aluminum spindles 1

[sinkworks]

i know applications such as honda use cast steel or iron spindles but does anyone make aluminum spindles and how feasible is it for a race application?

 

[GregLocock]

Yes they do. ZF Lemforder are one manufacturer. Given the comparitively low loads that a circuit car sees compared with a production car there should be no problem.



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Greg Locock

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[evelrod]

Aluminum and titanium is used in racing spindles. Al or Mg is often used for the hubs. Rather costly alternative to steel for most racing classes, IMO.

http://www.mpdracing.com/spring_hubs.php-8k

Rod

 

[evelrod]

Well that did not go as well as planned.

http://www.mpdracing.com/

and look under sprint products.

Rod

 

[GregLocock]

Your point about weight is a good one Rod, particularly on short spindles. The only time we see really significant weight savings is on tall spindle SLA designs, or, possibly, rear hubs, where the driveshaft needs a lot of structure to get around it. You might see a 20%-30% weight save going for forged aluminium compared with a cast or forged steel part, for a given level of stiffness and durability.







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Greg Locock

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[NormPeterson]

Apparently Coleman Racing Products will be offering a carbon fiber spindle, if that's of interest. It's listed in the issue of Circle Track magazine that just came in the mail today as one of the top 40 new products on display at the 2004 SEMA show (Las Vegas) and PRI (Indy). No price or other data available though.

Norm

 

[evelrod]

Norm, my issue came yesterday and I see the spindle. More like a steel spindle with Al control arms mounted to a CF plate. Looks WAAAAY too complicated for me. In my own racing efforts over the years, I find that the more parts you have, the more likelyhood of a failure of one of them.

On lightweight racecars, the aluminum or titanium spindles with a Mg hub should be a good way of reducng unsprung weight---albeit, a really high dollar item. I still think its a rather costly alternative to steel in most classes.

Rod

 

[ntsqd]

I'll venture that a fabricated steel upright can approach the weight of a Aluminum forging w/o giving up any rigidity. Check out some of the uprights on Chaparral's.

 

[Rob45]

Spindle deflection is a drawback with aluminum.

 

[pharan]

Racecar Engineering magazine has an article this month about spindle design

 

[EngJW]

I am really surprised that aluminum would be used for a spindle, but I guess if somebody tried it and it worked-----

A spindle is subject to bending stress, fatique, and it should not deflect too much. Aluminum is at a disadvantage in all of these. There is no definite fatique strength like there is with steel, and it has 1/3 the stiffness.

Weight should not be that big a factor if we are talking only about the spindle. The bulk of the weight is in the housing, control arms, and brake parts.

 

[sinkworks]

What about a cast titanium spindle?

 

[GregLocock]

Shrugs. What advantage do you see in Ti, given that hubs tend to be stiffness limited?

jlwoodward. Um, I don't think you realise how much weight we are talking about. A tall spindle on a full size car or truck will weigh upwards of 12 kg, so a 30% weight saving (times 4) starts to look very attractive.



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Greg Locock

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[EngJW]

Are you guys talking about the stubby shaft that the wheel bearings slip over, or the whole unit (upright?) that the linkages and calipers connect to? I may have misunderstood.

 

[GregLocock]

In our parlance a spindle is the thing that holds the brakes, wheel bearings and outboard ends of the suspension arms. You are describing a stub axle, or carrot.

If a spindle also has a driveshaft then we call it a knuckle.

A hub (these days) is the actual bit that holds the wheel bearings, typically bought in as an assembly.

eg Gen 2 or Gen 3 or Gen 4 parts in

http://www.ntn.co.jp/english/product/lineup/menu2-4.html

Cheers

Greg Locock

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[patprimmer]

Thanks Greg

That cleared up few things in my mind re terminology.

Regards

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[gnking]

Don't even think about aluminum spindles unless you want to kill someone. Read some basic information regarding the fatigue properties of aluminum and load cycling. Unlike steel, aluminum eventually will come apart with repeated flexing at any load. Steel fortunately has a load threshold below which repeated load cycling will not cause problems.

 

[sinkworks]

i know aluminum is not ideal for durability purposes, but for the advancement of a position in racing, an aluminum one that works for 1 race will be fine. i also think about the possibilty of titanium to keep the strength up but weight down. i also see that these would cost a lot, but for racing, once again there is no ceiling.

 

[GregLocock]

In my experience, to reinforce Rob's point, spindle designs are stiffness limited, therefore titanium will not offer much of a weight advantage over steel, and aluminium won't offer much of a weight advantage over titanium. Nonetheless, you should see about a 15% improvement in weight for a given stiffness, for each of those two steps. The gotcha is, of course, that with aluminium you are also going to have to watch out for strength issues, as you will be much closer to its limits.

I don't see much point in being alarmist about the fatigue properties of aluminium, real engineers have been successfully using it in high cycle fatigue environments for a long time. If you can get away from welds I can see no reason not to use it, if designed properly.



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Greg Locock

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[icrman]

Al is the last choice of material for a wheel spindle.
Carbon fiber? I just read an article in a science magazine about the tails comming off a certain aircraft, that are made of carbon fiber. So maybe it isn't as great as all think it is. Better stick with good ole chrome moly for that application.