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Login to post Forums » Grassroots Motorsports » 3/4 scale Class 1 race buggy

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June 14, 2009 7:55 p.m. Keith UberDork

We don't have a whole lot around here in terms of racetracks. There's a kart track here in town that runs track days for cars when I organize one - nobody else has done one for years. Otherwise, it's a 5-6 hour drive over several 10,000' passes to get to anything.

But we have a bunch of desert. Interesting desert with bumps and creases in it, and we're right next to Utah that is something like 2/3 public lands.

So I've started thinking about high-speed off-road rigs. Not Baja Bugs, although there are a few of them around here. Not a sand rail, as I'm not sure how they'd deal with our more difficult terrain. But a 3/4 scale version of a Class 1 Baja race buggy.

The real thing is powered by an LSx motor, usually - of course - and is relatively large as far as I can tell. They're also expensive naturally. I'm wondering about building one with a FWD powertrain in the back and everything scaled down a bit. Keep as much of the 22" of suspension travel as possible, but a lighter weight means less stress on, well, everything. I'd also like to be able to put it on/in my normal trailer. I'm not sure that could be done without making the track too narrow. Obviously, shocks are going to be a major expense. I'm not interested in something with a VW suspension designed pre-WWII, but niiice long control arms.

Call it a Locost Class 1. I figure it could be huge fun around here.

Anybody build anything like this? Ideas? Comments? Suggestions? Think I could make it street legal with some lights and removable cycle fenders? Right now it's a thought experiment, but that's how these things start...
June 14, 2009 7:58 p.m. griffin729 New Reader

IIRC, there are some buggies out there similar to what you're talking about. If nothing else I know one of the CORR class uses a VW air cooled.
June 14, 2009 8:22 p.m. Luke Dork

Here's some photos an e-friend from another forum took, at the recent Finke Desert Race in Alice Springs, Australia. The field is divided into various classes, including those to cater for smaller capacity engines. The 20V 4AGE was a very popular choice, along with VTEC Honda motors, L-series Datsun engines and SR20's, FJ20's etc. I would've thought, for this kind of racing, you'd really want the torque provided by a big honkin' V8. But I guess if you keep the overall weight down, it doesn't matter so much.

20V 4age Buggy - http://www.youtube.com/watch?v=Fwg9rHc_qtU

V8 Buggy - http://www.youtube.com/watch?v=ZkTblzGavNc
June 14, 2009 8:30 p.m. Keith UberDork

I'm actually going to be in Surfer's Paradise, Queensland in less than a month. There's a V8 buggy driving experience setup there if I feel like dropping the coin on it.

Thanks for the pictures - but they're still running torsion bar suspension. Check out the ground clearance of that one in the first pictures I posted. I'd want to build something with massively long control arms for maximum travel.

The engines are mounted backwards. Any idea how they're turning the drive around? I'd think a mid-engined setup might be superior to that sort of rear engined layout, I wonder why?
June 14, 2009 8:54 p.m. Luke Dork

Keith wrote:

The engines are mounted backwards. Any idea how they're turning the drive around?

I think a lot of the 4AGE powered vehicles utilise VW Kombi gearboxes with strengthened internals.
June 14, 2009 8:56 p.m. ReverendDexter HalfDork

Keith wrote: I'd think a mid-engined setup might be superior to that sort of rear engined layout, I wonder why?

I would think backweighting would keep you out of trouble, much like getting "behind" the saddle when you're going downhill on a mountain bike.

I'm also wondering if it helps with the car's balance when jumping, or landing from jumps.

Could also have to do with how wide a FWD drivetrain would be. That extra width would cause bind at much lower amounts of articulation.
June 14, 2009 9:15 p.m. Keith UberDork

I can see that - a transverse gearbox would mean short halfshafts, relatively speaking. Hmm, I know a lot of Audis hung a longitudinal engine out in front of the gearbox. How about one of the reverse-rotation Hondas hooked up to say, an A4 gearbox?

