I have a Modena that involved in 2 accidents years ago, with some repair work I can't really comment. today I finally took my time to measure the frame, using the method described in the 1st picture: put 4 dots on the floor and drew the 2nd picture assuming all a-arms are in spec, is my frame really that bad? or is it adjustable by playing with shims on arms? Image Unavailable, Please Login Image Unavailable, Please Login
It seems like it is off quite a bit; that is almost 3/4" and I don't know anything about a 360, but I know you can shim a Volkswagen Beetle out pretty easily. A good 4 wheel alignment may be able to get some of that back and possibly the front control arms could be machined and shimmed to get some more of it back.
The only real way to know is to put the car up on a flat table and have it corner weighted and ride height adjusted. The measurements to the body are meaningless ! MEANINGLESS !! The measurements to the chassis attachment points are all that really maters.
Well, his approach does not seem to perform measurements of the wheel center relative to the body. His method might be a first approach, but not necessarily show frame distortion. The differences in longitudinal direction may be masked by incorrect or different trailing angle adjustment. The diagonals additionally by variations in camber. Indeed, the only really reliable method is using the reference points on the chassis. Aside this, I do not know about the Modena, but with classic exotics differences as shown, if indeed existent at the chassis reference points, may even be factory original ....
I kind of understand my measurement is meaningless. but let's hypothesize that you distort a corner-balanced, straight, no-accident new car frame to a diamont shape. Isn't it going to show same weight on all four wheels? my point is, before I can corner weight the car, making sure the frame is straight is the first step to take, without which corner weight is meaningless.
If the car tracks straight, and takes an alignment, leave it alone... My limited experience with a prior car is that if you pull one parameter into line, another is then out of speck. Its like chasing your tail a bit.
Fully agreed. The weight approach does not really make sense. All four wheels will obviously never show the same weight. Even the wheels on one axle will not carry exactly the same weight (with proper wheel and chassis alignment), if the car´s design is not really symmetrical right/left. Just think of the many cars with asymmetrical fuel tanks, not to think of various auxilliary engine components, steering components etc. Chassis reference points may be found in service information, typically. I do not have a source at hand for the 360, but it should be researchable. Aside this, proper measurements may in most cases be done at chassis points near the inner lower wishbone ends. Just choose some and get going. To detect warping (alone) will make more reference points necessary, than the four at the wishbone ends. Just measuring the heights of said four reference points with the car standing on the wheels will quite likely be misleading
I'm no expert, but I agree. So let's say the car is off, but it takes an alignment, and drives great, what action are you going to take? sent it off to a frame shop for what outcome to be able to drive better than perfect? If it is pulling, wearing tires unevenly, squirrely then I'd act. The racers may disagree. Don't forget there are many parts between the frame and the wheel (where u were measuring from) that may be involved. And IIRC you had some issue refitting a control arm after doing the ball joints. Is that the issue? Sent from my iPad using Tapatalk
