What's Your Caster?

My LCA bushings are shot so I'm considering the AVO or Fulcrum Caster Adjustment Bushings (+.0.50 caster). I checked my last few alignments and the caster is consistent at:

 

LF: 6.05* RF:5.94*

 

I would like to validate if this is a 'typical' caster measurement for the GT LTD and that the offset bushing will achieve +0.50 caster increase. If you've had offset AVO or Fulcrum LCA bushings installed, please list your 'Before' and 'After' caster and any comments on the change in handling, etc.

 

It looks to me like a 2006 BMW 335i has just over 7 degrees of Caster... is anyone here running that much? It would be interesting to see the different set-ups.

bump

i believe ~6.00 caster is close to the factory alignment

I have the off-set control arm bushings. I know I'm running over 6 degrees but I know it's not near 7. After winter is over I am getting the car aligned again on a hunter rack, so I'll have a more precise measurement.

Just got my car realigned and mine is:

 

Left: 6.68*

Right: 6.20*

 

Nothing much done suspension wise, just coilovers.

put some kws, whiteline motorsport alk, and k-max camber caster plates on an sti with some other stuff recently.

 

http://jamalb.net/gallery/d/4552-2/0118092127.jpg

 

http://jamalb.net/gallery/d/4543-2/0119091057b.jpg

 

The corner balance and alignment didn't include caster alignment so we're not really sure where it's at. I would guess 10 or so degrees.

My LCA bushings are shot so I'm considering the AVO or Fulcrum Caster Adjustment Bushings (+.0.50 caster). I checked my last few alignments and the caster is consistent at:

 

LF: 6.05* RF:5.94*

 

I would like to validate if this is a 'typical' caster measurement for the GT LTD and that the offset bushing will achieve +0.50 caster increase. If you've had offset AVO or Fulcrum LCA bushings installed, please list your 'Before' and 'After' caster and any comments on the change in handling, etc.

 

OK, as promised- I have made my installs and have a new alignment. The results were not exactly what I expected-- Here's a summary of the installs over the past week:

 

Car- mostly stock Legacy GT Ltd, 2005 with 96K miles (ACT street clutch, LWFW, Cobb STS, tint, grill). I intend to keep the car for another five years, so I decided to do a re-fit of the suspension.

 

My Goal: Make the car suspension and handling dynamics 'better than new' or Spec-B+ (flamesuit *on*).

 

Front end:

- Cobb Front Sway Bar (stock endlinks)

- Whiteline Roll Center Kit- Ball Joints, Tie Rod ends still with stock struts/springs. I'm currently waiting on JDM pinks from EDO. I already have the Bilstein HD kits to go with it and will install when the springs arrive.

- New ball joint housings (L&R) - OK, so I broke the knuckle on one side b/c the ball joint was a rusty stubborn little turd (5 years of road salt really does a number on things!). I had no reason to suspect that the other side would behave any differently, so I just installed two new balljoints (with anti-seize) in two new OEM housings- good for another five years hopefully.

- New front bearings - installed and reduced the noise by about 60%

-AVO LCA offset bushings- pressed in correctly (lip at top, offset toward center of car per instructions).

-Cusco front lower suspension braces- replaces the LCA mounting plates and ties them to the subframe.

-Goodridge SS brake lines and flush

- Rotors turned, new ceramic pads installed

- new Bridgestone RE960's installed today

 

Rear end:

-Cobb rear sway bar and support brackets set of 'soft' setting

-Goodridge SS Brake Lines/Flush

-Rotors turned, new ceramic pads, rebuild and adjust emergency brake

-Bridgestone RE960's on rear

------------

parts on hand, to be installed:

- new rear bearing housings

- Cusco rear lower suspension braces complete with only Japanese instructions and crappy pictures

-------------

OK, here are the before and after alignment numbers when I got the 960's installed today- Note the Caster numbers... Also I'm not thrilled with the rest of the numbers- I would like more negative Camber and the toe closer to zero. I have the lifetime program, so I may go back in a few days and let someone else take a shot at it.

