Track Tac

Spindle angles and weight transfer

Skidude

Skidude

Member
How does changing spindle angle affect handling? For instance, an Eclipse Galaxy that came with 10*/10* spindles, but someone changed them to 7*/15* before I bought it. So, I nor my grandson (driver), have a clue how it handled with the 10/10 setup. I’ve heard the 7/15 will transfer weight quicker. Is that correct and exactly what does the mean? I’m suspecting transfer from left to right but would like some clarification. Would the 7/15 require less input from the driver? Would it make it dart?
 
An experiment to help understand can be performed on scales.

Set front geometry as recommended. Driver seated, of course. Put a couple sheets of waxed paper under each front tire.

With the steering lock set, remove one tie rod and lock spindle in straight ahead position.
Steer the other about 10 degrees forward and back, noting the difference in scale readings.

Do the same with the other spindle.

If you have access to both sets of spindles, do the same with other.

To understand the significance of scrub radius, simply move a spacer from outside hub to inside and repeat experiment.
 
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below is incomplete work in progress:

1. In all cases, it's air pressure that applies force to your contact patch.
2. Angle a tire more or sharper into the track and it concentrates more of the same weight to the contact patch.
3. That is also because the tire contact patch in all cases is laid down across its surface onto the track use more contact patch and you sort of also ease the tire more into the track.
4. 4. is the opposite of the last part of number 3 where you can say you will bang the tire more into the track because you apply the same weight to a smaller contact patch.
5. The rest is about how you direct or aim weight at a tire to get 1 thru 4 done and how quickly it gets done because you are moving along the track and your movement spreads out what you do.
6. Timing is doing the above on the track to a tire when and where it needs to be done.


How'd I do with the short of it 95 shaw?
 
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Skidude said:
Thanks for the reference. I’m slowly getting it.
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Trying to make it simple it's all about how you push each and every tire into the track.
You push a tire at the track in a particular way and the track will PUSH back at ya.
Getting the tire to do something for you is ALL about how you push it at the track.
It's that simple.

What's really cool is what your riding on is moving and it takes time to push a tire into the track and it takes time to actually do the pushing.
That's where matching a moving piece of steel to the fun of setup and figuring this stuff out, comes in. ... :)

Welcome to the thought process. ... :)
 
Skidude said:
Thanks for the reference. I’m slowly getting it.
Click to expand...
It takes a while sometimes.

My ah-hah moment came when I stopped thinking of removing weight from the lr, (which happens anyway),and started thinking about adding weight to the rr.
Adding weight means adding traction.

When you get it right, the adjustments make sense.

Good luck.
 
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Skidude said:
How does changing spindle angle affect handling? For instance, an Eclipse Galaxy that came with 10*/10* spindles, but someone changed them to 7*/15* before I bought it. So, I nor my grandson (driver), have a clue how it handled with the 10/10 setup. I’ve heard the 7/15 will transfer weight quicker. Is that correct and exactly what does the mean? I’m suspecting transfer from left to right but would like some clarification. Would the 7/15 require less input from the driver? Would it make it dart?
Click to expand...
someone that didnt know what they were talking about when they told you that, 7.5/15 slows transfer
 
This is a subject of interest to me. When speaking of transfer speeds: is it a reference of left side weight to right side weight or both left to right and back to the left? As an example if running the 7/15 the transfer from the left to right is slower than a 10/10 set-up AND it's also slower to transfer back to the right side. I can follow the left to right but can't make sense of the timing of the return action.
 
Dynamic weight transfers instantaneously.

Other weight transfers at the speed your chassis operates.

Watch left rear tires at turn-in.
The moment the driver touches the steering wheel to start going left as in the exact moment of turn-in, the left rear unloading starts.

Make the path of mechanical parts needed to unload the LR or put slop into the chain of parts and you can delay mechanical chassis movement, delaying unloading of the LR. But any weight transfer not associated with moving chassis mass still instantaneously goes right and forward or aft depending on if your accelerating or braking.

Also agreeing with Burris Racer if you make transfer slower to happen then the return of weight is also slower moving back.

IMHO a major part of front end adjusting if not the major part is adjusting the path of the weight returning to the back or as most think of it back to the LR.

You do have some control of the mechanical path of returning weight so you can control to some extent, whether some returning weight goes directly to the LR or do you need it to go to the RR and then to the LR.
What you might set up to do, depends on track conditions, track configuration, and how you're going to drive the track to be fast and also use your position on the track for racing needs.
 
Burris Racer said:
This is a subject of interest to me. When speaking of transfer speeds: is it a reference of left side weight to right side weight or both left to right and back to the left? As an example if running the 7/15 the transfer from the left to right is slower than a 10/10 set-up AND it's also slower to transfer back to the right side. I can follow the left to right but can't make sense of the timing of the return action.
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It slows timing and amount is reduced if you are running stock caster/camber settings, turning the wheel to the left starts it, its in steering input
 
We read a lot on here about drivers telling us their setup on the track is so good they don't even need to turn the steering wheel.
That is because tires working with the grip they have with the track and how it changes can also create steering input.
 
paulkish said:
We read a lot on here about drivers telling us their setup on the track is so good they don't even need to turn the steering wheel.
That is because tires working with the grip they have with the track and how it changes can also create steering input.
Click to expand...
Best handling kart will almost drive itself around the track, with just slight right pressure down the straights
 
Is there a correlation between the speed of transfer and sharpness of the turn? Meaning would you want a different rate of transfer for a tight turn vs a sweeping turn? I'm thinking yes but not necessarily a spindle change but through camber or RF air pressure. On a tight turn a slow transfer would hurt a bit on entry but help quite a bit on exit.
 
Burris Racer said:
Is there a correlation between the speed of transfer and sharpness of the turn? Meaning would you want a different rate of transfer for a tight turn vs a sweeping turn? I'm thinking yes but not necessarily a spindle change but through camber or RF air pressure. On a tight turn a slow transfer would hurt a bit on entry but help quite a bit on exit.
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In this situation, an adjustment of the link between the seat back and steering wheel could overcome the compromise.
 
Burris Racer said:
Is there a correlation between the speed of transfer and sharpness of the turn?
Click to expand...
Yes.
Anytime you turn or sharpen a turn it makes speed, so long as you have grip but not excessive grip.
Ever see a kart roll into a turn and they seem to, no not seem to but actually turn down and accelerate thru the middle of the turn and exit?
It's no different than an ice skater spinning with their arms out and then bringing them in tight to accelerate their spinning.
 
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