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Thread: Harley's 818S

  1. #361
    I had my rear lateral links parallel, as checked with a digital angle gauge. It wasn't enough. When I got a bump steer gauge and checked it, I had a fair amount of rear bump steer and it was making the car twitchy. I set it for just a hair of bump-in in the rear, mostly just to ensure that it never becomes bump-out under load.

  2. #362
    I've been working through one issue at a time, so now I'm ready to get back at the alignment.
    at low speed, its awesome, however at higher speeds, like 55mph and above, it is a bit twitchy like you say, or it seems to "hunt" to either side at the center position. You really have to concentrate to keep it straight.
    I was thinking now I will try to add the spacer in the LCA so I can adjust for a bit more caster, and I saw your comment about the rear bump steer in another thread. I'm not thinking that would affect steady state straight line twitchiness??? or does it?
    How did you adjust for a hair of bump steer? Slightly out of parallel biased toward the front lower, or rear lower? or do you need the bump steer gauge?
    I have been setting them parallel with the digital angle guage.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  3. #363
    Do you know how much caster you have now? I was able to get all I needed by flipping the hurricane bracket and cutting down down the rear tube nut on the upper a-arms a bit. I think I'm at like 5.5 degrees.

    So many things can cause twitchy handling. Having toe-out or zero-toe in the front, bump steer front and rear, and lack of caster, so it's important to check them all. And yes, rear-bump steer can make the car feel twitchy in a straight line as the suspension loads and unloads over bumps and ruts. It probably won't be as noticeable in a straight line as it is in corners, but I bet you could feel it.

    To get a hair of bump IN (very critical that it's bump-in and not bump out), you want the rear lateral link to be lower on the outside (toward the tire) end than the forward lateral link. The problem is, you can't really know how much you have unless you use a gauge. But in a pinch, I'd set them so your angle gauge reads maybe a tenth of a percent or two above 0. If you are laying the angle gauge across the two links toward the outside end of thinks, the front of the angle gauge should be higher than the rear.

  4. #364
    Quote Originally Posted by Hindsight2.0 View Post
    Do you know how much caster you have now? I was able to get all I needed by flipping the hurricane bracket and cutting down down the rear tube nut on the upper a-arms a bit. I think I'm at like 5.5 degrees.

    So many things can cause twitchy handling. Having toe-out or zero-toe in the front, bump steer front and rear, and lack of caster, so it's important to check them all. And yes, rear-bump steer can make the car feel twitchy in a straight line as the suspension loads and unloads over bumps and ruts. It probably won't be as noticeable in a straight line as it is in corners, but I bet you could feel it.

    To get a hair of bump IN (very critical that it's bump-in and not bump out), you want the rear lateral link to be lower on the outside (toward the tire) end than the forward lateral link. The problem is, you can't really know how much you have unless you use a gauge. But in a pinch, I'd set them so your angle gauge reads maybe a tenth of a percent or two above 0. If you are laying the angle gauge across the two links toward the outside end of thinks, the front of the angle gauge should be higher than the rear.

    I thought I dialed in 3 degrees of caster, but as you pointed out before, I measured it on the FFR weldment which may not be correct. I am going to do it again and measure the plus and minus angles you mentioned and divide by two. What did you set your angle gauge on?.
    When you say hurricane bracket what do you mean? flip the attachment of the rear of the LCA to the spindle? or flip the LCA rear mount with the squiggle down?
    And I didn't have to cut the nut to get my 3 degrees of caster, I just cut the thread, but if I go further, I will have to cut the nut as it is out of room.
    Thanks for your help, this is all new to me....
    thx again
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  5. #365
    Senior Member RM1SepEx's Avatar
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    Re-check that the rear lower lateral links are parallel, you could be getting the rear steering the car, can be very sensitive to throttle on/ throttle off. I think the car would be easier to setup if they eliminated the eccentric adj for the lower rear lateral link, you should use a length adj rear link to adjust toe in the rear
    Dan

    818S #17 Picked up 8/1/13 First start 11/1/13 Go Kart 3/28/14

  6. #366
    You can come by and borrow our castor/camber gage, easy to use and super accurate. We set our race cars up with it, and could not be happier! We string every car we have on rotating pads and use toe plates for toe. To measure bump steer, we took out the springs, set jack stands to ride height all around, then jacked one wheel up at a time and measured toe. We were able to get set to zero bump steer front and rear with this method.

  7. #367
    Quote Originally Posted by Harley818 View Post
    I thought I dialed in 3 degrees of caster, but as you pointed out before, I measured it on the FFR weldment which may not be correct. I am going to do it again and measure the plus and minus angles you mentioned and divide by two. What did you set your angle gauge on?.
    When you say hurricane bracket what do you mean? flip the attachment of the rear of the LCA to the spindle? or flip the LCA rear mount with the squiggle down?
    And I didn't have to cut the nut to get my 3 degrees of caster, I just cut the thread, but if I go further, I will have to cut the nut as it is out of room.
    Thanks for your help, this is all new to me....
    thx again
    Yeah I would not measure caster like that. I tried it after I set it using a digital gauge and it wasn't accurate at all. Maybe others have had better luck with it but not me. I set my angle gauge on a little jig I made that resembles this:
    https://www.quicktrickalignment.com/...quantity-copy/
    You have to turn the wheel 15 degrees to the left, measure, then turn back to center, then 15 degrees to the right and measure again. You subtract the two. Go to youtube and search "quicktrick caster" or even just "DIY caster" etc and you'll see. You can use two floor tiles with grease in between them for the pivots, and use cardboard taped to the floor to set your lines for 15 degrees. I think I have pictures of my doing that buried in my build thread somewhere.

