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  1. #1
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    Comp Coupe Caster

    Need help with Caster adjustment on Comp Coupe.

    A-arms have Monoball and VCC Camber shims.

    Current LF caster is +3.0, RF is +3.2. Looking to get both side to around +6.0

    How to I make the change? Is it with the aluminum spacers between A-arm and monoball or with the Camber shims?
    The 4 bottom A-Arm monoball spaces are all equal in length.

    Currently all the front shims are the "E" shim. LF Camber is -2.5 RF Camber is -2.7
    Would also like to get Camber to the -3.5 range.

    Thanks.

  2. #2
    caster is typically set with the front and rear lower control arm eccentrics (in this case shims). not sure about CCs but would think they are same

  3. #3
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    I'm use to the eccentrics types.

    Looking for pointers on which shims to switch to and which on which A-arm to out them.

    Got a bad hip and knee. trying to avoid randomly trying different combos and repeated tries to get close.

    Thanks

  4. #4
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    If you move the rear of the lower control arm out away from the frame the caster will increase and if you move the front of the lower control arm in towards the frame the caster will increase. There is no magic shim setup. To many variables. Also how are you measuring the caster? Front end alignment machine? Hand gauges? The amount you turn the steering wheel affects the caster number as well. If you only turn the wheel 1/4 turn while measuring you would get a lower reading then if you turn the wheel 3/4 of a turn.

  5. #5
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    Hi Tom,

    Checked it several ways. Longacre digital gauge with front of tire 15 degrees out and then 15 deg inward (total 30). 15 degrees seems to be about 1/2 turn of the wheel. And with a bubble gauge and 20 degrees, not quite 3/4 turn of wheel. Getting between +3 to +3.2 Caster.

    I'm going to try leaving "E" in the front, and try "G" in the back and see how much that adds. Hope it doesn't change the Camber too much.

  6. #6
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    Quote Originally Posted by Exhlr8n View Post
    Need help with Caster adjustment on Comp Coupe.

    A-arms have Monoball and VCC Camber shims.

    Current LF caster is +3.0, RF is +3.2. Looking to get both side to around +6.0

    How to I make the change? Is it with the aluminum spacers between A-arm and monoball or with the Camber shims?
    The 4 bottom A-Arm monoball spaces are all equal in length.

    Currently all the front shims are the "E" shim. LF Camber is -2.5 RF Camber is -2.7
    Would also like to get Camber to the -3.5 range.
    Quote Originally Posted by Exhlr8n View Post
    Hi Tom,

    Checked it several ways. Longacre digital gauge with front of tire 15 degrees out and then 15 deg inward (total 30). 15 degrees seems to be about 1/2 turn of the wheel. And with a bubble gauge and 20 degrees, not quite 3/4 turn of wheel. Getting between +3 to +3.2 Caster.

    I'm going to try leaving "E" in the front, and try "G" in the back and see how much that adds. Hope it doesn't change the Camber too much.
    Going with a G in the rear while leaving the E in front will definitely add more camber. That's what you want right? If not, change them in equal increments but the opposite direction. G in back and C in front should not change camber much if at all.

    If you're getting that much -camber with E's, you're doing great and have a lot of room to play. I have to be in the J range to get that much camber on my Gen4.

    I also have mono-balls. My lower arms are spaced evenly. My uppers however are offset towards the rear which helps increase caster.

    I tried reading caster on my car two different ways. Both times I came up with 5.5 degrees. Then I took it to an alignment shop and they measured 6.5. That's about all I can get without sacrificing camber.
    Last edited by Back In Black; 1 Week Ago at 10:48 AM.
    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile

  7. #7
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    Yes, I want to add more + Caster (only had +3 to start)


    Here is what I got with E's in the front control arm mount and G's in the back mount.

    LF: Caster +5.8 Camber went to -1.1 (Not enough)

    RF: Caster +5.8 Camber -2.9 (that seemed to work well) Not sure what happened to the LF? It lost a lot of -Camber.


