Suspension Discussion: Camber vs. Caster
Apr 26, 2011, 09:46 PM
#76
This is based on some rough measurements I did along with some data from a laser alignment.
Baseline Settings (measured):
Camber: 2.5*
Caster: 3.5*
Steering Axis Inclination Angle: 14.4*
Wheel for/aft: 0"
PSRS (hypothetical):
Camber: 2.6*
Caster: 5.6*
Steering Axis Inclination Angle: 14.5*
Wheel for/aft: +0.25"
PSRS w/Caster-Camber Plate Adjustment (hypothetical):
Camber: 4.1*
Caster: 7.6*
Steering Axis Inclination Angle: 15.9*
Wheel for/aft: +0.08"
This adjustment was based on a maximum amount of combined caster/camber that I could get if I had used my current plates with some minor modifications on how they mounted. It basically put the adjustment slot pointed towards the rear bolt so caster and camber weren't independently adjustable.
I believe steering inclination angle also has a big impact on the dynamic camber curve. I'm not too sure if going larger is a good thing or not though, particularly when using a heavy offset wheel where scrub radius can get out of hand.
Baseline Settings (measured):
Camber: 2.5*
Caster: 3.5*
Steering Axis Inclination Angle: 14.4*
Wheel for/aft: 0"
PSRS (hypothetical):
Camber: 2.6*
Caster: 5.6*
Steering Axis Inclination Angle: 14.5*
Wheel for/aft: +0.25"
PSRS w/Caster-Camber Plate Adjustment (hypothetical):
Camber: 4.1*
Caster: 7.6*
Steering Axis Inclination Angle: 15.9*
Wheel for/aft: +0.08"
This adjustment was based on a maximum amount of combined caster/camber that I could get if I had used my current plates with some minor modifications on how they mounted. It basically put the adjustment slot pointed towards the rear bolt so caster and camber weren't independently adjustable.
I believe steering inclination angle also has a big impact on the dynamic camber curve. I'm not too sure if going larger is a good thing or not though, particularly when using a heavy offset wheel where scrub radius can get out of hand.
Last edited by 03whitegsr; Apr 26, 2011 at 09:51 PM.
Apr 26, 2011, 10:09 PM
#77
Before I did any caster adjustment (camber plates or PSRS), my new wheels/tires were already too far back, rubbing against the side skirts when the wheels were turned. PSRS saved me from trashing $2500+ of wheels/tires. It moved it forward, and along with some other custom work I did, I was able to prevent it all from rubbing.
Apr 27, 2011, 04:16 PM
#78
This is based on some rough measurements I did along with some data from a laser alignment.
Baseline Settings (measured):
Camber: 2.5*
Caster: 3.5*
Steering Axis Inclination Angle: 14.4*
Wheel for/aft: 0"
PSRS (hypothetical):
Camber: 2.6*
Caster: 5.6*
Steering Axis Inclination Angle: 14.5*
Wheel for/aft: +0.25"
PSRS w/Caster-Camber Plate Adjustment (hypothetical):
Camber: 4.1*
Caster: 7.6*
Steering Axis Inclination Angle: 15.9*
Wheel for/aft: +0.08"
This adjustment was based on a maximum amount of combined caster/camber that I could get if I had used my current plates with some minor modifications on how they mounted. It basically put the adjustment slot pointed towards the rear bolt so caster and camber weren't independently adjustable.
I believe steering inclination angle also has a big impact on the dynamic camber curve. I'm not too sure if going larger is a good thing or not though, particularly when using a heavy offset wheel where scrub radius can get out of hand.
Baseline Settings (measured):
Camber: 2.5*
Caster: 3.5*
Steering Axis Inclination Angle: 14.4*
Wheel for/aft: 0"
PSRS (hypothetical):
Camber: 2.6*
Caster: 5.6*
Steering Axis Inclination Angle: 14.5*
Wheel for/aft: +0.25"
PSRS w/Caster-Camber Plate Adjustment (hypothetical):
Camber: 4.1*
Caster: 7.6*
Steering Axis Inclination Angle: 15.9*
Wheel for/aft: +0.08"
This adjustment was based on a maximum amount of combined caster/camber that I could get if I had used my current plates with some minor modifications on how they mounted. It basically put the adjustment slot pointed towards the rear bolt so caster and camber weren't independently adjustable.
I believe steering inclination angle also has a big impact on the dynamic camber curve. I'm not too sure if going larger is a good thing or not though, particularly when using a heavy offset wheel where scrub radius can get out of hand.
In any case I think that amount of caster is actually quite good for me, especially after hearing about Thoe99 talk about steering feel/response in the other thread, I think I will follow his recommendation to start around roughly 5 deg caster to start with.
