Spindle lessons

kyle luttrell · Posted: Sat Feb 16, 2013 6:52 am Post subject: Spindle lessons

Hey everyone,
I'm going to make a little video to show what a spindles does with more or less caster,camber and what the effects of different K.P.I angle has.

Be thinking of any other questions you may have.
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TJ Koyen · Joined: 03 Oct 2004 Posts: 1418

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mike clements · Posted: Mon Feb 18, 2013 5:01 pm Post subject:

Back about 5 years ago I was designing my Time Machine sprint chassis, I loaded up my motorhome and trailer and went to our local sprint track and ran nothing but spindle changes for one full week. We experimented with various lengths, materials, diameters, bearings, adjustments, etc.
At the end of it all, we had picked up our lap times by more than three full seconds. We accounted for tires and clutches and engines, etc also. I am convinced that lap time improvements were a result of the spindle changes.
I was the most shocked to learn that two sets of spindles built exactly alike, only different materials, made such a huge difference.
A race kart is so simple when viewed by Joe Public. But when a racer goes to really working on going faster, they are incredibly complex.
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Roger Nelson · Guest

Mr. Clements....would you be willing to share your findings. I race a laydown animal and have suspected that there is speed in the front end of these karts but we have such a low albeit......no vertical CG which I think would play into the mix.

kyle luttrell · Posted: Tue Feb 19, 2013 7:23 pm Post subject: Findings

Hey!
I'm guessing Clements will agree with me on this.

He can't tell you any given spindle will make you faster because he was testing his chassis and your chassis will react differently.

What you have to do is find a spindle manufacture you trust get a set of spindles and test those.

The spindles we manufacture are made of a very special grade of material that we found that is very consistent and has some other factors we really like when dealing with spindles.

First thing if you can find a consistent spindle you can began to test spindle k.p.i Ackerman and many other things and you know that if you get faster with one adjustment you know it's not the material of the spindle it's the specs of the spindles.

The next thing we are testing here at Luttrell racing is hollowing the axle to allow more flex... Soft spindle axles haven't been a leading factor for faster lap times so that is atleast a year out.

I kinda like sticking with what's fast Wink

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TJ Koyen · Joined: 03 Oct 2004 Posts: 1418

Greg Dingess · Advertiser Joined: 27 Aug 2012 Posts: 11

kyle luttrell · Posted: Tue Feb 19, 2013 8:44 pm Post subject: Re: Findings

Stewart Willis · Joined: 24 Oct 2008 Posts: 368

Hollow stub axles? I have seen many cadets now moving to 25mm shifter spindles. I would think that with hollow stubs you would have way too much geometry in the Kart to make it work.. thoughts?
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kyle luttrell · Posted: Wed Feb 20, 2013 3:01 pm Post subject:

TJ Koyen · Joined: 03 Oct 2004 Posts: 1418

kyle luttrell · Posted: Wed Feb 20, 2013 3:26 pm Post subject:

I was just stating if for some reason I needed a softer spindle I'd just hollow the axle of the spindle
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david mckee · Joined: 12 Jan 2010 Posts: 1

T J Great link!

mike clements · Posted: Mon Feb 25, 2013 9:54 am Post subject:

It's been my experience that a hollow spindle is stronger than a solid one. That is, of course, so long as you don't go too crazy with an oversize hole for the I.D.
A hollow axle has more surface area to hold it into shape. The solid axle has only one surface. Take a look at some of the late model stock cars and Indy Car spindles. Hollow. They do not want the spindle to flex.
I really don't mind sharing my findings with other people. We tried our spindles on as many karts as were available for testing here. One material was consistently faster. I believe that is because it did not flex. It's strength was properly used in transferring weight on corner entry.
Out of all the various materials we used, using 8620 steel proved over and over to be superior for quicker lap times and better and more comfortable driver feel. These were our findings and this worked for us.

* If you look up 8620 in your machinists handbook, this is the material suggested for use in building billet automotive camshafts. This is what we use when building our billet cams and it works so well because it resists deflection and also provides excellent wear characteristics. Just an FYI.
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Chris McGinley · Posted: Mon Feb 25, 2013 9:59 am Post subject:

Just wanted to add a note that some spindles (stub axles) are hollow ... I've broken a couple at the weld and discovered that it was not a solid piece. Not sure which manufacturers use solid and which do not, but thought everyone would like to know.
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