Wheel Alignement with Firm Feel UCA and soild subframe mounts

[Bruceynz]

Hi Guys,

Ok had the alignment done on the car after the FF UCA were fitted, boy they can pull some caster now, we could go well over 5 probably get more like 6+ degrees caster but alignment guy said didn't want to push it to far.

Caster is at a tad over 5 and camber -.45 so that should see it go ok, any wheel alignment gurus see anything wrong with that alignment setup?

Here is the alignment sheet, hope you can read it as it gets compressed when I upload it.

Thanks
Bruce

 

[Aspen500]

I see nothing wrong with those settings.
He probably didn't want to go any further with the caster because it could cause issues when turning. The more caster there is, the more the camber will change on turns. It's a case of getting a happy compromise. I'm sure the 5 degrees positive will give excellent straight ahead tracking and steering "self centering".

 

[Bruceynz]

yeah I told him to put 6 on it and he said he has been doing wheel alignments on old cars for quite some time (30 years) and he advised me 5 degrees would be more than enough, he said you have to be careful with cars that were not designed to have so much caster.

 

[Aspen500]

Sounds like he knows his stuff!

Side note: Our front end and alignment guy at work (now semi-retired) has been doing it for 40 years and I think he could align anything and make it go dead straight and wear tires perfectly even. He's good.

 

[Bruceynz]

He mentioned if you put to much caster on a car that wasn't designed for it then you run into other problems, he said some Europeans come out with 12 degress caster!

 

[Aspen500]

The late model Chargers and 300's run over 8 degrees caster.
He is right. If the rest of the suspension and steering wasn't designed for tons of caster you will have geometry problems on sharper turns, too much camber change on turns, might mess with the toe out on turns, could have suspension pivot bind, etc, etc, etc........................Kind of like when guys lower their cars (or rednecks lift their trucks 6") and leave the steering all stock and then have problems with bump steer or tire scrubbing. It all has to work as a system. Change one thing and you also have to change other things at the same time.

 

[Bruceynz]

Yes, he has had old Mustangs and he was telling how you can change things around in them and reduce bump steer quite a lot. Far as I know mustangs were notorious for bump steer. So he is on to things.

 

[Bruceynz]

The SAI is way out on my car, it aligned all ok and I did bring it up with him, he said it can just be someone hit the curb hard and may have altered it a little, or does the SAI change with the weak K member issue?

 

[Aspen500]

You could have a tweaked steering knuckle (spindle) possibly. If it is, to get camber correct the upper control arm would be moved in or out more than if it was all brand new parts. That puts the angle of a line through the upper and lower ball joints to change, making SAI incorrect. SAI isn't adjustable except to replace bent parts. The trick is to determine which part is the bad one.


I wouldn't worry about it. The only downside to having SAI with a 6 degree split is you MAY have a slight pull to one side at low speeds. SAI I the angle that causes the front of the car to lift slightly when turning and uses the weight to help with returning to center. Again, mainly at low speeds and sharp turning angles.