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Sidewinder. Should It Stay Or Should It Go.


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Ever had those toys that were such a large part of your earlier life but times change as you get older and now you look on and think maybe someone can as I always said about my Sidewinder, "have more fun than man is ever supposed to have".

How this machine come about was the birth of my oldest son that is now 24 years old. I was always into dirt bike riding in the states forests. Had been enjoying this sport since a teenager but there was one day in particular shortly after my son was born, a mate and I were in the Jenolan State forest riding our bikes and looking down at the speedo of my 84 Honda XR 500 with a brand new 580cc Wisco big bore kit I recently installed, ( certainly no slouch), realised we were doing over 100km/h along a very familar firetrail covered in rocks zipping past full sized pinetrees less than 2 meters each side of the track. One rock moves and your probably hitting a tree.

I got this sudden overwelming feeling, what if I crash bad, not something I ever did but one day your luck does run out. It wasn't the fear of dieing, if you have thoughts of dieing, you would never do this sport in the first place. It was more being paralyzed as a young father that scared me. I thought I owed my son better and simply slowing down and being more cautious was something I knew I couldn't maintain so I needed an alternative to a dirtbike that would still have me out in the wilderness that could go as fast but with a roll cage.

That was how the Sidewinder come about.

I saw some plans for sale for a single seater buggy called a Sidewinder in a People magizine and took a chance and bought them. The plans were from WA but it was designed as what I would describe a sand buggy and limited to a 250CC motor. As my intent was not for sand but very rough NSW firetrails, Iooking at the plans I realised I could beef this thing up, mainly through gusseting but also using thicker guage steel tubing so it could handle the much harder purpose I had for this machine.

The intent was to always to install up much larger motor as well and I also wanted it much safer. The plans only had rear brakes and while this was probably OK for sand dunes, certainly not suitable for some of the rocky downhill trails I knew the NSW forests were capable of handing out.

I also didn't like the idea of one brake line being ripped off meant no way of stopping this thing so I designed front brakes as well on a split braking system so if you lost the front or rear brake line, you had a backup and at least had a chance of stopping.

The original plans had HK-HG holden drum brake hubs on the front with no brakes on the cutdown Holden stub axles. I changed that for HK-HG solid discs I machined down to a smaller diameter and machined to just 7mm thick that allowed the 1000cc Kawasaki bike calipers I bought to go over and designed caliper attaching mounts to the stub axles.

A twin master cyclinder from a car, reshaped steel brake lines from a car cut and shaped to suit the buggy and I now had brakes I was happy with. Exceptional brakes actually. Never had a problem with those brakes and found them better than any car I owned actually.

As for the motor. I originally threw in the 500 now 580cc Honda motor but quickly found to restart, you had to get out and kickstart it. this had to go, I wanted and electric start.

Looked in many bike wreckers and come up with an Ex army Yamaha Tenere motor with only 600kms on it. Didn't even know there was such a thing but it is basically a XT660cc single with an overdrive 5 speed gearbox but more importantly, an electric start.

Bought just the motor, wiring harness and ignition modules. Needed the harness for the plugs as I was always making my own harness but didn't like the idea of tracking down plugs to suit a Yamaha.

Pedals come from a HQ-HZ, clutch, brake and accelerator pedals but were cut to half length to fit. Clutch was cable, brakes were twin hydraulic and accelerator pedal was twin cable with spring return. Didn't like the motorbike twist grip for the accelerator, bike brake handle and bike clutch handle the original plans had.

Gear shfter lever come from an arcade Afterburner cab, a TBar with rubber handle and a solid bar linkage with turnbuckles back to the bike motor sequecial gearbox. Again, didn't like the original design bike gearshifter that required you to stick your arm outside the machine and reach down to change gears.

Fuel tank was supposed to be a fully seam welded sheet metal plate design that I did build but wasn't happy with it's very limited fuel capacity and no safety devices. It was just a vented cap, with a welded pipe for attaching the fuel line to the bike motor carburetors. It also sat directly behind your head so it could gravity feed the bike's carburettors. I went for a 20 liter jerry can on the opposite side of the buggy frame to the motor to offset the weight of the motor, a part of the frame that wasn't used. I used a Farc electric fuel pump that feed a small 1/2 liter tank that would fill but not pressurise and then feed excess fuel back into the jerry can. The half liter tank had a pipe at the bottom that allowed a gravity feed fuel supply to run the motor with excess fuel the fuel pump supplied going back into the main fuel tank.

The upper tank wasn't vented so if you put the machine on it's roof, (did that a few times), you wouldn't get covered in fuel coming from the cap vent. The main fuel tank was vented but i put in a, similar to a PCV valve, that if the machine went over, the ball bearing would shut off the vent and not spill fuel on you under or beside it. The fuel supply line from the main tank to the 1/2 liter tank alos had a boat squeeze bulb in the fuel line so if the fuel pump died, you could manually pump this bulb and keep fuel getting to the upper tank and keep the machine running. Not for safety, just so you didn't have to push.

