removing grip

Mike Goebel · Posted: Thu Dec 06, 2001 6:45 pm Post subject: removing grip

quote:
Originally posted by Christopher LIvengood:

And you beleived this cause you said they were accelerations. And that they had nothing to do with turning because of that.

That doesn't make any sense. When your are turning you are accelerating towards the center of the turn. I has to do with change in direction. As John C said vectors can't be shown here. I'm done with this anyway.

Later

Mike G.

Christopher Livengood · Joined: 28 Nov 2001 Posts: 119

Gary, I was wandering how long it would be untill you made your presence on here.

Mark Dismore Jr · Advertiser Joined: 21 Jul 2001 Posts: 1096

quote:
Originally posted by Dave Embry:

haha!!!! Absolutely not!!

Say, how's your Dad. Has he gotten anything lined up for next year yet? Someone said the other day they thought he might be retiring.

The only retrirement dad is taking is the forced kind if he can't find a ride. He has a couple offers and is testing with a team this week in fact. Hopefully he will get something together soon.

Dave Embry · Posted: Mon Dec 10, 2001 6:56 am Post subject: removing grip

quote:
Originally posted by Mark Dismore Jr:

The only retrirement dad is taking is the forced kind if he can't find a ride. He has a couple offers and is testing with a team this week in fact. Hopefully he will get something together soon.

Well I certainly hope it all works out the way he wants. As I have told you in a personal email last year (if you remember)...but would also like to say publicly......is what a great Ambassador for karting/racing your dad is!

When we went to an IRL race at Texas Motorspeedway last year....we waited in a "LONG" line for an autograph from your dad. When we finally got up there (my 12 year old son Austin and I), Austin told Mark he raced karts and Marks eyes just lit up! He asked him what type karts he raced and told him about his karts which he said were "still sitting in his garage back home". He stood and took photos with him them pulled out some special photos and autographed them. We felt kinda bad with him taking all that time with us with such a big line still waiting behind us....but that made Austin's day to say the least!

Needless to say, he's Austin's hero and that's the hat you'll usually see him wearing at all our karting events!!

I know this has nothing to do with this thread but I just thought he did such a great job representing racing to the sport/kids that I would just like to say "thank you"! It's good for these kids to have someone to look up to and Mark is a great example of this.

Mark Dismore Jr · Advertiser Joined: 21 Jul 2001 Posts: 1096

See what you did that to your kid! You've infected him with the racing bug for the rest of his life! Everyone on this board knows there is no cure!

I guess it all goes back to, you can take the racer out of karts, but you can't take the karting out of the racer. Dad's been doing this stuff to long to give it up now!

Larry Hayashigawa · Posted: Sun Dec 16, 2001 7:47 am Post subject: removing grip

I not the expert on karts (used to race but don't even own one now but recently friends have let me race and practice them) but have been thinking about what are the dynamics of kart in a turn. I believe there are 2 or 3 phase thru a turn. The 1st phase is the entry phase, where the kart is going straight and now needs to turn. This is where front wheel caster and chassis stiffness affect how the inside rear unloads and whether it understeers or oversteerings. An interesting turn-in phase experiment would be to put your kart (with driver) on the scales and turn the steering wheel, tie a rope on the kart and with a small amount of force pull the kart to the outside of the "turn". You should see the inside wheel unload. What I have noticed driving a kart is that during the initial turn, the steering wheel has a lot more angle than during the mid or exit phase of the turn. This IMHO is to get the inside tire unload, so that the kart will turn.

Once the kart starts turning centrifugal forces/accelerations are applied to the kart,causing weight to be transferred to the outside tire. How much is transferred is a function of center of gravity (ride height is a component of), rear track width, speed, chassis stiffness (of which ride height is a component of), caster, steering wheel angle, tire pressure, driving style and who knows what else. During the mid phase of a turn, the steering wheel should have less of an angle that during the entry phase of the turn. IMHO mid turn requires less wheel angle because a major effect on unloading of the inside tire is due to "weight transfer" from centrifugal accel and therefore not as much steering wheel angle is required during the mid phase (compared to the entry phase) of the turn to unload the inside rear.

Throttle application during the turn will also change require that the steering angle be reduced or it may have to be turned in the opposite direction to maintain the intended path.

I have not thought through the exit phase yet.

Larry Hayashigawa · Posted: Sun Dec 16, 2001 8:27 am Post subject: removing grip

Sorry, got so wrapped in my theory stuff I forget the point. My point is where in the turn is kart not handling right is just as important whether the kart is understeeing or oversteering. I believe that a kart can do both in a turn.

Gary Lawson · Joined: 21 Aug 2001 Posts: 542

Larry you are correct. It usually happens when a kart it tight entering the corner and loose from the middle off. If could be hopping and the tires just give out. Or the front could be pushing and you turn the wheel real far and when the kart finally grips the back whips around and you think it is loose although the kart is actually tight.

Gary Lawson

Paul Kish · Posted: Sun Dec 16, 2001 5:01 pm Post subject: removing grip

"Larry you are correct. It usually happens when a kart it tight entering the corner and loose from the middle off."

Our rule number one, we run dirt, is match the tires to the track.

Rule number 1a would be, If the kart is loose on entry and pushes on exit the problem is the driver.

By the way Gary, if you dig a little on bobs you will find posted fixes for rule number 1a, other than what I wrote, that with a little bit of thought could be applied to sprint racing.

[ December 16, 2001: Message edited by: Paul Kish ]

Barry McCarty · Posted: Fri Dec 21, 2001 4:56 pm Post subject: removing grip

I don't know if you guys will buy this, but here is what I think. We are dealing with weight transfer. If the spring rate of the tires is very soft or the roll center is very low in the rear more weight will transfer onto the RR. Sure, there will be some weight transferred onto the RF, but by lowering the rear of the chassis that transfer will be less at the front (RF) and more at the rear (RR). this will cause understeer. Now on karts the front roll center is lower than the rear. The reason is that weight needs to come from the LR to the RF. Cross is used to balance the RF to RR ratio of weight transferred from the LR.

Adjusting the ride height alters that balance. My belief is that a lower end of the chassis will receive more grip due to the increased amount of weight transfer. And the higher end of the chassis will have less grip due to the decreased amount of weight transferred to that end.

Mike