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» Hello Spec Miata Community » SpecMiata.com » Spec Miata Setup Guide » Wheelbase- Left vs. Right- How close should they be?

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Author Topic: Wheelbase- Left vs. Right- How close should they be?
Jay Lutz
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Any thoughts, hopefully based upon tests or at least sound logic, on how close the left and right wheelbases must be.....so that handling is not impaired Right vs. Left? The spec book says 2277mm nominal I believe.

Just for reference......the roundy boys purposely shorten their left side wheelbase by around an inch to make the car turn left better.
Note: JD's Setup Guide V2 apparently is mute on this point so I'm guessing he feels it is irrelevant so long as everything else is setup properly.

Thanks, Jay

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Mike C Verified Driver Made Donation to Website
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At a neutral position they should be the same or your car is bent.

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Keith in WA Verified Driver Made Donation to Website
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I think JD just assumes they're equal.

For roundy round, it works to have them different. All other things being equal, shorter WB = tighter turning radius. The inside wheels track a tighter line than the outside so having the side with a tighter turning radius take a tighter arc is good. Turn the other direction and the tighter turning radius has to take the longer arc which can't be good and vise versa.

I'd guess a roundy round setup turning right = lots of slidey slide.

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Keith Novak
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Rich Verified Driver
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Track dependent. Make sure you slot your subframes for maximum adjustment.

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Rich Wiese

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Depends upon how well you're measuring caster. If caster is dead nuts equal side to side, wheelbase should be too I think. If estimating caster loosely (I do, no plates) no more than 1/16" to 1/8" or so.

Did you replace your Subframe after the shunt into the IRP wall mentioned in the other post? If not, I would. You may have to "slot" your new subframe for it fit onto the rails.

Blix Verified Driver
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If you have to slot your subframe, your car is probably bent, get it pulled back to shape or it won't handle consistently right to left. Honestly, if I saw someone with a slotted subframe I'd be kinda p***d off, because (in the NE) there are a few tracks that you only care about turning one direction, and that would be an nice (but illegal) advantage.

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Rich Verified Driver
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My subframes have always been slotted. I have special road-america subframes that allow the car to go through the kink without turning the wheel for minimum tire scrub.

'99's benefit more from this mod because of the increased surface area of their fenders.

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Rich Wiese

Spec Wrecker Ford

   

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