Suspension Crew - Your advice goes here.
 

Ran an autox this weekend and I'd say the car is feeling pretty good. However, I noticed a pretty big weak spot with the car, tight hairpins and sweepers. It just had too much understeer. I tried backing off the front shocks compression and adding more tire pressure up front, but to no real avail. What else can I do so the car is more neutral without dipping into the bank heavily.

Here's my current setup:

7/8" Front sway bar - stiffest setting
No rear bar
Koni Shocks
FM Springs (333/230)
-1.8 F | -2.0 R

I've had the front bar on the softer setting for years now and wit no rear bar the car felt great, however, it had too much lean and both my outside tires would lift and car felt uneasy. The current setup feels great otherwise, just not when I have to double back fast.

You can see what I'm talking about by comparing my car vs. this NC who was significantly faster than me:

was trouble spots were at 0:15, 0:25, & 0:35 the three hairpins.




now watch how this NC takes them, granted he has better tires a more low-end torque but he said he had no issue getting the car around them, my car wanted to push and i had to take them too slow.



0:15, 0:25, & 0:34

His time on that run was a 45.23, mine 48.39 I believe he was one of the fastest cars of the day, I want to be one of the faster guys of the day. I'm faster in the straights and slaloms, but I lost so much time where it counts.

My format for promoting oversteer is typically stiffen suspension rear and go high on the rear tire pressure (above where it grips the best).

my daddy always said: add traction to the end without it.

in order of easiest to hardest, I would try:

1. soften front shocks
2. reinstall rear bar (since you like flatter cornering)
3. go get the alignment you asked for (add a half degree of front neg camber)

btw... ur doin it rong

haha. inside i mean.

yeah I had the rear shock at full stiff and backed the fronts off a little, I could have softened it more, but got lazy.

My fear with the rear bar, even when I had the stocker on the rear was pretty unpredictable and would let go without warning. I have much better control of it now and if it does ever step out it's a breeze to get back in line.

Would I simply benefit from swapping my springs to a 500/350 GC coilover setup?

I'm in the same boat. I also want to be up there with the fastest cars of the day. Last event I was half a second slower than a stock 91 :( (good driver, good tires).

Its the hairpins and other such obstacles that are killing my times, I know it. I have too slow waaaayyyy down to make it through otherwise I plow. It wasn't much better in that regard with my stock rear bar fyi.

I think more camber in front might be the ticket.

BTW, you would need to lower front pressures for more front bite. +1 on adding some rear bar, or at least adding more rear pressure.

I went in to get a new alignment last week, i wanted -2.0F and -1.8R, unfortunately I had my dad take the car, the shop got it on the machine, said it looked fine my specs were too aggressive, and took it off.

I started the day with 32psi in the front and rear. The wear marks went too far on the sidewall. once I put them to 36psi they were about right, I didn't think of adding any rear as well.

You need more front bias than that. I'd say -2.2 front atleast. Alignment shops are really condescending when you give them funny numbers sometimes. Other times they just say "as long as you know what you're doing" and trust you. Most of the time, however, they treat you like an idiot and dont do what you say.

I'm wondering how much of your understeer is attributed to your driving style. Not being condescending about it, but you might not be getting good weight transfer to the fronts to optimise available grip. I know try to brake a little too late, I over work the fronts and end up understeering in tight sections. Unfortunatly, unless you're doing a TnT, trying different techniques is extremely difficult as you only get a few short runs and each autoX layout is different. I'd try going stiffer on the front bar and softening the shocks a good bit.

The battle i'm having is lifting the rear inside tire. I can raise the car up some and increase the droop, but that raises the COG. I have tried disconnecting the rear sway (running 12k/8k springs) but didn't really notice a difference... it could have been my mentality of driving with a different setup. I've also tried running everything on a the stiff side, which feels good, but I can notice the understeer. So far, running the front sway on full stiff, the rear on med. and the shocks 12clicks from full on the front and 15 on the rear have yeilded a very balanced car. My other problem is power delivery to the wheels :giggle:

My alignment specs would get posted, but I know it's all out of whack at the moment.

