Alignment specs

[CP]

I just discovered my spring 2006 alignment specifications in a pile of papers in the garage:

Before

LF/RF:
Camber -1.94* -1.08*
Caster 2.16* 1.87*
Toe -0.31in -0.34in

Total Toe -0.66in
Steer Ahead 0.03*

LR/RR:
Camber -1.20 -0.52*
Toe 0.33in -0.02in

Total Toe 0.31in
Thrust Angle 0.35*

After
LF/RF:
Camber -2.61* -2.53*
Caster 2.16* 1.87*
Toe -0.01in 0.00in

Total Toe 0.00in
Steer Ahead -0.01*

LR/RR:
Camber -1.63* -1.63*
Toe 0.01in 0.00in

Total Toe 0.01in
Thrust Angle 0.01*

I just got some caster bushings. Do I want to raise that number in the front, or lower it? How do those changes effect steering feel and suspension geometry in a corner?

 

The bushings you got will increase your front caster.

 

[iceman69510]

Increased caster improves turn-in response, essentially feeling somewhat like quicker steering ratio. You won't get hugely high numbers with those bushing I don't think, but lots of race cars use very high caster numbers. I made adjustable caster links for my datsun to achieve this.

You probably already know, but after increasing caster (or camber) you will need a new alignment for toe as it should always be adjusted last because it is affected by the other settings. I presume you will get one anyway because you will want to know what your caster is with the bushings installed.

 

[CP]

Thanks. They aren't going in until the spring, just before the annual alignment.

Strange that I just noticed this, but after 2 summers and many track days, my tires are starting to show the effects of lots of negative camber. The inside edges are considerably more worn than the outsides. This was to be expected, but I haven't noticed it until now. I've got 4 more track days to get through at the end of the month and then these tires will be done and teh snows will go on for the winter. I've been pretty impressed with the $100 Hankooks and will probably get another set next spring.

 

[skivittlerjimb]

Hey Cy,

My steering feel tightened up considerably after Al put in the Whiteline caster bushings. I can dig up the change in specs. from the file at home, but the difference was certainly noticeable. No downsides that I can tell so far.

Glad to hear the Hankooks have worked out so well. They seem pretty evenly matched with the Azenis in the tests I've seen and are a bit cheaper than the Falkens. Still, spending the extra $ on Toyo Proxes RA-1s is tempting but it probably doesn't make sense if you're driving the car all summer long on them.

-Jim B.
1432/2000
167k

 

[joec]

Are the castor bushing adjustable? I.e., can you rotate them to get balanced left/right values or do they only go on in one position and you get whatever they happen to be?

 

Not adjustable.

 

As stated, more caster will result in crisper turn-in. It will also make the car more stable on the brakes. We used to run a little more toe out when we increased the caster for good turn-in, but just keep in mind that this will induce more throttle-on understeer from the apex out so it's kind of a balancing act to find the right combination. I don't know about the geometry on a gvr4, but too much caster can also induce more bump steer. This is easy enough to check in the garage before the car gets on track. Sometimes an adjustment of the tie rod geometry is needed to reduce the bump steer and keep the car stable while transitioning.

 

[alik]

Based on my research for the Miata, you DO want to stagger the front and rear camber, but the rear must be larger than the front. Also, -2 and up camber is waaay too much. It'll help in the corner, but slow down the car on the straightaway (as in coming out of the corner).

My $0.02

 

[Larry Parker]

Camber is dependant on tire temps... For street cars the same front and rear wont hurt...

lp

 

[skivittlerjimb]

Quote:
Also, -2 and up camber is waaay too much.



Several folks on the board that run their GVR4s on road courses run -2.5 degrees camber up front without problems. In the back -1.5 degrees seems to be plenty. Going from ~-1 degree to -2 degrees up front with the addition of camber plates (and no other changes from my existing set up) greatly increased my grip through corners, including corner exit. I'm going to shoot for
-2.5 degrees next spring, as I think I do have a bit more room to adjust.

Miatas are very different animals than GVR4s!

-Jim B.
1432/2000
167k

 

[CP]

Quote:
Miatas are very different animals than GVR4s!



Exactly, which is what I said in my PM to you Al.

After 6 months of -2.5* up front, the insides of my tires aren't doing so hot, even with regular rotations. I think -1.5* in front is good if you plan to run the same tires for years at a time. Mine will need replacing every year at the rate I'm abusing them, so the additional wear isn't really bothering me. Plus it's only about $400 for some sticky street tires, which I can deal with annually.

However I'm considering getting some track wheels and R-compounds for next year's track days. Fitting them in the car is another story. A buddy with an EVO 9 has a tiny trailer on which he tows his track tires. I wonder how much weight a hitch would add to the rear end of the car; one that only needs to tow less than 300#s.

 

[atc250r]

IIRC I'm running -2.5* front and -1.5* rear with about zero toe front and rear. I'm very impressed with the improvement in handling from it. I'm lucky to have a few extra sets of the tires I'm using (thank you Acura /ubbthreads/images/graemlins/smile.gif) so I'm not too concerned with tire wear. I haven't rotated them since I'd just as soon replace the fronts twice before doing the rears.

John

 

[KT]

Quote:
Fitting them in the car is another story.



Two in the trunk & two in the back seat, in bags of course.

 

[CP]

Heh, yeah right. You ought to see all the crap that travels to the track with me. I barely have room for a second person in the car.

 

[kartorium]

rig the trailer hitch so it is a bolt on Cy, then remove it when you get to the races. Or get someone to build you one out of aluminimimum /ubbthreads/images/graemlins/smirk.gif

 

[alik]

I sit corrected.
/ubbthreads/images/graemlins/bawling.gif

 

[CP]

Meh...my picture of the Energy Suspension front end poly bushings I've got remaining was deleted.

Polish: I think it was you that identified them all. I'll post the picture again once we're able to do so. No need to show me where the caster bushings go; I remember /ubbthreads/images/graemlins/applause.gif But can you explain again what I need to remove to get at them?