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View Full Version : Over working rear tires NCMP


Clay Maddox
09-26-2005, 02:28 PM
I have a 05 Birel R30 with PRD Fireball. Whenever I run at NCMP, it over works the rear tires. It is not tight and hopping but it is not loose. We have it freed up to keep the revs up through the corners. I am only using the rear tires from the center towards the inside. I have ran DCMs and YHCs and it does the same thing. I have a medium 40mm axle, 54.75" wide in the rear, 44" wide in front, medium length hubs, no seat struts, cross weight is even, 45% frt and 55% rear weight, and douglas spun aluminum wheels. What do you think is happening? Would a softer axle help prevent over working the rear tires? Thanks for any suggestions.

Garry Lobaugh
09-26-2005, 07:50 PM
Very good feed back.

About 8 years ago we had a situation at an IKF Grand 4 cycle event.The customer was using a non Free Line wheel. Now I ask you why did you change wheels?

Remember, I'm the guy who writes the checks and creates the ideas, but I do know that we send the karts out with the best wheels, track tested to win races.

So this customer in the IKF Grands had the same problem, I simply said, lets change wheels to the Freeline wheel that comes with the kart.. His response was, "well this is what they gave me with the kart".. ah..now the real story comes out.. it appears the importer at this location had replaced the standard Birel sourced product with another wheel. You see it goes this way.. take the top product out of the box, replace with a lower priced product, and then when the Free line product is requested, you can make a few bucks!

I can gurantee improved lap times! Change to your original Free Line wheels or else call me to tell me what's up! Garry at 269-756-9133.... I really want to get to the bottom line of your story.

Jean Stafford
09-29-2005, 09:14 AM
How can you work the tires at NCMP???

Our CM32 Shifter doesn't work the tires there. WE have a hard time getting grip.

Softer axle will make the problem worse, I think, as would the Douglas, or any other spun aluminum rim. They're just too soft, and act like a soft axle.

You said," No seat struts." Tyr adding a set and tightening them up, Our rain setup is to remove or loosen the struts, therby gaining grip.

Go back to the factory setup. Freeline Mag wheels, "F" axle, and one set of seat stays, and use the red plastic bushings, not rubber. Start at 54-1/2" rear track, and set the front in the middle of the sdjustment. If possible shift some weight toward the read, about 1-2% for better balance, and lower the CG as much as possible. (Place the weight as low as possible.) Check the camber and get it straight up. Zero toe, and make sure the pitman arm is in the center of the throw.

Most people make the mistake of making adjustments in too great of an increment. I'm still pounding this into our crew chief. Make small adjustments. Two milimetersm of rear track adjustment per side, and one spacer of adjustment in the front. Tighten the rear bumper to 125In/Lb on each side.

You didn't mention how much experience you've had, so I'm thinking you're relatively new. Sorry if I'm wrong about this.

Jean Stafford
Stafford's Racing Products
www.staffordsraciing.com

Clay Maddox
09-29-2005, 02:13 PM
Jean,

Thanks for the useful information. I have been racing for 5 years and at NCMP on and off since it has been open. I came to this set-up because we had tried everything else. I ran the std set-up with freeline mag wheels, seat struts. This set-up would pull power out of the engine in the turns by not being free enough. I wanted to free the kart up so I took the seat struts out which helped, but not enough. We tried the douglas wheels to take grip away from the front and the rear and it worked. The kart freed up through the corners and didn't pull power away from the engine. We are preparing for the World TAG race so we're trying to perfect the set-up. Next week during a practice day, I might go back to the std set-up to see what it does. Thanks again for the useful advice.