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We have a discrepancy though. BillV stated in his last post that stiffer shocks in the rear will increase understeer. This contradicts my understanding as well as what I've seen Bill and others write in previous threads.
So either its a typo or I just learned something new . Bill, can you confirm please?
You may wish to revisit the rear caster(AKA KT) you want ~+3° 00' max, which off the top of my head is ~2 on the Motor sports gauge(0 is min and 8 or so is max), the higher the # on the gauge the slower the rear reacts in yaw.
a handy visual is where in the wheel well the tire sits, 0 caster is forward and lots of caster is back towards the muffler, you want the tire as far forward as is comfortable for you to drive.
The specs for alignment don't depend on ride height, they do depend on how the car is used, In general, more camber and less toe is more sporting the down side is more tire wear.
Regarding rear wheel caster and the motorsports guage, could you clear up something for me that I've been confused by? Does going lower on the guage correspond to lower caster angles or are they opposite? e.g. 0 on gauge moves toward 0 caster or 8 on gauge moves toward 0 caster.
Regarding rear wheel castor and the motorsports guage, could you clear up something for me that I've been confused by? Does going lower on the guage correspond to lower castor angles or are they opposite? e.g. 0 on gauge moves toward 0 castor or 8 on gauge moves toward 0 castor.
for the gauge pictured the higher the # the less caster, but not all gauges are the same, I also don't know what the calibration is between the #s on the pictured gauge and actual caster angle, In general the visual tells you what you need to know
tire forward is least caster(fastest reacting and twitchiest), tire towards the rear most caster(slowest reacting and most stable)
You want the wheel as far forward as feels comfortable for you. on the gauge pictured in the referenced thread 8 is least caster 1 is the most
Yes, this is the gauge being used. I'm trying to make sure I get this right in my notes for future reference. I'm paraphrasing you here, so let me know if I've got anything wrong.
"Kinetic toe should be a max of 3 or 3.5 on the motorsports gauge, even on both sides. A handy visual is where in the wheel well the tire sits, 0 caster is forward and lots of caster is back towards the muffler, you want the tire as far forward as is comfortable for you to drive. The higher the units on the gauge the further back the wheel and the faster the rear steering effects. Lowering the units on the gauge results in reduced caster and a more stable rear."
I think I found my problem. Check out these pictures:
Both were taken in my garage so not perfectly flat, but not too far off either. Pics are of my passenger and driver's side with the autometrics gauge in place.
Maybe I should reconsider my alignment guy?
Seems like this would explain the unsettled feeling I'm getting on rough roads!
Calling BillV... I've read the KT setting threads and confused as to what I should be seeing on this gauge for street use.
The autometrics instructions call for 1-4. The paragon instructions call for 4.5-5. Their numbers are reversed which adds additional confusion in the threads I've read.
So if you could clarify for me what your recommendation is on this autometrics gauge I'd appreciate it!
"Kinetic toe should be a max of 3 or 3.5 on the motorsports gauge, even on both sides. A handy visual is where in the wheel well the tire sits, 0 caster is forward and lots of caster is back towards the muffler, you want the tire as far forward as is comfortable for you to drive. The higher the units on the gauge the further back the wheel and the faster the rear steering effects. Lowering the units on the gauge results in reduced caster and a more stable rear."
I can't speak to what you should read on the gauge; but, your description of how caster affects stability is backwards. More caster = more stability, less caster = less stability. Too much caster will make the rear of the car less responsive, it will want to keep tracking in the same direction instead of changing direction.
I can't speak to what you should read on the gauge; but, your description of how caster affects stability is backwards. More caster = more stability, less caster = less stability. Too much caster will make the rear of the car less responsive, it will want to keep tracking in the same direction instead of changing direction.
The above is a quoted from BillV so I believe its accurate, though I do not in any way consider myself a kinematic toe expert.
I've just spent the last few hours trying to wrap my head around this by looking at my suspension, playing with the gauge, staring at suspension diagrams, imagining suspension movements and reading every thread I coud find on the subject.
The only thing I'd change in that quote is to state that more caster results in more rear steering effect and less caster results in less rear steering effect. I think I'll still target between 3 and 4 on the gauge and I did confirm that higher on the gauge corresponds to more caster.
I think I found my problem. Check out these pictures:
Both were taken in my garage so not perfectly flat, but not too far off either. Pics are of my passenger and driver's side with the autometrics gauge in place.
Maybe I should reconsider my alignment guy?
Seems like this would explain the unsettled feeling I'm getting on rough roads!
Just to make it clear. The problem I found was that the Kinematic Toe setting was much higher than it should be as well as being uneven from side to side (6.5 and 8.5). So my suspension is set for a lot of rear steer but doing so unevenly. So over a rough road my rear end is moving in unpredictable ways.
If I didn't have sport hardness bushings it would probably have been a handful. As it is, I find it annoying and a little unsettled on anything but smooth roadways.
Maybe I can help with a couple of misquotes in the thread..
bumpsteer: You do not feel bumpsteer in the steering wheel. The wheel stays still but the car changes direction "on its own". Freakly unsettling feeling, but not a "bump" that you feel.
Correcting oversteer/understeer:
First thing you have to ask is: "Which end of the car is giving up first?" (Understeer the front gives up first / Oversteer the rear).
The end that is giving up is being worked too hard, it has too much load.
So what can you do to move some load from the end that's giving up to the end that still has some traction?
You do that by adjusting the relative stiffness front to rear.. That can be spring, bar, shock compression, or shock rebound depending on where/when (turn-in, steady state, or track out) you are correcting...
03-07-2017, 11:48 AM
. Bill, can you confirm please?
