The YouTube one was a go-pro theres a vimeo (iPhone) video of that day that I posted that shows inside the car view. So basicly the car had two cameras on the car. The only reason I posted the YouTube one was because you could heard the pushing of the front tires.


Vimeo was uploaded as hd, hd won't play on the phone, sorry.

 

I can't watch the videos, but you could have the perfect setup and still get push. It is called DIU (driver induced understeer). We've discussed this, but I bet you need to go into the turns at a better angle ask less from the front tires. Maybe?

 

Tried that Dave and that's why I got beat by my co-driver. I gave up to much space and he took the tight line. O well. I'll try again this weekend! Hope your car is fixed and ready for this weekend. Good luck!

 

Wow...big pimping, nice!. I'll watch that when I get home then.

haha, I like DUI (Driver Understeer that was Induced)...as in the sentence "I have problems with DUI's while autocrossing"

 

Josh, your roll rates would indicate that your car should be pushy but you have seemed to cancel that out somewhat by running a pretty light amount of rear toe. I found rear toe be a very powerful tuning tool and especially on the AP1. If you add toe, your car will probably be too pushy and you'll need to up the rear roll rate or lower the front. Right now, you've dimenished the overall grip with the high split of roll rates on the axles and then patched the handling with rear toe. Your car toes out under braking which also occurs in slaloms and corner entry. By the time you get back on the gas there is a decent slide (rotation) already occuring. The next thing you know, you're eating dust and looking at where you just came from.

...maybe.

 

Matt,

How much toe in is required in the rear to not toe out under braking? Or atleast not pass 0 toe.

So basicly your saying my spring rates are to far apart and causing a diminishment of front grip. The lack of rear toe is the only reason the car is drivable?

That's wierd considering most people are split more then me.

I know of a national winner that's 800f/500r. And several people with 850f/700. Now I know you arnt that split.

So I need to fix the toe issue, how much toe is needed? And my options after that toe setting is to take out front bar or change springs to get that front stiffness vs rear stiffness closer?

Thanks for the input matt

 

The difference is not in your springs. It's in your sway bars. The MX5 bar is woth 84-ish lbs and the stock AP1 bar is worth 393 lbs. Because it's connected to both sides of the car's suspension it has even more impact.

I would think at .06* per side would mean you toe out at very little extension... some where the less than 1" range. Tuning toe is driver preference. It's a really powerful too for vehicle dynamics that the AP2s can't really take advantage of. Just put a 1/4" total and see if you like it. Your car will be much more stable on entry and will be more stable on exit as well... maybe too stable on exit.

The magic of the AP1 bump steer is that you can set up your car to do some slight rotation on entry and when you ease on the gas, the car toes in and gets stable. It also means that if you have to correct your line mid-sweeper, your slight accelerator lift means you get some passive steering back there. In the AP2 all a lift will do is transfer weight.

 

alot of fast people are using the miata bar and the no bar set-up though. right?

I'll try more toe, I feel it will push like a dump truck though. I guess I could add a bigger rear bar but I feel like everyone runs the no bar/miata bar set-up. how close are your spring rates together matt? I know you told them to me a few months ago but have you changed them since then?

 

If it pushes you can try more front camber. Not sure where you are at though.

 

Stock rear bar seems to work for the fast ap1 and ap2 drivers here on the west coast.