Author Topic: "L" Spindle set-up  (Read 31282 times)

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Offline Rooster

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"L" Spindle set-up
« on: May 18, 2008, 09:48:45 pm »
Where I race they require "L" Spindles.
LOL I am not going to call them "J" Spindles, that would make the tires sideways!

Any way,
Any body have any good tips on building with these?
We are allowed to modify the axle and lower the front end, so my plan is to basically chop off about 6-8" of axle and widen the center, then recess up into chassis.
How is having the axle center line that far below the spindle center line going to effect the geometry?
Will it exaggerate the geometry?

Some of the frontends I have seen, they "laid" the axle back, as well as up, adding drastically to the cam ber and KPI.

Any thoughts on this would be great as the chop saw is warming up!


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Offline kmowtion

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Re: "L" Spindle set-up
« Reply #1 on: May 18, 2008, 09:53:02 pm »
Using "L" Spindles, if you build in your camber they work ok. About 12*-14* seems to work pretty good from my experience with them. We have to run them as well. The way I build mine is this: If the machine is level front to rear I use 12*, then I add 1* for every inch that the front is lower.
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Re: "L" Spindle set-up
« Reply #2 on: May 18, 2008, 09:55:22 pm »
So you tip the top back 12*, what about KPI, some axles have it built in, some do not?
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Offline kmowtion

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Re: "L" Spindle set-up
« Reply #3 on: May 18, 2008, 10:01:14 pm »
All of mine have had it built in so I have never had to mess with it. I can't really help you on that, maybe someone else on here can. :confused:
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Offline John692

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Re: "L" Spindle set-up
« Reply #4 on: May 18, 2008, 10:01:52 pm »
http://www.youtube.com/watch?v=TcFHbiFpMeE

I was looking though youtube and found this.
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Re: "L" Spindle set-up
« Reply #5 on: May 18, 2008, 10:18:46 pm »
You Tube has it all lol
Thanks, Tha looks basically like what I was planning!
Only I guess I'll put some "twist" in the tube for camber
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Offline bountyhunter

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Re: "L" Spindle set-up
« Reply #6 on: May 21, 2008, 11:59:27 am »
 KPI as you call it works with caster the more kpi you have the more lift efect or the more the tire move up or down in relationship to chassis as you turn tire WE like to use helm joints so we can adjust caster and camber!

Offline mightymowe

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Re: "L" Spindle set-up
« Reply #7 on: May 21, 2008, 05:20:05 pm »
I think you have that wrong,the more kpi that you have the less lift you will have because you will have less tire scrub with more kpi.As you increase the castor you get more lift,kpi moves the pivot point farther out from the centre of your machine,and closer to the centre of the tire.
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Re: "L" Spindle set-up
« Reply #8 on: May 22, 2008, 08:12:29 am »
 I might be wrong.I thought that was one off reasons we use kpi !! but if it doesnt, Ill make none in my next set!! George ,squidd, wisdom Here!!!

Offline George Herrin

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Re: "L" Spindle set-up
« Reply #9 on: May 22, 2008, 08:18:44 am »
Read the article on our front ends. I will not run a front end without KPI.
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Offline grantwt

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Re: "L" Spindle set-up
« Reply #10 on: May 22, 2008, 12:41:59 pm »
KPI is important on any front end.  While increasing KPI can decrease scrub, if you imagine a front end with no caster and no KPI, it wouldn't matter how much scrub you had, you couldn't lift your inside back.

If you imagine an axle with no caster, and only KPI you will note that the tire is lowest while it is facing directly forward.  Turning the wheel either way causes the tire to drop.  This helps recover some of the directional instability that you lose by going to toe out.  The mower weight pushing down causes the wheels to center and go directly forward.

Lastly we add caster to our axles to make the inside tire drop MORE than the outside wheel while turning to give us the lift on the inside rear.

Finally scrub simply magnifies the amount that caster and kingpin angles lift.  More scrub, more lift, but you do pay with the ease of steering.  To much scrub and the mower can get very difficult to steer, especially while stopped.  Basically we are looking for a nice medium of the big 3 (KPI, Caster, scrub) where none of them are too radical.

Thats how I understand it at least!!  :P

Offline Old Goat

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Re: "L" Spindle set-up
« Reply #11 on: May 22, 2008, 01:06:23 pm »
What's scrub? I thought that's what my wife does to the kitchen floor!
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Offline grantwt

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Re: "L" Spindle set-up
« Reply #12 on: May 22, 2008, 01:49:48 pm »
Distance between center of tire where it contacts the ground, and the kingpin pivot.



Offline Gary Elder

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Re: "L" Spindle set-up
« Reply #13 on: May 22, 2008, 06:43:23 pm »
Doesn't caster and KPI do the same thing to a mower? If you had no caster, and spindals with KPI then the left tire ( if you're turning left) would go down while the right would lift and cause the left rear to lift. If you had no KPI and Caster it would have the same effect. Or do you just like using both?

Offline mightymowe

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Re: "L" Spindle set-up
« Reply #14 on: May 22, 2008, 08:04:28 pm »
If you have no kpi you will notice that the wheel moves a long way front to back when you turn the wheel,that is called tire scrub.The farther the wheel is from the pivot in your spindle the more tire scrub you will have.
 The caster does the most jacking on the rear tires,I think,but it also makes the steering want to centre itself after you turn the wheel.
David Peters