All the Baja unlimited buggies hang their engines out the back, so it must be what works. I've done a lot of mountain biking over the past 20 years, so the analogy works for me!
June 15, 2009 6:33 a.m. Jensenman MegaDork

How about using a Subaru drivetrain, thus putting the engine in the middle?
June 15, 2009 7:31 a.m. RossD Reader

I am guessing thats its not so much as it is the best layout as much as convention. What with all the beatle parts used in the past. A mid engine will work.
June 15, 2009 7:58 a.m. chaparral New Reader

There's a "kart track in town" and that's not your main form of motorsport? Seriously, call Doug at Shockwave in Arvada and get yourself a shifter.
June 15, 2009 8:01 a.m. alfadriver HalfDork

griffin729 wrote:

IIRC, there are some buggies out there similar to what you're talking about. If nothing else I know one of the CORR class uses a VW air cooled.

+1-

I'd take a very long look at the CORR rule book to find a class that has cars that you are thinking of. While their cars are expensive, I think building and designing your own will be far more so. While you are thinking "locost", there's no reason why a good fabricator can't copy a pretty decent design of a current platform.

As for the FWD "worries"- remember that many of them have the drive out of the rear bank of the engine, and it's fairly narrow at that point- possible to make some stub shafts that connect to some very high angle CV joints.

Another track to think about it a mini truck- say a Ranger, S10, Toyota kind of I4 or V6 powertrain. It's still a tube fram that you need to make, but actuating a live axle through 42" is easier than an independent set up that's intended to drive wheels from a short axle. Just a thought.

(the live axles I've seen were 4 link- basically a HUGE version of a Fox Mustang rear, with all 4 arms very long. Worked incredibly well- the team I worked with won Baja a few times with it)

Ok, thinking out loud- the more I think about it, the more "locost" it becomes- find decent donors- among the millions of Mustang rear axles out there, and design up a long wheel base Locost chassis. Basically, beef up the existing design, and push the wheels out a LONG way.....

Hmmm.

Eric
June 15, 2009 8:07 a.m. CrackMonkey HalfDork

Are you going to build the frame from scratch, or are you looking for a semi-pre-fab, where you just pick and engine and slap it in? Will it be raced, or is it just for play? Not that I know anything about buggies or off-roading, just curious.

Also, I would imagine somebody builds a sandrail with enough suspension?
June 15, 2009 9:55 a.m. Keith UberDork

RossD wrote:

I am guessing thats its not so much as it is the best layout as much as convention. What with all the beatle parts used in the past. A mid engine will work.

I don't think convention has a lot to do with a modern Class 1 desert racer. They're going to a fair bit of effort to hang LS7s off the back of these things, so the engine could go wherever they want.

This would be for play. I'd love to build the whole thing from scratch, especially as I can't find a class that would be appropriate for the sort of thing I'm thinking of. The Class 1 buggies are big - big engines, big wheels, etc. I'm thinking a bit smaller, but I'm not sure how small I can go without having to limit my suspension travel due to a too-narrow track. I think the exercise of building a high-speed big-travel rig like this would be really interesting, though.

Using a mini truck as a base turns this into a Trophy Truck - you'd have to run front engine. I haven't seen any frames for sale that do the sort of thing I want to do, they either seem to be VW based or there are a few full-on Class 1 frames for sale that have very high price tags. Besides, the best off-road rigs are built, not bought

Another obvious transmission choice is Porsche. Duh. A bit more expensive to find than a VW Passat though.
June 15, 2009 10:08 a.m. Wally UberDork

Keith wrote: Using a mini truck as a base turns this into a Trophy Truck - you'd have to run front engine. I haven't seen any frames for sale that do the sort of thing I want to do, they either seem to be VW based or there are a few full-on Class 1 frames for sale that have very high price tags. Besides, the best off-road rigs are built, not bought

For a while Ivan Stewart ran a mid engined Toyota pickup.
June 15, 2009 10:38 a.m. petegossett Dork

