Tire Wear Problem - Page 2 - Ford Muscle Forums : Ford Muscle Cars Tech Forum

cmefly · 01-15-2013, 03:48 PM

Quote:

Originally Posted by bassman97

It is if it's out of wack it can be. If the bottom ball joint is forward of the top balljoint, on the driver side, this would make the top edge of the tire lean in on right turns, and lean out on left turns (turn your wheels and look at the difference in angle). If caster is off, it'll wear tires in the turns, especially when taking them hard or if the body rolls a bit. But, this is usually not noticeable unless another angle is off as well, or if you take the turns very hard. On my truck, it's a combo of bad camber with my driving habits that wear the wrong edge of the tire.

Your kidding Right? If your lower balljoint is forward of the top ball joint you will have positive Caster and it will not wear your tires. You could not get a mustang to have enough Caster to ever get to a point of it causing any tire wear and if you could get the Caster to that point the wear would be so minimal it does not apply to the op's problem or anyone's for that matter. and to say it is usually not noticable unless another angle is off is telling yourself that the other angle be it camber or Toe is the cause not the Caster.

bassman97 · 01-16-2013, 06:14 AM

Quote:

Originally Posted by cmefly

Your kidding Right? If your lower balljoint is forward of the top ball joint you will have positive Caster and it will not wear your tires. You could not get a mustang to have enough Caster to ever get to a point of it causing any tire wear and if you could get the Caster to that point the wear would be so minimal it does not apply to the op's problem or anyone's for that matter. and to say it is usually not noticable unless another angle is off is telling yourself that the other angle be it camber or Toe is the cause not the Caster.

I used that as an example. Bottom line is, alignment angles are all connected. I'm not sure on the old cars how much camber is affected as the suspension cycles but say you're making a right turn, briskly. The suspension is set just barely positive for camber, positive for caster. The driver side will squat down, so camber should go negative (unless the old cars go positive while compressing). The turn means the positive caster adds more negative camber. On the passenger side, the tire goes towards positive and the caster adds even more positive camber. Now the passenger tire is running on the very edge (outside). Now, the driver side, with the weight, probably will be the tire dictating which direction to go (as it has the most traction). So, with toe in, the driver side will be turned more than the passenger tire (assuming the steering doesn't make the tire toe out), causing the passenger tire to drag. With less traction, it'll drag even more. And just like that, caster makes the tire wear. Adjusting caster towards negative in this case would decrease the driver side contact patch (and traction) and increase the contact patch on the passenger side, allowing it to help dictate the direction better, and drag less. Again, not noticeable if all the specs are set to work together but if not, caster will make things wear funny in turns. Hence why alignment shops will play with both caster and camber (if possible) to make the angles work together to minimize wear (and not just get each in their respective range).

cmefly · 01-16-2013, 02:37 PM

Quote:

Originally Posted by bassman97

I used that as an example. Bottom line is, alignment angles are all connected. I'm not sure on the old cars how much camber is affected as the suspension cycles but say you're making a right turn, briskly. The suspension is set just barely positive for camber, positive for caster. The driver side will squat down, so camber should go negative (unless the old cars go positive while compressing). The turn means the positive caster adds more negative camber. On the passenger side, the tire goes towards positive and the caster adds even more positive camber. Now the passenger tire is running on the very edge (outside). Now, the driver side, with the weight, probably will be the tire dictating which direction to go (as it has the most traction). So, with toe in, the driver side will be turned more than the passenger tire (assuming the steering doesn't make the tire toe out), causing the passenger tire to drag. With less traction, it'll drag even more. And just like that, caster makes the tire wear. Adjusting caster towards negative in this case would decrease the driver side contact patch (and traction) and increase the contact patch on the passenger side, allowing it to help dictate the direction better, and drag less. Again, not noticeable if all the specs are set to work together but if not, caster will make things wear funny in turns. Hence why alignment shops will play with both caster and camber (if possible) to make the angles work together to minimize wear (and not just get each in their respective range).

