For the record, I just my alignment re-done yesterday and was surprised with the results - pretty much what I wanted/asked for!hillman said:The suggestions for autocross use are not going to work well for this guy. First of all, I doubt he can get anywhere close to -2.5? in front, with those 17s... unless they really are only 5" inches wide, but I don't think that's what he meant.
I certainly didn't notice, since he didn't bother to post it in the thread. Also, I'm pretty sure he's not paying attention to this thread anymore anyway.twoina2 said:In case others haven't noticed, blckmr2gts has a 93T. His castor isn't adjustable and he should not use the 91-92 rear toe spec.
You're half right. POSITIVE caster means line from the lower control arm point to the upper control arm point (the ball joints actually, but close enough) leans back, like the rake of the windshield. This adds "camber on demand" as the wheel is turned, which gives more grip up front, which would tend to give you more oversteer characteristics, all else being equal.shanesublett said:The More neg your caster, the more your car is going to want to oversteer. Don't forget that the car pulls towards the side with the most neg (or least total) caster. Usually the steering gets easier as caster gets neg also.
If you want minimal tire wear, especially if you do have more negative camber than OEM spec, I would suggest that zero toe (dead straight ahead) would be best for street driving. The OEM spec is typically toed in a little for better stability and tracking.shanesublett said:As far as toe, I always stick with spec.
I respectfully disagree. While you seem to know what you're talking about, most alignment "techs" at shops don't understand fundamental vehicle handling and suspension design - they just get the alignment machine to read within spec. They don't like being told otherwise, and like all people, they're uncomfortable with new ideas and new procedures they're not used to.shanesublett said:I would suggest talking with the tech at the shop, since he will give you better work and not bitch so much about realignments if he is part of the descision making. No one wants to be told exactly how to do their job, especially when there's a good chance you'll need another align soon!
This is good to know, but I just want to add that it makes a big difference that you're using camber plates, instead of crash bolts. That allows the top of the strut to lean in, and give you more room for 17s.My main point was that it is certainly possible to get 2.5 degrees of negative camber up front with 17" wheels without rubbing (even with the car lowered substantially). I actually had 2.6 degrees on the right side before the alignment tech evened it out.
I thought volunteering this information might be useful to others who are researching MR2 alignments for autox use (as I was - that's how I found this thread in the first place).
You've got oversteer and understeer right. You just had flip-flopped the conventional interpretations of positive and negative caster. All I was saying is that as caster goes more POSITIVE (ie the front wheels move AWAY from the rear ones, if the upper ball joint position stays the same), you get more added negative camber on the outside front wheel as you turn the steering wheel, which tends to give more grip up front, and therefore less understeer or more oversteer.shanesublett said::thumbup Perhaps my understanding of under and oversteer are wrong. Isn't oversteer when you turn a little and get a lot? I was under the impression that the car tends to steer faster and more unpredictably as you bring the front tires towards the rear, or more under the center axle.