Hey Guys,

So the other day I got some new engine mounts installed in my 2002 GS300 Sport Design. In order to install the new mounts, the tech had to slightly undo the sub-frame bolts. Didn't seem like an issue to me, except for he warned me my alignment caster angle might be out because of this. Is there any truth to that, or is he just pulling my chain? Thanks!

 

So I just went to NTB for a free alignment inspection because I was curious if the technician was right in his assessment. Here is what I found out:

Measurements:

Front Left Caster: 6.7 degrees Front Right Caster: 6.4 degrees

Specified range for front caster is: 7.1-8.1 degrees

All other angles were in spec. The car seems to track correctly, so if left unadjusted what symptoms can I expect with the caster out?

 

Well what he should have told you instead was that he made a mistake by unbolting the subframe. Instead, he could have lifted up the engine just a bit to gain clearance. If the caster is off, but stays consistent, then you shouldnt' have too much problem. It's only when your caster bushings are worn out, then you'll start having problems with tracking and tire wear. Your tech should have never unbolt the subframe in the first place.

 

He said he tried to push the engine up further, but was unable to do so. Do you think he did any damage to the car at all by unbolting the sub frame??? Also, is the caster adjustable on the GS?

 

He couldn't push the engine up further because the transmission mount was holding the engine/tranny assembly down. He could have loosen the tranny mount instead.

I dont think he did any damage as long as he torqued the bolts/nuts back to original spec. Caster on our car is not adjustable at all. Only camber and toe.

 

He told me everything was torqued back to spec, and I have no reason to believe otherwise. Based on my caster specs, do you think I would have any problems at all?

By the way, cross caster is in spec at 0.3 degrees

Thanks for your help!

 

I dont think you'll have much problem. Only start worrying when you get irregular tire wear.

 

LOL when or if I get irregular tire wear? I thought caster didn't affect tire wear?

 

Caster does affect tire wear. If your caster is constantly changing, your toe will also change along with it since the caster arm and the lower control arms are connected. They're all linked together. On the 2nd gen GS, the caster arm bushings are probably the first to go out of all other control arm bushings. Most people get the dreaded steering wheel vibration because of this.

 

I don't have any steering wheel vibrations at all yet, knock on wood. Does this mean the caster should automatically correct its self, and I shouldn't be concerned?

 

Caster doesn't correct itself. It's fixed unless your bushings are worn out. Like I said, just watch out for tire wear. If you dont have any wear out of the ordinary, then I wouldn't sweat about it.

 

Got the car aligned just in case, turns out the toe was out a little and now the caster is just about in spec. Thanks for your help!

 

Toe is the main one you need to worry about as far as wear goes.

Caster is basically how far forward or back your wheel is within the wheel arch. it can change a little under load depending on the bushes. The more caster you have, the heavier the steering can be (in theory) but also the quick the wheel will return to centre.

if you slightly reduced the caster, provided toe was okay and the lower caster hasnt knocked the toe out, then you will probably notice next to no difference. On my S13 i got aftermarket caster rods and increased caster from around +4 to +8, and i felt only a slight different on turnin and a bit better repsonse to centre. but not hugely so. So with the power steering etc of a 2GS i reckon you would be lucky to even tell the difference.

also, stock arms arent adjustable, but you can of course get aftermarket adjustable arms for caster, camber and toe from the likes of Ikeya Formula and Nagisa Auto