Login Register Sign up for the GRM e-newsletter

Login to post Forums » Grassroots Motorsports » Suspension/Alignment Questions 86 Jetta GLi Drag/Autox
  • VWguyBruce

    Oct. 4, 2009 10:44 a.m. VWguyBruce HalfDork

    Fine tuning the suspension today. Adjusting the coilovers so control arms are parallel, going to the alignment rack, etc.

    Autox Question: I was reading Per's book again today and I think I have have my rates a little mixed up.

    Installed setup is:

    450# Front springs - Autotech 28mm Hollow front bar, strut bar 572# Rear springs - No rear bar, shock tower bar Poly bushings throughout, Camber plates w/ -2 degrees front, rear -1 degree shims

    I have not weighed the car yet, getting corner weighted this week, gutted interior.

    I have a rear bar, should I bring it just in case I need more rear rate? Are my rear rates high enough to run no bar? I got as close to 600# as I could find on a Challenge budget.

    Drag question: Will my alignment make ANY different on an 86 Jetta with a stock 1.8 8V motor with a cam/gear, exhaust, no accessories, nitrous? Should I make some marks for say, 0 Degrees, while I'm on the rack? I was intending to run the narrow stock rear wheels and load the rear shocks with bump stops. Should I bother changing things for the drags?

    Thank you experts.

  • iceracer

    Oct. 4, 2009 10:56 a.m. iceracer HalfDork

    As you said, you want O camber for the drags. Be aware that changing camber also changes toe.
    I would bring the rear bar, just in case.

  • VWguyBruce

    Oct. 5, 2009 9:14 a.m. VWguyBruce HalfDork

    I'm going to be spending some time on the rack with my alignment guy. I'm going to set several marks, 0, 1, 1.5, 2, 2.5. We'll check the toe at zero after we set the base alignment at 2.

    Thanks!

  • VWguyBruce

    Nov. 1, 2009 5:29 p.m. VWguyBruce HalfDork

    Just wanted to share in case anyone was curious, unlikely haha.

    Answers from Alan McCrispin and Steve Hoeschler at the Challenge. I can't tell you all enough how cool these guys were and how willing they were to help me dial in my suspension and just hanging out and talking cars. Steve Hoeschler spent a good 15-20 minutes talking about suspension setup/dynamics after he took 4 runs in my car. For what I spent on my trip to the Challenge this info was worth way more than I spent. Many many thanks to both.

    Both said 1/8 to 1/4 total toe out. I went with an 1/8" total toe out before I got there.

    Alan said -2 degrees negative, maybe a little more. Steve said -2.25 to 2.5 degrees of negative camber in the front. Steve Hoesler said these settings are adequate for autox and track on any car.

    Alan told me to loosen my end links until they were loose, he guessed the bar might cause loss of mechanical grip with the high spring rates. In my case, Steve said to disconnect the front sway bar. Was told by Steve that the car was loosing mechanical grip when the bar kicked in under load. He said I had plenty of spring to run with no bars. Bonus, money back in budget.

    In my case the rear was fine, it measured -2.25 negative camber with a -1 degree shim installed. I may remove this to gain more money back into the budget.

    He also told me to lower the rear some more but that's strictly for my application.

    Last recommendation from Steve was more tire. He recommended 225 preferably 235 or 245 wide tires on 8"-10" wide wheels. Wish me luck on this one within a Challenge budget.

  • Paul_VR6

    Nov. 2, 2009 10:03 a.m. Paul_VR6 Reader

    For drag I run -1deg camber and 1/16" toe out, but that's with 'too low' ride height (axles level not a-arms). On launch camber goes to almost 0 and toe increases a bit I think.

    Rear suspension should be stiff as possible, and as low as possible. If you have double adjustables, stiff compression and low rebound is good. In front, the reverse works well for damping, front spring rate never seemed very important.

    However, for a car in your time bracket, I think just practice getting the car out of the hole clean with driving technique is your best bet.

 

You'll need to log in to post.