Alignment woes - Update
06-30-2010, 06:52 PM
#16
Chronic Tool Dropper
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Joe--
Correct alignment is like night and day after poor settings. Glad you have it where you like it now.
With the car where it's happy, take a few minutes to measure --and record-- the ride height numbers for each corner, before you drive it again. In a month, check again and compare. If the height changes by more than a few MM anywhere, you'll want to get at least the front toe checked again. In six months, check the height again against now, same drill. Your payback will be in longer tire life if nothing else. The avatar pic shows a car sitting at less than 160mm in front, (dr bob's visual micrometer height gauge...) so very mall changes in ride height will make for bigger changes in toe as the car settles even more over time.
Correct alignment is like night and day after poor settings. Glad you have it where you like it now.
With the car where it's happy, take a few minutes to measure --and record-- the ride height numbers for each corner, before you drive it again. In a month, check again and compare. If the height changes by more than a few MM anywhere, you'll want to get at least the front toe checked again. In six months, check the height again against now, same drill. Your payback will be in longer tire life if nothing else. The avatar pic shows a car sitting at less than 160mm in front, (dr bob's visual micrometer height gauge...) so very mall changes in ride height will make for bigger changes in toe as the car settles even more over time.
06-30-2010, 07:37 PM
#17
Rennlist Member
not really, its the ratio of each side toe to each side toe when straight, in front. in otherwords, you can be way toed out in front and way toed in in the rear,but if its all even, the car will track straight away! this is why i can mess with my toe unit the cows come home and it always tracks straight. if one side of the rear vs the front, or caster is way off, it pulls.
If you are toed out a lot at the front and toed in a little at the rear and you have diagonal weight unbalance (we all have to a certain extent) you get pull. The more toe, the more sensitive to this.
And doing things right with a faulty machine is the same as doing things wrong.
I think mostly they do alignment right. I mean everything except calibrate the thing every other year.
And doing things right with a faulty machine is the same as doing things wrong.
I think mostly they do alignment right. I mean everything except calibrate the thing every other year.
07-01-2010, 03:33 AM
#18
Racer
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not really, its the ratio of each side toe to each side toe when straight, in front. in otherwords, you can be way toed out in front and way toed in in the rear,but if its all even, the car will track straight away! this is why i can mess with my toe unit the cows come home and it always tracks straight. if one side of the rear vs the front, or caster is way off, it pulls.
I've seen cars pulling to one side and then to the other only changing one pushrod lenght. More than once.
But alignment is always a resolving mistery!
Regards,
07-01-2010, 11:55 AM
#19
Rennlist Member
no, its well known that a car with a lot of toe out, will be darty. it has nothing to do with one side being "more heavily loaded" than the other. my car crossweights are within 5lbs of each other, but, there has been a time when it was 100lbs off, as in when I first set up my new race car. Had nothing really do do with straight line handling and "dartiness". a lot of toe in, for example, makes the car stable, but somewhat unresponsive. (and with a lot of outside tire wear).
if you have seen changing a pushrod length fix a pulling issue, that is really odd. think about it, the toe , as far as the driver is concerned, is self centering. how does the steering rack know that one side is shorter ? it doesnt, the wheels will always track straight and your steering wheel might be off a bit. you dont pull, unless you have something off with the rear of the car, or you have a caster issue. what could have happened with your situation,is that you also inadvertantly changed the camber and or caster by changing the toe and got that effect.
if you have seen changing a pushrod length fix a pulling issue, that is really odd. think about it, the toe , as far as the driver is concerned, is self centering. how does the steering rack know that one side is shorter ? it doesnt, the wheels will always track straight and your steering wheel might be off a bit. you dont pull, unless you have something off with the rear of the car, or you have a caster issue. what could have happened with your situation,is that you also inadvertantly changed the camber and or caster by changing the toe and got that effect.
What you say only apply to cars with same weight in both diagonals, don't you think so?. If both fronts point out, the one more heavily loaded "wins". (that's why yours darts in uneven surfaces). Perhaps you have always had sort of even weights across diagonals?
I've seen cars pulling to one side and then to the other only changing one pushrod lenght. More than once.
But alignment is always a resolving mistery!
