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Andrew Coulter
06-03-2004, 02:41 PM
Here is a rookie question for you guys!

Last race we pulled the fastest lap time at the Mid-West Sprint Series In springfield. But after around the 5th lap of the race the kart started to tighten up. By the end of the race we lost about seven teenths from the beginning of the race. We had the kart as loose as we know how to get it with out changing axles. Which i think could of been our problem.

We were running the AR-4 in yamaha supercan. Medium (M) axle, Rear track at 54', one pair of seat stays loosend up,. 1/16 toe out, low nitrogen tire psi. I'm guessing that we should have installed the F Axle?

My main question is if we install the F axle Will our lap times now drop at the beginning of the race and pick up at the end of the race? We are trying to get the kart consistent throughout the race but cannot seam to find a happy medium.

Please let me know if you have any tips!

Thanks,
Andrew

David Skinner
06-03-2004, 03:06 PM
Andrew:

Tell me about how the kart acts when the tires are cold and just getting up to temp. Does the kart initially push on entry or is it loose, etc....

Dave Skinner
MRP

Andrew Coulter
06-04-2004, 01:50 PM
Thanks Dave,

The kart is usually hard to place going in the turn when the tires are cold. Yet that is when I show my fastest lap time. After about the 5th lap the kart has good turn in, I can place it about anywhere I want on the track. But it seems to bind up and start hopping about midway through the turn, mainly in the right hand turns. I have tryed diffrent lines which helped a little, but the kart is still extremely tight. About the only thing that I could think of is a softer axle, or maybe the seat should be installed lower? Yet Im looking for a happy medium so I dont slow down my times to bad in the first half of the race.

Thanks for any advice you could supply.

David Skinner
06-04-2004, 03:23 PM
Andrew:

A "hop" condition is, sometimes, the hardest issue. It comes down to is the kart really over "stuck" or is it just on the verge of picking up the inside tire and tracking around the corner the way a kart should?

In certain respects, and I'll hop up on my soap box here, having "too much" grip in a race car is like saying that you're "too rich","too pretty", or the engine is too powerful. A way of looking at it is: if it's too stuck, just drive it faster.

How you use grip that is provided by the tires is the key. Getting the kart to work right, then being able to drive a properly working kart are the next steps. Here's what I would try (in the following order):

compare seat placement to dimensions given in the "seat position" thread
Run the front track as wide as possible and with as much caster as possible without causing a oversteer situation on corner entry, maintain rear track width.

If this doesn't help, tilt the seat back slightly from standard position and retest.

Garry Lobaugh
06-08-2004, 04:46 AM
Birel drivers do best using the MRP Race School driving lines. You may wish to take advantage of this summer school of driving while we have Boswell, Bussell and Schrieber teaching. Garry

Jason Matuszewski
06-08-2004, 08:58 PM
WIth a junior sportsman you would like to stay away from adding castor since thier momentum is not that great in the corners. Adding castor to a kart that is alrady to "STUCK" will only make the kart bind on entry as you turn in. I think he should have ended up with a short f or long f2.5 at 54-1/2". THe seat position if he finds he s stuck to much raise up and that will allow him to transfer more weight and get that inside tire off the ground.