ramblings, spindles and L blocks

foreverfaster

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Help me understand,...PRC.. just cuz i have them on my computer at the moment looking at their parts.. assuming they are much like everyone else. please help me understand the reasoning, of design and use of spindles and L blocks.

if an L block says it it a 7.5 kpi (guessing king pin inclination) Negative caster? So is its design that the base bearing and the locating pin do not line up with the heim center? safe to say the kart is engineered to preform with 7.5 neg or more in order to handle properly? why are they not all at zero?


the spindle itself, will also assume until educated differently, that the spindle assembly it self is a 90* angle both horizontally and vertically between the barrel and the actual spindle pin. if it's not at a 90 then it should have caster or camber built in. how would you know what it is if its not marked?
if the barrel is plumb, and the spindle pin is welded at a 90* vertical angel to the barrel, but it is welded at an angle such that say a straight line through it, would put it behind or ahead of the axis of the king pin bolt. would it be any different? how is caster built into a spindle?? if the spindle is listed as no cross, is this indicate a height difference in the pin ?
are the holes for the bearings in the spindle barrel cut on an angle so that it's not actually 90* to the pin that may be at a 90* would this build in caster?

what about the arm that the steering rod connects to??? there are so many facets to this single part of the kart yet it has SOOO much effect on how it handles... it really needs to be examined in great detail.
anyone understand what i'm getting at and have a way to educate me????
 
Here is a thread with some good diagrams about what the effect of kingpin inclination is and why we use it. Its a long thread with some distractions.

https://4cycle.com/karting/threads/spindle-angle.110398/


Quite a bit of the debate is because a certain member reads the definition of scrub radius differently than the rest of the world.

Over the last 4 years there have been several such discussions.
 
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The L blocks are designed to be used with certain KPI spindles to allow the heim to be proper length for use to set design camber. Basically moves lower kingpin hole in or out to correspond with spindle design for setting proper camber on that particular chassis.

Different manufacturers build different initial angles into their chassis base plate. ( the part the L block bolts to)
I know the system George Bark used put the plates perpendicular to the bottom of the frame, parallel to chassis centerline.

They also have the caster setting marks in the correct place to correspond with the caster also designed to be used with that spindle.

No cross simply means the height that the spindle is welded onto the barrel is different allowing low cross setup vs high cross setup without washers being all on top or bottom of spindle, leaving room for some adjustment in each way.
 
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Like what is mentioned above. The L-Block or C-hub for the spindle is welded to a certain degree to the frame. If you take a 15 degree spindle and put it on a kart that needs an 8 degree spindle you have to adjust the heim or pill to put the negative camber in the kart. But even at the most negative camber adjustment you might still be at positive camber.

In your third paragraph you spoke about 90 degree angles both vertically and horizontally on the spindles and how to tell. Most spindles are not going to be made like this. The caster will be 90 degree vertical, but not the camber, the horizontal axis.

My statement above will tell you that your have the wrong degree spindles for the kart. You just won't be able to get the negative camber adjusted back into the kart. One way to tell what degree they are if they are not marked is use a protractor with the kart on the ground.
 
The holes on the steering arms of the spindle dictate steering speed. The closer the tierod connection is to the kingpin, the faster the steering is.
We can also stagger the distance the attachment is made from the kingpin to create toe change as the front is steered. This is called Ackerman.
If we steer the LF faster than the RF at turn in, the weight jacking effect at the LF is enhanced because the front wheels toe out. The downside of this is that this creates toe in if we countersteer, which can have negative effects on traction for steering.

The base theory behind all of this is:
The LF gets you into the corner.
Stagger gets you thru the middle of the corner.
Cross gets you off the corner with speed and momentum.
 
Here is a thread with some good diagrams about what the effect of kingpin inclination is and why we use it. Its a long thread with some distractions.

https://4cycle.com/karting/threads/spindle-angle.110398/


Quite a bit of the debate is because a certain member reads the definition of scrub radius differently than the rest of the world.

Over the last 4 years there have been several such discussions.
We never really talk about the LF in terms of scrub radius, and the effects of camber on weight jacking at turn in.
If you look at the front view drawing in post #51 of the linked thread, and imagine the effect of moving from 3 degrees negative camber to .5 degrees positive camber. We can see the contact patch and , subsequently the scrub radius, moves farther away from the kingpin axis. This coupled with the enhanced positive camber gain from KPI and caster in the direction steered at turn in, creates substantial weight jacking to the RR.

Hope that helps answer some of your questions.
 
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We never really talk about the LF in terms of scrub radius, and the effects of camber on weight jacking at turn in.
If you look at the front view drawing in post #51 of the linked thread, and imagine the effect of moving from 3 degrees negative camber to .5 degrees positive camber. We can see the contact patch and , subsequently the scrub radius, moves farther away from the kingpin axis. This coupled with the enhanced positive camber gain from KPI and caster in the direction steered at turn in, creates substantial weight jacking to the RR.

Hope that helps answer some of your questions.
THANKS !!! THE Previous post , however long winded, was great "spindle angle"
 
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