Lazer AV4 too much grip?

K

Knight25

Member
I have been messing around with the setup/scaling on my kart for a while now, looking for speed with a clone. I finally am starting to get my lap times closer to where they need to be, but now that I've found some grip at about 63-64% cross, I seem to have a wheel hop type issue through the center of the corners. Would reducing cross help with this, or should I be looking at other adjustments? I tried raising air pressure, but that just seemed to make me loose on entry on top of the wheel hop through the center.
 
I guess that's what I'm trying to find, the balance between "free" and loose. I'll scale it out different ways and keep notes on it all so I can make adjustments on the fly and know what it's actually doing to the setup at the track. I'm starting to feel like I'm actually learning what different things affect on the kart. I've tried moving the L/R out previously and it just seemed to me like it loosened the rear up, but at that time I basically had no cross in it.
 
Let's start from the beginning see if we can figure out the issue, post all your set up numbers, including cambers, caster, front wheel spacing meaning are hubs in as close as possible , RTW inside edge of wheel to frame RR and LR, top of axle to top rear of the seat measures ?
How much rear stagger did you have on the 1/4 mile track ?
 
63% cross, 46% front, 57-58% left, R/F camber -2.5, L/F +.5, front tires in as far as they can be, rear are both equally close to frame/bearing hangers, approximately 3/8" on both. Approximately 1.5" front stagger and 1" rear stagger, and top of seat is 10" from top of axle.
 
Knight25 said:
63% cross, 46% front, 57-58% left, R/F camber -2.5, L/F +.5, front tires in as far as they can be, rear are both equally close to frame/bearing hangers, approximately 3/8" on both. Approximately 1.5" front stagger and 1" rear stagger, and top of seat is 10" from top of axle.
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Which engine class are you racing in ? and which weight class ?
 
Knight25 said:
Clone, and I run in a 410 weight class. I'm coming across the scales around 420ish
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Based on your info I'd suggest your hop is a result of to high VCG I'd lower the seat to 9" for your weight class, ( Make sure the bottom of the seat is not to high as well, bottom side of seat should be like 1/16' up into bottom of frame rails ) Then I would reset RTW move RR in 1/8" to 3/16" and move LR out to 3/4" make these adjustments then go back onto the scales, I think your numbers are real close, I'd add slightly more left side weight since xtra heavy say 59 %, for the bigger track I'd increase RF camber to 2.75 neg and reduce LF camber to .25 this will help with roll speed, moving the LR out will tighten on entry and loosen on exit, make no mistake the hop is slip grip,slip grip, repeat, with the high VCG and LR to close there working against rest of numbers causing the slip grip, that would be my take anyway.
Good Luck !!
 
racing promotor said:
Based on your info I'd suggest your hop is a result of to high VCG I'd lower the seat to 9" for your weight class, ( Make sure the bottom of the seat is not to high as well, bottom side of seat should be like 1/16' up into bottom of frame rails ) Then I would reset RTW move RR in 1/8" to 3/16" and move LR out to 3/4" make these adjustments then go back onto the scales, I think your numbers are real close, I'd add slightly more left side weight since xtra heavy say 59 %, for the bigger track I'd increase RF camber to 2.75 neg and reduce LF camber to .25 this will help with roll speed, moving the LR out will tighten on entry and loosen on exit, make no mistake the hop is slip grip,slip grip, repeat, with the high VCG and LR to close there working against rest of numbers causing the slip grip, that would be my take anyway.
Good Luck !!
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I did have the seat at 9", but it was uncomfortable for me, and also hard to see. I will definitely try the rest, and make sure of the seat bottom. My RF camber may actually be -2.75 now that I think about it. I know both rear wheels are very close to the frame rails, my "3/8" was just a number I picked without measuring, but the LR is definitely not 3/4. I'll make the adjustments and give it a shot. The slip grip is what I was trying to explain, I just didn't think to word it that way lol.
Thank you!
 
Something I don't see is what tires you are running, air pressure you are running and your durometer readings on the tires.
 
Colt sr said:
Something I don't see is what tires you are running, air pressure you are running and your durometer readings on the tires.
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33a, tried multiple different pressures, and they duro around 55. I do know the duro really probably needs to be up around 60-62, but I just don't have any tires that fit that duro.
 
If I remember correctly I ended on like 9 and 10, which made me loose on entry but still had the wheel hop in the center. Earlier in the day I was on 7.5 and 8.5 and I wasn't loose entering, and had the hop in the center just the same.
 
Knight25 said:
I did have the seat at 9", but it was uncomfortable for me, and also hard to see. I will definitely try the rest, and make sure of the seat bottom. My RF camber may actually be -2.75 now that I think about it. I know both rear wheels are very close to the frame rails, my "3/8" was just a number I picked without measuring, but the LR is definitely not 3/4. I'll make the adjustments and give it a shot. The slip grip is what I was trying to explain, I just didn't think to word it that way lol.
Thank you!
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Moving the seat is very important. With the weight you’re running sitting that high up causes problems. It also is more dangerous for flipping… i would figure out a way to lower the seat. I have one kart sitting at 8” and another 7.5”. You really should be able to see even at these heights.
 
Knight25 said:
If I remember correctly I ended on like 9 and 10, which made me loose on entry but still had the wheel hop in the center. Earlier in the day I was on 7.5 and 8.5 and I wasn't loose entering, and had the hop in the center just the same.
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Your air pressure seems a bit high for adult class. What pressure are you scaling at? What preps are you using? When are you applying these preps?
 
rswiggart said:
Moving the seat is very important. With the weight you’re running sitting that high up causes problems. It also is more dangerous for flipping… i would figure out a way to lower the seat. I have one kart sitting at 8” and another 7.5”. You really should be able to see even at these heights.
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Maybe it's just the way the steering uprights and everything are made and the fact that I'm 5'10", but if I lower the seat, I can't see over the tach that's mounted in the middle of the steering wheel.
 
Colt sr said:
Your air pressure seems a bit high for adult class. What pressure are you scaling at? What preps are you using? When are you applying these preps?
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I've tried as low as 3&4 with no change in cornering, but being much slower down the straights. The last time I scaled, I was on 7.5 and 8.5. the track I run doesn't seem to require me to wipe at the grid. I mostly use progrip 400, and then a dry bite when the track goes dry slick.
 
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