One question? If my ride height is XYZ with 1 inch rear stagger and an 1.5 in the front. and now I need 2 inches of stagger in the rear, the front staying the same 1.5, do I put my ride height back to XYZ by moving the weight jacker to get my ride height back on the LR the and washer back my cross?
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Rear rake back of kart
- Thread starter FULLOFQUESTIONS
- Start date
Barry Hastings
Member
This is my 2 cents on this...
I have played with ride height front to rear on sprints for years. Really able to tune HOW, the weight transfers. Being sprint dont do left to right chassis height normally. I read where someone said that this setup on the oval kart would help a terrible push. I think it would matter how you went about getting all the cross back...
You see in the sprint stuff if the front is higher than the rear it will want to unload the inside front first. When that happens it will put all of the turning effort on the outside front tire. In sprints we have skinny tires, so that is a lot to ask from a little tire resulting in the kart wanting to keep moving out of the turn with the font end. (understeer) So when we adjust the rear ride height to be higher than the front, the inside rear will lift first which will tend to want to oversteer, or if it keeps up too much or too early will make it spin to the inside.
So now to tilting the chassis and getting the cross back the same, I believe there is a difference in how to get the cross back... Say you have the understeer stated above, if you were able to get the cross back by only moving the right front I think would make that worse. now if you moved the LF the same as the LR would lower the front as well, and tend to keep it on the track for that fraction of a second longer...
Now we go down the idea of instant centers of pieces of mass (lead and driver) and how they intersect with the contact patches there is a whole other level of thought involved.
I hope we all can agree that 63% with all the mass on the seat is much different than 63% with 20 pounds of lead stacked on the right front and 20 pounds of lead stacked on the LR. All of the numbers on the scales would be correct, but the 2 karts would handle NOTHING like the same. Ok, that said every piece of ballast adds to the center of gravity and the CoG height, and everything does react thru the CoG as a whole, but everything does have its own instant center as well. Say you have 2 10 pound pieces of lead on the back of the seat, say you put the right one on at the top of the seat and the left one 6 inches lower. Run the numbers and the CoG height is X. But now you put all of that static measurement in to motion and things get interesting. First the largest ballast will tend to migrate to the outside of the turn (your body) AND that 10 pound piece of lead is trying to move the same way. The right side tires are resisting that movement and weight transfer happens.
Now for the interesting bit... That 10 pound piece of lead, with its instant center is trying to move toward the right rear. IF you draw a line from the lead to the RR contact patch, you can see the angle of that the "force" is moving onto the RR. NOW if you move the right piece of lead down and the left one up the same amount you would still have the same wheel weights 99% the same CoG height, but that instant center of mass on the left piece of lead will have a different "force" angle to the RR, and there should be a different in the feel of the kart.
NOW, what got me down that particular line of thought was seeing Scott Bloomquist have 30 to 40 pounds bolted to the roll bar behind his head on his dirt latemodel
Static weighing is only a start of beginning to see the whole picture.
Again, these are my observations.
I have played with ride height front to rear on sprints for years. Really able to tune HOW, the weight transfers. Being sprint dont do left to right chassis height normally. I read where someone said that this setup on the oval kart would help a terrible push. I think it would matter how you went about getting all the cross back...
You see in the sprint stuff if the front is higher than the rear it will want to unload the inside front first. When that happens it will put all of the turning effort on the outside front tire. In sprints we have skinny tires, so that is a lot to ask from a little tire resulting in the kart wanting to keep moving out of the turn with the font end. (understeer) So when we adjust the rear ride height to be higher than the front, the inside rear will lift first which will tend to want to oversteer, or if it keeps up too much or too early will make it spin to the inside.
So now to tilting the chassis and getting the cross back the same, I believe there is a difference in how to get the cross back... Say you have the understeer stated above, if you were able to get the cross back by only moving the right front I think would make that worse. now if you moved the LF the same as the LR would lower the front as well, and tend to keep it on the track for that fraction of a second longer...
Now we go down the idea of instant centers of pieces of mass (lead and driver) and how they intersect with the contact patches there is a whole other level of thought involved.
I hope we all can agree that 63% with all the mass on the seat is much different than 63% with 20 pounds of lead stacked on the right front and 20 pounds of lead stacked on the LR. All of the numbers on the scales would be correct, but the 2 karts would handle NOTHING like the same. Ok, that said every piece of ballast adds to the center of gravity and the CoG height, and everything does react thru the CoG as a whole, but everything does have its own instant center as well. Say you have 2 10 pound pieces of lead on the back of the seat, say you put the right one on at the top of the seat and the left one 6 inches lower. Run the numbers and the CoG height is X. But now you put all of that static measurement in to motion and things get interesting. First the largest ballast will tend to migrate to the outside of the turn (your body) AND that 10 pound piece of lead is trying to move the same way. The right side tires are resisting that movement and weight transfer happens.
Now for the interesting bit... That 10 pound piece of lead, with its instant center is trying to move toward the right rear. IF you draw a line from the lead to the RR contact patch, you can see the angle of that the "force" is moving onto the RR. NOW if you move the right piece of lead down and the left one up the same amount you would still have the same wheel weights 99% the same CoG height, but that instant center of mass on the left piece of lead will have a different "force" angle to the RR, and there should be a different in the feel of the kart.
NOW, what got me down that particular line of thought was seeing Scott Bloomquist have 30 to 40 pounds bolted to the roll bar behind his head on his dirt latemodel
Static weighing is only a start of beginning to see the whole picture.
Again, these are my observations.