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..