Unsymmetrical Wear...

[slomove]

After only 6000 miles (and otherwise still in pretty good nick) my right front tire shows some disturbing wear on the inside, see below.

They are admittedly not the top notch (Yoko AVS ES100) but not that bad for touring.

 

My previous tire set did not do that and I did not change camber or toe. The setting is anyway a compromise with my bias ply track tires (0.5 degree negative camber and 0.25 degree toe-in) and I would expect rather some wear on the outside with these radials. When I let the steering wheel go, the car runs dead straight ahead.

 

Am I overlooking something here or may there be other reasons for this?

 

Thanks, Gert

 

Right front

http://www.usa7s.com/aspnetforum/upload/1768032691_RightFront.jpg

Left front (much less wear but also unsymmetrical)

http://www.usa7s.com/aspnetforum/upload/562386580_LeftFront.jpg

[solder_guy]

I donno .. but I have the exact same tires.

 

Rob

[slngsht]

at .5 degrees camber, that doesn't make any sense

[Boxologist]

my fronts looked like teh right tyre when i got bck from TotD. both insides scrubbed to the wear bar. i thought it was really bad camber, but when i had the car align in september it was in spec. slightly more than your values. if it tracks straight on a non canted road, ur thrust angle/cross toe is fine.

 

if u look at any of my pictures it looks like my fronts run ~4-6 degree of camber but its just slighly more than 1 degree. rotate ur tyres more frequently and be prepared to have them swapped sides every other year or so to maximize their lifetime.

[Dave W]

I have the same tire and .7* camber with even wear. I would look at the bushings, there may be a dynamic deflection issue. Does sound strange if the toe checked out as being OK.

Dave W

[BobDrye]

Are you checking the caster, camber and toe with you in the car? This could make a big difference.

[WestTexasS2K]

It appears to be an alignment issue. tow out would cause it or worn tie rod end that is letting the tire turn out when loaded. I would check all your bushings, ball joints, tie rod ends, steering rack bolts. give it the old wiggle test then jack the front up and unload it and see if you can find movement some where. Also check your wheel bearings the retaining nut could have backed off. I run 1.0 degree of camber and my tires wear much more even than that.

[slomove]

Thanks all for the advice. I guess just assuming that the suspension setting is still as it was 2 years ago isn't good enough....I will do a thorough adjustment and joint/bearing check.

 

One good point was mentioned: with the PNW2007 tour and our weekend blats I did almost all of the mileage with a passenger while I did the measurements just with a simulated driver weight. Also, most of the mileage was on crowned country highways which I read may make a certain difference (compared to flat multi-lane roads or race tracks).

 

Gert

[Davemk1]

Did you ay you checked the rear thrust angle?

 

Dave

[slomove]

Did you ay you checked the rear thrust angle?

 

Dave

 

No, I did not. What is the easiest way to do that? Just measure the distance between the front and rear wheels?

How much tolerance is acceptable?

 

Gert

[Davemk1]

I don't know what the easiest way is but this way seems pretty easy.

 

I used string pulled across the sides of the rear wheels pulled forward past the fronts. The rear track is wider than the front so you can pull the string right past the fronts. Then measure from the string in to the front wheel. On my Birkin the rear end was twisted. I installed Woody's trailing arm kit and they are adjustable so I was able to adjust the length of the arms and get the rear axle perpendicular to the chassis center line and parallel to the front axle centerline.

 

After I did mine I noticed that the rear just felt more stable at highway speeds. Not a day and night difference but it's nice to know it's right.

 

If you are careful and take your time you get very consistent, repeatable results.

 

I hope that makes sense and helps.

 

Dave