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Thread: GC Set-up Baseline

  1. #1
    Join Date
    Jul 2006
    Location
    Raleigh, NC
    Posts
    415
    My Cars
    E36 Track Rat, E46 M3 DD

    GC Set-up Baseline

    I recently came into a set of used GC coil-overs and camber plates. 525 lb fronts, and 650 lb rears. It is their standard single adjustable track set-up. Car is an E36 328 sedan, that is used as a cheap / fun HPDE car. Car is currently running on Kosei 17x8.5 with 235/45/17 RS4s. Car currently sits on H&R race springs with Bilstein sports of unknown mileage (presuming 100k+ miles) with swapped M3 top-hats and one camber shim. Hotchkis front sway bar, stock rear. Hawk HP10 pads. Car is driven to the track, but rarely street driven. I picked up the GC set-up for a steal, so couldn't really pass them up.

    Anyone want to provide some baseline set-up advice, as far as ride height, shock setting, and alignment targets I'm not asking for anyone's secret sauce recipe to allow me to get that ever elusive "winner" trophy at the next BMWCCA HPDE. I'm just trying to get it in the reasonable range before the first track weekend.

    I have access to a set of scales and camber gauge, but will get a full alignment from a performance shop after installation.

    Thanks!

    Glenn

  2. #2
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    3,847
    My Cars
    1995 M3
    Here's my basics.
    95 M3, near OEM weight (easy stuff removed).
    ~3/4" rake measured at lift points.
    I'm at about 13.5" front ride height (center of hub to heighest point in fender opening), and 12.5" rear ride height. (I tweaked these last year and haven't remeasured exactly).
    I run about -3.5 camber up front and -2.5 rear. 0 toe front, touch of toe rear. Max caster front (touch under 8).
    550/650 rates, Toyo RRs.
    Front UUC ARB is at full soft.
    Rear ARB is OEM.

    The car is to the point that one position on the ARB, and/or a few PSI tire pressure changes its balance.

    My TCK SA damper settings are weird. One end is close to full hard, the other near full soft. The car handles pretty damn neutral though. I'm going to re-set my dampers this weekend, and see where they end up again.

  3. #3
    Join Date
    Aug 2009
    Location
    Metro DC
    Posts
    826
    My Cars
    79 323i, 94 325is, 13 M3
    Congrats on scoring a deal on a used set. Whenever I need coilovers, I search for that deal for months, and it never shows up.

    Okay, this stuff is kind of like religion, politics, or taste in barbeque, but here's my take on the process.

    I run alignment settings pretty much like aeronaut's on my E36. I have swapped hats and one camber shim like you.

    People say E36s like front springs that are about 100-150# softer than the rear because of the different wheel rates front and rear. I'm not 100% certain, but I think the dampers GC uses are able to control the spring rates you have. It's more spring than they used to sell with their street/track kit, I think, but I seem to remember they had headroom into the 600's.

    I lower the front height so the front control arms just start to slope up towards the wheel side, and then back it off and set the height a little bit higher than that. The front suspension gains negative camber as it compresses, which is good. But I'm told that, as the control arm slope changes direction, the rate at which it gains negative camber is decreased quite a bit. Plus I'm told going too low with struts buries the roll center.

    Wedge -- I go for setting up the rear 3/4" higher than the front, measuring the difference at the two jack points. Some times I can get away with more or less but the hard braking gets twitchy if I have it wrong, and it's really easy to tell when it's wrong. Hopefully, I have enough height adjustment on the rears to achieve this angle relative to the front height I just set.

    I set all the dampers to full soft, and drive the car for some laps to see if it's rubbing under compression. With 500/600 spring rates and Koesi 17X8.5 ET 40 wheels, it's not likely to rub much. If it's bad, I roll/pull the fenders until it clears fairly well. I don't bother dialing in the fender clearance 100% until I get the damper settings figured out and confirm my sways don't need rebalancing.

    A car is flat-out gonna understeer if I'm turning in at too much speed or pinching the exit, and it will flat-out oversteer if don't get my understeer under control PDQ or I use too much throttle on exit when the steering angle is still dialed in. Nothing about coilover adjustments will fix that. I'm just trying to use the dampers to balance the way the car body rolls in and flattens out, so whatever grip I have can be used. For example, if I turn in, and the front of the car gets to it's settled roll position later than the rear end of the car, I will get more understeer than I will have if I can get both ends to roll and set in a coordinated way.

