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:
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
stock 12mm bar
stock end links
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...
say **** it and drive as is. Maybe go full-soft on front konis but sounds like bad idea with 440 springs
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.
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.
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.
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.
I googled and found this. Same thing as you're talking about?
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.
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).