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New alignment

Posted: Tue May 14, 2013 4:36 pm
by Popstoy
I just got more agressive, the hell with tire wear. I went from 1.5 neg camber to 2.2 neg camber in front, and backed off the castor a bit. Not a hint of push, while blasting the corners. I left the backs at 2.0 neg. and 1/16 total toe in, never had a problem with oversteer. Bob

Re: New alignment

Posted: Tue May 14, 2013 5:44 pm
by Omg10ae
Bob who does your alignment ? I need to find a better shop.

Re: New alignment

Posted: Tue May 14, 2013 7:02 pm
by Ski_Lover
Need More :)

Edit: I've never got the skinny on R888's, but according to Tirerack they like 1-3 negative camber (less than I expected)

Re: New alignment

Posted: Tue May 14, 2013 8:57 pm
by Saphire NB8C
bob, youre back!

Re: New alignment

Posted: Tue May 14, 2013 10:42 pm
by minime
Interesting - can you tell us what suspension set up you have and what wheels/tires you are using? Shocks/springs/sways and wheel offset in particular.

I assumed most of us preferred more bias on the front end, but you said you were running more bias on the rear until now - did you find it tended to understeer?

I used to run about even on the camber, but am now running the rear a little more conservative. Unfortunately I could only get -1.7 camber max on the fronts so I need to drop the ride height and/or possibly change out my bushings for offset bushings. I have -1.4 on the rear.

A few of my high power turbo'd track buds are running minimal rear camber, but significant front camber(-2.5 front, -1.25 rear) and find it is a great balance.

Re: New alignment

Posted: Wed May 15, 2013 7:15 am
by Popstoy
Kaus Racing, in Castro Valley did my alignment. They orginally set up my suspension 6 years ago, after the Tein's Flex's had settled. Back then, I was on some heavy 16 by 7 Enkies with 195/45 T1S's. Today I'm running on a set of 15 by 8 Konig's and 195/50 R888's. They're a 12 pound +25 offset wheel with slightly stretched tires. My ride height is 12 1/2 front, 12 5/8 rear. My right front is camber challenged to a neg 2.2, with max castor of 5.5 and 0 toe. I did have a little push with the old alignment, particularly at entree. With this new alignment, the car feels alot more confident without a hint of understeer. I'm running the big hollow 1 1/4" flyin miata swaybar up front, and a 5/8th's solid jackson racing rear sway in back. The new set up feels fairly neutral, maybe a tad oversteer. I haven't had the oppertunity to test the limits yet. I'm expecting more camber wear up front, and shortly will be headed to Amercia's Tire, for a free rotation and rebalance. I like the R888's, except for the tire noise, but the noise goes away after they get up to temp. Bob

Re: New alignment

Posted: Wed May 15, 2013 9:26 am
by minime
Nice, thanks for the feedback Bob, this helps us all out figure out what we may want to try on our own cars.

Re: New alignment

Posted: Wed May 15, 2013 6:05 pm
by rennkafer
You might not get as much tire wear as you'd expect, Bob. My car has been -2.3 front camber, 5* caster, 0 toe in front, -2.0 rear camber, 0 toe for over 3 years and 8k miles on the same 180 treadwear tires (225/45-15 RS-3's). I still wear the outer shoulders the most and have no detectable camber wear on the tires.

There was just a thread on MT.net about this... the big boys (Emilio, Savington, etc) are running 3.5-4 degrees up front and ~2 degrees in the rear. Apparently the more front camber the better, but the rear seems to not improve past 2 degrees. This is on track only cars, of course.