I take it you have never done any Alignment work. You do realize that what you are saying does not apply to the real word of street driving and alignments. i have set up cars for bonneville, Scca,Drag racing, circle track and regular ole street cars and Caster is not a concern with tire wear. I can take a old 65 Mustang and set the Caster at zero with -.5 Degrees of Camber and toe in at 1/16" and get the same tire wear if I set the Caster at 3.5 degrees positive with Camber and toe the same. How do you explain that? To get Caster into the equation of tire wear it would have to be at the Extreme and you just can not get there with normal adjustments. If you have a tire wear problem it is going to be from the Camber ,Toe or both not the positive Caster. As a side note I like to add as much Caster as I can to these old cars. If Manual steering daily driver usually no more then 2 degrees, if power steering closer to 3.5 degrees positive or more.

427cougar · 01-16-2013, 02:46 PM

Agree,
x2 what cmefly said. Caster is not a tire wear angle.

Mustang chris....somewhere in this thread you said that the toe was set at 22 degrees, did you mean .22?

I would get the tire wear issue fixed BEFORE messing with the Shelby drop, just my opinion.

Steve

FEandGoingBroke · 01-16-2013, 11:01 PM

OP must be spam.....

bassman97 · 01-17-2013, 06:09 AM

Quote:

Originally Posted by cmefly

I take it you have never done any Alignment work. You do realize that what you are saying does not apply to the real word of street driving and alignments. i have set up cars for bonneville, Scca,Drag racing, circle track and regular ole street cars and Caster is not a concern with tire wear. I can take a old 65 Mustang and set the Caster at zero with -.5 Degrees of Camber and toe in at 1/16" and get the same tire wear if I set the Caster at 3.5 degrees positive with Camber and toe the same. How do you explain that? To get Caster into the equation of tire wear it would have to be at the Extreme and you just can not get there with normal adjustments. If you have a tire wear problem it is going to be from the Camber ,Toe or both not the positive Caster. As a side note I like to add as much Caster as I can to these old cars. If Manual steering daily driver usually no more then 2 degrees, if power steering closer to 3.5 degrees positive or more.

Like I've been saying, caster rears its head on turns which induce a lot of body roll. If caster isn't set to work with the rest of the alignment settings, it will cause tire wear in the turns. If you baby the car on the street, you won't notice anything. If you drive it hard on the street, you will notice it. It's not a matter of having done an alignment or not. It's a matter of simple trig which would show this. Again, I don't know how much camber is affected in compression on these old cars, so I have no idea how much a bad caster angle will affect tire wear. But if OP drives his car like it was stolen, a bad caster angle may cause the tire wear, even if his other specs are in range.

cmefly · 01-17-2013, 07:27 AM

Quote:

Originally Posted by bassman97

Like I've been saying, caster rears its head on turns which induce a lot of body roll. If caster isn't set to work with the rest of the alignment settings, it will cause tire wear in the turns. If you baby the car on the street, you won't notice anything. If you drive it hard on the street, you will notice it. It's not a matter of having done an alignment or not. It's a matter of simple trig which would show this. Again, I don't know how much camber is affected in compression on these old cars, so I have no idea how much a bad caster angle will affect tire wear. But if OP drives his car like it was stolen, a bad caster angle may cause the tire wear, even if his other specs are in range.

So explain to me as i am a simple man, How much Caster is a bad caster angle? I do not think you realize that positive Caster is a good thing.

FEandGoingBroke · 01-17-2013, 07:43 AM

Positive caster allows your wheels to self center doesn't it?

Bikesandfires · 01-17-2013, 10:02 AM

Quote:

Originally Posted by FEandGoingBroke

Positive caster allows your wheels to self center doesn't it?

YEP...And helps to hold a straight line and stabilize the steering...Ever push a shopping cart and one of the front wheels shimmied left and right constantly....Bad caster setting...