Vorshlag 468x60 Banner
PrevPrev Go to previous topic
NextNext Go to next topic
Last Post 27 Mar 2012 11:08 PM by  djsilver
camber adjustment via lower control arm on struts
 12 Replies
Sort:
You are not authorized to post a reply.
Author Messages
cdlong
New Member
New Member
Posts:74


--
22 Mar 2012 01:17 PM
    15.8.H.4 says you can use a lower control arm to adjust camber and include a non standard ball joint. Doing this on a strut front suspension would then require a fixed upper mount, not a usual camber plate. Some quick measurements makes me think the lower control arm would need to be about an inch longer to maintain the same camber (the distance the strut top is offset from the center of the stock strut mount), which is probably outside the range of adjustment of most aftermarket control arms. I know I can't also install camber bolts but since shocks are free, I should be able to slot the lower holes on the coilover to get approximately the camber I want and then weld a washer in place to fix it at that point. Camber is then only adjustable via the lower control arm, and it's not excessively longer than stock. Is that all correct, would stand up to protest, and a good idea? I'll write a letter but I want to get a good idea first before I spend too much brain power on this, and it will change some other plans I have for the immediate future.
    mrazny
    Basic Member
    Basic Member
    Posts:462


    --
    22 Mar 2012 02:11 PM
    Did you look into offset bushings? Those are free. If you're just looking fora little bit more, look into that first. the e90/e82 BMW's could get an extra .5 degrees from offset bushes, and you're not depending on washers to hold your camber.
    cdlong
    New Member
    New Member
    Posts:74


    --
    22 Mar 2012 05:19 PM
    I'm not looking for more camber, I'm looking to use a lower control arm for minimal adjustment so I can use a non standard ball joint.
    solo-x
    Veteran Member
    Veteran Member
    Posts:1244


    --
    23 Mar 2012 03:29 PM
    Unofficially, I think what you propose would be legal. As for whether it's a good idea or not, it's hard to say. Seems like a lot of work to try to fix the roll center height. You might want to investigate the impact on bump steer and front track width before pulling the trigger on something like this.
    djsilver
    Basic Member
    Basic Member
    Posts:187


    --
    23 Mar 2012 03:52 PM
    Moving the top of the strut in with a camber plate or moving the ball joint out with a longer LCA also increases your "steering axis inclination", which isn't necessarily a good thing, but if it's the only way, it's better than not doing it! Doing it at the LCA will give you more inside tire clearance as well. And yes, if you changed the location of the pivot point for the ball-joint, you'll need to move the tie-rod end pivot point to match or you'll cause bump-steer.
    Andy Hollis
    Senior Member
    Senior Member
    Posts:6197


    --
    23 Mar 2012 04:49 PM
    cdlong wrote:
    I'm not looking for more camber, I'm looking to use a lower control arm for minimal adjustment so I can use a non standard ball joint.

    "Tall balljoint"? I believe the following restriction shoots you down:

    5. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.

    Use of a balljoint with a different length violates this.

    Marshall Grice
    Basic Member
    Basic Member
    Posts:303


    --
    23 Mar 2012 05:39 PM
    Andy Hollis wrote:
    cdlong wrote:
    I'm not looking for more camber, I'm looking to use a lower control arm for minimal adjustment so I can use a non standard ball joint.

    "Tall balljoint"? I believe the following restriction shoots you down:

    5. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.

    Use of a balljoint with a different length violates this.

    the 2012 rules add some interesting bits to this in SP.

    "A non-standard ball
    joint which is present in a compliant camber kit replacement control
    arm is permitted to offset from the standard point the spindle
    mounting location from the control arm plane."

    Andy Hollis
    Senior Member
    Senior Member
    Posts:6197


    --
    23 Mar 2012 07:25 PM
    Marshall Grice wrote:
    Andy Hollis wrote:
    cdlong wrote:
    I'm not looking for more camber, I'm looking to use a lower control arm for minimal adjustment so I can use a non standard ball joint.

