Caster out of spec?

[NocturnalEmber]

One of the areas that I'm not familiar on is alignment and suspension geometry. Probably my weakest link.

Can someone take a look at this and explain to me why the caster would be out of spec on a stock car? Granted I know the factory specs are 7.58 +/- .5 degrees.

Tech said the caster on the RF is "not out of spec" ...so naturally I'm curious..

Why would the machine flag it as out of spec if its not out of spec?

I understand there might be some rounding that I'm not seeing in the report, but for a car that rolled off the assembly line less than a year ago part of me does find it concerning. If my front right is 7.0, even looking at the maximum allowed variance it would have to be 7.08, so I'm off by .08.

I'm not expecting the caster measurements to both be in the middle with a comfortable margin on each side, but I at least think its concerning. Can someone help me make sense of it?

Sponsored

 

[Hasan]

It is showing as "out of spec" because the measurement 7.0 is outside the range 7.1 to 8.1 set in the system.

 

[NocturnalEmber]

It is showing as "out of spec" because the measurement 7.0 is outside the range 7.1 to 8.1 set in the system.

I understand it's out of spec, I thought I had mentioned in my OP that the tech said its "not out of spec" when its showing that it is indeed out of spec. Fixed that in my post.

 

[MavJ]

I believe the toe in of your front might the compromise your tech made causing less caster.

I’d suggest 0 toe in and maximizing camber -1.9 (i think -1.9 is the max obtainable) and maximizing caster (i think 7.5 is max obtainable) from stock oem.

I think for aggressive street or mild track -2.5 camber and 8.0 caster would be ideal — someone more familiar with the supra chassis can correct me. But my tire wear and experience with bmws suggests this to me.

 

[NocturnalEmber]

I believe the toe in of your front might the compromise your tech made causing less caster.

I’d suggest 0 toe in and maximizing camber -1.9 (i think -1.9 is the max obtainable) and maximizing caster (i think 7.5 is max obtainable) from stock oem.

I think for aggressive street or mild track -2.5 camber and 8.0 caster would be ideal — someone more familiar with the supra chassis can correct me. But my tire wear and experience with bmws suggests this to me.

Car is 100% stock, ideally I'd want to get more proficient with the chassis in a stock form, then move onto a more track focused alignment when my abilities can perform to it.

I guess in the meantime my main concern would be what would cause that caster to be out of spec on a basically < 1 year old car with 3,200 miles on it.

The tech wrote "not out of spec" (was accidentally cropped out in editing) next to that RF caster rating, but gave zero context as to why.

I'm not sure how sensitive the A90 chassis is to the alignment prep, but I have no way of knowing if he did it properly (ballasts, etc.) I do know now that you are also supposed to do it with a full tank of gas, which the car didn't have going in (had about 1/2 a tank) but I have absolutely no idea whatsoever how significant that would be, if at all.

 

[Hasan]

Car is 100% stock, ideally I'd want to get more proficient with the chassis in a stock form, then move onto a more track focused alignment when my abilities can perform to it.

I guess in the meantime my main concern would be what would cause that caster to be out of spec on a basically < 1 year old car with 3,200 miles on it.

The tech wrote "not out of spec" (was accidentally cropped out in editing) next to that RF caster rating, but gave zero context as to why.

I'm not sure how sensitive the A90 chassis is to the alignment prep, but I have no way of knowing if he did it properly (ballasts, etc.) I do know now that you are also supposed to do it with a full tank of gas, which the car didn't have going in (had about 1/2 a tank) but I have absolutely no idea whatsoever how significant that would be, if at all.

Generally, it happens if you hit something like a big hole or a curb or something. Macpherson strut suspensions are more prone to this as they usually don't have adjustable caster. You can dial it in by using adjustable camber/caster top hat plates.

Its not off by much, and I wouldn't be concerned about it.

 

[Traxion]

.2* Caster difference is nothing. It's not out of spec because there's no caster adjustment on the car. This can come down to many things like tolerance and placement of the top holes the strut bolts into. If anything that's better than most stock cars. Ignore what the machine says is in/out of spec. That stuff just pulls from a database and it's also a setting that can be overridden anyway. Knowing what alignment specs you want and what is possible is more important than what the machine says is good/bad.

The only thing of note I have to say is that 0* toe in front would have been better long term choice but it's more than fine with what you have.

Sponsored