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Chris Parks
Joined: 09 Sep 2001
Posts: 1504
Location: Australia, not USA state,
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 Posted: Sun Jan 30, 2011 3:47 pm Post subject: |
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Everyone is on about the spindle flexing along its length, or so I presume. It was pointed out to me that this was not as great a problem as the flex at the inner end where it joins the upright body of the spindle. Hence why some are a push in fit not a welded and machined assembly. Can someone do a stress analysis on the difference. I know we had to increase the machined radius to reduce flex at this point. I am just going on memory here as it was quite a few years ago and the engineering was done in the US not Australia.
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understeer happens on road courses and usually is pronounced with a British accent. Push happens on ovals and usually is pronounced through a wad of chew. Other than that, I don't think there's a difference - Jim Derrig
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Chris Livengood
Joined: 24 Jul 2001
Posts: 2432
Location: United States, Pennsylvania, Da Burgh
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| Posted: Sun Jan 30, 2011 5:17 pm Post subject: |
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I already built an upright type spindle and fitted it to a kart last year. Unlimited and independent caster and camber adjustment. I have little to be impressed with after that.
If we are trying to cut spindle deflection we are only as strong as our weakest link. Better look at the spindle bolt first. The rest of it is trivial.
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Chris Parks
Joined: 09 Sep 2001
Posts: 1504
Location: Australia, not USA state,
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| Posted: Sun Jan 30, 2011 5:40 pm Post subject: |
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| Chris Livengood wrote: | I already built an upright type spindle and fitted it to a kart last year. Unlimited and independent caster and camber adjustment. I have little to be impressed with after that.
If we are trying to cut spindle deflection we are only as strong as our weakest link. Better look at the spindle bolt first. The rest of it is trivial. |
The bolts is not much of a problem if it is at least 10mm. In fact it it is only loaded at the bearings in the are which is well supported. The bolt is only an issue where eccentric adjusters are used. There is nothing to stop anyone using a bigger bolt on a kart if the upright is custom built. Are you going to market these Chris and have you played with adjusting the KPI and leaving the camber the same? Much to db gained there I think. I doubt if I will ever do it as we have not run a sprint kart for some years and I have other business interests these days.
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understeer happens on road courses and usually is pronounced with a British accent. Push happens on ovals and usually is pronounced through a wad of chew. Other than that, I don't think there's a difference - Jim Derrig
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Chris Parks
Joined: 09 Sep 2001
Posts: 1504
Location: Australia, not USA state,
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| Posted: Sun Jan 30, 2011 5:42 pm Post subject: |
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| Chris Livengood wrote: |
If we are trying to cut spindle deflection we are only as strong as our weakest link. Better look at the spindle bolt first. The rest of it is trivial. |
In your estimation, others may well think differently.
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understeer happens on road courses and usually is pronounced with a British accent. Push happens on ovals and usually is pronounced through a wad of chew. Other than that, I don't think there's a difference - Jim Derrig
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Chris Livengood
Joined: 24 Jul 2001
Posts: 2432
Location: United States, Pennsylvania, Da Burgh
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| Posted: Sun Jan 30, 2011 6:19 pm Post subject: |
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| Chris Parks wrote: | | Chris Livengood wrote: |
If we are trying to cut spindle deflection we are only as strong as our weakest link. Better look at the spindle bolt first. The rest of it is trivial. |
In your estimation, others may well think differently. |
It's not an estimation. If you are trying to increase the strength (in this case in terms of resistance to flexation) of a system starting with it's weakest point is only logical. How can this be denied? How many spindle bolts have you bent without bending the spindle?
Others will of course think differently. However, in this case, I believe I have produced the most thorough examination. At least of the ones offered so far in this thread. It's fun to produce a dialectic for such problems because people will continue to believe whatever nonsense they are sold simply because they are too lazy or too naive for rational thought with regards to many karting based discussions (meant in the most genuine tone of voice). Chris, as a long time poster and conveyor of many interesting and well supported theories, you of all people should understand this.
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Jeff Lund
Joined: 02 Jul 2008
Posts: 45
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| Posted: Sun Jan 30, 2011 8:52 pm Post subject: |
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I may be wrong, but just from my occasional rumaging around the specs of newer karts it looks like most equipped with 25 mm spindles do have a 10 mm spindle bolt. That's just if I remember right because I really don't feel like looking it up.
