replacement BILSTEIN shocks is not the same as Mazda choose as original equipment (Mazda used at least three different BILSTEIN shocks that I know of from 1990 till 2005); most say it is better. Both the HD and the Sport valving is the same and will support spring rates up about double the Miata OEM springs; with a custom revalve much more than that.

My own observation concerning BILSTEIN shocks is they gave me the highest overall ride height on a stock suspension. I measured this after installing BILSTEIN, Koni, Tokico, Showa shocks on a 99 Miata with stock springs. In stock class autocross, this meant less negative camber up front where I needed it most, so I choose to use something else.

[Loren]

Talk to Ben about tires. He's got a half-used set of RE-71's on Miata wheels that we bought for the FASTiva. Obviously, we're not using them. Would be a good place for you guys to start. (oh, and Ben doesn't buy into the whole "don't buy good tires" thing... he wants to be competitive!)

Shocks: Look at where your competition is using. Philip - Eh, it doesn't matter. Jamie - Koni Sports. Jason- I don't know, maybe Koni?

What Joe says about ride height variation with shocks can be true. (has to do with the gas pressure in the shock adding "effective spring rate", and thus giving you more static ride height) But, it doesn't necessarily matter, at least not on stock suspension. With soft stock spring rates, you're still going to get body roll, and what matters is you total DYNAMIC camber. How much camber do you have (more specifically, how close is the contact patch to being flat) when cornering at full load? It's all about the wonderful "camber curve" that a double wishbone suspension gives you. If your static height is a little higher, but you're still going to compress as far down as the guy who's a little lower, you'll end up at the same total dynamic camber, even though you have slightly less static camber.

Bilstein shocks are non-adjustable, have very stiff "low speed" compression damping (low shock shaft speed... as in, road undulations, steering inputs, etc) which gives them sharp steering response. But, their valving is "digressive", meaning that as the shaft speed increases past a certain point, the shock gets SOFTER. So, if you hit a BIG bump, the shock will suck it up. But, if you hit small bumps (like a washboard road), you feel EVERYTHING. Bottom line, Bilsteins have great steering response, but tend to ride a little rougher on the street. You need to decide which side of that compromise you want to be on.

Koni shocks are rebound-adjustable, and have fixed compression damping that is softer than the Bilstein. When you adjust the stiffness of a Koni, you are ONLY adjusting the rebound. Going stiffer does affect steering response, but in a different way. Instead of resisting downward force (compression) on the outboard side of the suspension, it resists upward force (rebound) on the inboard side of the suspension. Ride quality on the street can be considerably better, especially if you keep them adjusted on the softer side. And they are adjustable, so you can tweak them for both ride quality and handling balance. Word of caution about Konis: The adjustment valve is physically located at the bottom of the shock (even though the knob is at the top), and if you bottom out the shock even once, it instantly destroys the valve! Be sure you have proper bump stops in good condition. (this was a mistake Philip made... and, I made the same mistake on a lowered Miata once upon a time)

Both Konis and Bilsteins are rebuildable and revalvable. For a casual autocrosser, I question whether it's worth the expense of doing so, however. (but never throw away your old shocks, someone will always buy them, even if they need to be rebuilt)

Those are your best bet shocks for stock class without getting stupid expensive. On the cheaper end, you used to be able to get KYB AGX fairly cheap. They are adjustable, and you might get 2-3 years or more out of them. Their adjustment adjusts both compression and rebound. On the NB, they had 4 adjustment positions. (NA, it was 8 positions) I don't even know if those are still availalbe, people don't talk about them much any more.

Another possible option would be Tokiko adjustables. I know zip about them, but have heard good things.

[jev61]

I will try to take each questions at a time. You will hear over and over: Tires, shocks, and alignment. Those are the Big 3.

Tires/Rims: Recommend strongly you get 200 treadwear Extreme Performance Tires to fit the rims you have now; next summer will be a good time to sort out rims. DIREZZA ZII STAR SPEC's would be your go fast choice from Tire Rack. When I started autocrossing I thought I would learn on the tires I had, several events in an experienced autocrosser, who has probably forgotten more than I've learned, told me I would not develop as a driver on the crap tires I was using and let me have his take-offs from the previous season. It was an eye opening experience.

