Sidewinder build

Sidewinder build

Postby DaveEstey » Thu Sep 29, 2011 12:41 pm

Tracey likes the Miata too much for me to put a full cage in it so I'm undertaking a more advanced build with her blessing.

I was going to keep this under wraps but I want to make sure I'm not building something that won't pass muster.

Over the winter I'm starting a project for a dedicated car using a Yamaha R1 engine similar in design to this:

Image

I'll be using Miata parts wherever possible (brakes, hubs, differential) to keep costs down and to work with something that's a known quantity/quality.

Aside from the obvious lack of a roll cage in the pictured vehicle, something I would have in mine, are there any inherently bad ideas with something like this as a hillclimber?

I'm particularly interested in concerns about the engine being next to the driver.

Thanks ahead of time,
Dave
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Re: Sidewinder build

Postby jkale » Thu Sep 29, 2011 5:10 pm

I just cant imagine hitting a tree like I just did with the engine in between me and the cage..

..But looks like a cool project
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Re: Sidewinder build

Postby walterclark » Thu Sep 29, 2011 6:25 pm

I would put the engine behind me and use the side-side space around the driver as crush space in the event you have happen to you what Joey had happen to him at Ascutney.

From a safety standpoint - other than the cage as you noted - be sure the engine bay has covers to prevent anything that otherwise might spray on you in the event of a failure, mount the fuel cell in as a protected location (s) as possible, dont run fuel lines thru the cockpit and keep them away from sources of heat and sparks (like a shorting battery cable), especially consider how things would fail in a crash and try to keep them from hurting you.
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Re: Sidewinder build

Postby sdwarf36 » Thu Sep 29, 2011 6:41 pm

An R1 would lend itself to doing this nicely-the trans gears are "stacked' making the motor very short front to back (as its in the bike.) I'd like to see a picture of how the motor drives the rear axle-what I'm picturing is a severe driveshaft angle at rest-and when the suspension compresses it puts the shaft in a totally different plane.
Translating road racing to hillclimbing:
Proper tire selection== nothing hooks up on moss or wet leaves.
Staying on the racing line==anything paved is considered good.
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Re: Sidewinder build

Postby DaveEstey » Thu Sep 29, 2011 8:22 pm

The engine will use a driveshaft adapter made by Hawk before running through a Spicer PTO to the Miata rear diff (4.11 LSD) then through Miata rear axles to drive the wheels. Top speed will be gear limited with my rubber to less than 120mph unless I manage to find a taller Miata final drive (I think there's a 3.90 out there somewhere) The rear diff is solid mounted so there won't be any movement for the shaft angle to change but you're correct in thinking it will be a sharp(ish) static angle. So far the guy who built the above car hasn't had any issues with shaft longevity (giggle).

As for crush zones. My chassis is going to be based on a locost 7 chassis with the front end dramatically shortened to the point where there's room for the steering rack, brake M/C's and an 8 gallon fuel cell. The battery and radiator will be mounted in the rear.

Long story short, my chassis will be wider than the above vehicle which means more room between myself and the engine. I'll also run a spine down the center of the chassis for strength and to put a substantial barrier between myself and the engine. The cage will be 1.5" x .090 DOM which I feel is plenty beefy for a car with a target weight of 1,000 lbs.

Another thought is to add something akin to beefy nerf bars on the sides to serve as crush zones, likely with 1.25" tubing.

Thanks for all the feedback.
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Re: Sidewinder build

Postby sdwarf36 » Thu Sep 29, 2011 11:29 pm

Unless you run a tall tire (bigger than 72") you will just make 100 with even a 3.90. I'm on the limiter with a 3.58 at the end of the straight at Okemo at 114mph.
8 gallons? What-you just want to fill up once a season? :lol:
I'm wondering what the rear weight is-I'm 57% with the motor in front.
Translating road racing to hillclimbing:
Proper tire selection== nothing hooks up on moss or wet leaves.
Staying on the racing line==anything paved is considered good.
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Re: Sidewinder build

Postby DaveEstey » Fri Sep 30, 2011 7:51 am

I'll be autocrossing and eventually road coursing it so I figured an 8 gallon cell would be a good compromise.

The pictured car was (if I recall correctly) 60% rear weight.

Edit: Found the info.

"57.6% rear weight and 49.7% left/right with driver"
Last edited by DaveEstey on Fri Sep 30, 2011 9:28 am, edited 1 time in total.
1987 Mazda RX-7 GXL (Hillclimb)
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Re: Sidewinder build

Postby 3rdgendennis » Fri Sep 30, 2011 8:09 am

FWIW, look up the weight difference in DOM 1.5" and 1.75" tubing. Its not much, and the 1.75" would be safer....Josh and I originally planned for 1.5" tubing, but on paper, the weight difference was so small, we opted to go the safer route.
http://mobile.pirate4x4.com/forum/showt ... p=10190074
1.75x.095= 1.596 #/ft
1.5x.095= 1.426 #/ft
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Re: Sidewinder build

Postby DaveEstey » Fri Sep 30, 2011 9:22 am

That's a good point and a great link. I'll keep that in mind when I call in my metal order.
1987 Mazda RX-7 GXL (Hillclimb)
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