JR2 Rival - Loose on Entry

R

race760

Member
We consistently fight a loose in condition with our kart at our local track. Running a big tube Rival on a low bite-sandy track. In most cases the kart will remain loose on entry even if the track gets good and bites up. We are typically really good center off. We are good on tires and win races but this loose entry situation is preventing us from running better and for more wins.

I would appreciate some thoughts on how to methodically solve this issue. Below is our setup with Umax's recommendations in parenthesis. Again we are running on a low bite track which consistently requires a tire in the low 40's and high 30's. The track is around 630 feet in length.

Left = 55 (Umax = 54-55.5)
Nose = 45.5 (Umax = 46-47)
Cross = 60 (Umax = 60-69)
RF Caster = 11 (Umax = 10)
LF Caster = 9 (Umax = 7)
RF Camber = -2.75 (Umax = -3)
LF Camber = 0.25 (Umax = 0.5)
Fstagger = 1.5" (Umax = 1 1/8 - 1 1/2)
Rstagger = 1" (Umax = 3/4 - 1 1/4")
Front Tires Spacing = 1/4" off (Umax = 1/4" off)
Rear Tire Spacing = RR 1/4" off / LR 1/4"+ off to give total width of 38 3/4" (Umax = same as where we are set)
Axle in stock position (back holes)
Caster blocks in stock position with both in back holes

Here are some things we have tried and made it better but never completely eliminated loose entry condition:
1) Lowered LF camber (less positive to as low as 0)
2) Increase RF camber (more negative to high as -2 7/8)
3) Pulled RF wheel out by 1/8"
4) Lowered left to 54

Again this is a consistent issue for us so appreciate any help.

Thanks
 
At only 45.5 nose on a Jr 2 are you sure it's not a slight push and drivers not giving wheel a quick tug and it snaps loose ?
Or does the driver say it enters good and breaks loose ?
 
The entry is good. We actually started on 46% and backed it off late last year. The condition is usually there the whole race. The only time it almost goes away is if the track is extremely good (which is rare).
 
Loose on entry problem is most always an overloaded RF or under loaded RR.
First things I would do is reduce RR air pressure by 1/2 lb, and prep the RF less. If that didn't cure it drop RR air by another 1/2 lb, I'd consider raising cross by at least 2%. Curious you are running whats normal for most a 1 lb air pressure split ?
 
race760 said:
Again this is a consistent issue for us so appreciate any help.

Thanks
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Not having much experience in LTO, in fact very little, I'm thinking your rear stagger is off. I could give you a number if I knew the radius of the turns. Another thing, that LR is kind of light. As good as your list of your set up is, you forgot total kart and driver weight. No big deal. The percentages stay the same.
 
alvin l nunley said:
Not having much experience in LTO, in fact very little, I'm thinking your rear stagger is off. I could give you a number if I knew the radius of the turns. Another thing, that LR is kind of light. As good as your list of your set up is, you forgot total kart and driver weight. No big deal. The percentages stay the same.
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You can tell from the numbers given its a kids class.
 
Al, the title of the thread is"JR2 Rival - Loose on Entry". JR2 is a junior class. I think most series run the JR2 classes at 290 lbs and age is 7-12.
 
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alvin l nunley said:
You're right, I missed that. lol must pay more attention. Good morning, some coffee would be nice. lol
Considering that, is that big tube frame appropriate for that class?
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big tube is just the standard 1 1/4, they sell an 1 1/8 tube chassis too
 
You don't mention your air, what is your normal pressure and what tire?

I'd be dropping air in that RR until the looseness subsides....
 
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