Today I replaced all four tires on my '04 MCS at my local Firestone dealer. The new tires are Bridgestone Potenza RE960AS Pole Position 205/55R-16. At 74,000 miles they replaced a second set of Goodyear Eagle F1 GS-D3 Maximum Performance Tires which have been discontinued. I wanted better ice and snow traction than the Goodyears had provided which was none.

Driving home from the tire shop, each time I hit a bump I heard a rubbing noise at the right rear of the car. On getting home I noticed that the right rear tire had barely 1/4" clearance from the black fender trim piece. I could also see some rub marks on the trim piece where the tire had hit it lightly.

Comparing the gaps between the tire and rear fender mouldings on both sides of the car (and the gaps between the front of each tire and the nearest fender moulding) -- it became clear that my right side wheel was sitting about 1/2" further to the rear in the wheel opening than was the left side wheel in its wheel opening space.

QUESTION: DOES ANYONE KNOW WHETHER FIRESTONE COULD HAVE ALTERED THE FORE-AND-AFT ORIENTATION OF THE RIGHT REAR WHEEL THROUGH IMPROPER JACKING OF THE CAR ?

Does anyone know whether there are any fore-and-aft adjustments that can be made to the rear wheel suspension/location assemblies to move the right wheel further forward ?

Thanks for any help anyone can provide before I confront the Firestone dealer with this issue.

 

Nothing to do with your tires.....you just happened to notice it because your new tires are bigger than you old tires...you have a suspension issue....I cannot immangine what a tire place could have done to cause it, sort of having your car fall off the lift. Perhaps you have a flat strut, or maybe some bad bushings and ball joints. Get it looked at ASAP.

 

I've had two cars in the shop lately with this same problem. Basicly the trailing arm on each was bent. Not enough you could see it in the arm, just enough you could see the wheel not centered in the wheel well.

 

So, I have this same exact issue. Same wheel and everything. How in the hell can a $325 (realoem) part just bend? I was thinking I had a blown shock. Any empirical way to measure this bend in the trailing arm?

 

The term you guys are looking for is caster adjustment. On the MINI I'm not sure if there is any OEM adjustments for caster, it's just one of those things you'll have to figure out on your own. AFAIK no company makes rear caster adjustment kits for our vehicles.

 

yeah I only think of front wheels when I think of caster. Can the rear control arm bushings be so shot that the trailing arm is allowed to go out of spec?

 

"Caster" does not apply to rear wheels/axles. Caster concerns steering wheels, and there are no factory adjustments for this (on the front). http://en.wikipedia.org/wiki/Caster_angle


I would have your bushings (a-arms and trailing arm) checked before going and replacing your whole trailing arm. The trailing arm replacement would be costly if it is only bushings that have failed.

 

Caster does apply to both ends of the car. Caster is simply the measurement of the offset of the wheel center point and the upper suspension attachment point.

If the trailing arm has been damaged it will change the location of the wheel in regards to the upper suspension point. Thus moving the wheel either forward or backwards. This changes the caster.

 

 

The rear suspension parts in these cars are designed to be sacrificial. In other words, in minor impacts they bend/break so more difficult/expensive parts (such as the subframe and/or unibody) don't.

This is actually one of my concerns regarding most aftermarket rear control arms.

 

+1 - modern vehicles are also designed for "controlled crush" in an accident, evening out forces. That said, I'd be suspicious that it would "just bend" - could be some as simple as a parking lot 'nudge' in the wheel (seen that before) :dunno:

 

Just curious where you got your info from ? B/C everything i have read and been taught over the years says castor only applies to steering axles. Castor only plays a roll when the wheel as the ability to turn. When the wheels are fixed (rear) castor is not measured, b/c it doesnt apply.

http://www.familycar.com/alignment.htm

http://www.circletrack.com/chassiste...ngs/index.html

http://www.ozebiz.com.au/racetech/theory/align.html

http://www.ehow.com/about_5076739_ca...djustment.html

http://www.tirerack.com/tires/tirete...e.jsp?techid=4&


It is no wonder why the Mini Community seems to only take steps backwards rather than forward. The amount of mis-information is just unbelievable.

Even if you move the upper rear shock mount it wont change a single other part of the alignment. Not the case for the front strut.

 

Back to the OP, if they put a jack under the car and picked the trailing arm instead of the plastic jack point that could have bent it :dunno: - and there is no "fore-and-aft" adjustment to the wheels...

 

I agree with this, but this is not one of those cases. Rear wheels DO have castor, also called steering axis inclination. It is determined by the geometry of how the suspension links attach to the upright, and how stiff the bushings are at those moutning locations. Rear wheels steer naturally because their toe angles change slightly in different ways depending driving conditions, due to suspension travel or bushing compliance. The steering effect is small, normally less than 1 degree, but it has a significant effect on the handling of the car. And from an engineering standpoint, rear steer caused by suspension travel or road forces is exactly the same as front steer caused by turning the steering wheel.

Rear castor is typically not adjustable, and if the factory got it right, there is very little reason to change it. Especially since measuring and understanding the full effect of such a change requires million dollar test rigs or $30,000 software packages.

So, this is not misinformation. If anything, maybe Bigshot's comment is a little to0 technical for this topic.

 

Lightweight aluminum control arms are meant to take compression, tension, and buckling loads, Not bending loads. If someone tried to jack up or support the car by the contol arm, or if it was ever towed by strapping to the arm, it could bend very easily. This is precisely WHY the part costs $325. It's optimized for function vs. weight under reasonable circumstances.