Chassis Setup
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Does anyone know how much if any the toe changes with the body and driver weight added? My camber changes by 0.1 degree just by adding driver weight and body work. It is hard to get distribution of body weight using lead, and I don't have enough to replicate me. My solution has always been to set the chassis minus 0.1 then add body and crew chief and make final check. I just haven't (yet) made a small set of toe plates to recheck toe with body on.
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Needs a Life!!!
Posts: 1200
Joined: Wed Nov 30, 2011 1:38 am Location: Sunnyvale, CA Chassis: 068 415 Facebook Page: http://facebook.com/HSERacing |
Have you checked how the driver affects corner weights?
Dave Harriman
"It looks crazy, I understand. But, we only live once and I am going to give it a good try." - Alex Zanardi |
Yes I have, 61% to the rear almost equal left and right.
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If you want to be that precise, have someone measure the ride height when you're in the car, then put the car on wooden blocks of that height (disconnecting the shocks) to get the precise camber. If you really want to be precise you'd also need to consider aero downforce as well.
Then again, if you measured the front end of the field I'd bet there's more than .1 degree of camber difference amongst the group and every corner is not necessarily the same. Camber's probably the least interesting of the setup options affecting handling (bump steer can do funky things, and caster, toe, shocks, bars, preload, ride height, corner weights, etc. can have substantially more affect than .1 degrees of camber). Personally, I've probably moved mine around .5 or more over time, mostly to compromise some performance for tire longevity, or to tune for characteristics of specific tracks (running asymmetrical setup on ovals being the most interesting.) Bob Breton - SRF 51 - San Francisco Region
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Former Specracer National Champion |
I think you are over thinking it...
As long as you keep your measuring and setting practices consistent you should have nothing to worry about. Going along with what Bob said, 3.0 degrees of camber on one guys gauge might read 2.7 on another gauge. Plus a half turn on the camber heim usually gives you a little more than .1 of a degree change. Right? Bump steer is almost out of my pay grade but if your bump is correct, should driver in or out of the car be irrelevant? |
Your right Mike, 1/2 turn on the lower control arm 5/8 rod end gives over 0.1 less than 0.2 depending on the starting point. These digital gauges can be a real pain because they give such a precise measurement, it was faster (better?) with the old bubble gauge if one justified it was close enough.
It's hard for me to say which item is the most important, incorrect toe or bump steer can make the car almost un drivable under braking. Camber and caster certainly impact tire wear and heat to the extent they become used up far too soon. I agree the drivers at the front could drive ill handling cars with great success remember racerX's last to first with a wrecked car, but my lack of talent requires all the help I can get. |
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