building a dirt buggy

[EddieWalker]

Renze,

It's really starting to come together!!! The way you have the roll cage built, it almost looks like you should be pretty safe if it rolls. Of course, five point straps are what will make the difference of keeping your arms or head from being crushed if it ever happens. I've been in two rollovers and both times, it happened so quickly, there was no way of keeping my arms in place. One time I was straped in and kept safe, the other time I was drunk on a beach in Bali and flew out onto the sand.

Eddie

 

[Renze]

Renze,

It's really starting to come together!!! The way you have the roll cage built, it almost looks like you should be pretty safe if it rolls. Of course, five point straps are what will make the difference of keeping your arms or head from being crushed if it ever happens. I've been in two rollovers and both times, it happened so quickly, there was no way of keeping my arms in place. One time I was straped in and kept safe, the other time I was drunk on a beach in Bali and flew out onto the sand.

Eddie

Someone suggested welding a 1" pipe in the angles of the main hoops of the rollbar, to make up for the loss of strength due to the kinks from the 3/4" pipe bender radius in 5/4" pipes. I think its a good idea to weld some pipes here and there, not just for strength but also to grab on. In case we scratch a tree in the bush with one of the side pipes of the passenger cage, the fingers are around a handlebar inside the cage, instead of wrapped around the outer pipes which means the fingers are on the outside of the cage, unprotected.


I still need to add a crossbar in every square, to get the rigidity and stiffness i want... But i want to do that AFTER i have the buggy resting on its own springs.
As long as no triangles have been added, i think the buggy will settle itself so that equal weight is on the wheels left/right, while bending into positon as it is slightly tordated now.
Then i'll start welding the triangles, so i give the body its torsional strength from a start point where all wheels rest equally to the ground.

With a project like this, with so many bends and angles and radii, it just doesnt work measuring an angle and then saw that angle on the band saw, you'll just have to get yourself going with the angle grinder and bench grinder, untill the pipes fit in place.

 

[dbdartman]

Good idea, the inboard grab handles! Keep the hands & feet INSIDE where they are safer. Foam pipe insulation might be a good idea around passengers also. Pad where the arms, legs & especially heads may meet bars.

Not sure what to do about the front springs. Adding weight seems counter-productive to me, but since this is a low cost play toy any alternative would likely be much more expensive or involved. What ever you do, DO NOT cut the springs shorter. This will only make them firmer!

 

[have_blue]

Renze, I came in late, but your project is fascinating. I have always dreampt of designing and building my own buggy. I got the hair brained idea that I would use tires and suspension from 2 125-175cc dirt bikes, and an air cooled engine from a larger street bike.

I'll be waiting hungrily for your next installments.

 

[Renze]

Good idea, the inboard grab handles! Keep the hands & feet INSIDE where they are safer. Foam pipe insulation might be a good idea around passengers also. Pad where the arms, legs & especially heads may meet bars.

...I am playing with the idea of building a dashboard out of 1/3 sections of old car tires... When i bolt them together on the heels, and leave the sidewalls alone so they can belly out under pressure, they will sorta work like an airbag, just without the pyrotechnic trigger device ...

Yes adding weight will be counter productive... but anyhow, this way i can use complete car components bolted all together. If i wanted a better weight distribution, i'd have to get a Volvo 340 tranny (same as 740 etcetera) and rear axle to bolt up to this diesel, and put the motor up front and bolt the tranny directly to the rear end to get a good weight distribution..

For the average bush racing, it will do fine empty, but at high speeds on the road, i think i need to balance the weight to keep it on the road...

anyhow, i still dont have a clue about how much the engine and tranny weigh, and how much weight i have to add to make balance. Maybe a good sized battery moved up front will give enough weight distribution, because the whole bugster weighs next to nothing. this thing is so light that i dont have to add much weight to change the F/R ratio big time..

5/4" pipe weighs 2.6 kg per meter. Untill now, i used 8 lengths of 6 meter, which means that the cage so far, weighs no more than 125 kg....

