Banked corner push

Make and model of chassis
04 GP Racing (new to me this year), with CR80RB shifter engine

I need help with
Sticking to the bottom of a banked turn

What I’ve tried so far
Adjusted air pressures, toe

We have a “high speed” (~50-60 MPH) banked corner that I have a problem holding the bottom (sticky) line with. I bought some new hubs, and plan to go from a 67mm hub to a 90mm hub to try and keep the front end from pushing up through the corner. It doesn’t oversteer on any corners (once the tires are up to temp), so I think this is a reasonable thing to do. When widening the front, is there anything else I should change - such as making the front corners somewhat asymmetric in width?

Thoughts?

1 Like

Any chance the track is Boston F1 Outdoors?

No, the “Daytona” corner at JRP in Tulsa, OK.

I think I could pick up 1-2 seconds if I could stick to the bottom and not have to lift much or any going into it.

As ridiculous as it may sound if you have grip in other corners, it could be your driving…

Otherwise, my first thought is that your camber could need adjusting. Perhaps slightly more positive (comparatively), although this depends on how the tires look through the corner.

Are you entering the banked section high and not able to bring the kart down to the apron?
Or
Are you entering the banked section low and sliding up the embankment?

I don’t know the corner but am willing to bet the banking is forcing the rear axle to lay flat, i.e., can’t jack the kart, and driving the front into the push.

How do other karts handle the turn. What’s the relative difference in the tires between what we’re comparing too as well.

I’ve never been able to really dial out a push in a sprint kart on a heavily banked turn without compromising the entire lap. But it does depend on the degree of push I guess.

Because the kart is being compressed into the bank, I don’t think there’s a lot you can do other than add caster/rake/scrub radius to. In simple terms, add caster and or widen the front to literally pull your inside rear up and unload it.

Of course that’s going to impact the other turns, depending on where you may find yourself widening the rear track to keep it down more in the tighter turns.

Other measure would include stagger, but again, while that would help you in that turn, it’s going to hurt elsewhere.

On a banked corner, you’re never going to get the inside rear to lift properly, so the kart isn’t going to rotate traditionally. However, you have the banking to help you, so it’s not a major deal. The biggest thing is making sure the balance is dialed in so you aren’t catching the rear or pushing the front.

I think widening the front track width is the best course of action in terms of chassis adjustments. However, you may find that as you adjust for that corner, you give up some of the handling in other parts of the track (as others have said). Like Eric said, it could be a driving or line issue. Since banked corners are unorthodox compared to a flat corner that karts are normally dealing with, they might require an unorthodox line. Both banked corners I can think of off the top of my head (the “Monzas” at MRP and CHMS) require a totally different line to what would normally be expected. I’ve always found that driving the kart hard down to the bottom at turn-in and letting it drift up a bit in the middle allows the banking to catch you and you can drive it off the corner again, making a double-apex. A bit like driving a sprint car.

2 Likes

How do other karts handle the turn. What’s the relative difference in the tires between what we’re comparing too as well.

The TAG karts go though the turn staying mostly on the bottom, but at least one other shift does push up a little, just not as much. That is most likely due to the total mass being more with my kart and myself compared to the young kids. That’s why I was looking at making the front a little wider to help reduce roll a small amount (I’ll take what I can get). Looking at the data I’m getting about 2.2 Gs there on 1 race old tires.

Are you entering the banked section high and not able to bring the kart down to the apron?
Or
Are you entering the banked section low and sliding up the embankment?

I’ve always found that driving the kart hard down to the bottom at turn-in and letting it drift up a bit in the middle allows the banking to catch you and you can drive it off the corner again, making a double-apex. A bit like driving a sprint car.

I’m entering the corner on the bottom, and leaving about mid way up, unless I put too much steering angle into the fronts and then I get oversteer. That would normally be an ideal line (I would think), but unfortunately due to the lower classes that don’t have the speed to push them up in the corner, all the rubber collects there making it a hairy place to be.

I’m going to go for the wider front to see what that does. If it’s too bad in practice for the other tight turns, I’ll swap back. Thanks for all the suggestions!

BTW, the corner in question is on the North end - should have posted this link before, but just though of it:

https://www.google.com/maps/place/JRP+Speedway/@36.0891132,-96.0594454,67m/data=!3m1!1e3!4m5!3m4!1s0x87b695678bf65ff1:0x463ef0e363d4ecd!8m2!3d36.0882168!4d-96.058966