Shocks: I posted about BILSTEINs already. Nobody will argue seriously against Koni adjustables either; probably one of the best off-the-shelf choices. Sachs and KYB GR-2 (Excel) are budget options if you can find them significantly cheaper than BILSTEINs. Either way, you most likely need bump-stops. Loren can tell you how to use Honda stops or you can get these: http://5xracing.com/i-20923093-5x-racin ... ry:1231717 if you like the Easy Button.

Sway bar: Does not count as a modification; I like the Racing Beat bar http://www.racingbeat.com/Miata-1990-20 ... 54103.html with the Sway Bar Brace Kit http://www.racingbeat.com/Miata-1990-20 ... 54122.html installed with Locktite. I like the tubular sway bars because they can weigh less than the solid bars; but don't buy it from Racing Beat, they charge too much, find it online for less.

Radiator: I have an OEM style (plastic) radiator made by Koyorad with Mazda cap for $50. Cap and radiator are one year old.

Other suggestions? Get an autocross specific alignment from someone who knows what that means. Joe Brannon, Todd Byram, or Vortex Motorsports if need be. Read this: http://949racing.com/miata-race-alignment-info.aspx Pay attention to the Street Alignment section, it will apply to what you have. I use Vortex and take them the numbers I want them to use for an alignment; few people will do that for you.

[Carracer]

Tires/Rims: Stock NB 15s and a set of RE-71R, or KUMHO ECSTA V720. You could stop at this point and the car would be prepared enough for S4.

Shocks: A lot of S4 cars run Koni shocks. But, I would recommend the BILSTEIN B6. No settings to mess with, they work, and IMHO give better road feedback than Koni. I would still claim Koni's are the better shock when they work ( if they lasted more than 3 events ) but harder to get 100% out of. Can't go wrong with either. Event the OEM replacement KYB GR-2 would get the job done. This shock advice is coming from me so you might just want to ignore it

Sway bar: I would skip this for now and just disconnect the rear bar. Gets you 50% of the advantage with 0 cost.

Radiator: Any plastic one will do.

Unless you plan on track days in the future I would sell the roll bar. It's extra weight and I don't like them in a car without a helmet on. Head + roll bar is not a great combo if you get rear ended.

[Jamie]

So- since i'm hungry for wisdom, i'll open the floor to your venerable feedback:

Venerable? (Well, Loren did turn 50....)

I'm a bit more minimalist than Joe when it comes to throwing parts at cars -- in fact, my first recommendation is other than maintenance items that must be fixed, change nothing but tires for the first several events. I'll also lay out how different choices line up against the SCCA Street Category rules, as you may decide to play in that sandbox at some point...at least you'll have the information to use when it comes to spending money on things.

Tires/Rims: Not wanting to get race tires yet. I've read about some 99's having 15" rims- are they better/worth investing in/appropriate?

15" rims will give you a wider array of tire choices, so they're worth it eventually just for that. For FAST, the rim size is free both in diameter and width. For SCCA, you can change the stock rim size plus or minus an inch, but must keep the stock width and offset...not difficult. And good, lightweight wheels can be had for around $100 ea, which is about as cheap as you'll ever get good wheels.

Suggestions for autox friendly street tires? Tire Rack options and the Miata forums were overwhelming.

Uncompetitive tires are not that much cheaper (if at all) than competitive ones. Even RE-71s or BFG Rivals don't turn to rubber dust that fast, especially since you're not driving the car daily. And there are some good, low-cost competitors showing up...Nexen is making a new tire (N FERA SUR4G) that impressed testers at both local and national levels, and it's not much over $100 a tire in 15" diameter.

Better yet, if Ben has leftover RE-71s from the FASTiva, use them up first!

Shocks: Bilsteins? Koni? Was looking at Bilsteins... they come in a few options- sport vs HD I think?? Adjustable, non adjustable? HELP!

Unless they have to be replaced, I recommend leaving the shocks alone for now. The stock Miata shocks are not all that bad -- get used to the car first, which will both help you decide and let you save money for a final solution, rather than something interim.