I'm just gonna rationalize in my own way the reason why 25 mm is the hot stuff right now (so I might be one of those lazy and naive people Livengood is talking about). The 25 mm spindles are less flexible than the 17 mm and they provide a more stable footprint for the front tires as a result. The manufacturers compensated for this by redesigning, or tweeking as a better term, the frames and found some positive results. Even if the difference in laptimes are tiny, the added feel in the front is worth it.
So my logic might be wrong, but that's the impression I've gotten. If anyone wants to correct me feel free, but please be nice about it. I'm no engineer, just going from my experience of driving and tuning these things. |
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Chris Livengood
Joined: 24 Jul 2001
Posts: 2432
Location: United States, Pennsylvania, Da Burgh
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| Posted: Sun Jan 30, 2011 9:55 pm Post subject: |
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| Jeff Lund wrote: | I may be wrong, but just from my occasional rumaging around the specs of newer karts it looks like most equipped with 25 mm spindles do have a 10 mm spindle bolt. That's just if I remember right because I really don't feel like looking it up.
I'm just gonna rationalize in my own way the reason why 25 mm is the hot stuff right now (so I might be one of those lazy and naive people Livengood is talking about). The 25 mm spindles are less flexible than the 17 mm and they provide a more stable footprint for the front tires as a result. The manufacturers compensated for this by redesigning, or tweeking as a better term, the frames and found some positive results. Even if the difference in laptimes are tiny, the added feel in the front is worth it.
So my logic might be wrong, but that's the impression I've gotten. If anyone wants to correct me feel free, but please be nice about it. I'm no engineer, just going from my experience of driving and tuning these things. |
Jeff, I don't dispute your findings in any manner. I'm guessing that your findings are based on empirical evidence.
The point that I attempted to make is that people fail to ask the why their findings are of the nature that they are. Not that they don't draw realistic understandings of final affect. To reiterate, I don't disagree that people see a difference in chassis characteristic. I just don't believe that the perceived change is a result of what they think it is. In this case, a 25mm spindle.
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Chris Brunnemer
Joined: 13 May 2009
Posts: 582
Location: United States, Indiana, McCordsville
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| Posted: Mon Jan 31, 2011 9:45 am Post subject: |
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| Jeff Lund wrote: | I may be wrong, but just from my occasional rumaging around the specs of newer karts it looks like most equipped with 25 mm spindles do have a 10 mm spindle bolt. That's just if I remember right because I really don't feel like looking it up.
I'm just gonna rationalize in my own way the reason why 25 mm is the hot stuff right now (so I might be one of those lazy and naive people Livengood is talking about). The 25 mm spindles are less flexible than the 17 mm and they provide a more stable footprint for the front tires as a result. The manufacturers compensated for this by redesigning, or tweeking as a better term, the frames and found some positive results. Even if the difference in laptimes are tiny, the added feel in the front is worth it.
So my logic might be wrong, but that's the impression I've gotten. If anyone wants to correct me feel free, but please be nice about it. I'm no engineer, just going from my experience of driving and tuning these things. |
Just spit balling here but i believe someone on here earlier (Tom Sekey?) said that they didnt feel a difference in the high speed corners but did in the low speed corners. i wonder if this is because of the added stress put on the spindles due to more steering input thus deflecting the spindle more. this would become a problem with the 17mm spindle as the more load would induce less negative or more positive camber. this could change the handling characteristic in a negative way and the 25mm spindle would help that. just an idea though. |
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Larry Hayashigawa
Joined: 21 Oct 2001
Posts: 399
Location: United States, California,
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| Posted: Mon Jan 31, 2011 10:07 am Post subject: |
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Chris,
| Quote: | | If we are trying to cut spindle deflection we are only as strong as our weakest link. Better look at the spindle bolt first. The rest of it is trivial. |
The spindle bolt is in shear, so it's likely very stiff in comparison to its size. The bending pieces are the most compliant; chassis, wheels and stub axles.
