13 replies to this topic

[ChrisA]

I'm going to get the alignment tweaked on the car this weekend and right now the car is on it's rollers. These are the stock 14x6 with IIRC a 35 or 40-mm offset, which have a nice lip for the alignment targets. Race wheels are TDs with 25-mm offset. Will the offset difference effect the alignment to the extent that I should put the TDs on the car?

[James York]

You didn't say how you were doing your alignment, but as long as the wheels are matched and true, using those wheels will not change the alignment from your race wheels doing it any way I know possible.

Some sort of laser alignment machine may still do it with unmatched wheels but I am not sure of their capabilities.

[Kyle Burkhardt]

I'm going to get the alignment tweaked on the car this weekend and right now the car is on it's rollers. These are the stock 14x6 with IIRC a 35 or 40-mm offset, which have a nice lip for the alignment targets. Race wheels are TDs with 25-mm offset. Will the offset difference effect the alignment to the extent that I should put the TDs on the car?

It may affect corner balance which could affect alignment, so I'd get it done with the wheels you intend to race on.

[wheel]

I have no affect on alignment.

wheel

[ChrisA]

Well, I think my last guy, who seemed to care about his work, is too busy, 'cause he isn't returning calls... So, I'm going to be trying my local Firestone , which uses the Hunter laser equipment. Their guy will let me sit in the car while he does the work. I'm keeping my fingers crossed that they'll hit my numbers.
I've given thought to getting the equipment and doing them myself, but I'm thinking I may get a Traqmate first.

Anyway, I've been told that wheel diameter won't effect alignment, but offset will. Just trying to get a consensus on what's what. It's going to be 100 out this weekend and I'd rather not mess with changing wheels if it's not necessary.

[Tom Hampton]

I'm no expert, but my intuition agrees with Kyle. The corner weights are affected by the verticle distance from the suspension to the tire....particularly the inside edge of the tire in a high camber steup. Both the vertical compliance of the tire and the offset of the inside edge will affect how much the spring is compressed as the spring perch is adjusted.

So, if you change all that using a higher profile tire, on a rim with different offset...I don't see how the results can be THE SAME. However, I don't know if the difference is material. Only scales could answer that for sure. One way to find out? Take your rollers with you, do the alignment on the TD's, and then switch to the rollers at the end and remeasure the setup.

[Mike Collins]

So long as your rollers are a match set you will be fine. Just don't have low profile tires in the front and snow tires on the back.

[James York]

So long as your rollers are a match set you will be fine. Just don't have low profile tires in the front and snow tires on the back.

Exactly. The key here is all the wheels are impacted the same, so the net effect is ZERO.

[fishguyaz]

i thought that if you are taking the time and $ to set up the car, then it should be done "as in race trim".
that means set your ride height before going for the alignment, and unless you, or something of equal mass is in the driver seat you will not get the accuracy you are paying for since the total wieght can/will effect ride height, and the ride height will effect other aspects of the alignment such as camber/toe.

[ChrisA]

i thought that if you are taking the time and $ to set up the car, then it should be done "as in race trim".
that means set your ride height before going for the alignment, and unless you, or something of equal mass is in the driver seat you will not get the accuracy you are paying for since the total wieght can/will effect ride height, and the ride height will effect other aspects of the alignment such as camber/toe.

Err, yeah. I did say that the shop will let me be in the car when the alignment is set. I set the ride height last weekend with car weighted for me.

[Zauskycop]

I'm not going to disagree with the experts, however this is something I have always wondered about. If you are stringing a car and measure the front of the rim to the tire, and the rear of the rim....the diameter of the rim WILL make a diffence in this case, albeit probably very minor. The further you get away from 0, the more profound effect it will have. I mean (just for example) take it to an extreme...a 13" rim to a 20" rim. If both are set to toe out, the 20" rim will be MUCH closer to the string at the front, and much further at the rear, than the 13" rim right?

Obviously they have no effect on an alignment rack as it measures the angle rather than actual toe.

So I guess what I'm saying is that 1/16" toe out per side will have a greater ANGLE on a 14" rim than a 15" rim if stringing??

[HoneyBadger - BrianW]

So I guess what I'm saying is that 1/16" toe out per side will have a greater ANGLE on a 14" rim than a 15" rim if stringing??

You are technically correct. Some shops use toe in/out angle just because of this. Keep in mind you are talking about 1/15 of 1/16" inch. That is a totally negligible amount IMHO.

[Mike Collins]

Not to rain on anyone's parade, but I have only done this about 1 million times. We are not comparing 13" rims to 20" we are comparing a set of stock rollers with stock tires to a set of race tires. The circumference of those two are virtually identical. I am willing to bet the outcome for this driver will be the same.

I align my car EVERY Tuesday on a state of the art alignment rack. My alignment settings have changed by the end of every race even if I don't ever hit anything or drop a tire. With the equipment I use, I can take the car off the rack, drive it around the block put it back on the rack and see change. Not change that will make a difference but measurable change.

I am CERTAIN he will be fine with street rollers on the car.

[Zauskycop]

Oh I agree with you Mike, and agree that the difference is virtually nil. It was just a concept I was discussing. You are correct a MILLION times!