Meant to put -2.5F and -2.2R. That's the printout I gave them. They used to be a good shop, PBC, but now they have seem to have been bought out and are a general repair shop, not a spec miata shop anymore.

I guess I'll be giving the alignment another shot before anything else drastic.

Please do and let me know what difference it makes.

Doppelganger; you could be right. I'm having the same problem, however, and have had many chances to test out some different things and just cannot make my car rotate around sweepers and sharp corners. It really does seem to be mostly related to the way the car is set up. Yes i'm a bad driver still and need much improvement on these points, but at the same time its hard to improve when your car doesn't do what you tell it.

These are my weakest points and i'm certain that when I figure them out i'll be one of the fastest cars of the day at our local autox events.

this is what happens when i run a rear bar:



and here through the first slalom and at the end around 0:14:

Same problems i had. Although, it looks like we were both running bad tires at the time that we had a rear sway...have you run good tires with a rear sway at autox yet?

Brain, what kind of diff do you have? A good bit of power on understeer could be caused by some lockup on power.

FWIW, my wife's n/a (used to be my track car) is dead-balls awesome neutral at track days with the FM 2.5 setup, front bar set to stiff, rear in the middle, max caster, neg 1.0 in front, 1.5 in back, zero toe in front, 1/16 toe in (max) in back. I run 2 psi less in back than in front. It has an open diff. Note that I have .5* bias in back, which is what I will keep no matter how much camber I dial in.

Looking at your approach to the first hairpin at 0:15, as hard as you were getting in, you need to be doing some trail braking if you don't want to plow. If you look at that other guy, his entry was WAY slower. With your belching turbo beast, you can enter slower and power out, you don't need to get in quite so hard. That car will seem like a different animal if you slow that entry.

Torsen rear with 4.1 gears. Five years ago before the turbo and after autoxing the car 5 years N/A prior to that I had the thing nicely setup and was getting top times.

Watch my tach, I'm braking into the turn and I even blip the clutch to try to rotate it. I'm down to 2K in second gear, I probably could have benefited by dropping it in 1st. This is why large turbos plus autox kinda stink.


What if any benefit will these cool frame rails I have yet to install give me?

You had crap tires in those videos though, right? The easiest/cheapest thing that I think would help would be reinstalling the stock rear bar. Most people who pull the rear bar are running springs that are significantly stiffer than FM rates, grippier tires, etc.

With my 450/300 springs and both front and rear FM bars it's just slightly tail happy. I'm going to put the stock rear back in and I should be pretty happy with that. But I don't like how it handles with no rear bar (disconnected end link) and 300# springs back there, no matter how much I play with the Konis or adjusting air pressure, it just understeers too much for me.

In general I'd say you can go with stiffer springs. I was worried that, omigosh I'm tripling the stock rates so it'll be way too stiff :giggle:, but the roads around here are pretty good. 450/300 is totally streetable.

the tires weren't that bad. i just blamed it on them, both videos were on RT-215s, they weren't even at the wear bars, but were old, the second video they were still new.

my probably is my power output, I really hated the unpredictably with the rear bar. I blame my pole incident on it. It's only going to get worse once I put a smaller turbo on next week.

Playing with Shaikh's camber curves tools, it really looks like i need that alignment i quoted above (-2.5F and -2.2R). I also seem to have coilover sleeves and 550/300 springs on their way to me. Once I fit them I might try the stock bar again, if I can find it. I think I at least have a FM bar that i can put on the softest setting.

I just finished throwing in Konis and 450/300 springs yesterday. I have a 7/8" front and the stock rear.

Like Scott I'm just a little tail happy, but manageable, which is good for me to prevent grenading 6" diff. I'm biased since I despise understeer, and learned on oversteer machines (83 Celica, 80 Corolla, 92 240).

Yeah but didn't that happen in, like, February? On a wet road? I'd blame it more on a cold/wet road and cold tires, and maybe a bit on the driver (sorry man :laugh:), than on the presence of a rear sway bar. Many years ago through the snake at VIR, I spun the ass end of dad's RX-7 around on a wet track, and the car was not inherently oversteery to begin with. Granted, the bar reduces the compliance of the rear suspension. But cold/wet road + cold tires = low traction, if the turbo spools up in the middle of a corner you will break traction and the ass end will go around. If you set up your suspension based on your experience in poor road conditions, it's going to understeer just as soon as the weather warms up.