 

[Renze]

I made some little progress today, but as Neil armstrong said, a small step for men is a giant leap for the project itself

I bent some pipes today and finished the rear frame. I didnt get far enough to get the spring struts in place, but i did get them carrying the buggy with help of two pieces of scrap iron tacked to the frame.

The buggy rolls on its own 4 wheels now !!!

I was able to roll it outside of the workshop, into the bright sun and take some pictures.
Now when it is moving on its own wheels, i am also able to roll it into the corner and get my hay wagon in the workshop. This is just a day of work and i dont want to postpone it untill the buggy is done.


Attached are some pictures, taken in the august sun: They are taken by the same Nokia cellphone as the others, but are a lot brighter and clearer than the previous ones.

Seeing the buggy rolling on its own wheels, is the kind of progress that encourages me to continue on the project with even more effort than before.


As you can see in the pictures, i havent locked the steering on the rear axle yet.

 

[Renze]

We made a bit of progress today:

I fixated the rear spring struts, and welded the first cross brace into the rear of the roll cage.

I also mounted the steering wheel, which on its own, was a quite simple task, however i had to get it in a position where it wouldnt collide with the pedal tray with brake booster. That took the most time, because the steering shaft needs to stick inbetween the brake and clutch pedal.

Monday i will get some more pipes from work, and weld supports for a floor pan, and also a mid tunnel between the seats, under which the electrics, clutch, brake and gear controls can go. But also to add structural strength in case of a frontal crash.

As you can see, i use an original Volvo steering wheel: People asked me why i didnt go with a fancy sports wheel: The reason is simple. The Volvo wheel is designed to decelerate a human body in a crash. The steering wheel of my friend's Honda CRX was totally bent and the steering column broke off. If the steering wheel and column didnt give, his internal bleedings would have been fatal.

 

[Renze]

some more pictures taken today with some daylight.

first image shows the steering wheel bolted to a console with some scrap threaded rods.
It needs an extra brace but i need the pedal tray in place before i can determin where it can sit.

second image shows the mounting of the rear spring struts with angle iron. I think this also needs a pipe for bracing.

3rd picture is a rear view, it shows the diagonal pipe in the rear of the passenger cage, as well as the driveline. You can see a rusty turbo there... this one needs to get tweaked for some extra performance, i want at least 110 hp.
I expect the Diesel torque to be beneficial in long hillclimbs. 110 hp isnt as much as commercial VW bus based buggies have, but the torque will do the trick in offroad driving.


4th picture is a side view, i welded the 33mm (1" ??) brace pipes in place, which makes the whole buggy (not just look) a lot stronger.

 

[Brad_Blazer]

Renze,
It's really coming along nicely.

"Yes adding weight will be counter productive... but anyhow, this way i can use complete car components bolted all together. If i wanted a better weight distribution, i'd have to get a Volvo 340 tranny (same as 740 etcetera) and rear axle to bolt up to this diesel, and put the motor up front and bolt the tranny directly to the rear end to get a good weight distribution.."

Of course you could add another complete engine and transaxle up front
I remember reading about a test mule GM built like that years ago - it supposedly had incredible performance.

Very nice work and documentation.

Brad

 

[Renze]

I added some crossbars in the rollcage structure past few evenings..

 

[Dougryan]

Seems that your exhaust pipe exits below your frame. That will definately get damaged. Any way to route it up higher?
Doug

 

[Renze]

Yes, the original exhaust downpipe goes below the subframe under the floor of the car.
I bolted the first muffler off, the elbow above the rear axle rotted off on its own, one of the reasons i bought a new car and use this one for fun.

Anyway, there is no chance to re route the pipe unless i make a new downpipe/manifold behind the turbo. Its a cast iron piece that collects both the mainstream exhaust flow, as well as the flow from the waste gate into 1.
I need a straight tractor pipe sticking upwards, but as long as i dont have everything else installed, no need for an exhaust anyways... It's going to be one of the last things to be done.


I am thinking of making some kind of ski's on the front of the buggy, to make it slide easier over obstacles.

Some sheetmetal plate on the original Volvo front end caused trouble by penetrating the radiator, which was the reason that we could only jump for 1 saturday. because the buggy is rear engined, i dont have to worry about the radiator anymore, but i think a belly rack would help sliding over obstacles, and would reduce the risk of front flip when the nose digs into the ground.

