Wheel Size/Alignment

[Aggressor]

As many of you may know from this forum and homecoming events, I have had alignment and vibration problems with my car that just remained an unsolved source of frustration since the car was purchased in 2001. The fix was relatively simple once understood.

After 12 years of dealing with steering that just never seemed right along with some nagging minor constant vibration at higher speed I found the problem. When my car was being manufactured by Unique I ordered my Compomotive wheels along with my tires. I was expecting the front wheels to be 15" X 9" as per my order. The front wheels shipped by the dealer were 10 inches wide with much of the extra width offset to the outside. To compensate for this extra roadforce leverage additional toe-in is required. Right now toe-in is a hair short of 1/8" per side or just short of 1/4" total.

Defining the problem took a long time and recent chassis alignment research/study confirmed my suspicion.

Aggressor can now run over 65 mph without steering uncertainty and vibration. She still shakes, rattles, and vibrates the cockpit quite a bit but that only comes when the engine's trying to hookup to pavement.

-Geary

[weaver]

Are you still running the original tires?

[Aggressor]

Alan - The original tires were changed prior to Homecoming 2012. As you can recall you set me up with an on-car wheel balancing appointment with Luther for this persistent problem.
Now the car is rock steady and I appreciate the efforts of you and Maurice to help with this problem. I ordered the wheels through Alan Paxton and 10" wheels were drop-shipped to you instead of 9". This explains why the alignment specs don't work for me as there must be considerably more roadforce pressure on the extra outward offset. It was shocking to measure the wheel and discover the different size after a dozen years of ownership.
My final alignment specs are:
Front Camber : - 3/8 Degree Right and Left Side
Front Caster: +3 1/2 Degrees Right and Left Side
Front Toe-In: Less than 1/8 Right and Left Side for just under 1/4 total (I was at 1/8 and just tweeked both sides in a hair width. I did not re-measure after a very successful final road test)
Rear Camber: - 3/4 Degree Right and Left Side
Rear Toe-In: 1/16 Right and Left Side for 1/8 total

The only concern remaining is that my front 245/60's are stretched to fit 10" wide wheels. My original front tires never really wore bad but I now feel they are operating out of design spec as mounted. The radial sidewalls are most likely not flexing as designed. I guess as long as they remained sealed to the rim I have no real worries.

-Geary

[weaver]

You running 10" front and rear, that is a wide wheel for the front.

[Aggressor]

Alan - I have 10 x 15 fronts and 11 x 15 rears. My first 2 Unique cars ran 8 X 15 fronts and 10 x 15 rears. I wanted to go up 1 inch on both fronts and rears on this car.
I did not realize the problems that could occur with that decision in 2001.
While I changed the front wheel bearings prior to this years homecoming they showed no extraordinary wear. The front suspension components all seem tight with no exceptional wear noted except for the steering rack. The rack was fine spindle to spindle but the bushings that center the rack within the steering assembly were totally beaten allowing much lateral movement within the tube. The beaten rack was also replaced prior to 2013 homecoming.

-Geary

[spd4me]

Geary - Did you do the toe-in yourself? My FIA use to float around at high speeds and would drift off every time I drove on top of a groove in the pavement. Looking at the front tires showed no wear inside or out. I took a string and aligned it with the back tire, pulled past front tire and measured distance from string to back of rim and to front of rim. Turned strearing rod until I got 1/8" more on front. Seemed to work. Still floats a little. Will vibrate between 60 to 65 mph. Always looking for way to smooth out ride. Nothing worst than driving down interstate and people passing seeing my hand shaking on wheel.
Bob

[Aggressor]

See below text

-Geary

[Aggressor]

Once again see below

-Geary

[Aggressor]

Bob - Toe, Camber, Caster - All done in-house. After wasting money on numerous bad alignments I recently started doing my own. Watching obvious errors done by laser guided garage monkeys in alignment shops gets pricey and out of frustration you buy equipment to do it yourself.
Simple bubble levels have been used forever to accurately set camber and caster and a simple trammel bar can accurately set toe. I purchased a Fasttrax Caster/Camber gauge. This is a $200 unit that contains bubble levels and you can add optional arms to measure toe if you want. I use a trammel bar is made of 1/2" metal conduit for toe.
I have aligned my Unique, 72 Triumph GT6, 86 Trans Am, 68 Mustang, and spot checked Sharon's 325CI prior to trade in. For shop clients I have aligned a 96 Camaro, 78 Fiat 124 Spyder, 2006 Lancer Evo, and 3 street rods. All with great success.
If you've ever watched a "professional" alignment you see that the person doing it will be happy to get your vehicle specs anywhere within an acceptable tolerance range and does not usually spend additional time zeroing in on a precision value. You'll find that your car can be off a few degrees in camber and caster and still feel stable even if not correct. Toe is a more sensitive subject and needs to be approached with more precision. The Fasttrax alignment gauge is claimed to be within an 1/8 degree. I don't know if I'm within an 1/8 but it's really close as bourne out by my results.

-Geary