You will enjoy the new springs. Any idea what kind of ride height you'll have to run in order to get -2.5° of front camber? Methinks pretty low but I haven't tried. Other random thought- the FM rear bar is pretty damn stiff even on the softest setting.

even still. If I was on the street on a perfectly ideal day and taking a fast corner I could loose the rear without warning, now I can go balls deep without worry, if it starts to step out I can feel it and correct.

I'm pretty sure I can get close to -2.5 now, if not I'll just go for the max I can make. I'm at 12.5" F and 12.75"R.

what kind of toe are you going to run? I've been playing with the idea of zeroing my toe.

I have 1/16" out F and 1/16" In R. 3.80° Caster.

where's one find a skidpad around these parts? or how much is the summit point skidpad for rental? :)

$20 for the entire day when the drifters are out using it. No joke.

I was having the same trouble as you, severe understeer. Pulled my 1 1/8" RB front bar and installed 7/8"FM. (no rear bar) then I had severe oversteer. However, I noticed that the RB was pretty much seized on the bushings when I pulled it. Went back to RB 1 1/8" hollow bar, oem rear, handles awesome now.
So, try lubbing up your front sway bar.
'91, FMII GT2554R, 4.1 Torsen, AFCOs 400/275 springs Trackdog I/C, DIY water injection, 2001 Sport brakes, etc.

need full alignment numbers

My alignment is currently:

Front:
Camber: -1.8L -1.9R
Caster: 3.8°
Toe: 1/16" out

Rear:
Camber: -1.9L -2.0R
Toe: 1/16 in


I have a set of coilovers coming my way, looking at Shaikh's spreadsheet just swapping them in will result me in his recommended "stiff" setup for his FM2 car.

Honestly, looking at the comparison with the NC run, its looks to me that you are braking too late and causing the understeer. I can't tell where you are in relation to the cones, but the NC driver is on the brake earlier, rotating, and back on the gas at the apex. Slow in, fast out and shortest distance will always win.

In the 1st and 3rd hair pins you are almost all the way to the back of the feature before you can get the car turned (and you seems to be still braking). Try braking a little earlier and get the car rotated a slower speed.

As for no rear bar, from what I've experienced with an open diff and from what I've been told by people experienced with a Torsen, its the way to bandaid the situation slightly. Most people have told me to skid a Torsen and go to a "real" diff. I also run more camber in the rear than the front to compensate for the extra roll in the rear (2.0f/2.5R). Worked out well, but I was fighting blown shocks most of the time.

I ended up taking that line to make the late apex, if I turned slower/earlier it was worse and slower overall. And I was plenty slow before I took them, you can see in 2nd gear I was under 2000RPM, major slowness. The first corner I might have come a little hot in, but the rest I wasn't. Just look at that sweeper, its a fairly easy corner. It's 180° but its not tight. I couldn't give the car gas through the corner else it would head straight for the pointer cones. Same thing with the last one, I took out the cone you see at 0:38 once or twice that day. And I did try a few different approaches each run.

I've been autoxcrossing this car for close to 10 years now, I used to be pretty fast with -2F and -2.5R...when I had 90rwhp.

The real problem is it's hard to find solid advice from people who autox/race high powered miata.

new setup: 550/300 + that rear bar you were talking about

I still think you should take 5 minutes and disconnect your front end links, and make sure your sway bar moves freely. I was suprised to find mine was seized up, couldn't budge it. too stiff front=understeer.

I just moved it to the stiffer setting last week. while it was a bitch to do, it was not binding. Before going stiff, it had too much oversteer and felt shitty altogether. I liked how it handled but for those corners. I just need to be a real man and run new springs with better rates. FM springs are great for a GT car with leather seats and cup holders.

