Don't overlook the fact that your custom wheels were installed when the old, partially worn pads were still on the car. New pads each have over 3/8" more lining which moves the caliper 3/8" out closer to the wheel. If you need proof, have the brakes or tire people take a front tire off, remove the spacer and put the tire back on. If the wheel is locked up or makes a scraping noise, remove the wheel and look for the witness marks, (scrapes on the caliper or inside of the wheel.
I suspect the brakes people were correct. The only thing they could do to cause a problem with original wheels is to install pads with linings that were too thick, and that isn't very likely. There just isn't that much extra room when the proper pads are installed. The fact that spacers solved some problem by moving the wheels out a little should be proof something is wrong. If you still have the original manufacturer-designed wheels, put one of them on and see if the brakes still interfere. If they do, it's a caliper installation or pad problem. If the original wheel fits fine, as I expect it will, it's a wheel problem. No wheel salesman is going to want to admit there is a problem with their product. And quite frankly, I've never heard of a "temporary" spacer. It is common to install spacers with after-market wheels. As a point of interest, selective wheel spacers are available for some truck models to solve an alignment pulling issue. These are also not temporary.
If you find shiny scratch marks on the inside of a wheel but not on the caliper, look for "casting flash" on the caliper. This is a raised sharp edge caused by molten steel seeping through the joints of the mold. This extra metal can be easily filed or ground off. It usually isn't done during the manufacturing process because it's an unnecessary step that would increase the cost.
When you change from what the manufacturer designed into the complete steering and suspension system, you risk changing the handling characteristics. It is important for your new wheels and tires to result in the same "scrub radius" that was designed in. Scrub radius is affected, in part, by wheel offset, wheel width, and outside tire diameter.
In its simplest terms, scrub radius affects how the front of the car responds to one tire hitting a bump and how well the steering returns to center by itself after you turn a corner. More importantly, front wheel drive cars have a highly modified scrub radius designed in as part of the braking system. All modern cars have brakes with a dual hydraulic system. If a leak develops in one half, the other half is strong enough to safely stop the car. Older rear wheel drive cars have separate front and rear hydraulic systems, but front wheel drive cars have such a high percentage of drive-train weight in the front, a leak in the front hydraulic system would make the car very hard to stop because the rear brakes only do 20 percent of the stopping. To address that issue, all manufacturers use a "split-diagonal" hydraulic system. One front and the opposite rear brake are on the same hydraulic circuit. When half the system fails, only one front brake is working. With a scrub radius typical of a rear wheel drive car, that one working front brake would tug the steering wheel out of your hands causing a severe safety issue. By redesigning the scrub radius for this split-diagonal system, the tire with the working brake will want to pull hard toward the center of the car offsetting the tendency to pull the car toward that wheel. The result of this careful engineering is a car that stops relatively efficiently, in a straight line, and is easy to steer while only half of the brakes are working.
When wheels are installed with a different offset, width, or tire diameter, the scrub radius changes. You very likely will not notice the change because both front brakes are working and are balanced, but if there is a failure in half of the hydraulic system, you could be in for a huge surprise the next time you try to stop. Now you have a mismatched brake pull one way and a scrub radius pull the other way that are not equally offset by the other wheel.
Your wheel salesman can tell you if any measurements are different than on your original wheels. When a wheel manufacturer's goal is simply a change in appearance, they are very aware of sticking to original design measurements, but they are also willing to build and sell what customers want. The insurance adjusters are the people who really love anything that potentially changes the handling of a car. And lawyers are experts in spinning these modifications into much bigger issues than they probably are, even if you are not at fault in a crash.
One last thing to consider; it would be smart to double-check the lug nuts periodically. It's important to use a click-type torque wrench. Most Chrysler cars, with steel wheels, call for 95 foot / pounds. This insures the wheels won't fall off, studs and nuts won't be stripped, a 90 pound girl can get them loose to change a flat tire, and most importantly, they are all tightened evenly to prevent warping brake rotors. Aluminum (mag) wheels are soft and can crush a little resulting in loose wheels. A loose wheel will wobble on the studs and distort the friction surface that holds the nuts tight. No lubricant should be allowed on the nut-to-wheel contact points either. A LITTLE grease on the threads of the studs is acceptable but never use anti-seize compound. Also, don't use any lubricant at all on anodized studs. They have a yellowish or bluish plating and are usually found on Asian cars. They might also be shiny silver, not the normal dark color.
Friday, June 12th, 2009 AT 3:23 AM