LocostUSA.com

I completed my first locost by taking a project and finishing it. Since doing that and driving it at autocrosses, (still have not licensed it) I have identified flaws in the original design I dont like.

I picked up a matching frame to my car on the weekend and am dangerously close to building a 2nd car to improve the design and use up some of the extra parts ive accumulated. First car used chevette spindles which are very small but hard to get parts for.

What is the spindle of choice these days? Still Miata?

If volume of users is the deciding factor, it looks like the two choices are Miata (as you note) and Mustang II. I have no idea what makes a better spindle though.

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Figuring out how to build in the bucolic garden state
Build log: viewtopic.php?f=18&t=18224

If aftermarket support is important to you, Mustang II/Pinto is a good choice. The original cars have been gone for over 30 years, yet there's a huge aftermarket for these spindles, including dropped-spindles, brake systems, ball joints, etc. Because of their popularity (particularly among the hot rod fraternity), there are large numbers of manufacturers, and the competition has made 'em cheap.

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/

The Vintage Dwarf Car guys may want those Chevette spindles.

I am leaning towards fabricated spindles to get the geometry I want.

Some things Ron Sutton has said caught my fancy.

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Honey anyone?

I used the Mustang II/Pinto spindles, and I'm happy. There are lots of parts and accessories available, and for me that was important. Also, I've used a Ford rear end, so the bolt pattern needed to match. However, having said all that, there are still some issues. The aftermarket parts are very heavy (the Granada kit is very popular), unless you go with the Wilwood drag kit; and the off-set (back spacing) is designed for wheels from 30yrs ago. Today's wheels are much tougher to fit. I needed a 3/4 in spacer, which then required longer wheel studs.
So it all depends what you are aiming for. As always.

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Martin


My build log:
viewtopic.php?f=35&t=14520&start=0
My build video:
https://vimeo.com/143524140 password "matovid"

Chevette spindles are on the existing car and it spent too much of its life in baskets to take them off so they are staying.

My intention of a new build is to correct design issues from the original build which was an MCC7, I want it to be as light as possible so no fiberglass body, utilize all the spares I have and be economically feasible so no carbon fiber or unobtanium metal. If a single source donor gets most of what I need, then thats what I will aim for. Theres a running 91 Miata not far from me that looks like its done a somersault so it may be the source of the front end.

My major spares are: Toyota 2tg Engine, T50 trans, LSD diff. Biggest beef about the current 7, aside from the fiberglass body is the lotus 3pt rear end. Theres no way to make those parallel and having a ball joint in the bottom of the diff just doesnt make any sense at all.

I have decide to use Mustang Fox body spindles because of the upgrade options. The FF5 guys seam to have good luck with them in the handling department.

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-STu

There is no shame in defeat, so long as the spirit is unconquered

My Build Log

The problem with production car spindles is the design is compromised for "packaging".

With a Locost those limitations do not exist, and in striving for optimal geometry is not obtainable using off the shelf parts.

Specifically I am looking at the relationship between KPI and Caster.
Many folks just look at what happens to the angles with the wheels straight.
I plan on turning my steering wheel a bit and believe there is a certain amount of magic in those angles relationship with the rest of the car.

If you just want something to hold up that corner of the car there are many off the shelf parts that will work.

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Honey anyone?

I think reducing the KPI is a good thing to pursue. Stuie, I think that's the basic issue with using adapters on the Fox spindles, I would avoid that choice.

I've been looking at fabricated oval track spindles. Summit lists something like 125 different part numbers for these from Kaiser. They come in different axle pins, different pin heights, different spindle heights and different KPI.

I like the parts choices available for the Pinto spindle, the big drawback for these is the amount of offset which requires wheels with a lot of offset to reduce scrub and that reduces choices. I wold try to reduce offset first and then go for KPI. Reducing KPI makes offset worse, so that's why my priority.

I think that wether you do parking lot events or track events leads you to different tradeoffs. In a parking lot you will spend more time with the wheels turned because some turns are tighter. On a road course you don't want to turn you wheels more than you can help because it causes drag and reduces your cornering ability. It reduces your cornering ability because when you run the front tires at a different angle than the rears you can't run the rears at enough of a slip angle anymore.

I would like to have a fabricated spindle for us, there's a couple of people lined up to help on this, but some choices still need to be made.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

In my opinion, start at the tire size and work your way in. Tire choice will drive wheel choice, will drive spindle and brake choice. For example, 4x100 is far and away the easiest bolt pattern to find proper lightweight 15 (or 16) inch wheels for. This means if you want to run a tire that uses a 15 inch wheel, Miata is the easy button for decent geometry. If you don't care about wheel weight, or want to run tire sizes for 17's, 5-bolt hubs MII w/ Granada hubs would also be a fine option.

I have SN95 spindles, which are similar to Fox spindles, but use a sealed bearing and separated hub/rotor with a 5x4.5 bolt pattern. I think those differences generally make them better than the Fox spindles for weight and wheel/tire/brake options. This is not the easy button though. I would not necessarily recommend them to just anybody, and have not come up with anything resembling finalized geometry for them just yet, but they do have their potential merits as well. Consider that on a MII or Miata spindle, the caster vs trail offset and KPI are both locked in. So the only 'geometry' you can adjust is the inboard mounting points, and outboard it's just the static alignment settings. However, for the SN95 there is one off-the-shelf option from Whitby that reduces KPI relative to the standard F5 bracket, from 18 degrees down to 9. And even though the lower ball joint being mostly locked for position means there will still be some limitations and compromises, if you're willing to fabricate your own UBJ adapter bracket, you can not only adjust KPI, but caster vs trail offset as well. This actually opens up considerably more customized geometry options than are available from a typical MII or Miata spindle. Of course, I'm still not 100% certain that the additional design freedom will actually gain anything yet either...I suppose doing so should probably be bumped up on my list of things to do while my build is stuck in Purgatory.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

And let's hear from the voice of experience on custom uprights.

If you make your own you will definitely want to make a couple extra and carry them with you every time you go to the track.

WHEN you go off and torque one (the typical bent & welded uprights aren't as resistant to forces as the stock ones) you will want to have another readily handy because you can't just run down to the local parts store and get one like you can with a stock unit. Your whole day is done if say that's done on the first lap (don't ask how I know).

They also require constant inspection for cracked welds

If you are going to machine one then you might as well buy Dennis Palatov's, but Locost they ain't.

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

That was my thinking, as well. OEM items are typically built to withstand a lifetime of abuse, supporting a car 3X the weight of a Locost - breaking one, on one of our cars, would take an enormous amount of effort. The idea of being able to source a brand new replacement for around $150, within a day or two, makes sense to me.

Now, if I had a large CNC-controlled mill, I might consider giving it a go, as the required precision would be available, but the cost of such machines is prohibitive to one as lowly as myself (a lot of my parts are auto-wrecker sources, cleaned up & re-purposed...because I can't afford new parts). I sure wouldn't bet my life on a spindle I made with the resources & tools I have available. To those who do have the necessary resources, though, I say "Kudos!" - you're a better man than I am, Gunga Din!

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/

You got an address for this 'Din' guy?

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Mike - Read my story at http://twinlakesseven.blogspot.com/

I was on the hunt for some chevette spindles, they get a decent amount of praise(from the 13'' wheel crowd). Miata parts popped up local and cheap

I'm still pleased with the boxed plate ones I made. They're simple to make and you don't need a mill or lathe - just the bolt on hub of your choice. If you make the "box" as large as you can package it really ups the strength and stiffness (the arm will fail long before the upright).

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-Andrew
Build Log
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