Re: New alignment

Posted: Wed May 15, 2013 7:11 pm
by Popstoy
Bill, less or the same camber wear would be great, we'll see. Strange thing is my rear camber has been -2.0 for along time, yet the rear tires are wearing even, with no appearant camber wear. At the same time, the front's with -1.5 showed mild camber wear. I've listened to a few opinions, as to why, maybe the understeer, maybe too much castor, who knows? 2.2 neg up front, with 5.5 castor, solves a bunch of problems for me, no more push, no more tire/fender rub at full left lock. Most importantly, no lift off/snap oversteer, a common tendency when pushing at corner entry. Toyo recomends -6 camber, but that's at full bump, not static, on their R888's. Any how, I had the tire's rotated this morning and went for a 50 mile loop of my favorite twistys, what a world of difference. The car is just so much more confident feeling. Bob

Re: New alignment

Posted: Wed May 15, 2013 7:44 pm
by Nikwit
What sort of toe did you have? Toe can create wear that looks almost the same as camber. I usually match my front camber (2.3*) to a bit of toe-in, somewhere in the stock range, and get good wear. For a dedicated track car, I wouldn't want the toe-in, but for my DD, it works out fine.

Re: New alignment

Posted: Thu May 16, 2013 9:54 am
by Popstoy
Nikwit wrote:What sort of toe did you have? Toe can create wear that looks almost the same as camber. I usually match my front camber (2.3*) to a bit of toe-in, somewhere in the stock range, and get good wear. For a dedicated track car, I wouldn't want the toe-in, but for my DD, it works out fine.

It's not toe, cause I'm not running any (read 0 toe in front). Now the back is a different story. I find with the back, I like a little toe in, but half of the factory's recommendation of a 1/16th per side. Without some rear toe in, the back of my car feels like a fish's tail, wagging back and forth at freeway speeds and above. Bob

Re: New alignment

Posted: Thu May 16, 2013 12:58 pm
by Nikwit
In a RWD car, 0 static toe up front is toe-out while you are driving, as a result of the road force applied to the tires (look up Scrub Radius if you want to go into detail). If you toe the front in a bit statically, it will result in 0 dynamic toe while driving. Toe it in a bit more, and you get dynamic toe-in, which can help to reduce the effect of camber wear. Go too far, and you lose some of the snappy turn-in feeling. I generally run mine right about at the stock toe number, which works quite well.

Re: New alignment

Posted: Thu May 16, 2013 1:07 pm
by minime
So is it safe to say if the driver is in the seat during the alignment and you set 0 front toe it will yield 0 dynamic toe(at least when the suspension isn't under compression) while driving?

Re: New alignment

Posted: Thu May 16, 2013 1:12 pm
by red5racing
FWIW, I have rear toe-OUT and am still alive

Re: New alignment

Posted: Thu May 16, 2013 1:26 pm
by Nikwit
minime wrote:So is it safe to say if the driver is in the seat during the alignment and you set 0 front toe it will yield 0 dynamic toe(at least when the suspension isn't under compression) while driving?


No, scrub radius has nothing to do with weight of the driver/passengers (beyond the slight rideheight change affecting bump steer). It's about road force. That is to say, as you roll down the road, the tires/suspension are pushed toward the rear of the car (in most cars, Miata included). The center is somewhere between the LCA bushings, I'd wager. So 0 static toe turns into slight toe-out while moving. The amount will probably increase as you increase speed.

In a FWD car, the power being put to the front wheels has the opposite effect, pulling them toward the front of the car and toeing it in.

Re: New alignment

Posted: Thu May 16, 2013 3:31 pm
by Popstoy
You present an interesting theroy, and given with oem bushings it would be even more true. I'm above the ride height, that would produce bumpsteer, plus I'm running polybush bushings for less bushing deflection. The only toe change I'll see with suspension compression is toe out. Given the big air dam/splitter below my front bumper, I only get more down force with speed. Most everything is a trade off, I'll gladly exchange tire wear for handling prowlness. Bob

Re: New alignment

Posted: Thu May 16, 2013 8:00 pm
by Nikwit

Re: New alignment

Posted: Fri May 17, 2013 6:29 am
by Popstoy

Thanks for that! It explains a few experiences I've sensed, since changing to the +25 offset wheels. I had thought it was simply the wider wheel stablizing the tire contact patch. Now I realize, the smaller offset has given me a neg scrub radius, possibly a good thing. Good in the fact that it causes toe-in for stability at speed, under braking, and a generally improved confident feeling. Bob