 

[Renze]

My friend put a video on YouTube of the car that we took the parts off for the buggy, prior to disassembly:

YouTube - springen met een auto

A fully 1050 kg car was a bit too much on smooth springs to jump with: I guess with a buggy being half the weight on the same springs, it will be a bit better in terrain, as the ride height is a lot higher which leaves more spring travel.

 

[RobertN]

I was thinking the same thing. I do not know how popular they are outside the US, but they would be worth investigating.

Steering brakes would be a great thing for a buggy like this.

You might also search on the old Honda Odessy. Not the mini-van; this is a 70's/80's single seat buggy with a rear single cylinder air cooled engine. On thing they used to do on those was had restraints on the steering wheel, so your arms didn't fly all over during a roll over.

I would look at the vw sand/rail buggies. They do not have anything close to 50/50 balance. They do jumps fine. Steering may be light, but you can use independent rear brakes to help with understeer.

 

[Renze]

Some photos of yesterday:

photo 1 shows the work so far: seats mounted, and a lot of struts and crossbars added. Now i need to weld some strips against the pipe to bolt the plywood floor to, and i want to make a mid tunnel to mount the gearstick to, and run all the cables underneath.

Photo 2 shows the workshop after i added 2 500 Watt halogen lights: As you can see from previous photos, my workshop was a dark cave. It's amazing how much light 15 Euro worth of Halogen lights can give !!!

I just need to screw them to the roof beams in the highest part, so that they only shine their light down: When i put them to the wall and aim them at 45ｰ the lamps are still to bright in the edge of your eyes to work properly...

 

[Renze]

I was thinking the same thing. I do not know how popular they are outside the US, but they would be worth investigating.

Steering brakes would be a great thing for a buggy like this.

You might also search on the old Honda Odessy. Not the mini-van; this is a 70's/80's single seat buggy with a rear single cylinder air cooled engine. On thing they used to do on those was had restraints on the steering wheel, so your arms didn't fly all over during a roll over.

You cant find any real buggies in Holland: i've only seen 1 or 2 VW based street buggies. Problem is that most of our rough land is protected and cops will be all over you if you head into the dunes or bush. I live in the bush too, and know the playground better than any cop so i'll keep ahead of them...

After looking at some YouTube movies of LS1 V8 powered sand rails, i'm not afraid of the weight distribution of ours: Those sand rails have the engine placed behind the transaxle, putting a lot of weight out back. Our buggy has the engine a little bit in front of the rear axle. When i put the heavy Scania truck battery up front, i estimate the weight will be distributed perfectly to get enough traction at the rear and at the same time be safe to corner at speed.. But time will tell.

 

[patrick_g]

Renze, I'm glad to see your going to have some fun. Not to pour cold water on it but... I think your tube frame will rack and don't you need some triangularization in the corners in the horizontal plane?

Not trying to be spoiler of your fun but I have spent years playing in tube frame rides off road in Baja California, SOCAL, Arizona etc. (Would you believe we even have a little set of desert dunes called Little Sahara hear in Oklahoma.) I have seen an awful lot of frame failures in home brew rigs and not nearly all of them were welding problems. They were design problems. If you can get your hands on a copy of "Sand Sports" or a similar magazine you could see many examples of tube frame off road fun cars. Here is their URL:

Welcome to Sand Sports Magazine Online<meta name="keywords" content="Motorcycles,rails,sand,sand sports magazine,engine,tools,wheelie,speed, quad,atc,atv,offroad,offroading,jeep,dirt,vacation"> <meta name="description" content="Sand Sports Magazine preveiws and sales information">

All I have left these days is an air cooled '62 VW bug with wheel base shortened 14 inches and the body replaced with fiber glass beach buggy (Myers Manx style) It has a full roll cage over the people and another over the engine. Never rolled it so far but it should roll like a scarab hauling manure with all the overhead protection.