If you must change the shocks, my own experience is Koni Sports over Bilsteins, but I can find you just as many people recommending the other way around. The most important thing is to remember to replace the bump stops...the stock Mazda bump stops disintegrate. I think Loren has found some Honda Civic bump stops that fit, otherwise, you can find good aftermarket ones from places like Good-win Racing (In fact, they're a good source for reasonably priced aftermarket Miata stuff across the board.)

Sway bar: I can have *one* and it not count as a mod, right? They're only about a hundred bucks I've read.

The "change one sway bar" rule is from the SCCA rulebook. FAST doesn't care. Most drivers change the front bar to sharpen up the steering, even at the cost of a little understeer. Some even remove the rear. I have stock bars on both ends, and everyone raves about how well balanced it is. I know of other Miatas that absolutely need a bar on one end or the other to behave well. I recommend leaving the bars alone for now, and seeing what the car wants.

Radiator: not urgent, but plastic looking it's age. i'll pick an aluminum one up if there's an opportunity (Rumor has it Joe might have one? If so, let's make a deal! )

The rad's free in FAST, but SCCA requires you to run the stock (plastic) item. Honestly, if it's not leaking or showing cracks, leave it be for now. They don't go bad that fast...at 261,000, I'm only on my second rad.

Other suggestions?

Ditch the double hoop when you get a chance -- it's not legal as a roll hoop in any sanctioning body, so it's just dead weight up high, where it does nothing for you.

Register with Mazda Motorsports...ridiculously easy, costs nothing, and gets you access to factory parts at around half price.

Miata.Net is your friend...bookmark it and spend lots of time there. They have the sales brochures for all years, which are a good guide to what features were produced together. For FAST, a feature simply has to have been offered on some variant that year; for SCCA, you have to build out the variant in stock form, unless using another allowance within the rules. Not as onerous as it sounds...just a little attention to detail.

Autox has captured my heart...

And is on its way to capturing your wallet. Welcome to S4.

[jev61]

If your 1999 Miata has a Torsen LSD, it is either a HARD-S or a LS, unless the previous owner swapped one in.

If it has leather seats, it is a LS with the normal SPORT-S suspension. If it does not have leather seats, look under the hood for a shock tower brace. That would be an indication of the HARD-S suspension, look under the back end of the car for yellow shocks. If you have yellow shocks, then you might not need new shocks yet, just new rear bump stops.

There is a tag inside the passenger side door opening labeled Vehicle Information. It has an entry for suspension: STD S, SPORT S, or HARD S. STD S = 14 inch wheels. SPORT S = 15 inch wheels, same suspension as the STD S, and the Torsen LSD. HARD S = 15 inch wheels, Torsen LSD, and the coveted harder springs, BILSTEIN shocks, etc.

[Loren]

It's an almost certainty that you need rear bumpstops on a used NB. Unless the PO changed them RECENTLY. The strange rubber compound they use for the rear bumpstops literally turns to dust in about 3 years. The fronts are a different compound (a more standard poly foam) and last a very long time.

I have a set of the Honda bumpstops that Joe mentioned. Just ordered them for the Mirage, but opted to not use them. (because I remembered that the hole in them is not a large enough diameter for a strut suspension) Let me know if you want them. You can trim them just a little bit (with a knife, easy to do) and have a bump stop better than the stock rear bump stop. Similar to the front bumpstop (same material), but longer. And they're cheap. I'll sell you my pair for $10. I probably paid $6.xx each plus shipping for them last week.

[jev61]

Not related to this discussion, but Matt if you are reading this, the bump stops that come with the VMAXX coilovers from Flyin Miata use that same "strange rubber compound they use for the rear bumpstops literally turns to dust in about 3 years". Ask me how I know. That is all, back on topic.

[jev61]

If you are going to "borrow" Ben's tires and wheels for the upcoming season, ask to "borrow" his larger front sway bar too. Tell him you won't wear it out.