Stiffer front stub axles will maintain geometry better with the front wheels and one would think a larger contact patch resulting in more grip right at turn in but may not generate any more grip than a 17mm once the front end is turned because of front end kinematics.
I would think that there might be more flex designed into a chassis with 25mm spindles because a certain amount of flex has to be provided by the chassis system in order to make the kart turn. Maybe chassis flex is better than spindle flex.
I heard that in two years we will see 60 mm axles and 30mm front stubs. 
Larry |
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Colin Edwards
Joined: 30 Sep 2009
Posts: 87
Location: Australia, Not USA, Melbourne
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| Posted: Mon Jan 31, 2011 2:33 pm Post subject: |
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A by-product of using 25mm spindles is the improved hub location provided by larger ID and OD bearings. The virtual elimination of float and resultant camber and toe changes when using 25mm spindles as opposed to 17 may not improve laptimes much but significantly reduces unanticipated front end geometry dynamics. Maybe it is this that provides the better "feel" of the kart.
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Chris Livengood
Joined: 24 Jul 2001
Posts: 2432
Location: United States, Pennsylvania, Da Burgh
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| Posted: Mon Jan 31, 2011 5:03 pm Post subject: |
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| Larry Hayashigawa wrote: | Chris,
| Quote: | | If we are trying to cut spindle deflection we are only as strong as our weakest link. Better look at the spindle bolt first. The rest of it is trivial. |
The spindle bolt is in shear, so it's likely very stiff in comparison to its size. The bending pieces are the most compliant; chassis, wheels and stub axles.
Stiffer front stub axles will maintain geometry better with the front wheels and one would think a larger contact patch resulting in more grip right at turn in but may not generate any more grip than a 17mm once the front end is turned because of front end kinematics.
I would think that there might be more flex designed into a chassis with 25mm spindles because a certain amount of flex has to be provided by the chassis system in order to make the kart turn. Maybe chassis flex is better than spindle flex.
I heard that in two years we will see 60 mm axles and 30mm front stubs.
Larry |
My upright front end is already planned to utilize a 40mm front axle. I know I can make a killing off all of the Turkey's who drink Kool-Aid and wear foil hats.
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Jim McMahon
Joined: 07 Apr 2007
Posts: 2657
Location: United States, St. Paul,
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| Posted: Wed Feb 02, 2011 9:30 am Post subject: |
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| Chris Livengood wrote: | | . I know I can make a killing off all of the Turkey's who drink Kool-Aid and wear foil hats. |
Don't forget to offer a cryo-treated one too for extra $$.
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GPI Racing | WildKart | Maxter | Hoosier
Karting Festival @ Blackhawk Farms June 1st-2nd. |
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Matthew Tangeman
Joined: 28 Jul 2004
Posts: 47
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| Posted: Tue Feb 15, 2011 8:23 pm Post subject: why 17-->25? |
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All the technical aside, perhaps 'planned obsolescence' is in effect. The only way to keep margins up is to make new incompatible products. Auto industry has perfected it. 17mm hardware is very generic nowadays, and has been copied by the aftermarket making manufacturer's margins slim in a down business cycle. Aha, let's make 25mm vs 17mm hardware. Voila! Problem solved. Now, let's lobby WKA and let only certified manfacturer's chassis onto the grid. (think Stars at 1st, etc etc).
Am I off base here?
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The more we know the more we know we do not know. |
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Jim McMahon
Joined: 07 Apr 2007
Posts: 2657
Location: United States, St. Paul,
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| Posted: Tue Feb 15, 2011 10:44 pm Post subject: Re: why 17-->25? |
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| Matthew Tangeman wrote: |
Am I off base here? |
I think both yes and no. Build in obsolescence sure, that makes sense. But theres nothing in regs to say you can't use older equipment or that it HAS to be current CIK homologation. Pretty sure if you scour the man cup grids you'll see 17mm spindles with 8mm kingpins on karts.
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patrick slattery
Joined: 23 Apr 2004
Posts: 786
Location: United States, Ohio, cleves
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| Posted: Wed Feb 16, 2011 6:44 am Post subject: |
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| With an Arrow karts, you can switch back and forth from 17-25mm spindles with out removing anything but the shafts which are interchangeable. It pretty slick and a great tuning tool. |
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