It's like it popped out of my head.

I'm getting the itch to build something fast with big suspension travel - but not on a massive scale. Think of a scaled down Class 1 racer, with a much lower budget. Use Miata uprights, a FWD drivetrain in the back (or Subaru, 818-style) and just scale everything down a bit.

Around here, we have a huge amount of desert available, both tracked and wide open. There's also quite a bit of rock crawling (it's not that far to Moab) and I think this would be fun for blasting around on rough roads and over the hills.

This thing popped up on eBay, it's the same sort of thing I was thinking. I'm not sure the 'Busa engine is the best choice here, although it doesn't need to be geared for 200 mph and it would save weight. Thoughts?

http://www.ebay.com/itm/Hayabusa-Full-Blown-Off-Road-Class-10-Race-Buggy-/171266727598?ssPageName=ADME:B:SS:US:1120

Insane levels of awesome. I can already see this thing with a huge "BRAWNDO - THE THIRST MUTILATOR" decal down the sides.

Any idea how much power you want to get out of her? As hefty as the Hybusa engine is, I think for the power, it's a great option. Is less power and slightly less weight a better option?

I'm thinking that torque would be more useful than screaming power, but that's what gearing is for. It's certainly easier to change the gearing when you've got a chain drive like this, something like a Subaru 2.5 might be geared too tall even if it has the low end the Busa doesn't. I wonder how that Busa clutch would deal with having to climb a steep hill.

Every time I've pictured a bike engine version, I've pictured something more scaled down than this. But I'm not sure if I'm right about that.

To be clear, I'm not really considering buying this. It's just the closest thing I've seen to what I was thinking of. Most smaller buggies have a VW front suspension, but I want more travel than that.

Keith Tanner wrote: Every time I've pictured a bike engine version, I've pictured something more scaled down than this. But I'm not sure if I'm right about that.

I have to agree... bike engines are just not designed to deal with the same mechanical issues that 4 wheels represent.

Besides the subby option... there is always the flipped transaxle VW air cooled option as well... not the highest tech... but you can get good power from it... you don't have to worry about coolant loss, and you don't have to reinvent the world to make it work

Take a locost frame and apply longer suspension links/shocks.

Win?

Keith Tanner wrote: I wonder how that Busa clutch would deal with having to climb a steep hill.

Would a GSX-r be a better option?

With as much torture as the clutch will receive, I'd bet it will need something a little different.

Apexcarver wrote: Take a locost frame and apply longer suspension links/shocks. Win?

Other than the front engine aspect, maybe. It's interesting to note that buggies are always mid- or rear-engined, even when not built out of an old VW. There must be a reason. Traction, possibly. I'd love to be educated why.

Keith Tanner wrote:

Apexcarver wrote: Take a locost frame and apply longer suspension links/shocks. Win?

Other than the front engine aspect, maybe. It's interesting to note that buggies are always mid- or rear-engined, even when not built out of an old VW. There must be a reason. Traction, possibly. I'd love to be educated why.

I would think that the rear-weight bias would make them less likely to "nose-in" on whoops. This would likely be the worst type of crash in open desert runs?

I would think along the same lines as NGTD. It reminds me of watching SST at the stadium. Those trucks are mid-engine and still like to nose down.

i can dig it......

Looks like a great idea. With the 'busa engine, it won't be great for rock crawling and you'll need to get a running start at hills, but it'll be great for high-speed desert driving. I'd be most worried about the oiling system, stock 'busa motors are known to starve easily when put into 4-wheeled vehicles. A high volume oil pump will make starvation easier.

Edit: If the 'busa engine blows up put a Suzuki G13/G16 series in it. A G13A may struggle to get a vehicle up to highway speeds, but they're ultra simple and reliable, light, and never get oil starvation in a longitudinal arrangement, not bad on gas, and they'll take you to the same speeds offroad or drive the vehicle up a wall from a standing start.

How fast do you plan on going? With gearing so the top end is 50mph instead of 200mph I bet that engine would have no trouble pulling anything up a hill. Clutch abuse? You'd hardly use it! Fully engage the clutch at 0.5mph and the rest would be done with the throttle. I guess if it started slipping due to being overpowered you'd end up with clutch trouble.

But I like your idea of something a little more scaled down. Then again it's hard to get a scale on the eBay auction one.

N Sperlo wrote: I would think along the same lines as NGTD. It reminds me of watching SST at the stadium. Those trucks are mid-engine and still like to nose down.

Didn't Galileo have something to say about weight and the speed of a falling object? Trophy trucks are front engines. I agree that auguring in is something that would be best avoided.