Cool. I found that I oversteered like crazy with the FM bar set on stiff. I don't like the angle of the end links on stiff. Had to back off the throttle on fast sweepers or it would over rotate. Times went down almost 2 sec when I switched back to my 1 1/8" hollow bar because I could keep on the throttle. My friend "Deerhunter" with his 435 rwhp stroker had same problem using the FM bar, temp. cure was to turn down the boost. We were both running AFCOs with 450/300 springs. (recently changed my springs to 400/275)

They posted the results from that autox finally. I'm in the top third this time, not the bottom third :P Still a good number of miatas faster than me, but a few were on r-comps.

woot:

http://boostedmiata.com/projects/coilovers/DSC_0001.jpg

How much did they set you back?

By no means have I managed to figure out this autocross thing since getting more power but one thing I learned is that you should try and always keep your hands on the wheel. You feed it through a lot and adds time, we've got quite a good steering ratio so if you're moving your hands a lot it may mean your turning too late and having to over compensate.

It was at a test n tune day where I had someone sit next to me that they pointed out the same thing with me. I smoothed my inputs and while it was a bit slower at first, I managed to cut down my overall times and didn't have to do as much steering.

Life was certainly easier when I had stock power!

Scott, if you rotate too much with the new rates, get a tubular front bar and keep your rear bar installed. Rotating the car at low speeds without a rear bar is near impossible, especially on street tires.

Looks like ebay sleeves + QA1's.

What's the logic behind the 550/300 setup? Especially with no rear bar you're going to have trouble getting the car to turn. I'm on 450/300 with OEM rear bar and I still have too much understeer. Might be okay for the track, but I'd try to loosen the car up for auto-x.

he has aftermarket rear sway bar that will go along with these

The 550/300 setup with no rear bar is actually what Shaikh recommends on his suspension worksheet:

I do have an aftermarket rear bar that I can put back in and fool around with at the next autox (aug 29).

It is also lot dependent. A setup like that would be more for a SCCA style event where the car is going to be seeing faster speeds. Local lots tend to be smaller with lower speeds and more bumps making them a different ball game. Your money would have been much better spent on R-compounds and by that I mean an Auto X compound. Either a Hoosier A6 or a Kuhmo V710.

After watching your video, here is what I noticed. First off, you need to be smoother with your steering and gas inputs. Your steering inputs look abrupt and are not in synch with throttle inputs (picture a string tied from the bottom of the steering wheel to your right foot.) You shuffle your hands when you are not seeing enough lock on the steering wheel to do so. This costs time. There are times in the video when you can be more aggressive with your throttle. You need to learn how to modulate the brake pedal and
trail brake. This will allow you to drive faster into a turn, brake later and rotate the car that way. Your understeer looks mostly driver induced. However, you need to put the rear bar back in. If you think that the rear bar caused your car to crash, think again. The accident probably could have been avoided by a more experienced driver. However, thats how we learn. I totalled my AP1 S2000 by looping it into a guard rail. Did it suck? Yes. Did it give me that drive to be a better driver? Sure did. Am I a much better driver now than I was 2 years ago with the S2k? You bet your ass.

FWIW, I am now regularly competing for FTD with my 99 CSP Miata and it is not nearly modified enough to class rules in it's current state.

Here is my setup:

-Basic bolt-ons at the moment (Adaptronics and TMW ITB's going in as we speak)
-Tokico Illuminas with new FM Springs (setup works great on bumpy lots, but is a little soft for track days with high speed / high grip turns)
-RB 1 1/8th tubular bar at full stiff.
-99 Miata 12mm rear sport bar.
-1.6 Camber F and -2.0 R
-1/16 toe out F and 1/16th toe in R
-Basic weight reduction i.e. no ac, cruise, Momo wheel, Bride bucket, gutted trunk, and other misc tidbits. Car still has full interior, PS, and a hard dog bar for track days.
-225/50/14 Hoosier A6's on C-stock 14x6 Kosei wheels. Bought them with 2 auto x events on them for a measly 400.00 for wheels+tires. Although, this setup is no wheres near ideal for a CSP car, but it is enough to keep me competitive locally.

I plan on doing some auto X with my 91 Turbo Miata eventually and it is going to be setup pretty much the same as my 99.