Hell, it might be worth it to track down Ivan's shop's contact info & give them a call/email. You have enough clout in motorsports they'd probably be willing to talk to you & give you some feedback/input.
June 15, 2009 10:53 a.m. sachilles Reader

A friend of mine recently bought a sand viper. Impressive little machine. You definitely want a full face helmet when driving one. He brought it a local rallyx course that was hosting a eurostyle rallyx. It looked far smoother on course than most of the prepared subies.
June 15, 2009 11:25 a.m. alfadriver HalfDork

I still think a basic off road front engine live rear axle can be built based off of a Locost design. Use one of the widebody chassis, double the tube size for most tubes, longer and wider wheelbase, and it's not all that hard to fabricate.

Especially if you do a 4 bar set up similar to a Mustang. I wish I had a photo of the truck I was lucky to help with, but that's what they had and it worked in spades.

With a mustang rear, there's no reason you could not use a 4 cyl set up.

How heavy is a basic locost chassis? And how much heavier would it be if you kept the wall size the same, but doubled the size of the tube? (probably double, right? With that, a simple body would work just like the above chassis.

BTW, not only a full face helmet, but filtered and cooled air. Or at least filtered.

Eric
June 15, 2009 11:28 a.m. jeffmx5 New Reader

Have you looked at the motorcycle powered buggys? I remembered coming across these in the past - quick googleing -

2-seater with 19"/20" of suspension travel, 112" wheelbase 90" track Hayabusa power Sinister Sand Sports

first hit on google: http://www.minibuggy.net
June 15, 2009 11:35 a.m. DWNSHFT New Reader

The rear engine location is going to help you put power down, a la 911. But, not knowing anything about offroad, that there might be something about how it flies and lands. But the trophy trucks do it front engined, right? So either way you can work around a mid engine.

David
June 15, 2009 11:48 a.m. amg_rx7 Reader

DWNSHFT wrote:

The rear engine location is going to help you put power down, a la 911. But, not knowing anything about offroad, that there might be something about how it flies and lands. But the trophy trucks do it front engined, right? So either way you can work around a mid engine.

David

I think they are all mid-engined.
June 15, 2009 11:54 a.m. RossD Reader

Okay, so looking at the pictures above, it looks like you could hide a rear engine inside of a production sized truck bed. Why dont the trophy trucks have them rear mounted? Or do they?
June 15, 2009 12:05 p.m. wherethefmi HalfDork

Like this?!?

http://www.fiberspec.com/DooleyMotorSports/
June 15, 2009 12:15 p.m. Keith UberDork

Jeff, thanks! That's the sort of thing I was thinking of. Something with some real front tires, maybe, but I hadn't come up with the term "mini buggy" yet. Or at least, not with that sort of layout.

Love the Sinisters. This is basically what I was thinking of, but with a car engine. Motorcycle engine is an interesting idea though - if the whole thing is light enough, maybe the lack of torque wouldn't be a problem. They also gear them down significantly. Some great frame design shots on that website. Their specs say 1200 lbs, as opposed to a Class 1 baja racer weight of 4000 lbs or so.

Yum:

Other than being a space frame, I think this would be far enough from a Locost that there wouldn't be much point in trying to start from published Locost frame designs.

We don't have that much pure sand around here. Here's the sort of thing I can play on:
June 15, 2009 12:23 p.m. alfadriver HalfDork

RossD wrote:

Okay, so looking at the pictures above, it looks like you could hide a rear engine inside of a production sized truck bed. Why dont the trophy trucks have them rear mounted? Or do they?

Of the SCORE trophy trucks, I don't know of any of them that run an independant rear. And like any driveshaft- you need a decent lenght to make sure that the angles are not too much.

BTW, it is legal to run IRS, but it's a lot easier to have HUGE wheel travel on the driven wheels via live axle.

Eric
June 15, 2009 12:27 p.m. Keith UberDork

Class breakdown:

http://www.desertrides.com/reference/racing_classes.php

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