building a dirt buggy

[patrick_g]

Patrick, The eaten brass propellers tale must be an urban legend.. Electrolysis only works with DC, because the material is drawn with the current, from the positive to the negative pole.... with alternating current, there is no noticeable movement of material from one pole to the other...

Renze, I guess we will just have to agree to disagree on this one. The electrolytic action is not a reversible process. Think of the electrochemistry involved and how the electrodes involved act as a diode with resulting rectification (meeting your stated DC current requirement.) A mechanical analog would be a ratchet. You can wiggle the wrench in alternating directions but the net result is unidirectional (even though there is some "waste motion."

There are active systems for electrolytic protection with sense/reference electrodes in contact with the water. These systems impress the required balancing current to protect submerged metal. These typically cannot produce enough protection current to offset leakage current in the water due to reversed polarity of the AC power.

There can be other effects as well: I was literally hosing out the interior of my sailboat and decided to move a hotplate away from the top of the gimbaled alcohol range to clean the stove top and about a microsecond later was on the other side of the cabin tingling all over. My brief electrocution was some amazing to me as I had previously opened the main AC breaker and was some curious as to the source of the current that had repeated the famous "Galvanic" frog experiment on me.

Seems my boat was wired backwards! Neutral went to the main breaker and hot went to all outlets all the time. Opening the breaker stopped things from running by breaking the circuit but still there was 120 volts available with respect to "EARTH ground" or "OCEAN ground" as the case may be. I was standing in a mixture of fresh and sea water. Needless to say I stopped cleaning and started reversing two wires to correct the problem!!!

This was shortly after I got the boat and it had not previously had shore power connected for long so no particular damage. I later ended up living on that sailboat for 9 years and it is a good thing that I found the problem early on and corrected it. Not happy about the way I found it but happy THAT I found it.

It is BAD PRACTICE to use just any automotive type battery charger on a boat since some use autoformers to get the lower voltage and this does not give input to output isolation and promotes electrolysis problems by providing a current path from the AC input to the batteries which will have their negative posts connected the the bonding system connecting all wet metal on the boat.

If you are still not at all persuaded, not even a little bit, talk to an experienced marine electronics tech with good expressive abilities.

Pat

 

[Renze]

Patrick,

the ratchet analog makes it plausible to me... i'll look into it because it kinda interests me...

 

[excelagator]

Very cool build. I am jealous........

I raced RC cars for 7 years and I can explain some stuff about handling.

Yes 50/50 weight distribution is ideal and makes the buggy handle neutral, but it depends on personally driving preference. Having the engine in the rear "plants" the rear end better IMHO passing the apex to get back on the throttle. This also helps or aids in being able to throttle steer too.

You mentioned getting the buggy to jumping correctly. If you could pre-load the front springs a bit or install a spacer to raise the front end a bit. I probably would not go more than 1 inch or 25 mills. The other thing is at the start of the ramp ease off the throttle just a bit and back on the throttle again. This pre-loads the spring also.

I like you build very much the only thing I would have done is kicked back the top of the front shocks more maybe 10 degrees. This would help the springs preload better too on the jumps and the front wheels center themselves exiting corners. Plus would take bumps better.

Cool build,
Dan

 

[Renze]

Dan,

The front shocks are mounted alike the Volvo design, like they were in the original car, at the same angle. They do tilt backwards a bit, not much.

About preloading the springs, i have more weight in the back than in the front, and i identical suspension F/R (in fact i use 2 front ends of 2 cars)
I assume that would give the desired effect.

In my first couple of cars, i wore hand brake cables quite often due to my addiction to drifting. The 440's with rigid rear axle would drift quite nicely, though they were a bit too wobbly to take them out of a drift smoothly with front wheel drive power. when the rear wheels, from a side slide drift, were tracking again (rolling straight i mean) the car would allways shake a bit.


What i'd use a buggy for, is jumping and drifting. I choose to shorten the wheelbase by 2 inches vs. the original car, because it would make the steering more responsive, and allow for a shorter turn when making a controled drift. It will handle jumps a little less than a long wheelbase buggy, but it will improve handling.

 

[KubotainNH]

What's the latest with the buggy? I watched it the thread for a couple months and then it stopped. :-(

 

[Renze]

I bought a tractor after having driven it in 2nd, 3rd and reverse gear. when i got it home i found that 2 teeth were missing from the gear of the 4th speed.... I felt the best way to deal with this major disappointment, is to begin overhauling immediately and drop everything else. I put 2 new gears and about 8 new bearings into it.

I parked the buggy in the back of the workshop, and i want it out of there... that means i'll have to finish and paint it first before i can put it out in the rain...
After a bankruptcy and a take over at work, i think i'll have some energy to spend on hobbies again, from now on...
Actually you guys asking, is an extra tickle to get going with it again.. maybe tomorrow.

 

[patrick_g]

Life is what happens while we are making other plans.

Pat

 

[Renze]

Life is what happens while we are making other plans.

Thats a true saying !!
Anyways, we finished the buggy this year.

Radiator went to the back, the original water hoses are used. Too much work to put it in front, we had a mudfest to make it to:
gear shifter needed some modifications, because the gearstick used to stick to the back in a 15 degree angle and is now mirrored because it runs from back to front (fwd transaxle used in a rwd vehicle) the H pattern was rotated 30 degrees so you were shifting semi sideways... welding the hinges to the rod in another angle fixed that.
An old propane bottle serves as fuel tank (thick enough to withstand some impact) the 440 had a wee little intercooler placed in front of the left front wheel, so it would only function at highway speeds, for fuel economy. Since we want more power, the big intercooler of a 2.5TDI was placed in front of the 440 radiator, with electrical fan which is turned on with a battery charger clamp after the warming up lap. Its a Diesel so i dont want to waste head gaskets by gunning a cold engine, even though its flat out all the time on the corn stubble.

Here a little testdrive after corn harvest, now it is done after 8 years:

I already screwed the wastegate tighter a few turns, but what we need now is more fuel: the Lucas pump isnt as easy to tune as the Bosch, you have to unscrew a plastic bung that is designed to be screwed in one direction. I'll have to try to undo the screw on the spare engine first, if that one comes out in one piece i'll try to undo the one on the engine that runs...

Oh, and most urgent is installing the roll stabiliser. At the moment we drive without one, and i didnt dare to gun the engine in 3rd gear as well (you can hear me shift up and let it coast) because it gets quite unstable above 70kmh.

The saturday before, we ran it on neighbours stubble field flat out in 3rd gear which should be 100kmh. clods of dirt and corn stubbles splattered in my face and my eyelids were folded by the wind. So next time you can see me wearing a helmet

 

[AGRIMAN]

Renze,

Nice ride. I see you mentioned a mud fest, did you build it just to play around with or do you plan to race it?

Check out the below link of some hill and hole racing. As you can see, we can get some air time.

BLOWER MOTOR AIR @ WGMP HILL N HOLE - YouTube


Sent from my iPad

 

[Renze]

This the Dutch style, not as spectacular, its just a pasture thats turned into a bog once a year... this time they didnt add water because mother nature served mud...

https://www.youtube.com/watch?v=UWR_fg2JVxQ

you can watch me at 3 minutes 5 seconds, there was a car class, 4x4 class and special class. I had to do the special class because our vehicle wasnt really a car, but some guys raced an Opel Manta with a small block V8 and a Mercedes Sprinter rear axle with rice paddy duals.

After every heat, an excavator stirred the mud deeper. The wheeled Liebherr had to row itself along with the digging arm because even beside the pit it was too muddy to drive.