Regards,
I've seen cars pulling to one side and then to the other only changing one pushrod lenght. More than once.
But alignment is always a resolving mistery!
Regards,
07-02-2010, 03:38 AM
#20
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Mark,
Obviously experience has the final word. If you had big toe out and uneven diagonals (no side to side, but diagonal to diagonal) and no pull that's it. End of discussion.
Just for the mental exercise:
The self centering mechanism is about three things. Castor, that lifts the car when you steer. Always there, unrelated to weight.
Then we have two more: Offset, because the pivot point of the tire is not in the center off the contact patch (usually to the inside), causing steer moment with drag or braking force. Trailing, because the pivot point is not in the center of the contact patch (usually to the front, like supermarket carts) causing steer moment with lateral force. Offset and trail are cancelled with equal weights in both sides. When you go straight, the pull is zero, when you corner, mainly because of the trail, the steering "pulls" to the opposite side, so if you release the wheel, it unwinds back to straight.
Sure, if you shorten one steering arm, causing more toe out, next time out the car will still go straight, only steering wheel will not be centered. No pull.
But if you shorten a push-rod, and you destroy the diagonal balance, centering mechanisms, mainly offset, will work more in one side and the car plus the steering wheel will pull. How much? Till it makes the car corner bit, and transfer a bit of weight to the other side and then make them equal. If you force it straight, you need constant effort in the steering wheel.
F3 cars have normal offset but huge trail (trail help the driver "feel" the front grip), and they have ultra-stiff rates (1000kg/cm at 550kg weight) so 1mm in the pushrod makes a hell of a difference in weights. Maybe that's why it was evident.
Offtopic: Love your videos, old ones and new ones. Good car you have, and good hands handle it! Thanks for sharing1
Obviously experience has the final word. If you had big toe out and uneven diagonals (no side to side, but diagonal to diagonal) and no pull that's it. End of discussion.
Just for the mental exercise:
The self centering mechanism is about three things. Castor, that lifts the car when you steer. Always there, unrelated to weight.
Then we have two more: Offset, because the pivot point of the tire is not in the center off the contact patch (usually to the inside), causing steer moment with drag or braking force. Trailing, because the pivot point is not in the center of the contact patch (usually to the front, like supermarket carts) causing steer moment with lateral force. Offset and trail are cancelled with equal weights in both sides. When you go straight, the pull is zero, when you corner, mainly because of the trail, the steering "pulls" to the opposite side, so if you release the wheel, it unwinds back to straight.
Sure, if you shorten one steering arm, causing more toe out, next time out the car will still go straight, only steering wheel will not be centered. No pull.
But if you shorten a push-rod, and you destroy the diagonal balance, centering mechanisms, mainly offset, will work more in one side and the car plus the steering wheel will pull. How much? Till it makes the car corner bit, and transfer a bit of weight to the other side and then make them equal. If you force it straight, you need constant effort in the steering wheel.
F3 cars have normal offset but huge trail (trail help the driver "feel" the front grip), and they have ultra-stiff rates (1000kg/cm at 550kg weight) so 1mm in the pushrod makes a hell of a difference in weights. Maybe that's why it was evident.
Offtopic: Love your videos, old ones and new ones. Good car you have, and good hands handle it! Thanks for sharing1
07-02-2010, 02:55 PM
#21
Rennlist Member
interesting.
I think we are saying the same thing, at least as far as the possiblity of one tie rod being shortened, and having it still track straigth in come cases with big toe out. the rest is some good detailed information by you. thanks.
I dont know why my car (a few versions ago) had a slight pull and recently, I havent seen a pull in the past few years. settings seem to be the same, with some small differences. could be diagnal weights , or other factos. Im just glad I can mess around with toe when needed and nothing else really changes. (near equal cross weighs and at 100lbs diff too.
Thanks for the video mention. Sure is fun making them too! The car is just so much fun to drive on the track!
Mk
I think we are saying the same thing, at least as far as the possiblity of one tie rod being shortened, and having it still track straigth in come cases with big toe out. the rest is some good detailed information by you. thanks.