This boat fuel idea did actually get used once. 180kms away from the 4 X 4 and trailer we used to get the machine into the state forest and our camp site, the fuel pump did die with no way of recovering the buggy if it couldn't get out under it's own power.

The rear axle was solid 1 1/4" 60 ton torsional rated bar. I had to order that and get it keywayed to suit the rear holden wheel hubs, drive sprocket mount and rear disc brake mount. The guy I ordered it from thought it was to wide for a Harley Davidson trike which was about the only thing people used such a strong bar for. The rear axle was that strong so you could jump the machine which it did many times without failure.

Steering was a modified and shortened Mini steering rack and pinion assembly, Had to cut the housing and shorten the rack cutting it about 250mm shorter and welding the rack back together, file finish the teeth on the rack so it couldn't bind. I surprised myself I actually achived that first time around. Rod ends and drag links by original design were factory Mini parts. I broke 5 of these fortunately never in a place I couldn't recover the machine from till I converted these parts from 3/8" mini parts to 13mm Toyota parts. Never had a problem again however I always carried rod ends, drag links as spares along with two spare drive chains, spare cables for accelerator and clutch cable, spare CDI box, spark plug and ignition lead. Never did have a reason to use these spares except the drive chains. Ended up changing these and the sprockets for 1000cc Kalwasaki parts but again, always made sure I had a spare.

Seat was from a Mazda RX7 and was vinyl so rain didn't effect it and I installed a 4 point racing harness.

All the electrics in the harness were double circuited so everything had a backup circuit should the main wire fail. Last thing I wanted was tracing wiring failures in the wilderness and I also used circuit breakers rather than fuses so you could rest rather than needing spare fuses.

I put some driving lights on it, brake light and a large car battery so at night, it floodlight the forest but also lighting that lit up the machine when needed for repairs at night if need be. Never did need those but good insurance.

Made a sheet metal toolbox, like a boot for a car and made a steel frame on it's lid. We used that frame many times for things like a tent and camping equipment when we started travelling deep into the forests for overnight stays well away for the main camp and 4 X 4.

I used that machine for over a decade after building it which took 18 months from the plans and probably 1 year of modifications to make the machine better to it's near bullet proof design it is now.

What stopped me using this machine was my mate I went in the forests with suddenly died so no more 2 weeks at a time annually in places like the Cooma wilderness area, that was our favourite but also the Janolan State Forest, The Snowy Mountains National Park and Victoria's Alpine National park were places we would ride this machine.

I did still continue but on day trips on my own but it simply wasn't the same nor as safe going to such isolated places on your own with no backup motorbike just in case.

A year after his death we bought the farm and the wife refused to let me take this machine and leave it there fearing it would be stolen. It is a rather in your face machine and is rather loud.

The machine's colour I choose was dark green because I learnt cammo does help after owning a Honda bright orange XR and it wasn't unusual to have National Parks and Wildlife helicopters suddenly appear in the sky over us as doing this shit we loved was pretty much illegal and our vehicles were certainly not registered.

Back to where this post all started. My son, the one that actually created the reason for me to build this thing originally and get off the bikes wants to buy it off me. I say buy but it would be more a gift with him simply paying for it's upkeep and possibly replacing parts that time hasn't been kind on.

What to do?. Keep it in the family or move it on. As much as I'd like him to have and enjoy it and I have made this machine as safe as I possibly could, my mate and I did clock this thing at 120km/h and it was still accelerating, I just ran out of the emergency RAAF dirt runway that is in the middle of one of the forests I mentioned so it is quite capable of killing you. I only ever hit a tree at 60km/h when a rod end failed and it bounced off with little more than a scratch however it fucked me up bad with a bruised liver for about a week. I also rolled it 4 times on another occassion and got out laughing.

I have a couple of old pictures of this machine from trips we did in the forests I'll put up when I find them if your interested.










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Comerang near the Tuross River NSW...



After a very step climb we attempted the previous days but snow prevented us getting here. Not the buggy, my mate's motorbike but this day success. He went up first and took this picture of me coming up the last hill...



End of the trail. Didn't bring a chainsaw and impossible to cut a path around this tree so we set up camp just back behind this pictures location. Cooma Wilderness area. pretty sure this was the last forenight trip we ever did together. I came back the following year by myself for a couple of days and drove the buggy, can't get 4 X 4s here, to this exact place and had a drink to him..






Edited by Autosteve
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  • 3 weeks later...

Keep it for the memories. My dad has stuff longer than i been around and each has a memory of importance linked to its past. I remember them plans. Dad still has some somewhere for the amphibious 6 wheeler.





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Arr the 6 wheel drive. Noot story there. I was well underway making one after building the buggy. A machine the wife and kids or whoever could come remote camping and just a damm fun machine but then we bought the farm. Best machine for the farm was quads and the farm, building the farmhouse took all my spare time so the 6 X 6 was one project I never did get to finish.

He's some pictures of it during the build before I stopped....






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