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Thinking Of Building Roll Center Adjusters

Discussion in 'Aftermarket Modifications' started by racerb, Feb 6, 2014.

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  1. racerb

    racerb Well-Known Member

    I'm looking to build roll center adjusters for my Celica project and if they turn out well enough I may start offering them for others with lowered and race prepared Celica's. These will only work on the front suspension, as there are too many attachment points in the rear to make this an easy fix. I will post more details as I work on these adjusters and hopefully have multiple setups for different amounts of lowering.

    racerb :eng101
     
    racerb, Feb 6, 2014
    #1
  2. BogzillaGTR

    BogzillaGTR Active Member Super Moderator

    Good luck ! Would be cool to see it in action.

    Sent from my HUAWEI G510-0100 using Tapatalk
     
    BogzillaGTR, Feb 6, 2014
    #2
  3. Hazzmac92

    Hazzmac92 Well-Known Member

    Good luck
    I'd be keen if you make them
     
    Hazzmac92, Feb 6, 2014
    #3
  4. Mafix

    Mafix Owner Staff Member Administrator Donated!

    i've looked at mine a lot. i dont need them. my tie rods and control arms seem in alignment.
     
    Mafix, Feb 9, 2014
    #4
  5. racerb

    racerb Well-Known Member

    Are your front lower control arms sitting level with the ground, or pointing slightly upward?
    If so, you need these adjusters just as I do, to angle your control arms in a more downward rake. What these do, is return the suspension back to a more natural geometry and reduce bump steer under compression.



    racerb :eng101
     
    Last edited: Feb 20, 2014
    racerb, Feb 10, 2014
    #5
  6. Mafix

    Mafix Owner Staff Member Administrator Donated!

    I would assume upwards a bit. I don't recall. I've never felt any bump steer in mine, that's not to say it doesn't have it.
     
    Mafix, Feb 20, 2014
    #6
  7. racerb

    racerb Well-Known Member

    No Willy, you want your lower control arms to be lower at the hub attachment point, these adjusters will simple be a spacer between the control arm and the lower ball joint. This will put your front suspension back in a natural geometry, because mac struts don't give enough geometry control.

    Here is what is available for the Hondas, my design will be somewhat heavier duty for racing purposes.....http://www.ebay.com/itm/Megan-Racin...ster-Blue-Only-Pair-Acura-Honda-/181250535356


    racerb
     
    Last edited: Feb 20, 2014
    racerb, Feb 20, 2014
    #7
  8. BogzillaGTR

    BogzillaGTR Active Member Super Moderator

    I would be very interested in buying something like this as I do have a fairly bad bump steer as my car is pretty heavily lowered. uploadfromtaptalk1392956675755.jpg

    Sent from my HUAWEI G510-0100 using Tapatalk
     
    BogzillaGTR, Feb 20, 2014
    #8
  9. Mafix

    Mafix Owner Staff Member Administrator Donated!

    no worries, i am well aware of the geometry, i've just never had an issue. if you make these you may want to consider tie rod kits as well. since moving the lower control arm will also necessatate moving the tie rod.

    i honestly think mine point up by about an inch at the ball joint. i know they just point down when lifted. i know the 185 guys are going nuts trying to engineer a repair for this. they noted that a simple ball joint spacer will not be enough. it also makes all kinds of other issues. Martin is working on making a long stud ball joint but he has had a couple failures so i'll wait to see what he does.

    oh and another fun thing...kyle was using aluminum rod for rear control arms. guess what broke on a high g turn...
     
    Mafix, Feb 22, 2014
    #9
  10. celicaman

    celicaman Well-Known Member Donated!

    I was actually looking at mrp' s fwd corolla roll center adjusters as the bolt pattern looks identical to the celicas ball joint bolt pattern
     
    celicaman, Mar 6, 2014
    #10
  11. racerb

    racerb Well-Known Member

    If they have something that will work, this would save me time in trying to re-engineer the system. My only thought was that I might work on different thicknesses for a way to fine tune for different track setups and amounts of lowering. I'll have to look at what MRP has to offer!

    racerb :science
     
    racerb, Mar 6, 2014
    #11
  12. racerb

    racerb Well-Known Member

    Wow just saw the price on the MRP kit, I was hoping to build a spacer type setup that would sell for less that $50 per kit! The last custom parts I had made for my homebuilt rear camber plates cost less the $25 per set, and I still some of those left over for my other Celica.

    racerb :eng101
     
    racerb, Mar 6, 2014
    #12
  13. Mafix

    Mafix Owner Staff Member Administrator Donated!

    i looked when it was on the lift today. with the car in the air, the control arms are flat. so the must be upwards when loaded.
     