I dont know why my car (a few versions ago) had a slight pull and recently, I havent seen a pull in the past few years. settings seem to be the same, with some small differences. could be diagnal weights , or other factos. Im just glad I can mess around with toe when needed and nothing else really changes. (near equal cross weighs and at 100lbs diff too.
Thanks for the video mention. Sure is fun making them too! The car is just so much fun to drive on the track!
Mk
Mark,
Obviously experience has the final word. If you had big toe out and uneven diagonals (no side to side, but diagonal to diagonal) and no pull that's it. End of discussion.
Just for the mental exercise:
The self centering mechanism is about three things. Castor, that lifts the car when you steer. Always there, unrelated to weight.
Then we have two more: Offset, because the pivot point of the tire is not in the center off the contact patch (usually to the inside), causing steer moment with drag or braking force. Trailing, because the pivot point is not in the center of the contact patch (usually to the front, like supermarket carts) causing steer moment with lateral force. Offset and trail are cancelled with equal weights in both sides. When you go straight, the pull is zero, when you corner, mainly because of the trail, the steering "pulls" to the opposite side, so if you release the wheel, it unwinds back to straight.
Sure, if you shorten one steering arm, causing more toe out, next time out the car will still go straight, only steering wheel will not be centered. No pull.
But if you shorten a push-rod, and you destroy the diagonal balance, centering mechanisms, mainly offset, will work more in one side and the car plus the steering wheel will pull. How much? Till it makes the car corner bit, and transfer a bit of weight to the other side and then make them equal. If you force it straight, you need constant effort in the steering wheel.
F3 cars have normal offset but huge trail (trail help the driver "feel" the front grip), and they have ultra-stiff rates (1000kg/cm at 550kg weight) so 1mm in the pushrod makes a hell of a difference in weights. Maybe that's why it was evident.
Offtopic: Love your videos, old ones and new ones. Good car you have, and good hands handle it! Thanks for sharing1
Obviously experience has the final word. If you had big toe out and uneven diagonals (no side to side, but diagonal to diagonal) and no pull that's it. End of discussion.
Just for the mental exercise:
The self centering mechanism is about three things. Castor, that lifts the car when you steer. Always there, unrelated to weight.
Then we have two more: Offset, because the pivot point of the tire is not in the center off the contact patch (usually to the inside), causing steer moment with drag or braking force. Trailing, because the pivot point is not in the center of the contact patch (usually to the front, like supermarket carts) causing steer moment with lateral force. Offset and trail are cancelled with equal weights in both sides. When you go straight, the pull is zero, when you corner, mainly because of the trail, the steering "pulls" to the opposite side, so if you release the wheel, it unwinds back to straight.
Sure, if you shorten one steering arm, causing more toe out, next time out the car will still go straight, only steering wheel will not be centered. No pull.
But if you shorten a push-rod, and you destroy the diagonal balance, centering mechanisms, mainly offset, will work more in one side and the car plus the steering wheel will pull. How much? Till it makes the car corner bit, and transfer a bit of weight to the other side and then make them equal. If you force it straight, you need constant effort in the steering wheel.
F3 cars have normal offset but huge trail (trail help the driver "feel" the front grip), and they have ultra-stiff rates (1000kg/cm at 550kg weight) so 1mm in the pushrod makes a hell of a difference in weights. Maybe that's why it was evident.
Offtopic: Love your videos, old ones and new ones. Good car you have, and good hands handle it! Thanks for sharing1
07-02-2010, 03:19 PM
#22
Nordschleife Master
The multi-piston calipers are unlikely to drag but those parking brakes still can. Fist calipers will bind up so the outside pad doesn't release anough.
07-02-2010, 03:37 PM
#23
Rennlist Member
nah, it wasnt a pull due to brake drag. it was fixed with a 4wheel alignement that I over saw. same thing with the new car. straight as an arrow. Just a pleasure to drive on the street and racing too!
mk
mk
Check brakes and tires for this. Just a light drag will make it pull at speed. Also, a dragging brake may increase its drag as it heats up.
The multi-piston calipers are unlikely to drag but those parking brakes still can. Fist calipers will bind up so the outside pad doesn't release anough.
The multi-piston calipers are unlikely to drag but those parking brakes still can. Fist calipers will bind up so the outside pad doesn't release anough.
