TR2/3/3A Front end alignment and tire wear

[sp53]

Front end alignment and tire wear. The last time I took this tr3 to a tire shop I got new Cooperbtires and an alignment. The car went straight at all speeds with no pulling, but I noticed that after time the outside tread on both front tires wore more quickly. I think remember hearing on the forum that this cause by no camber adjustment? Is that correct?

 

[CJD]

In general, camber has to be way off to cause wear. Unless you see the front tires at a severe angle in relation to the angle of the rear tires, you can most likely eliminate camber as the problem. Outer edge wear is normally too much toe in, or aggressive cornering. So, toe in is most likely the adjustment that's off.

 

[bnw]

John, I've seen excessive positive or negative camber destroy a tire in no time. Toe usually leaves a knife edge on the outer edge of the tire that can be felt running your hand over the tire in one direction, but not in the other. Camber has the tire tilted so the wear is consistent, Toe being off has the tire constantly scrubbing, thus the knife edge. Camber usually does not cause a pull but toe does. This has been my experience with "modern" domestic and foreign vehicles. I know nothing about how this effects my TR3. BTW, did you get anywhere with the guy with the TR2 seats?

 

[Geo Hahn]

...Outer edge wear is normally too much toe in, or aggressive cornering...

I get more wear on the outer edge even with what I think is a spot-on alignment - but much of my driving is twisty roads and the beauty of the TRs is that you can take those at near the limits of what the car can do (with skinny tires) and still not be in a lot of trouble. Porsches go thru the curves faster but their mistakes are big mistakes.

I suppose I could get more miles out of the tires by flipping them left to right but that would require de-mounting and re-mounting them -- for that much work I want to have a new tire.

Yes, I can believe that severe toe-in wear would include feathering so checking for that is a good idea. I never measure camber on the TRs as there doesn't seem to be much point.

 

[CJD]

The best example of camber on our skinny tires is the original beetle. They always sit with noticeable negative camber at the rear because of the swing arm suspension. But, the rear beetle tires still wear even. This is true of skinny tires, and we are actually running beetle tires on or TR3's.

As the footprint widens, then camber becomes critical. On a Porsche with 50 series tires, a degree of camber can lift the edge of the tire off the pavement. Our tires are not anywhere near that critical.

Caster has the most affect on a car pulling. Unfortunately, our castor is not adjustable, and if you even tap a curb with our frail vertical links, you have likely induced positive castor on that side. Since most of us clip the right curb the most, most cars will pull to the left. The only solution is to remove and straighten the vertical links.

Toe out makes a car feel "Darty", wanting to follow road crests and having bump steer. Toe in is stable, but it adds drag, wearing tires and reducing mileage. Like I said, outer wear can very well be from having fun in the curves on country roads!

 

[sp53]

Caster has the most affect on a car pulling. Unfortunately, our castor is not adjustable,

So is castor the toe in or out and camber the vertical perpendicular of the wheel? I was asking because I am thinking going with the spin balance and perhaps a front end alignment, but if they cannot fix it or I do not need the alignment why bother. My back is just gotten so bad over the years that if I did purchase a tire balancing machine the work of putting them on and off can cause too much physical pain.

 

[Darrell_Walker]

https://en.wikipedia.org/wiki/Caster_angle

 

[Geo Hahn]

Caster is why a shopping cart with swiveling wheels (they're even called casters) will roll mostly straight if you give it a push.

But since the TR3 (as far as I know) is non-adjustable in that dimension and the caster spec is 0° (no help in straightening the wheels) you are mostly left with getting toe-in right.

 

[bobhustead]

Despite the absence of intended adjustment features, camber and caster can adjust themselves due to wear in suspension parts like control arm bushings. TR3s can also suffer cracks in the tabs on the frame which hold the horizontal "bolt" atop the frame to which the lower control arms are attached.
Bob

 

[TR3driver]

There are also tricks, techniques and outright modifications that can change both caster and camber on our suspensions.
Probably the most common way to change caster is to just install the parts from a later TR4 with 3 degrees of caster (trunnions, upper A-arms, ball joint, steering lever). With the later A-arms, you can supposedly slot the bolt holes for the ball joint, and get a camber adjustment that way.
Some racers even build adjustable length A-arms.

One trick for reducing camber is to shorten the brace that runs between the spring towers. One of the modifications is to turn the upper pivot 90 degrees and mount it to a piece of angle iron bolted to the original location. Supposedly raising the upper pivot point also reduces bump steer.

Here's another mod for adjusting camber
https://www.revingtontr.com/shop/pr...k77l74gn7f1k10&CarType=TR3&ProductID=RTR3112K

I haven't done much with the TR, my former TR3A wore the wide (205) front tires surprisingly evenly, while the current TR3 is definitely wearing the outside edge faster. But on a previous non-TR with 205 tires, I found that even 1 degree change in camber (which was within the range given by the factory) made a significant difference in tire wear. Seemed like it even improved handling a little bit, although not much. I definitely plan to try some of the above tricks, eventually.

First of course, I'll check the current camber and see if it reflects some damage that should be corrected, like the cracks Bob mentioned. On one of my previous TR3As, a lower pivot was broken loose completely, which caused the brakes to pull something awful. Two different alignment shops failed to spot the problem. Then when I had a local "foreign car" shop repair the damage, they put the pivot a good two inches away from where it was originally! And swore to me that the alignment was correct.

I've also seen the TR3 upper A-arms bend and crack. The ones I'm using have been reinforced to hopefully prevent that, by boxing in the rest of the channel. Dunno for sure if it helps, but they were still in good shape even after the accident.