Clod Buster suspension question

[cobalt 20]

Does the Clodbuster's suspension locks up under accelaration?(like the luchnbox)

What i mean is that rear shocks extend when accelarating and the vehicule has no rear suspension.(we get the bouncy effect on rough terrain)

Does the Clod suspension reacts the same way?

Thanks!

[Saito2 7327]

No. The Clod Buster's ladder bar suspension is linked solidly through a series of mostly ball jointed attachment points. Any axle rotation is stopped by a small anti-rotation bracket the attaches the gearbox to on of the ladder bar's lateral stabilizer links. The Clod hops and bounces because mainly (aside from issues like bouncy twin friction shocks at each corner and big tires) because of its high unsprung weight. Most of the Clod's weight is concentrated in the twin gearboxes due to it motor-on-axle design. The chassis is basically there just to hold the electronics and provide suspension attachment points. Someone even made a chassis from a coconut once which was an interesting way of displaying its limited effect on overall performance, lol.

The Lunch Box's slotted axle mounts and inferior stock wound axle springs (which break in short order) allows for rotation at the axle's front end which simultaneously pulls the shocks on the opposite end to full extension. Properly locating the axle with solid connections like the Clod Buster transfers rotational energy into the chassis, which can cause a wheelie. The Lunch Box only wheelies once the slack is taken up by the gearbox mount slots (and consequently, the shocks pulled to extension) and then the energy is transferred to the chassis. 

 

 

 

 

[Mouc-RC 529]

Thanks @Saito2 for heads up on the Nut Buster: https://imgur.com/a/nut-buster-worlds-strongest-clod-buster-chassis-u59uM

Crazy stuff, everyone should read! :)

[cobalt 20]

Thanks Saito for the explanation

 

I wonder if the entire gearbox and arm assembly still tries to push up against the chassis, but the cantilever arms being so long Vs the wheel torque effect, that the resulting upward force on the center brace is too low to push against the weight of the chassis and thus, forces almost cancel each other out, and so no effect on the shocks.

An intereseting experiment would to assemble a entire suspension and gearbox with wheels and tires, and power the motor, i think the the pivot points of the cantilever arms will want to pivot clockwise.(upwards)

Just curious...

[Saito2 7327]

7 hours ago, cobalt said:

I wonder if the entire gearbox and arm assembly still tries to push up against the chassis, but the cantilever arms being so long Vs the wheel torque effect, that the resulting upward force on the center brace is too low to push against the weight of the chassis and thus, forces almost cancel each other out, and so no effect on the shocks.

I see where you're going with this.

I think it has to do with energy transfer and where that energy goes. In the LunchBox's case, if the gearbox could not rotate up, I'm not sure the rear shocks would be pulled down. All the energy would be transferred into the chassis. The shocks are pulled down because the whole gearbox assembly is allowed to rotate (within the travel of the slots at least). I'm not sure the simpler, fixed pivot Grasshopper rear, for example, pulls the shocks to full extension.

With the Clod, that energy is transferred straight to the chassis (and as you mentioned, the center of the chassis at that). In fact, if it weren't for the Clod's low chassis weight and high unsprung weight, the rear shocks would probably compress/squat, not extend, under the load of acceleration. Typical mod Clods of our time move do squat because the shocks are moved much closer up the link toward the center of the chassis which reduces the mechanical advantage they have in their stock location.

At one time in my distant past, I drag raced, and this is the theory I'm bringing to the table with this discussion. Axle rotation was an issue with the leaf sprung Novas I typically ran. I ran (and still do) old school traction bars or slapper bars to counteract this rotation (which led to axle tramp in leaf spring applications). A more extreme measure, particularly used in Gassers, was to run long ladder bars that attached much farther forward in the chassis. Now there's a whole discussion about leaf spring function, shackles, competing angles and the need for housing floaters to prevent bind on a full size application but that's getting too far into the weeds here. At any rate, once the energy was put into the chassis, raising the front end, which would aid weight transfer to the rear, causing rear squat and hopefully better tire bite on the launch.

[Carmine A 2074]

On 9/30/2024 at 5:20 PM, Saito2 said:

.....With the Clod, that energy is transferred straight to the chassis (and as you mentioned, the center of the chassis at that). In fact, if it weren't for the Clod's low chassis weight and high unsprung weight, the rear shocks would probably compress/squat, not extend, under the load of acceleration. Typical mod Clods of our time move do squat because the shocks are moved much closer up the link toward the center of the chassis which reduces the mechanical advantage they have in their stock location......

I've also done a lot with Clods in the very late 80's - early 90's.... mostly for truck pulling though. 

I recently built one, replacing the oversized pogo sticks with proper 130mm oil shocks (4 instead of 8), which did make an improvement... along with servo on each axle, instead of Tamiya's ridiculous steering (HUGE difference!). I also added 80g of lead where the central servo used to be.  But I never thought of moving the lower shock mounts on the lower arms (AKA Axial Bomber). The extra leverage makes sense.  That might achieve what I'm looking for. Thanks! 😊