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Old 07-11-2011, 02:43 PM   #1
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Default Help me sort out my suspension

Hey guys. Here's the problem - car mostly understeers and is difficult to rotate on tight low speed autocross turns. However it handles great pretty much everywhere else (street and 1 hour of track).
I want the car to rotate a little bit better and spend the least amount of money.

What I have:
Front:
  • 440 springs
  • 1.125" hollow RACE bar up front (stiffest one Racing Beat makes, 3/16" wall thickness vs 2/16" regular hollow bars)
  • 949 end links
  • 2.2* camber, 5* caster
  • 12.25" ride height
Rear:
  • 300 springs
  • stock 12mm bar
  • stock end links
  • 2.9* camber
  • 12.75" ride height

koni sport and 15x9 6uls with rs3 @ 24psi all around.

I'm mostly clueless when it comes to suspension. What options do I have? I'm thinking...
  1. say **** it and drive as is. Maybe go full-soft on front konis but sounds like bad idea with 440 springs
  2. get a 0.675" rear sway
  3. get 350 rear springs
  4. sell a kidney and buy xida club sports
  5. ???
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Old 07-11-2011, 02:47 PM   #2
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reverse your camber from F to R.
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Old 07-11-2011, 03:14 PM   #3
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That's a $100 option
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Old 07-11-2011, 03:19 PM   #4
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not if you eyeball it. lol. you can try disconnecting the rear bar to see how you feel.

Might just be too much front bar, is it in the stiffest setting or the outside hole?

I'm running 400/333 on my tiens (7/8 F bar on full stiff and stock 12mm rear) love the balance. My alignment is probably -1.8 F/R
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Old 07-11-2011, 04:12 PM   #5
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yeah the front bar was a mistake. it's way too stiff.
disconnecting the rear is supposed to make the understeer worse, no?
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Old 07-11-2011, 04:18 PM   #6
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increases oversteer.
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Old 07-11-2011, 04:23 PM   #7
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you sure? I mean I'll try it, but kind of seems counter intuitive. Removing the sway effectively makes the rear end softer and more grip in rear than back = more understeer.

Quote:
Originally Posted by 949 says
Disconnecting the rear sway bar on a lowered Miata allows the inside wheel in a turn to droop further. Since the inside front with swaybar still attached will not droop, rake changes. This means the front stays low, the rear jacks up in a turn. The effect is slight but it changes the roll axis, camber gain and a few other things. For autocrosser, this compromise is usually worth it as it will greatly reduce wheel spin and reduce oversteer during low speed transitions. For track use however, this will usually result in terminal understeer that will have you pulling your hair out trying to get rid of.
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Old 07-11-2011, 04:29 PM   #8
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disconnecting the rear = more grip in the rear = understeer.

BUT, if you have an open diff, disconnecting the rear will keep both tires in contact with the ground better, allowing for less unloading of the inside wheel (more power oversteer).

Only way to find out is to try.
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Old 07-11-2011, 04:37 PM   #9
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I should have explained it the way cardriverx did. I was getting lazy and was completely wrong by saying increases oversteer.

Which hole is your front bar on? I know y8s the tiens as well with the hollow front bar and no rear and his is more tail happy than mine (NB va NA), but same shocks and springs.
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Old 07-11-2011, 04:41 PM   #10
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I'm using the outer hole which is softer setting, AFAIK. I'll also get a Torsen sooner than later.

I'll try disconnecting the rear sway and if that works, great. In the long run I'll probably just get stiffer rear springs, like 350lb.
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Old 07-11-2011, 10:16 PM   #11
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Try upping the tire pressures in rear and a bigger bar. That will help you rotate better at lower speeds, yet make the car more prone to snap-oversteer at higher speed. Did you try brake earlier and harder? What about more aggressive rear pads? We do not have sufficient power to power over (like the big HP cars) but we do have a well balanced chassis. You can brake hard while turning slightly until the car rotates, then apply power smoothly but firmly. If that fails, try the e-brake. I know that most folks in these forums hate the Drift King type posts, but I have had moderate success with turning using the e-brake during wet surfaces with understeer. You have to practice a lot and you may flat-spot some tires, but it is worth it. Just pull steady, hard and smooth and release just as smooth (like trail-braking but with the right hand) and quick. It helps to rotate the car. Another option is LFB (left foot braking) which I am not very good at (although I enjoy it on go-karts) but this year I will practice more.