So, apparently this is Class 10 MC. I think I know what MC stands for. Weights around 2000 lbs, which surprises me.

Here's a Class 10 video with a surprise ending. Or maybe not a surprise. Definitely sub-optimal.
http://www.youtube.com/watch?v=kPsYIsto5Us

A build diary with some layouts of a frame here. Offroad guys do some nice fab work.
http://racingsouthwest.com/forums/topic/65148-class-10-mc-race-buggy/

This is a nice deep rabbit hole. There's some interesting stuff here with regards to suspension design - they apparently look for minimal lateral displacement of the contact patch over the range of travel, amongst other things. I'm going to have to learn what "axle plunge" means.

ooooooooooo https://www.youtube.com/watch?v=13rELGs_ZLE

DaveEstey wrote: ooooooooooo https://www.youtube.com/watch?v=13rELGs_ZLE

I was about to post that

Looks like he has a whole bunch of videos. Make that a two-seater and it's just about perfect.

https://www.youtube.com/watch?v=Ho0v1vw7wTY

Check some off road racing websites for cars for sale. Even with a little wear, they are usually already sorted and are a blast to drive. Two seaters from class 10 are cheaper. Are you going to go real far from your tow vehicle? If not, you can lighten up a desert car by forgoing any tools or too many spares. Try to find a short course 1/2 1600, air cooled, decent suspension travel, best of all, simple.

Couple of general comments that you probably already know about - and I admit, I'm several years out of date on my off-road buggy info, so this isn't very up to date. You can get a lot of travel out of a VW trailing arm front end, partly by resetting the torsion bars (or replacing with coil overs) also by installing longer trailing arms. Downside is that unless you're careful about setting them up, you can get some pretty significant bump steer effects. Also, if you're used to power steering off road (like I am, I'm a wuss these days),your arms will take a real beating in rough terrain. I remember the year (long, long ago)I brought my wife's Baja Bug up to the San Juans, it worked very well, but with no power (it was a big bore 1192) I had to charge some of the rocky climbs, and boy, did my arms know it the next day. Bought a 4WD Toyota the next year and returned the Bug to street use.

For gears, an early Bus transaxle with reduction gears can help, if you want IRS (and again the aftermarket has trick trailing arms) just use a really torquey engine if you're aiming for low-range-and-slow type driving. As you know from your Westy, you can swap anything onto a VW transaxle.

An advantage of building on a regular 2-seat buggy rail frame is that you can license it, which helps if you're in an area like the San Juans where you can't get from one trail to the next without going on public roads - like over at Lake City. And you can tow a VW based buggy with darn near anything, fix it with a hammer, and spares are everywhere.

Yamaha V-Max engine?

Power 113.5 hp (84.6 kW)[1] Torque 83.1 lbf·ft (112.7 N·m)[1]

Keith Tanner wrote: Looks like he has a whole bunch of videos. Make that a two-seater and it's just about perfect. https://www.youtube.com/watch?v=Ho0v1vw7wTY

Are you capable of fabbing that guy up?

Axle plunge is the difference in the distance from the gearbox output to the outboard drive flange, between max and min travel. This is what the reduced lateral displacement is about. You don't want to have to sort out CV/tripod joints with huge amounts of plunge clearance because of the clearance needed on the inside of the hub (inside the rotating bits).
Some of the longest suspensions I have seen actually have the inboard pivots across centerline, with the suspension links crossing over each other...

Here's a Class 10 video with a surprise ending. Or maybe not a surprise. Definitely sub-optimal.

Yeah, maybe not a surprise given the behaviour of the vehicle over several of the smaller humps. I think the attitude of the vehicle coming off a jump has more to do with the suspension setup than where the weight is. Stock pickup trucks are horrendous about this because the rear suspension is designed to carry literally a ton of weight that isnt in it when you take it off a jump, so the excess rear spring launches the back off the jump much harder than the front and you nose in. This is not an inherent behaviour to the vehicle layout, but tuning it out results in a relatively squishy rear that would need to be made up for in other ways if you wanted the vehicle to do something other than land a sweet jump. It seems like a pretty complicated setup challenge unless you are just designing the vehicle to do that one thing and basically nothing else. Maybe then it's not so bad.

Make first a crawler gear and 2 your primary launch gear and that thing would be insane.

Mickey Thompson had a front engine buggy in the 70's, might have been a v8 if I remember right. If you build your own, take the time to properly set up the buggy to jump, otherwise bad things happen. The one I raced in the late 80's had the rear soft and front was stiff. This gave us, for our particular car, a nice flat launch off the jumps. We only had the torsion bars for springs and could set our preloads. We ran a 2/ 1600 in short course in the midwest. That meant no coil overs.