romandian

triangle?

k24556

There are litttle triangles molded into the tread at the edge of the tread proper that can be used to gage contact patch. Usually, you will see really rough wear on the tread and a fine wear pattern approaching the little triangles. If you get this you have about the perfect tire pressure/alignment for your driving style and the track conditions. If the little diamonds are gone, you have to do some trouble shooting to determine why. I know the triangles are on the Nittos, but not sure about other brands.

romandian

interesting. where are they?

k24556

Right here:

Soloontario

I have a stock C5Z suspension (with more recent addition of Strano bars and DRM Bilsteins) and usually run a square set up on 18 X 10.5s.
Always torque to spec and never had an issue with loosening of the stock bolts. (Still not quite sure what the "overcentered" bolt is. Does that mean that the majority of the eccentric bolt plate is above the centerline?)

My issue is that with neg 2.2 camber, I lose a lot of caster. Have not tried removing a spacer on the rear of the UCA arm which should help, but I also clearly have some walking of the LCA rubber bushings such that the rear one is compressed and the front one is pushing out the front of the LCA with the net effect being that the car has moved forwards on the LCAs (or the LCAs have moved backwards relative to the car which is the same thing) meaning I have less caster.

OTOH, the car is still fairly stable on the road at 5 degrees caster as long as the toe settings are within reason. My question is, given that most of us are using tires with sig more grip than stock and high caster measurements increase the wear on power steering pumps, is it reasonable to actually want high or even stock caster measurements?

Also , if you remove the UCA washer just on the rear, does it cause any issue with how the front sits and does if give a small increase in neg camber?

k24556

There is a pic in post 15. Yes if you get the eccentrics above the cl of the slot (in the crossmember) it is harder for them to drift down.

If you put spacers in the top behind the dog bones,you will take away the negative camber you just put in. Having one in and switching it front to back of the individual dog-bone is a pretty good method to dial in cross-caster. You may have to re-check both camber and toe afterward.

The other thing to remember about caster measurements is that they are a secondary measurement. That is you are taking two camber measurements, AND relying on a correction factor to get an estimate of the tilt of the axis of spindle thru the ball joints, which is the caster. So, there are errors a bunch creeping into your measurement. Saying you have 5 deg camber is almost a guess IMHO. Anyone that reports a decimal point after a whole number is kidding themselves. Look at all the error potentials, how accurate are your camber measurements, do you have runout in your wheels, did you turn the wheels EXACTLY 20 deg for the camber measurements, What suspension bushing is worn.

I worry more about the cross caster which will have some affect on high speed stability. If both caster [approximations] are within spec. I quit adjusting.

If you get your camber set and toe for both high speed stability, and good cornering, you are there. Finally, I see the same compression you are seeing in the bushings when adjusting. It all goes away when you test drive the car. Do all your adjustments, test drive and get some hard starts, stops, and turns and everything will find a new center.

romandian

thanks for the picture. i found the triangles on my r888s. never noticed them before. i will watch them from now on.

romandian

i found the spacers behind the dog bones, they are definitely there. i removed 4 of them on one side and stacked 6 of them under the front dog bone on the other. i have 3 of the 4 excentrics maxed out and managed 1.4° and 1.5° camber (l/r) in front. i succeded to adjust caster more or less to where it was before. well, i had some time so i looked up caster measurement. the formula, btw seems to be:

delta camber x delta steering angle/57° (57° being 180°/pi).

so its easy, if i turn the wheel left and right i get 59°. so the change in camber is my caster.

i will drive the car and then maybe go back on caster again, but it felt much less stable last time, so it looks like i will be making some camber plates next weekend.