    Mafix, Mar 8, 2014
    #13
  14. racerb

    racerb Well-Known Member

    Yeah, mine are sitting almost flat with the car on the ground and no engine in the bay, so extra weight would most likely turn them upward somewhat. I want to angle them downward at least 3/4" to 1" when on the ground, when I raise it up now they droop down a good amount. Hoping to sell the Yaris soon (not that I really want to) and will be back to concentrating on the Celica, so will check with my local Machine Shop guy. Will update you guys on the progress and hopefully have something available for sell to you guys!!

    racerb :eng101
     
    racerb, Mar 9, 2014
    #14
  15. Mafix

    Mafix Owner Staff Member Administrator Donated!

    some of martins findings:
    Ok for those trying to do something like the roll center adjusters I made, don't. This didn't quite achieve what I was shooting for and will not be enough to correct roll center.... I have talked to Randy Noll on mr2 boards who is working on one hell of a SM2 Mr2 and he pointed out one minor flaw in my design... pivot points.... it's the pivot points that change the geometry and it's the pivot points that will raise the roll center... sooo, the quest continues....
    As for the steering correction, that worked perfectly and I could actually tell the difference during an autocross....
    I am working on a new spindle mod, I'll keep you all updated once I get all the little kinks figured out... hint: bigger front bearing, 5x114.3 bolt pattern and quicker steering response will be the results...
     

    Attached Files:

    Mafix, Mar 14, 2014
    #15
  16. Mafix

    Mafix Owner Staff Member Administrator Donated!

    from all my reading, it seems the ball joint needs to be extended, not spaced.
     
    Mafix, Mar 14, 2014
    #16
  17. racerb

    racerb Well-Known Member

    Due to the design of our ball joint, I have not found a replacement (press-in) unit for it. Some of the Honda ball joints are more like ours and the after-market roll center adjusters for them are of the design I'm looking to replicate. Since 90% of my time will be spent on road courses versus autocross courses, I feel the changes will be more useable and difference making.

    My design would use longer press in bolts and a longer third bolt, somewhere between 20-25mm would be the final amount of rise for these cars. Most of the popular RC adjuster out there are for drift cars, so they are also trying to get more steering angle as well, this is not a concern with our cars, just correcting control arm placement. I'm using the NASA PT rule book to my advantage on this, because I'm not allowed to change the in-board pick up height of control arm attachment, which would be nearly impossible with our cars.

    https://www.google.com/search?q=rol...center-adjusters-ball-joint-extenders;640;480
    https://www.google.com/search?q=rol...center-adjusters-ball-joint-extenders;640;480

    racerb
     
    Last edited: Mar 14, 2014
    racerb, Mar 14, 2014
    #17
  18. Mafix

    Mafix Owner Staff Member Administrator Donated!

    the only other concern I would have is wheel clearance.
    and I had a thought for a spacer...just buy another ball joint and cut the joint off. heavy but good for a prototype.
     
    Mafix, Mar 14, 2014
    #18
  19. racerb

    racerb Well-Known Member

    The first prototype will be made on a water jet table just like my rear camber plates were made. This means they will be much cheaper to make, but if these prove to be too heavy as well, then I'll have some machined out of aluminum. I have a Fastenal just down the road from the house, so I'll be turning to them for all the hardware. My buddy Ippolito at 2JRacing has already built similar adjusters for the Sentra's he builds and races, and wheel clearance is not an issue.

    racerb
     
    racerb, Mar 14, 2014
    #19
  20. JEM

    JEM Member

    Exhuming the thread here...

    Spacing the control arm down from the ball joint does not change the geometry, the effective control arm is from the centerline of the inner pivots to the center of the ball joint no matter how the arm meanders in getting there.

    The only way I see to move the outer pivot down is a longer ball-joint stud, the VW/Audi-style stud extenders won't work as ours is a tapered stud.

    You'd need either a usable ball joint with maybe an inch longer stud, or something like the Howe or QA1 circle-track ball joints with the replaceable ball/stud assembly in varying lengths:

    https://www.howeracing.com/p-7933-howe-22418-fits-k719.aspx

    http://www.smileysracing.com/shopping/?ic=1540

    then fabricate a carrier from one of the threaded ball-joint tubes, waterjet a tab to weld to the tube that'd bolt up to the control arm. Conventional wisdom says everyone but some GM cars uses a 7-degree taper on the ball-joint stud but I've never measured a Celica balljoint stud taper...

    Once you've done that you've also changed the relationship of the control arm to the steering tie rod, and you'd either need to lower the outer tie-rod end an equal amount (maybe very difficult unless you're lowering the ball joint a BUNCH, in which case you could, I guess, ream a taper into the BOTTOM of the steering arm, machine a conical spacer, and put the tie rod end in the bottom of the steering arm) or raise the steering rack (have to look at that one...) or some combination thereof.
     
    Last edited: Jul 24, 2014
    JEM, Jul 24, 2014
    #20
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