    "Tall balljoint"? I believe the following restriction shoots you down:

    5. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.

    Use of a balljoint with a different length violates this.

    the 2012 rules add some interesting bits to this in SP.

    "A non-standard ball
    joint which is present in a compliant camber kit replacement control
    arm is permitted to offset from the standard point the spindle
    mounting location from the control arm plane."

    Good point. I missed the SP reference above. That new verbiage moves SP away from ST (literally) in this instance.

    djsilver
    Basic Member
    Basic Member
    Posts:187


    --
    23 Mar 2012 07:42 PM

    Marshall Grice wrote:

    Andy Hollis wrote:
    cdlong wrote:
    I'm not looking for more camber, I'm looking to use a lower control arm for minimal adjustment so I can use a non standard ball joint.

    "Tall balljoint"? I believe the following restriction shoots you down:

    5. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.

    Use of a balljoint with a different length violates this.

    the 2012 rules add some interesting bits to this in SP.

    "A non-standard ball
    joint which is present in a compliant camber kit replacement control
    arm is permitted to offset from the standard point the spindle
    mounting location from the control arm plane."

    I get a headache every time I read this one. The use of the singular "plane" ignores that there's 3 of them! in/out, up/down and fore/aft. Double check me but I just downloaded the latest version and I don't see #5. 15.8 H ends with #4

    gavin
    Basic Member
    Basic Member
    Posts:217


    --
    24 Mar 2012 12:30 AM
    There was a thread already about this when the new language of "alternate ball joint" came out. First thing everyone though was ..."oh yeah...roll center correction for strut cars", but its a dud. Unless you figure out a way to legally change the steering arm/ball joint/steering rack geometry to take advantage of whatever "alternate ball joint" you use...congrats, your bump steer now completely facked :(

    Gavin

    cdlong
    New Member
    New Member
    Posts:74


    --
    26 Mar 2012 11:16 AM
    Yeah, I had this idea when the language was introduced last year, I couldn't remember why I dropped it. Now I do. Since I can't move the tie rod end position, It's probably a decent bit of trouble just to shift the problem around. I was thinking of raising the car and running 275/35/15s which should raise the roll center without raising the CG.
    solo-x
    Veteran Member
    Veteran Member
    Posts:1244


    --
    26 Mar 2012 12:23 PM
    djsilver wrote:
    Moving the top of the strut in with a camber plate or moving the ball joint out with a longer LCA also increases your "steering axis inclination", which isn't necessarily a good thing, but if it's the only way, it's better than not doing it! Doing it at the LCA will give you more inside tire clearance as well. And yes, if you changed the location of the pivot point for the ball-joint, you'll need to move the tie-rod end pivot point to match or you'll cause bump-steer.

    That bolded part is not legal in SP.

    djsilver
    Basic Member
    Basic Member
    Posts:187


    --
    27 Mar 2012 11:08 PM
    solo-x wrote:
    djsilver wrote:
    Moving the top of the strut in with a camber plate or moving the ball joint out with a longer LCA also increases your "steering axis inclination", which isn't necessarily a good thing, but if it's the only way, it's better than not doing it! Doing it at the LCA will give you more inside tire clearance as well. And yes, if you changed the location of the pivot point for the ball-joint, you'll need to move the tie-rod end pivot point to match or you'll cause bump-steer.

    That bolded part is not legal in SP.

    And that's why this allowance isn't a home run for extended ball-joints as a method of adjusting the roll center.

    You are not authorized to post a reply.


    Woodhouse Motorsports SPS 88x31 Button
    G-Loc Button Vorshlag 88x31 Button
    Leroy Engineering Micro Button Sunoco 88x31 Button

    Advertise on SCCAForums.com and reach thousands of visitors per day!

    SafeRacer FREE SHIPPING over $99

    Shop for Pirelli tires at Tire Rack. blank



    Sunoco Bottom 468x60 Banner