I haven't got a lot of engine work in this one so it doesn't wheelie. Fuel cell is in front, batt amidships. I have put some creature comforts on it since moving to Oklahoma. I have a removable surrey top for sun protection. It attaches to the roll cage. I have removable cloth doors with plastic view ports and snap in place curtain around the back. IT doesn't rain into the car much unless you drive fast or the wind blows hard. It is street legal and lisc for the street but IT is mostly used off road. It is good for running the sandy areas beside the local rivers when they are not in flood stage. I catch a little air once in a while on my land but try not to break it too much. So far I have had no major crashes with it but did have a rear axle break and fall off while towing it through Dallas Ft Worth area on its own wheels. Apparently the axle was cracked from my previous antics and just chose that time to finish cracking and fall off.

Back to your project:

An in-line style electric lift (fuel) pump is only a few bucks so getting the tank out front for helping with the CG should be dead easy. It isn't that your fuel tank is really heavy but when you take it off the back and put it in the front it helps nearly double. If you put the radiator out front and use an electric fan in addition to moving the fuel tank you will probably not have to move the seats to get a decent CG.

Best of luck, keep showing pix and HAVE FUN!

Pat

 

[Renze]

Patrick,

i'm taking it step by step: the triangularisation in the floor and roof will follow, but i have to work out the previous steps first.
Actually i want to add 2 slide rails of 1x2" square tubes underneath, to make the belly slide easier over the hills and dunes in the bush.

Putting the fuel tank and radiator up front might be a good idea: this way we'll get a little warm when racing the corn stubble after harvest during the chilly autumn.

The intercooler should stay back, or the hoses get too long and i'll be getting too much turbo lag...

When i put the radiator above the engine, it takes away all my rear view, and putting it in its original position wont work really well either, because then it would be right behind the seats where the air flow is limited.


So, things to throw forward: a 30 kg Scania truck battery (heavy duty) an original Volvo fuel tank with electrical prime pump, and a radiator...

The original fan of the Volvo, like most fwd cars, is electric anyways. I kept the originals from 2 cars..

 

[patrick_g]

Renze, If you have enough fan power you can tilt the radiator quite a ways, even horizontal and have a decent sized radiator up front but not obscuring too much view.

Skid plates under everything that can be harmed by impact with dirt, stumps, rocks and such is a terrifically good idea.

Now that I have seen pix of the more completed car, it is looking much much better except for the skinny little undersized tires. You can go narrower up front to get some bite to help turn it but you need more tire in back.

From the safety aspect I recommend at least some decent 5 point harnesses and good helmets. If you don't put canvas or sheet metal or something on the sides to keep body parts in during a roll over you invite trouble. Expanded metal (not too big of holes) is good as dirt will always find a way in to the car but will fall out through expanded metal. It is good to have at least some expanded metal in low areas to avoid collecting sand and dirt.

I didn't see a rack or tie down for the cooler or beverage holders. Some of the gimbaled holders used on boats work sort of OK if the can is at half capacity. What, no audio system? Not even a PA horn and amp to enable you to blast out several bars of "Ride of the Valkuries" from Die Walkure ala "Apocalypse Now?" I didn't see any signs of a mount, regulator, or other parts of a propane injection system to super boost the diesel when appropriate. It could be separately controlled from the manual waste gate override that lets you get some REAL BOOST.

Pat

Pat

 

[Renze]

Pat,

i cancelled the two 15" Conti offroad tires, even though i could get them for a 50% OEM rebate through my employer. I cant fit them or they'll touch the spring struts...

Anyways, i'm not riding sand dunes, but mostly forest soil and dirt roads. In mud, wide tires dont help, because you'll be moving too much mud before the tires get any tractions in the solid underground.

I think i'm going to buy a set of deepcut rally tires. They are of chinese chewing gum make, but they dont cost much anyways.

I think i'll stick with my original 14" rims and buy those 185/70 R14" rally tires from opgesnedenbanden.nl


The propane and water injection, i''m thinking of that... I was thinking of using an additional waste gate actuator to control water and propane injection, but off course as you say, i can attach to the existing waste gate actuator to control both the waste gate as usual, and also the propane valve and water nozzle.

Do you know of a valve that could be used to dose the propane ? Maybe dismantle my old gas BBQ ???