    With single adjustables, I go out and do some laps and pay attention to what's happening in the corners. Most likely it is understeering on corner entry, so I stiffen the rear dampers one click (whatever 1/5th of the total adjustment range is) and go back out again to see what happened. Stiffening the rear should allow the front of the car, which will be softer, to take a set going into the turn faster than the rear end, and give the front more grip. But I don't want to overshoot the rear stiffness, because it can lead to rear wheelspin on exit or even unloading the inside rear wheel. If one click isn't helping enough to dial out the understeer, then I try two clicks. And so on.

    If I'm getting oversteer on exit, (instead of understeer on entry), then I will stiffen up the front end one click and go back out to see if that's good or I need another click maybe. Lather rinse repeat.

    With a light car like an E36 I'm trying to get the minimum amount of rebound stiffness necessary to create even transitional grip balance between the front and rear ends on corner entry and exit. I'm not trying to increase roll stiffness by cranking the dampers way stiff. Springs are for roll stiffness, dampers are for balancing the front and rear to make the car rotate to my unique preferences as a (admittedly lame) track driver.

    If I put in one click and things get better, then put in another click and things aren't clearly even better than 1 click, I will usually back off a click and see if I'm still good.

    I try to get one end ironed out reasonably well, I write that down, and then see if I can get any better traction out of the other end.

    First time through, when I'm doing that second end I often wind up with several clicks applied and no improvements. That's when it's a PITA.

    It could be, I just can't get any more from the second end with the setup I have.

    Or it could be I have a shade too much on the first end, and if I backed off it a little bit, I could go back to zero on the second end and then work my way up to some happy medium. So I try that. I

    f I strike out there, I might zero out both ends and see if it was even possible to get better behavior out of the second end, regardless of how much it screwed up the first end. If I can get some improvement in the second end that way, I write that down and then start seeing if I can get the first end under reasonable control with more rebound and kind of split the baby.

    But after all that, I might just wind up full soft on one end and some adjustment on the other end, and that's just the best I'm gonna get.

    If I have the springs 100-150# apart and I can't get the car balanced because one end just seems way off, then I have to start figuring out whether I have too much sway bar on the front (leads to understeer) or on the rear (leads to oversteer).

    If the car is just too damn twitchy whatever I do with the dampers and it won't settle in a corner, that probably means I have more spring than the dampers can control. So they need revalving, or I need 4 new springs with less poundage.

    When I do get it right, it's obvious to me that it's all clicking. I'm not fighting the car and it just flows. Or as much as a hack like me is capable of flowing. If other E36s on comparable tires are just pulling away from me, and I'm trying weird lines trying to find something that will catch up, it's still wrong.
    Last edited by JBasham; 03-12-2018 at 10:45 AM. Reason: Edited bad info about front control arms and camber
    If God meant for man to motor-swap LS engines into track cars, He wouldn't have created Corvettes.

  4. #4
    Join Date
    Jul 2006
    Location
    Raleigh, NC
    Posts
    415
    My Cars
    E36 Track Rat, E46 M3 DD
    Awesome answers from both of you. Thanks! Just got the fronts mounted, and will put the rears on tomorrow. They "look" faster already :-)

    Oh, at $250 for a full set of GC coil-overs with camber plates, pretty hard to mess up that deal. I've been slowly upgrading the low budget track rat over the last two years primarily by waiting out the great deals.

  5. #5
    Join Date
    Aug 2009
    Location
    Metro DC
    Posts
    826
    My Cars
    79 323i, 94 325is, 13 M3
    $250? Go ahead. Rub it in. I paid $300 for one of their discontinued conversion kits -- no camber plates, no dampers.
    If God meant for man to motor-swap LS engines into track cars, He wouldn't have created Corvettes.

  6. #6
    Join Date
    Jul 2006
    Location
    Raleigh, NC
    Posts
    415
    My Cars
    E36 Track Rat, E46 M3 DD
    Yup, $250. The rears need to be rebuilt (which was disclosed by seller), but heck that's less than going price for the used camber plates. They were listed on one of the GRM forums, with no shipping. After several will you ship yet emails, seller finally caved :-)

    I take pride in doing more with less.

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