[SallyFinney]

Hey everyone!
It's been a busy week, lots of work, so it's finally time to focus on the Miata. (nothing like last minute)
Thanks to all of you for feedback. It's been super useful. The advice to set some $ aside for parts/etc in my budget was gold. I got the car for $3800 (I'm pleased considering it's rock solid and it's been *meticulously* maintained) Basically the only things I'll need now are the 'rules' - tires, shocks and alignment. I'll be able to do that since I've got some $ left over.
I've been reading a lot of the forums too, lots of good stuff there.

SO, here's the update:
The roll bar is going bye bye.
The Festy's RE-71's are on as of today. (holy crap-what a difference!!!)
I'll get the tires flipped and aligned ASAP. I think Carl can do both of those, right?
Loren, I'll take you up on your bump stops. I'll text you to arrange something/pick up. Thx for the offer. Mine are totally gone.
The rims were 14's not 15's. My bad. But now they're rocking the 15's w the RE's so we are in business.
I reached out to Joe B to help w the shocks, etc. Hopefully I'll hear back from him soon that he can help me out. (messaged him here on the forum/gave him my #)
Joe, the shocks arent yellow. I called Mazda directly and read the VIN to them, and they told me I had a LSD but I'll admit the lady seemed kind of confused and may have just told me something to make me happy. Ben said he'll know once he drives it on course, but since it does not have anti-locks it's prob an open diff. If it is, that puts me in the class I originally wanted - yay.
I've decided on Koni's. They'll be here soon. (I live on a long 100 year old brick lined street, and I don't want to beat the car (and myself) to death coming home w the Bilsteins. (thx Loren & Ben for addressing that) Hopefully they'll last a while (crossing fingers Philip!)
Lots to do and a short time to do it all. I'm hoping to get everything settled so it'll be ready for this weekend's open, but if not, it'll def be ready by the classic.

It's gonna be a great season! Can't wait : )
Much thanks guys.

[twistedwankel]

Joe will do the alignment after Carl mounts and balances the tires. They are only a few miles apart.

If you step on the gas in some loose gravel on the street and leave two black marks it's an LSD. If there is only one mark it's an open diff. Or just rev it up in your driveway with a warm engine and pop the clutch at 2am.

Save all your paperwork and receipts for the Koni's. They do honor their lifetime replacement to the original purchaser. You just have to get someone to put them on and off for you with the "exchange" program and get another alignment. Koni (for a deposit) will ship you a pair in advance. You return the original pair in the same box the new ones came in.

[Loren]

Uh, this weekend is the Classic-ish. Next one is the Open.

[SallyFinney]

Uh, this weekend is the Classic-ish. Next one is the Open.

Yeah. Did I say otherwise? Yeah I did. I knew what I meant. Lol

Good to know about the konis. Thx for the clarification, Doug. I'm used to one stop shopping. Lol So glad I can have ppl who know what they're doing, and not give my $ to franchises

[twistedwankel]

So go to Dunnellon and beat up on the car as it is. I assume you can still sign up? If you want to see how bad it is let Farm Truck drive it once or twice in the fields Ride along and find out what not to do.

[SallyFinney]

So go to Dunnellon and beat up on the car as it is. I assume you can still sign up? If you want to see how bad it is let Farm Truck drive it once or twice in the fields Ride along and find out what not to do.

Farm truck??
Oh I signed up, Believe me!
Just having the new tires on is crazy different. Can't wait to really push it (well, push it for me lol)

[AScoda]

Push it.
Push it real good.

[SallyFinney]

Ben says it's not autocross til ya spin out. Had yet to do that in my g. Let the good times roll

oh, did i mention that im ordering some re-71r's from discount tires for when it's time to replace? They're on super sale (thx philip for letting me know/btw- got ANOTHER $60 rebate after i applied for their credit card-so basically, they're almost free... $290 for 4 )

Guys, I'm totally becoming one of "those people" aka garage stacked w tires, always surfing for parts, etc. how did i catch this disease so fast?
ya'll are a bad influence.

[Jamie]

Guys, I'm totally becoming one of "those people" aka garage stacked w tires, always surfing for parts, etc. how did i catch this disease so fast?
ya'll are a bad influence.

You'll know it's terminal when you start using tires as a unit of currency. As in, "this dinner out was two tires."

[SallyFinney]

!