Spindle Angle
- Thread starter MAS
- Start date
A simple experiment at home would be;
Remove left tie rod and lock left spindle in the straight ahead position.
Place kart on scales with 2 pieces of paper with baby powder between under the rf tire.
Read scales as normal with the rf straight ahead. Then turn left normal turn in amount. read scales again.
Edit;
Anti Monkey Butt Powder will work also.
Remove left tie rod and lock left spindle in the straight ahead position.
Place kart on scales with 2 pieces of paper with baby powder between under the rf tire.
Read scales as normal with the rf straight ahead. Then turn left normal turn in amount. read scales again.
Edit;
Anti Monkey Butt Powder will work also.
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Working only at the rf to try to understand changes here.
If you look at the camber curves, you can see the 12/12 curve offers a lot more camber change when we countersteer.
Because of the camber change, the center of the contact patch moves away from the kingpin axis, and begins to jack some weight into the rf/lr.
This can be a good thing for the run off the corner as it helps reload the lr.
However, if we countersteer entering the corner, then need to steer left again, we are now unloading the rf tire.
If the loss of weight is enough, we now have a push.
Is the rf overloaded, or underloaded?
Better yet, what is the driver likely to report?
Thanks Ted.
If you look at the camber curves, you can see the 12/12 curve offers a lot more camber change when we countersteer.
Because of the camber change, the center of the contact patch moves away from the kingpin axis, and begins to jack some weight into the rf/lr.
This can be a good thing for the run off the corner as it helps reload the lr.
However, if we countersteer entering the corner, then need to steer left again, we are now unloading the rf tire.
If the loss of weight is enough, we now have a push.
Is the rf overloaded, or underloaded?
Better yet, what is the driver likely to report?
Thanks Ted.
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There was talk of reverse caster in this thread.
We can view the effects at the right front with the 12/12 picture.
By lowering the caster to 10 degrees, and leaving KPI the same, the curve simply rotates forward to show less camber change at both ends.
Because of the effect of KPI, no weight is jacked at turn in. Less weight is jacked at countersteer.
These effects can be seen on the scales using the method outlined earlier.
We can view the effects at the right front with the 12/12 picture.
By lowering the caster to 10 degrees, and leaving KPI the same, the curve simply rotates forward to show less camber change at both ends.
Because of the effect of KPI, no weight is jacked at turn in. Less weight is jacked at countersteer.
These effects can be seen on the scales using the method outlined earlier.
I have done this it will prove how kpi effects weight jacking and all front end geometry changes for that matter. Start with your baseline setup 5 degree spindles wheel locked at zero record all weights now turn left 15degrees record weights . Now put 15 degree spindle on set camber caster to baseline straight record weights turn left 15 degrees record weights. For me I can feel how much load I have on rear of kart and will adjust kpi or camber or caster but use the the scales turning left 15 degrees to see how much of a change it made on the rear. The scales at zero and then at 15 degrees will show you all you need to know. This will show you how the kart works in the corner take your time and do it and it will really help your understanding.
XXX#40
2A supporter
Spending hours on the scales making adjustments and noting the differences is a huge benefit to understanding whats going.
You can also make these adjustment to time the weight transfer and control how much is transfered
Exactly timing
A couple of notes.
A true zero scrub radius (yes, Al, that is what it is called) setup will have half of the contact patch inside the kingpin axis, which may result in some strange readings on the scale as you begin to move the wheel.
Where would we use less KPI?
Where the front tires makes enough grip at turn in to not be upset by a loss of weight on the contact patch. We would use the camber change to help the rest of the corner.
Another thought is when using a taller than normal rf tire. as in treads, to move the kingpin axis back to the designed alignment with the contact patch.
Everyone wants to talk about the entire setup and what changes do to that, usually at max load on the tire. Sometimes we need to look at a small section to truly understand.
The best way to go faster in a low power/ momentum situation is to not slow down as much. If you are off at corner entry, there is no way to gain that time lost back later in the corner.
A true zero scrub radius (yes, Al, that is what it is called) setup will have half of the contact patch inside the kingpin axis, which may result in some strange readings on the scale as you begin to move the wheel.
Where would we use less KPI?
Where the front tires makes enough grip at turn in to not be upset by a loss of weight on the contact patch. We would use the camber change to help the rest of the corner.
Another thought is when using a taller than normal rf tire. as in treads, to move the kingpin axis back to the designed alignment with the contact patch.
Everyone wants to talk about the entire setup and what changes do to that, usually at max load on the tire. Sometimes we need to look at a small section to truly understand.
The best way to go faster in a low power/ momentum situation is to not slow down as much. If you are off at corner entry, there is no way to gain that time lost back later in the corner.
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paulkish
old fart
I can see many ways to be off on corner entry. What is on your mind when you explain being off on corner entry cannot be made back?
... started to add more but without knowing your understanding of being off on entry in this particular case, I don't know what to write thoughts about. In my opinion no matter what corner or part of a corner if your not able to be accelerating the quick from the slow is about who maintains momentum best no mater if it's a box stock or sprints at the finals in Charlotte I just returned from viewing the last three days.
By the way Brad Sweet who I've been rooting for all year since Volusia being able to run second one spot ahead of Donny took the points in the last race of the year. Brad and Donny went into the last race with just a 2 point difference. ...
Donny passed Brad one time during the race but at the next turn Brad decided he wanted it badder the Donny. Sorry don't mean to side track this thread but just now got back and I'm still a bit excited about being able to watch the year end finish. ... racinnut15xm
Member
Yeah when Donny went by i was like rut ro, Brad kicked it into another gear. Think he was riding a little before the 15 came byI can see many ways to be off on corner entry. What is on your mind when you explain being off on corner entry cannot be made back?
... started to add more but without knowing your understanding of being off on entry in this particular case, I don't know what to write thoughts about. In my opinion no matter what corner or part of a corner if your not able to be accelerating the quick from the slow is about who maintains momentum best no mater if it's a box stock or sprints at the finals in Charlotte I just returned from viewing the last three days.
By the way Brad Sweet who I've been rooting for all year since Volusia being able to run second one spot ahead of Donny took the points in the last race of the year. Brad and Donny went into the last race with just a 2 point difference. ...
Spindle angle effects scrub radius. S/R has to be very different on the l/f and r/f on a kart, most of the weight jacking is coming from this. Spindle angle and caster create a camber curve when steering. Some people want to see caster in a certain range of the spindle angle. I understand the theory ,but in actual setup I don't follow it.
alvin l nunley
Site Supporter
"Spindle angle"?
Are we talking about "kingpin inclination", maybe "castor" or is it "camber"? Most dirt karts have all 3!
Are we talking about "kingpin inclination", maybe "castor" or is it "camber"? Most dirt karts have all 3!
See the original post.
How do you build a spindle with caster and/or camber built into it?
Your first post on this thread suggests you knew this also.
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https://books.google.com/books?id=r...pin inclination for zero scrub radius&f=false
The range is intended to keep camber gain in an acceptable range.
Kpi by itself creates positive camber gain. Caster offsets this camber gain.
More caster than kpi rolls the camber gain curve backward.
Another tuning tool.
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