Before I did any caster adjustment (camber plates or PSRS), my new wheels/tires were already too far back, rubbing against the side skirts when the wheels were turned. PSRS saved me from trashing $2500+ of wheels/tires. It moved it forward, and along with some other custom work I did, I was able to prevent it all from rubbing.
Do you think a steering bushing would help restore some of the steering? or I'm assuming the loss of steering is just the inherent nature when there's a longer wheelbase or something?
When you talked about how the steering slowed down, are you referring to the ratio, or the actual response - i dont want to turn my wheel and wait a split second for the car to turn, but i think that's kind of what you implied, about slaloms in autox and having to antcipate to turn the wheel earlier. or is it that you had to anticipate that you'd have to turn the wheel more?
sorry for the confusion
Apr 28, 2011, 06:51 AM
#79
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After adding the PSRS, I wouldn't say that the steering has slowed down, it just feels ... different. I can't really explain it. The on-center feeling and turn in don't really feel any less sensitive than stock, it's just different, and certainly the overall performance is better.
l8r)
l8r)
Apr 28, 2011, 08:08 AM
#80
After adding the PSRS, I wouldn't say that the steering has slowed down, it just feels ... different. I can't really explain it. The on-center feeling and turn in don't really feel any less sensitive than stock, it's just different, and certainly the overall performance is better.
l8r)
l8r)
Apr 28, 2011, 04:34 PM
#81
that's a lot of increase in caster from a single change of adding the PSRS, unless I'm confusing something. You mentioned ur current plates but ur table goes from a stock caster to what I'm assuming is just adding the PSRS in the second table. does the PSRS really add that much caster?
In any case I think that amount of caster is actually quite good for me, especially after hearing about Thoe99 talk about steering feel/response in the other thread, I think I will follow his recommendation to start around roughly 5 deg caster to start with.
gotcha, thanks.
Do you think a steering bushing would help restore some of the steering? or I'm assuming the loss of steering is just the inherent nature when there's a longer wheelbase or something?
When you talked about how the steering slowed down, are you referring to the ratio, or the actual response - i dont want to turn my wheel and wait a split second for the car to turn, but i think that's kind of what you implied, about slaloms in autox and having to antcipate to turn the wheel earlier. or is it that you had to anticipate that you'd have to turn the wheel more?
sorry for the confusion
In any case I think that amount of caster is actually quite good for me, especially after hearing about Thoe99 talk about steering feel/response in the other thread, I think I will follow his recommendation to start around roughly 5 deg caster to start with.
gotcha, thanks.
Do you think a steering bushing would help restore some of the steering? or I'm assuming the loss of steering is just the inherent nature when there's a longer wheelbase or something?
When you talked about how the steering slowed down, are you referring to the ratio, or the actual response - i dont want to turn my wheel and wait a split second for the car to turn, but i think that's kind of what you implied, about slaloms in autox and having to antcipate to turn the wheel earlier. or is it that you had to anticipate that you'd have to turn the wheel more?
sorry for the confusion
Steering bushings won't solve the issue of "loss of steering". This degradation is more due to the steering (pivoting) plane of the wheel. It's bent more backwards now. In the extreme case (a theoretical one), if you have 90 degrees of caster, when you turn the wheel, you are adding camber proportionally to how much you turn. At that extreme, you probably cannot turn the car. So in conclusion, the more caster you have, the less direct steering you'll have control of. The 'anticipating' turning description is more about having to turn the wheel and get out of the 3" left/right (from center) dead zone. It's not really a dead zone, just an area that responds less to steering compared to the rest. That's the best I can describe it. You'll definitely notice it when you get into high extremes of caster, but it's not nearly as bad as people say. Not even close to what a regular car is like.
This is how you get extreme caster
! I'm not sure what else you do to get more than what I have though--7.3 degrees.
Apr 28, 2011, 04:59 PM
#82
I don't even notice it anymore cuz I've gotten so used to it. But if I can remember, the steering wasn't so linear anymore. Turning on the first 3" wasn't as sharp as turning more after that.
Steering bushings won't solve the issue of "loss of steering". This degradation is more due to the steering (pivoting) plane of the wheel. It's bent more backwards now. In the extreme case (a theoretical one), if you have 90 degrees of caster, when you turn the wheel, you are adding camber proportionally to how much you turn. At that extreme, you probably cannot turn the car. So in conclusion, the more caster you have, the less direct steering you'll have control of. The 'anticipating' turning description is more about having to turn the wheel and get out of the 3" left/right (from center) dead zone. It's not really a dead zone, just an area that responds less to steering compared to the rest. That's the best I can describe it. You'll definitely notice it when you get into high extremes of caster, but it's not nearly as bad as people say. Not even close to what a regular car is like.