    So in an attempt to kick out the bottom of the tire equally I retried the LF with D's in the front mount and H's in the rear
    Caster stayed at +5.8 and Camber increased a little to -1.4 (still not enough though)

    Any suggestions..?
    Maybe C's in the front mount and I's in the rear.

    My upper control arm mounts do not have any Shims.
    Last edited by Exhlr8n; 1 Week Ago at 01:29 AM.

  8. #8
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    Quote Originally Posted by Exhlr8n View Post
    Yes, I want to add more + Caster (only had +3 to start)


    Here is what I got with E's in the front control arm mount and G's in the back mount.

    LF: Caster +5.8 Camber went to -1.1 (Not enough)

    RF: Caster +5.8 Camber -2.9 (that seemed to work well) Not sure what happened to the LF? It lost a lot of -Camber.


    So in an attempt to kick out the bottom of the tire equally I retried the LF with D's in the front mount and H's in the rear
    Caster stayed at +5.8 and Camber increased a little to -1.4 (still not enough though)

    Any suggestions..?
    Maybe C's in the front mount and I's in the rear.

    My upper control arm mounts do not have any Shims.
    You went from -2.5 to -1.1?? That doesn't seem right. Changing from a E to a G in the rear mount should have increased negative camber. You sure you don't have the shims in backwards? The holes should go towards the outside of the car.
    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile

  9. #9
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    Quote Originally Posted by Back In Black View Post
    You went from -2.5 to -1.1?? That doesn't seem right. Changing from a E to a G in the rear mount should have increased negative camber. You sure you don't have the shims in backwards? The holes should go towards the outside of the car.
    I'll double check, pretty sure they are in correctly, because the caster increased as the G pushed the lower ball joint forward.

  10. #10
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    Quote Originally Posted by Exhlr8n View Post
    I'll double check, pretty sure they are in correctly, because the caster increased as the G pushed the lower ball joint forward.
    When you make changes like that you should also re-check and adjust your toe or it will throw off your camber measurements. Bounce the car and roll it forward/backward as well.
    Last edited by Back In Black; 1 Week Ago at 11:26 AM.
    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile

  11. #11
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    Yes, rolled car back and forth, bounced , turn wheels.

    Just by eyeballing it after changing shims to G it looked like it lost about 1/2 it's Neg Camber

    I did recheck toe with toe plates, surprisingly it was still @ 1/8" toe out. I did not restring to check squareness though. I'll do that and recheck toe.

    Thanks, and Happy Thanksgiving..!

  12. #12
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    Quote Originally Posted by Exhlr8n View Post
    Yes, rolled car back and forth, bounced , turn wheels.

    Just by eyeballing it after changing shims to G it looked like it lost about 1/2 it's Neg Camber

    I did recheck toe with toe plates, surprisingly it was still @ 1/8" toe out. I did not restring to check squareness though. I'll do that and recheck toe.

    Thanks, and Happy Thanksgiving..!
    Very odd behavior. Wish I was there to see it.

    Happy Thanksgiving to you as well.
    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile

  13. #13
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    I agree, freaking Odd.

    Rechecked toe after stringing, front only lost maybe 1/16 out? (it was 1/8" out before changes). So no real change in toe.

    The rear stayed same ( 1/8" in, didnt make any shim changes there, so shouldn't have changed anyways)

    Guess I'll try C's in the front and I's in the rear mount.

  14. #14
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    RF E and G

    Front mount E
    RF Front mount E.jpg

    Rear mount G
    RF Rear mount G.jpg

    LF D and H

    Front mount
    LF Front mount D.jpg

    Rear mount H
    LF Rear mont H.jpg
    Last edited by Exhlr8n; 1 Week Ago at 12:55 PM.

  15. #15
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    I assumed you were doing a "left" install on both front and rear, not just the rear. That's why you're losing all your camber. All my shims are installed "left". All the way around.
    Last edited by Back In Black; 1 Week Ago at 03:59 PM.
    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile

  16. #16
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    Won't I loose +Caster if I turn the fronts the other way? (should definitely gain Camber)

    Ended up with "C" in the front and "J" in the back. That combo keep me @ +5.8 Caster and got to -2.0 Camber.