------------------------------

Alignment baseline: 1/28/09

 

Left Front Camber, Caster, Toe:

Actual: -0.11, 6.10, 0.03

Specified Range: Camber: -0.75 to 0.25, Caster: 5.17 to 6.67, Toe: -0.08 to 0.08

 

Right Front Camber, Caster, Toe:

Actual: 0.03, 6.08, 0.00

Specified Range: Camber: -0.75 to 0.25, Caster: 5.17 to 6.67, Toe: -0.08 to 0.08

 

Left Rear Camber, Toe:

Actual:-0.56, 0.03

Specified Range: Camber: -1.42 to 0.08, Toe: -0.08 to 0.08

 

Right Rear Camber, Toe:

Actual: -0.74, 0.02

Specified Range: Camber: -1.42 to 0.08, Toe: -0.08 to 0.08

 

Front:

Cross Camber: -0.13

Specified Range:-0.75 to 0.75

Cross Caster: 0.02

Total Toe:0.03

 

Rear:

Total Toe: 0.05 (range: -0.17 to 0.17)

Thrust Angle:0.01 (range: -0.33 to 0.33

---------------------------

Post-install & Tires alignment (from today, 2/18/2009)

 

Left Front Camber, Caster, Toe:

Actual: -0.13, 6.19, 0.03 (yes, that's a 0.09 increase)

Specified Range: Camber: -0.75 to 0.25, Caster: 5.17 to 6.67, Toe: -0.08 to 0.08

 

Right Front Camber, Caster, Toe:

Actual: 0.10, 6.43, 0.02 (Caster increase of 0.35)

Specified Range: Camber: -0.75 to 0.25, Caster: 5.17 to 6.67, Toe: -0.08 to 0.08

 

Left Rear Camber, Toe:

Actual:-0.56, 0.01

Specified Range: Camber: -1.42 to 0.08, Toe: -0.08 to 0.08

 

Right Rear Camber, Toe:

Actual: -0.53, 0.07

Specified Range: Camber: -1.42 to 0.08, Toe: -0.08 to 0.08

 

Front:

Cross Camber: -0.03

Specified Range:-0.75 to 0.75

Cross Caster: -0.25

Total Toe:0.01

 

Rear:

Total Toe: 0.08 (range: -0.17 to 0.17)

Thrust Angle:0.03 (range: -0.33 to 0.33)

-----------------------

So..... overall the car feels great- no more body roll, firm controlled footing. Very nice, but I was expecting at least a +0.3 caster increase from the offset bushings. I checked the install- even marked the control arm at the point that it would offset towards the center of the car (per the instructions).

 

So could some of the other part swaps have affected the caster? I have a couple of days to think about next steps on this.......

 

Any thoughts?

Hi,

Not sure if you resolved your question, but I reviewed my before and after caster settings after getting the AVO caster kit installed and I ended up with a .2 increase on the left and a .4 increase on the right. Not quite what I expected either. Still a very definite improvement in highway stability , but at some loss of initial turn-in.

Hi,

Not sure if you resolved your question, but I reviewed my before and after caster settings after getting the AVO caster kit installed and I ended up with a .2 increase on the left and a .4 increase on the right. Not quite what I expected either. Still a very definite improvement in highway stability , but at some loss of initial turn-in.

 

 

Interesting- I finally got my Bilstein HD and STI Pinks (along with Saggy Butt Shims) installed a few weeks ago. The suspension is officially 'done' (for now). Here is a comparison of my Caster values:

 

Before LCA offset installation:

LF: 6.05* RF:5.94*

 

After LCA offset installation (with Whiteline Roll Center Kit installed also):

LF: 6.19* RF: 6.43*

 

After Bilstein HD and STI Pink spring install (Alignment Date 8/15/09)

 

LF: 6.56* (range 5.17 - 6.67)

RF: 6.75* (range 5.17 - 6.67)

 

As you can see, the values increased to where I would expect them to be, however I'm not sure how the struts and springs would affect the caster- could the lowering of the suspension geometry because of the new struts and springs have an effect on the Caster values? I wouldn't think so, but there are the numbers...

 

The alignments were all performed at the same location (Firestone) but I'm not certain that they were done on the same machine-so there could be some variation there (I think they have two alignment bays). I have the same person perform the alignments each time- a fellow Subie WRXer, so I know he does a good job. Regardless of the values on the alignment printout, the car feels more planted and I'm happy with the final result.