This is how you get extreme caster! I'm not sure what else you do to get more than what I have though--7.3 degrees.
Steering bushings won't solve the issue of "loss of steering". This degradation is more due to the steering (pivoting) plane of the wheel. It's bent more backwards now. In the extreme case (a theoretical one), if you have 90 degrees of caster, when you turn the wheel, you are adding camber proportionally to how much you turn. At that extreme, you probably cannot turn the car. So in conclusion, the more caster you have, the less direct steering you'll have control of. The 'anticipating' turning description is more about having to turn the wheel and get out of the 3" left/right (from center) dead zone. It's not really a dead zone, just an area that responds less to steering compared to the rest. That's the best I can describe it. You'll definitely notice it when you get into high extremes of caster, but it's not nearly as bad as people say. Not even close to what a regular car is like.
This is how you get extreme caster
! I'm not sure what else you do to get more than what I have though--7.3 degrees.
Apr 28, 2011, 07:10 PM
#83
Glad to see my old thread coming back to life!
Thoe I like what you did to those plates I'm going to have to try removing some material from mine to see how far I can get it. I'm guessing coilovers are a necessity though since my springs are touching the fender well as is.
Thoe I like what you did to those plates I'm going to have to try removing some material from mine to see how far I can get it. I'm guessing coilovers are a necessity though since my springs are touching the fender well as is.
Mar 10, 2012, 08:01 PM
#85
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Glad to see my old thread coming back to life!
Thoe I like what you did to those plates I'm going to have to try removing some material from mine to see how far I can get it. I'm guessing coilovers are a necessity though since my springs are touching the fender well as is.
Thoe I like what you did to those plates I'm going to have to try removing some material from mine to see how far I can get it. I'm guessing coilovers are a necessity though since my springs are touching the fender well as is.
I don't even notice it anymore cuz I've gotten so used to it. But if I can remember, the steering wasn't so linear anymore. Turning on the first 3" wasn't as sharp as turning more after that.
Steering bushings won't solve the issue of "loss of steering". This degradation is more due to the steering (pivoting) plane of the wheel. It's bent more backwards now. In the extreme case (a theoretical one), if you have 90 degrees of caster, when you turn the wheel, you are adding camber proportionally to how much you turn. At that extreme, you probably cannot turn the car. So in conclusion, the more caster you have, the less direct steering you'll have control of. The 'anticipating' turning description is more about having to turn the wheel and get out of the 3" left/right (from center) dead zone. It's not really a dead zone, just an area that responds less to steering compared to the rest. That's the best I can describe it. You'll definitely notice it when you get into high extremes of caster, but it's not nearly as bad as people say. Not even close to what a regular car is like.
This is how you get extreme caster! I'm not sure what else you do to get more than what I have though--7.3 degrees.
Steering bushings won't solve the issue of "loss of steering". This degradation is more due to the steering (pivoting) plane of the wheel. It's bent more backwards now. In the extreme case (a theoretical one), if you have 90 degrees of caster, when you turn the wheel, you are adding camber proportionally to how much you turn. At that extreme, you probably cannot turn the car. So in conclusion, the more caster you have, the less direct steering you'll have control of. The 'anticipating' turning description is more about having to turn the wheel and get out of the 3" left/right (from center) dead zone. It's not really a dead zone, just an area that responds less to steering compared to the rest. That's the best I can describe it. You'll definitely notice it when you get into high extremes of caster, but it's not nearly as bad as people say. Not even close to what a regular car is like.
This is how you get extreme caster
! I'm not sure what else you do to get more than what I have though--7.3 degrees.
Sep 20, 2012, 03:38 PM
#87
So okay, I get the adjustments to the front in relation to handling, but what about adjustments to the rear? Right now I'm stuck with -1.2 on the left and -1.5 on the right for camber, with .06 and.07 for toe, with 0 for thrust. Do I even need to mess with the rear camber?
I bought some camber bolts for the front, and my right is -1 off from the left and I've got it maxed out (-.4 Left, -1.4 Right)...so I'm hoping the 1.75 bolts will give me more play. Caster in the front is +2.3 Left and +2.1 Right, and I can't see adjusting this without buying the nice $500 plates. This is a daily driver and I'm just looking to maximize tire wear while improving steering response (avoiding obstacles, not so much hairpin turns).
If you want to maximize tire life and you just drive around town all day, you don't want a lot of camber. You should be absolutely sure your toe is zero, though.
Any recommendations on how to proceed? I'll be installing the camber bolt on the front right to give me more play with camber....but should I be trying to match the stance to the rear that I can't adjust? It seems weird to be that the rears would be a degree and change off from the fronts...would that make me go wide in turns?
Find a new alignment shop, because wherever you went isn't doing a good job at all.