    Made it to Laguna on Friday. Car handled better with the added Caster, less twitchy (went from +3.0 to +5.8)

    Left install is with the Radius top left corner away from frame on the forward most mount, correct?
    So when I install the rear shim on the same mount, the radius will be on the bottom (if I want to see the Shim Letter) or put the radius on the top and letter faces inward. Shouldn't make a diference as long as it matches with the front shim, correct?

    Freaking brain fog when it comes to grasping these damn shims, lol

    I don't see how, but is there a way to gain Caster and not effect Camber?

  17. #17
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    Quote Originally Posted by Exhlr8n View Post
    Won't I loose +Caster if I turn the fronts the other way? (should definitely gain Camber)

    Ended up with "C" in the front and "J" in the back. That combo keep me @ +5.8 Caster and got to -2.0 Camber.

    Made it to Laguna on Friday. Car handled better with the added Caster, less twitchy (went from +3.0 to +5.8)

    Left install is with the Radius top left corner away from frame on the forward most mount, correct?
    So when I install the rear shim on the same mount, the radius will be on the bottom (if I want to see the Shim Letter) or put the radius on the top and letter faces inward. Shouldn't make a diference as long as it matches with the front shim, correct?

    Freaking brain fog when it comes to grasping these damn shims, lol

    I don't see how, but is there a way to gain Caster and not effect Camber?
    Yes. It's a give and take kind of situation. Depends on how you want your car set up. How much tire wear you can live with, etc. In my case, I set my camber based on tire temps and to a degree, tire wear. Tires are expensive and not getting any cheaper so I want them to last as long as possible. I set my camber where I wanted it with the largest shim in the rear mount and whatever caster I got I had to live with. And I made sure I didn't have any cross caster in the process.

    Yes, left install is with the radius away from frame. Doesn't matter if the radius is at the top or bottom. Shims pairs should be the same letter and oriented the same...left or right install. Doesn't matter if the letter gets hidden as long as you can see one of them. You should be writing all this setup stuff down anyway. Helps with the brain fog.

    Since you have monoballs, you can get more caster if you put offset spacers in your upper a-arm mounts and shift the arm towards the rear of the car like I have in this pic. Sorry for the blurriness but you get the idea.
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    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile

  18. #18
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    Thanks again for your help!

    I can see that the rear spacers are shorter, moving the upper ball joint rearward.

    I'll check the top spacers don't remember if they are off set or not, I removed the bottom ones and measured them and they are the same length.

    On your set up. How much shorter are the top rear spacers compared to the top front spacers?

    I definitely like the increase in Caster. I got a little squirely coming out of left hand turn 11 before powering up the straight (Accerated to early) car oversteered right 45 degrees then back and forth a few times, but I was able to gather it up and pull out of it. Probably would have spun out completely the way the car was previously set up.
    Last edited by Exhlr8n; 1 Week Ago at 01:03 PM.

  19. #19
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    Quote Originally Posted by Back In Black View Post
    Since you have monoballs, you can get more caster if you put offset spacers in your upper a-arm mounts and shift the arm towards the rear of the car like I have in this pic. Sorry for the blurriness but you get the idea.
    I see what you did there...
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  20. #20
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    Quote Originally Posted by Exhlr8n View Post
    Thanks again for your help!

    I can see that the rear spacers are shorter, moving the upper ball joint rearward.

    I'll check the top spacers don't remember if they are off set or not, I removed the bottom ones and measured them and they are the same length.

    On your set up. How much shorter are the top rear spacers compared to the top front spacers?

    I definitely like the increase in Caster. I got a little squirely coming out of left hand turn 11 before powering up the straight (Accerated to early) car oversteered right 45 degrees then back and forth a few times, but I was able to gather it up and pull out of it. Probably would have spun out completely the way the car was previously set up.
    You're welcome! Happy to help if I can.

    Don't know the thicknesses and the car is put away for the winter. Sorry.
    2008 Viper ACR
    2009 Viper SRT-10X | 190mph Standing Mile | 10.76@133.7mph 1/4 Mile


 

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