BMI Racing Discussions
#7921
Jason...
You have PM.
#7926
I was able to perform a good bit of testing today which resulted in the following mod/rubber/asphalt setup with the new BMI Xray chassis in its stiff form with front and rear stands. As you can see I still have a little of my foam/carpet setup included (anti-dive, hard arms, stands, etc.), as I'm looking to minimize changes needed to switch environments. If anyone has an extra car, I'd be glad to abandon this route.
I originally started with a short wheelbase and the car was hooked everywhere, except in low speed corners when exiting on-power. I tried just about everything to get it to hook up, but only maximizing the wheelbase worked. The short wheelbase works well for me with high grip carpet, but not at all with the stiff chassis on low grip asphalt. Once I increased the wheelbase, added 1mm of front droop (to help the weight shift to the rear when the throttle is first applied) and raised the rear ride height by .5mm (to prevent pushing on initial corner entry and in high speed sweepers), I was able to increase my steering dual rate another 5 points which gave me really tight steering without losing the rear while hard on the brakes or the throttle. With these changes, taking a high speed sweeper took the least amount of steering input to date with any car I've run and corner speed was pretty good with just the right amount of chassis roll.
I've spent a lot of time these last two weeks on both carpet and asphalt to find the optimum camber link settings for camber gain throughout the BMI chassis' roll, regardless of how much roll is induced through the suspension. What I found is that the settings I've come up with translate into maximum tire contact patches in both environments. I confirmed this on asphalt today as the RP's had even wear patterns and inner/outer edge temperatures after a few packs. The only change needed on any track is to increase the static camber in the front and/or rear by .5 to 1d as traction is increased. The front and rear shouldn't need more than 2 degrees of static camber in high grip environments. Just examine the tires after a 5 minute run to make sure that they are wearing evenly across and adjust the static camber as is necessary. Therefore I'd highly recommend the camber link mounting positions & shims in the setup below for the BMI chassis. I tried the new rear long link mounting positions on carpet, but the camber gain was not enough and the car kept riding on the edges of the rear tires which eventually led to chunking and oversteer after a few laps on two sets of freshly trued foams. The car would work well until the first small chunk and then rear grip was lost mid-corner. If using rubbers, it may work for you if you need more rear end rotation mid-corner, but I'll have to test that next time (maybe tomorrow).
http://www.teamxray.com/xforum/xform...3&setup=t1fk05
I originally started with a short wheelbase and the car was hooked everywhere, except in low speed corners when exiting on-power. I tried just about everything to get it to hook up, but only maximizing the wheelbase worked. The short wheelbase works well for me with high grip carpet, but not at all with the stiff chassis on low grip asphalt. Once I increased the wheelbase, added 1mm of front droop (to help the weight shift to the rear when the throttle is first applied) and raised the rear ride height by .5mm (to prevent pushing on initial corner entry and in high speed sweepers), I was able to increase my steering dual rate another 5 points which gave me really tight steering without losing the rear while hard on the brakes or the throttle. With these changes, taking a high speed sweeper took the least amount of steering input to date with any car I've run and corner speed was pretty good with just the right amount of chassis roll.
I've spent a lot of time these last two weeks on both carpet and asphalt to find the optimum camber link settings for camber gain throughout the BMI chassis' roll, regardless of how much roll is induced through the suspension. What I found is that the settings I've come up with translate into maximum tire contact patches in both environments. I confirmed this on asphalt today as the RP's had even wear patterns and inner/outer edge temperatures after a few packs. The only change needed on any track is to increase the static camber in the front and/or rear by .5 to 1d as traction is increased. The front and rear shouldn't need more than 2 degrees of static camber in high grip environments. Just examine the tires after a 5 minute run to make sure that they are wearing evenly across and adjust the static camber as is necessary. Therefore I'd highly recommend the camber link mounting positions & shims in the setup below for the BMI chassis. I tried the new rear long link mounting positions on carpet, but the camber gain was not enough and the car kept riding on the edges of the rear tires which eventually led to chunking and oversteer after a few laps on two sets of freshly trued foams. The car would work well until the first small chunk and then rear grip was lost mid-corner. If using rubbers, it may work for you if you need more rear end rotation mid-corner, but I'll have to test that next time (maybe tomorrow).
http://www.teamxray.com/xforum/xform...3&setup=t1fk05
Last edited by teamgp; 07-30-2005 at 09:04 PM.
#7928
How much lighter and stiffer is the TC4 BMI chassis? What does it cost?
#7929
Here's what I'm talking about Jason ref. PM.
here is a pic. Thanks
#7931
You think so Joe B.
#7933
Jason you have a PM, please respond.
#7935
Sup Jason....The new setup was awesome today