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Discussion Starter · #1 ·
I've got a problem with front tire wear. I've replaced every component on the front end with the exception of springs. Alignment was aligned within spec but I had trouble with the caster on the drivers side.

The wear is happening from the inside out (side of tire facing engine) and is happening pretty rapidly. I've burned through a complete set of BF Goodrich tires and now have been replacing tires with used tires as necessary to keep up with the problem as I investigate all possibilities. I've run out of ideas, and my tires continue to wear. Toe is within spec, tire rods are new, drag link is new.
 

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I've got a problem with front tire wear. I've replaced every component on the front end with the exception of springs. Alignment was aligned within spec but I had trouble with the caster on the drivers side.

The wear is happening from the inside out (side of tire facing engine) and is happening pretty rapidly. I've burned through a complete set of BF Goodrich tires and now have been replacing tires with used tires as necessary to keep up with the problem as I investigate all possibilities. I've run out of ideas, and my tires continue to wear. Toe is within spec, tire rods are new, drag link is new.
If you are wearing the inside edge your either Toed out or have two much negative camber. Set your alignment so your caster is about 2 degrees positive and your Camber is .5 degrees negative and toe in at 1/16 to 1/8". Have you done the Shelby/Arning drop yet?
 

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I've got a problem with front tire wear. I've replaced every component on the front end with the exception of springs. Alignment was aligned within spec but I had trouble with the caster on the drivers side.
What kind of trouble?

Are your aprons in good shape or flexing?
 

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I see you name has a 66 mustang in it. Is that the car with tire problem ? Have you canged the engine to a bigger one or made the front end heavier in some way ? Just a thought but I would think you need to take it to another line up place.

My dully has been lined up 3 times and still screwed up. They changed the camber cause they could not take it far enough to the left, it pulled right. Now it pulls left and the stearing wheel is not lined up as a car or truck wheel should be. I think to another person as well for me and you.
 

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I had the same issue, it was too much negative camber...
I eated two Dunlop SP9000 within 2000 kilometers (they were almost slicks!)
 

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Discussion Starter · #7 · (Edited)
Everything in my car is stock. No shelby drop, and original engine with some bolt on modifications. All front end parts are just stock replacement, nothing for performance. I did the alignment at school with the help of my teacher. Toe in was set at exactly 22 degrees, negative camber was to spec, and caster wasn't perfect but within one degree of being in spec (both sides, passenger side tire isn't wearing).

EDIT: The only thing that really modifies how my car goes down the road is the previous owner installed air shocks in the rear. Shocks up front are new Gabriel Shocks.


What kind of trouble?

Are your aprons in good shape or flexing?
Simply couldn't get in the right amount of shims for caster and camber to be right on target, so the camber was put as a little bit higher of a priority. Caster was still within spec.

No idea if my aprons are flexing or not, but I'm willing to expect it to be anything. All the conventional problems seem to be checked off by now.
 

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First thing is do the Shelby/Arning drop. It will greatly improve the handling and at the same time lower the front 5/8". When you do the drop it will give you an increase in caster and positive camber on the early 65/66 mustangs. You will remove at least 1/8" of shims and have more adjustment for positive Caster. I can explain anything you do not understand. I have my own computerized Alignment machine at home and have done this mod on lots of Falcon/Comets and Mustangs. Do a search for Shelby Arning drop ,lots of good info. Drill your holes 17/32" on the 65/66 cars and 1/2" on 67 and newer cars. Your alignment is causing the tire wear. use the specs I gave you. Mike
 

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Discussion Starter · #9 ·
First thing is do the Shelby/Arning drop. It will greatly improve the handling and at the same time lower the front 5/8". When you do the drop it will give you an increase in caster and positive camber on the early 65/66 mustangs. You will remove at least 1/8" of shims and have more adjustment for positive Caster. I can explain anything you do not understand. I have my own computerized Alignment machine at home and have done this mod on lots of Falcon/Comets and Mustangs. Do a search for Shelby Arning drop ,lots of good info. Drill your holes 17/32" on the 65/66 cars and 1/2" on 67 and newer cars. Your alignment is causing the tire wear. use the specs I gave you. Mike
Only problem with the shelby drop is the last owner already tried this, but drilled the holes in the wrong spot. We were going to do this when we rebuilt the front end but it was pretty much impossible to drill the holes in the correct spot. (if anyone's wondering, we don't have the upper control arms in the wrong holes) So I'm pretty much stuck with the stock setup.

The only thing left that could be wrong is the incorrect caster on the drivers side. After driving a little bit today, it was easy to see that the drivers side has gotten worse while the passenger side still looks good as new (which is an improvement, because they were both wearing pretty bad before).

I'm driving my car to school again friday to correct this. But what is the correct way to adjust caster on these old cars? I understand adding and subtracting shims, but how is it different from adjusting camber?
 

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last owner already tried this, but drilled the holes in the wrong spot. We were going to do this when we rebuilt the front end but it was pretty much impossible to drill the holes in the correct spot. (if anyone's wondering, we don't have the upper control arms in the wrong holes) So I'm pretty much stuck with the stock setup.
your not stuck....weld/fill in holes, then re-drill holes in proper location...;)
 

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Only problem with the shelby drop is the last owner already tried this, but drilled the holes in the wrong spot. We were going to do this when we rebuilt the front end but it was pretty much impossible to drill the holes in the correct spot. (if anyone's wondering, we don't have the upper control arms in the wrong holes) So I'm pretty much stuck with the stock setup.

The only thing left that could be wrong is the incorrect caster on the drivers side. After driving a little bit today, it was easy to see that the drivers side has gotten worse while the passenger side still looks good as new (which is an improvement, because they were both wearing pretty bad before).

I'm driving my car to school again friday to correct this. But what is the correct way to adjust caster on these old cars? I understand adding and subtracting shims, but how is it different from adjusting camber?
Like RAGGAREN said weld up the holes and get the correct template and drill new holes. It is a huge differance in how the car drives. Caster is not a tire wearing angle. If you are only wearing one tire you have too much negative Camber on that wheel. If you add an equal amount of shims to both front and rear upper control arm bolts it will increase your Camber and if you remove an equal number of shims it will decrease your Camber. To change Caster add a shim to the front bolt and it will increase your Caster and if you remove a shim from the rear bolt it will also increase your Caster and keep your Camber close to where it was. Set your alignment to the specs I gave you, not the Factory settings.
 

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No idea if my aprons are flexing or not, but I'm willing to expect it to be anything. All the conventional problems seem to be checked off by now.
See Attached Below-
 

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Discussion Starter · #13 ·
I guess it's time to fix up those holes, save up for a brand new set of tires, and buy that set from a place that will align my car and warranty it. I've eaten through too many cheap tires. I guess the fact that I didn't do the drop would explain why I couldn't get the caster set as high as people recommend.
 

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Caster is not a tire wearing angle.
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.
 

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I guess the fact that I didn't do the drop would explain why I couldn't get the caster set as high as people recommend.
The drop has nothing to do with your present problem. The drop is a handing enhancement.

Did you notice my above post at all?
 

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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.
 

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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).
 

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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.
 

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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
 
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