Do some reading on J-turning. I did it all the time in my RWD Pick-ups and they u-turned on a dime on wet surfaces (rain and snow).

Good luck with your problem. It seems to me that if the car is well balanced in other aspects, you should introduce some higher level skills for those times when the car does not work the way you want it to.
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Old 07-12-2011, 03:20 AM   #12
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Thanks for the info! Yeah driver mod would be the best thing. I had several people drive my car and the best driver didn't have a single complaint about it. Everyone else found some fault....

Tire pressures.. yeah, thought about it. I like running 24psi everywhere since the tires contact well (did the chalk thing) and wear even. Plus I feel like that's a hack with running different tire pressures to correct MASSIVE understeer issues. Maybe to fine-tune...

I went ahead and bought 400lb springs for $70. Feel like a decent deal. Figure in the worst case I have some extra variable to play with. If it ends up being too tail-happy I can put the front sway into hard setting and remove the rear sway. I also have a 11mm sway laying around, but doubt I could even notice the difference (i'm a mediocre driver at best).

On the last autox I tried braking late and turning in earlier - that worked GREAT. But I was still a second off my friend in a 10AE with same wheels/tires. He hated my car though.. said it was hard to drive.

tl;dr here's a vid from this sat. with my brand new spanking camera + phone track app combo.

Turns at 0:13 and at 0:18 were the ones I was having issues with. And 0:28 but I think that was just bad line + going too fast.
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Old 07-12-2011, 08:29 AM   #13
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Are you on sleeves? You should have told me I have two 7.9" 391 lb/in springs you could have...

I think I have a 12mm rear sway, what year was the 11mm on? we could swap.
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Old 07-12-2011, 01:45 PM   #14
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Aw damn.

I think 12mm is 90-91. Are those the springs you were coilbinding? I have adjustable perches but dunno if there's an inch to move them.
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Old 07-12-2011, 01:50 PM   #15
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I never ran them, would see no reason they would bind up front at that rate.

My rear sway is from a 93 IIRc. I can measure.


going to lost dog tomorrow night if you wanna come by. although i dont have the springs on me I do have 6" 6K ones handy.
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Old 07-12-2011, 03:26 PM   #16
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Are the front sway bar bushings binding and or hitting the control arm? Mine were on both issues. Once I trimmed the bushings and lowered the links my car turned like magic.
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Old 07-12-2011, 03:35 PM   #17
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I googled and found this. Same thing as you're talking about?

Quote:
I'm sure most of you guys saw Andy Hollis' write-up on the pointy board about sway bar binding problems. I checked mine out recently and, sure enough, they were binding so bad that I could not even move them. I run a 1.125" hollow bar on front and a .625" on rear, so neither is stock and both use poly bushings. The way I fixed the problem was to remove the mount/bushing, clean thoroughly, and then used a belt sander to grind off the "excess" bushing material until it didn't extend past the face of the mounting bracket. I regreased the bushing with "Pure Polaris" grease (used this grease on my poly suspension bushings, and they're still squeek-free after 2+ years). Reinstalled sway bars and now they are free to rotate no matter how tightly you torque the brackets.
I never did that and those bushings were kind of tight. If that makes my car turn better I'll send you some beer.
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Old 07-12-2011, 03:50 PM   #18
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Why do you have your fronts on full stiff fail? Adjust the shocks, take out a little rear camber, and play with tire pressure.
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Old 07-12-2011, 06:05 PM   #19
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Fronts are half way right now, rears full stiff. I'll try full soft. I was, however, under impression that it's a bad idea to run full soft when your spring rates are almost maxing out the shock capabilities (440 springs on koni sports).
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Old 07-12-2011, 07:19 PM   #20
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the konis have plenty of rebound to control them, at full soft.
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