Author Topic: x-weight change  (Read 6726 times)

Offline north pole racer

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x-weight change
« on: July 26, 2012, 08:01:48 pm »
i have a 34 ford coupe. just weighed it at 53.8% x-weight. 50% l/r, 50.7f/49.3r. im running 285lf spring,325rf,185lr,200rr. i weigh 205lbs. why would my x-weight go down to 52.1% with me in it as appose to raising slightly?




Offline justfreaky

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Re: x-weight change
« Reply #1 on: July 26, 2012, 08:10:42 pm »
Because you didn't weigh the car with you (or approximate weight) in it?
???
Better to be hated for who you are, Than to be loved for who you are not.


Offline VMS Motorsports

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Re: x-weight change
« Reply #2 on: July 26, 2012, 08:29:01 pm »
Alot of factors would factor into it, caster, seat location, wheelbase, etc
JIM BUCHER
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Offline Earnst85

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Re: x-weight change
« Reply #3 on: July 27, 2012, 12:45:25 am »
My brain tries to justify it in this way:

Your lightest spring is on your LR, therefore it would compress the most. The LR compressing lowers the LR ride height (relative to the the other corners compression). When you  lower  a corner height, you lessen its weight and transfer it to the other corners. Hence by moving weight from the LR, the cross weight goes down.

At least that is what my brain tells me. As I am relatively new, perhaps others with more experience could either support my theory or correct it.
Chad Earnst #85
Central PA Legends

knoxracing

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Re: x-weight change
« Reply #4 on: July 30, 2012, 08:48:44 am »
Its relative to the high cross you have with no driver. This is not abnormal with a 200 lb. driver and 51% cross.


Offline north pole racer

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Re: x-weight change
« Reply #5 on: July 31, 2012, 01:20:52 am »
i have had a few people tell me that my car should push like a plow truck with 53% x-weight but it doesnt. its usually loose in if cross is lower then what it is now.   lf spring is 285,rf 325,lr 185 and rr 200. it does roll over onto the rr heavily on corner exit to the point that we raised the fender slightly for clearance. we run on fairly flat 1/4 mi pavement. since im new to this im open to suggestions. is this normal? should it be sprung differently or any other options? last thursdays race we started with 20psi l side and 30 right. took out whatever we gained from heat,usually 2-3 psi per 25 laps.(had to run 3 25 lap mains for rain make ups) . we took a few lbs out before last main and added one turn to rf and removed one turn from lf.  weighed the car tonight on cold tires,pressures were 16 left and 24 right and cross was 53.2%. getting the lr to do its share of the work seems to be the challange.