    On the hurricane bracket, I flipped the attachment to the lower control arm, but also had to ensure the squiggly part of the bracket was facing the same way as stock (I can't remember if it's up or down - I did it wrong initially and Bob noticed and corrected me as he has done for a number of other guys).

  8. #368
    Quote Originally Posted by Hindsight2.0 View Post
    Yeah I would not measure caster like that. I tried it after I set it using a digital gauge and it wasn't accurate at all. Maybe others have had better luck with it but not me. I set my angle gauge on a little jig I made that resembles this:
    https://www.quicktrickalignment.com/...quantity-copy/
    You have to turn the wheel 15 degrees to the left, measure, then turn back to center, then 15 degrees to the right and measure again. You subtract the two. Go to youtube and search "quicktrick caster" or even just "DIY caster" etc and you'll see. You can use two floor tiles with grease in between them for the pivots, and use cardboard taped to the floor to set your lines for 15 degrees. I think I have pictures of my doing that buried in my build thread somewhere.

    On the hurricane bracket, I flipped the attachment to the lower control arm, but also had to ensure the squiggly part of the bracket was facing the same way as stock (I can't remember if it's up or down - I did it wrong initially and Bob noticed and corrected me as he has done for a number of other guys).

    Thanks, I'll check the links and your thread. Sounds like I can switch the hurricane bracket. I know I have the LCA mount correct with Squiggly down because I had to change it once to get it right.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  9. #369
    little victories.....
    Originally I set ride heigh to 4 3/4 inches.
    Somehow it ended up lower than that.

    A couple days ago I re-adjusted the ride height to 4 3/8 inches all around.
    Then I set the rear lateral links to be slightly lower on the rear link than the front link (0.25 degrees on my digital level).

    Subtle, but much better driving and tracking. Car does not "hunt" as much at speed. Still does a bit, but I suspect I can eliminate that when I work on the front caster.
    One thing at a time.

    Oh, and I had my car back to the dyno. I installed the Cobb 3 port boost controller. and had it re-tuned. What a DIFFERENCE!!!

    For anyone out there who is not getting 15 psi boost, you probably have a faulty boost controller.
    I just installed the one that came with my donor, not knowing that it wasn't working till I went for the dyno tune. It limits you to 7 - 9 psi.
    However, now with the re-tune..... different story.
    Now I get full 15psi and FULL Pull... wow does it haul!

    Unlimited wheel spin in 1st and 2nd gear....... need I say more?
    245 rear wheel Hp. I'm happy with that.
    I'm already having to really watch the throttle on takeoff and on any corner.
    A little too much throttle and the car is sideways......
    on the other hand, play with just the right amount and it just takes off.
    Lots of fun.....
    Last edited by Harley818; 09-24-2017 at 12:29 AM.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  10. #370
    Senior Member
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    Jun 2013
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    245whp and full spin in 2nd?
    Frank
    818 chassis #181 powered by a '93 VW VR6 GT3582R ~400whp/wtq+
    Go-karted Aug 5, 2016 - Then May 19+21, 2017
    Tracked May 27/July 26, 2017

    Bulid time, including registration 3283.5h in 148 work week time and 3.5 years elapsed

  11. #371
    Senior Member
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    I had 261 whp and I could break it free in first, and if I really dropped the clutch,I could get some spin in second. It definitely takes some effort though. Do you have an open diff? I could see it easy to get one wheel to break free, but with my locking diff, it isn't easy to get both.

  12. #372
    Moonlight Performance
    Hindsight's Avatar
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    Glad you are getting things sorted and under way!

    Did you do the bump-steer on the front yet? That's going to have a huge impact in stability.

  13. #373
    Yes, I have an open diff, so maybe just one side. Feels awesome though..... and the car just seems to slide so nice through the corners unless you dip too deep.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  14. #374
    Quote Originally Posted by Hindsight View Post
    Glad you are getting things sorted and under way!

    Did you do the bump-steer on the front yet? That's going to have a huge impact in stability.
    yes I did the bump steer right from the start based on your info. 46mm spacing. I didn't measure with a bump steer gauge though, so I don't know if its the same as yours. I have a 2002 rack.
    I'm pretty convinced its the caster that needs attention.
    The adjustment I made on the rears though based on your info for rear lateral link just a hair lower has had a positive impact on the straight line tracking.
    On a smooth or recently paved road, it actually tracks great. However, we have quite a bit of pavement here that has the ruts from the big trucks..... so I think I'm getting a lot of tire steer. With the minimal caster thats a problem. If i dial in a bit more caster it should be better.
    Harley
    Bought 2002 Donor Jan 2014
    First Start Jan 18, 2015
    First Drive Feb 14, 2015

  15. #375
    Moonlight Performance
    Hindsight's Avatar
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    Good good! Yeah your bump-steer should be close - the only thing is that you are running a 2002 rack while I'm running a 2007 rack. The frames for the 818 are different based on steering rack year. As long as the two different 818 frames position the centerline of the rack at the exact same height, the 46mm number should get you close.

    Also ensure you have enough toe-in front and rear. 1/32" to 1/16" front, and 3/16" to I think 5/16" rear. I'm running 1/4" rear but talked with Wayne today and he said 3/16" rear is working well for him. But more rear toe-in is supposed to make the car more track-stable, which makes sense. Can really cook the tires on the track though, especially if running a lot of negative camber.

  16. #376
    THat's allot of rear toe! We run 1/16th on track, front and rear. Interesting.

  17. #377
    Moonlight Performance
    Hindsight's Avatar
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    I'm new to alignment on mid-engine RWD cars. I agree that it sounds like a lot! But looking up the settings on relatively similar cars like a Porsche GT-4 and you'll find settings of around or just shy of 3/16" in the rear.

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