blue_na wrote:Thanks for the input so far, I probably should have mentioned this setup will be 99% road use, only the very occasional track day.
As suggested, I think I will go with max castor then max out whatever camber I can get from the stock suspension, though I am unsure about the toe, since I only plan on running road tyres (For now anyway), and don't want tyre wear to be excessive.
I think I will consider 0 toe on the front, but what effect will this have on wear?
Will running 3mm toe-in on the rear cause alot of wear? What kind of value would be a happy medium for rear toe in terms of stability and tyre wear?
Cheers, Nathan.
As I said above, 0 toe on the front WILL give you tramlining but no additional wear.
The front won’t track in a straight line but follow all the bumps, cambers, ridges, etc on our fantastically maintained roads. If you’re happy with that in a 99% road car then go 0 otherwise stick in 2mm toe in.
Another thing to remember that under braking the front suspension bushes deform and the alignment goes towards “toe out”. By setting it at 0 it will end up toe out and darting around under brakes.
Having rear toe in is very important on an MX-5. It reduces the change of having the rear let go suddenly under roll oversteer conditions.
2 - 3mm in will not effect your wear and is what is recommended in your owners manual.
blue_na wrote:
Also, you say 16" on an NA are slow, should I swap the 16" NB rims for a set of 15" NB8A rims?
I don't want to go right down to 14's due to choice of rubber and looks.
Cheers, Nathan.
15s would be better.
You know that to improve responsiveness in an engine you lighten the flywheel. By lightening the flywheel the engine doesn’t have to overcome unnecessary mass, so it spins freer and quicker in its charge to the red line. There are some downsides but we’ll forget that here.
Now think of your rims and tyres as flywheels. Increasing the weight of a wheel by 0.5kg really is like adding 2kg to your flywheel. The engine needs to turn that extra mass. It will spin slower, be less responsive, etc.
So by going back to 15s you reduce the additional mass of the 16” rim and tyre that the engine needs to turn. There are additional benefits to the suspension also as the unsprung weight is reduced, handling will improve.
Remember that a lot of the "specs" that the guys are throwing around here are really for MX-5s that are tracked on a regular basis and are set to suit their personal requirements. You’re not doing a lot of trackwork so by sticking with the settings above you will have a MX-5 that’s comfortable to drive on the road yet for more responsive than the standard settings from Mazda. You can do a search to find those standard settings elsewhere on this forumn