Kurt Bilinski's build

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Midlana1
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Re: Kurt Bilinski's build

Post by Midlana1 » 02 Dec 2009, 07:14

Jim has found difficulty fitting the front shocks so I'll make some wood "A-arms" and see what's going on; Jim and I are using different shocks, but the OD should be the same.

The issue is having enough clearance through the top A-arm, but more importantly, keeping the motion ratio high. Yes, the shocks can always be made to fit by leaning them over more, but the geometry conspires to requiring crazy high springs rates to support the vehicle. As it is now, spring rates of around 400 lbs are needed, and I don't want that going much higher else the springs become harder to find in such high rates.

All of this becomes a non-issue if the upper A-arm is forced to work, made to go round the shock and spring, wherever it needs to go. The trouble is it then requires builders to bend the tubing, and I'm not sure it's reasonable to assume builders can do that. If I were building just one car, I'd make it happen somehow, but this is supposed to be easy to build.

Of course, that said, going rocker arm is an even bigger PITA, work-wise and cost-wise, so we'll see how it turns out. These things have a way of designing themselves if given the chance. That is, just put everything in place and see what we have to work with. Usually one nice simple solution tends to fall out.

About the heat, good question. I've been assuming that because Midlana is light, and because they won't be raced for hours on end, that the shocks will never get worked hard enough for temperature to be an issue. Now, if we were talking off-road cars, I'd absolutely agree with you. One benefit of the flat dash is having tons of data acquisition ability, so after the car's built I may instrument all sorts of things to see what's what. (Of course, by then the shocks are already a done deal, so if they do get hot, they'd have to have cooling air routed to them.)

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Re: Kurt Bilinski's build

Post by emgr3 » 02 Dec 2009, 19:32

Midlana1 wrote:No, but it turns out it wouldn't be different enough to matter, meaning there's already a couple good spots for the bellcrank pivot.

The thing people who are in love with inboard suspension don't realize is the cost. Using two good quality needle bearings for each bellcrank, and two more rod-ends for both sides, it'll be another $300-400 easy. This can turn into a case of "be careful what you wish for" sort of thing :?
Does it need to be a needle bearing? What about bronze oilite bushings? Even if they wear out faster they're like $2 apiece.

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Re: Kurt Bilinski's build

Post by Midlana1 » 02 Dec 2009, 19:51

The fallback plan is spherical bearings, also used on the Kimini rocker-arms.

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Re: Kurt Bilinski's build

Post by justin.s.gray » 03 Dec 2009, 05:23

Here, I figured it out!... This is what I have resorted to to keep myself sane. Otherwise I would have to be in the garage building my own!
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Midlana1
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Re: Kurt Bilinski's build

Post by Midlana1 » 03 Dec 2009, 06:58

I know you're sorta kidding, but we can't connect it to the top A-arm because the resulting assembly will be too tall. For general shock placement, it's either what you have there, or rotating the shock and bellcrank so that they face toward the rear. It'll be mocked up in wood and will solve itself, if the original outboard setup doesn't measure up.

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Re: Kurt Bilinski's build

Post by Midlana1 » 12 Dec 2009, 22:39

Started on resolving the front A-arm questions - not enough to post pictures yet. I'm still trying for a traditional outboard-mounted shock, but we'll see how it goes.

In other news, I'm realizing the consequences of building a high-power engine. All manufacturers' drivetrains have weak links, and in the Honda's K-series, it's the transmission. Had I stuck with a stock solution, it might not have been an issue (though even normally-aspirated engine builds are running into trouble.) There are solutions, in the form of straight-cut gears using either OEM syncros or even a dog-engagment setup. That's the big benefit of Honda, tons of aftermarket support, but it comes at a big price.

I wonder how the gearbox holds up in the 300 hp Ariel Atom...

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Re: Kurt Bilinski's build

Post by Midlana1 » 13 Dec 2009, 21:32

Turns out there's a switch input on the Hondata ECU that selects one of two boost-by-gear tables. Great... one will be set to very low boost for normal driving, and maybe even track use, at least initially. Handling has to be tested before going nuts with power.

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Re: Kurt Bilinski's build

Post by Midlana1 » 16 Dec 2009, 16:10

Debated the outboard shock vs. push-rod setup (in a separate thread elsewhere.) The decision's to have provisions for both, with most of the book focusing on the push-rod since it's more involved. Builders can choose which they prefer.

The upper A-arm is changing; the tie-rod end presently used as the top upright pivot will be replaced with a spherical bearing, and the rear leg of the A-arm will be a separate tube, attached via a reverse-clevis to the forward tube. Both upper and lower inboard pivots are being changed from horizontal to vertical to get rid of the kinks.

All this is slightly more work but I realized in the quest to make the car easy to build, safety was being compromised. Can't have that...

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Re: Kurt Bilinski's build

Post by Langan » 16 Dec 2009, 20:48

Thanks for the change I agree with it 100%

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Re: Kurt Bilinski's build

Post by Midlana1 » 16 Dec 2009, 22:13

Man, all my internet buddies are offering their own versions of "That's the worst looking A-arm I've ever seen!" Yup, it is. I built it, listened to input, don't like it myself, and changes are being made. If only everyone would accept design input - both good and bad - and get on with things.

Hey, maybe I'll take down the picture of the offensive A-arm and claim it never existed...

I'll be making a new arm tomorrow and that'll be that.

Who needs enemies when...

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