Wheel Weights!

Steve · #1 03-29-2005, 08:05 PM

OK, I geared my Monster down enough so it will now pull a cat, it's a hill climbing, rock crawling, baby waking truck at that. It's not fast, doesn't steer well, in fact it's really slow and loud...all that a truck should be. Problem is she flips over backwards when negotiating steep climbs, hence the wheely bar craze. However, a wheely bar on a monster truck, especially a rock crawling monster, is just not acceptable, as I'm sure many of you truck guys will agree.

so, BEHOLD the Steve Wheel Weight! In an attempt to get as much weight as close to the ground as possible, I filled a wheel with molten solder, and after pulling the warped, cracked, unusuable wheel off the hardened solder core, Whallah! I had an 8g lead donut, which fit very nicely into another wheel. The downside is it requires a wheel per mold.

Now I'm sure one of you brainiacs out there will figure out a way to do this without sacrificing a wheel. Some thoughts I had (after the sacrifice):

Clay instead of solder. Not tried.
Coiling cold solder inside the wheel well. Works, just not as heavy
Using something else for a mold.

In summary, it works..oh yes, it works. Hills that were previously unclimbable have been scaled, and it makes the truck heavy as hell, which just adds to it's truckness. Have to mention that with some dremmel work, the weights would be removeable as well. AND you can polish them to a mirror shine for a cool inner wheel effect. It's also important to note that you will require 4 wheel weights if you plan to go down steep hills, or she'll just go head over tea kettle the other way, or I suppose you could back down, but that phrase is just not in the truckster vocabulary.

Pics should follow shortly, but man, it's just a lead donut.

chilli_mp138 · #2 03-29-2005, 11:02 PM

Steve--

Great idea; thanks for posting it. It will be interesting to see what replies come forth.

In my model railroading, I use adhesive-backed lead weights to make cars track properly on the rails. They come in several different sizes and weights and are usually available at hobby shops in the model railroading section. They might be an alternative for those who can't do the wheel weights. On my MT crawler I use a black Hummer H2 body which leaves plenty of room between the chassis and the roof. I've thought of moving the battery to the top of the chassis and filling the empty battery well with lead weights.

Tell me, if you would, what the final gear ratio is on your MT. What gears and motor are you using? After seeing a picture elsewhere, I rebuilt my gear box from a ratio of 27.98:1 to 83.95:1 by using a 6-tooth pinion and a blue gear from a ZZ.

Steve · #3 03-30-2005, 06:54 AM

Maybe you could figure out my gear ratio, I haven't the foggiest idea what it is.

What you see is a red MT idler, a blue ZZ idler, and a green MT idler. The yellow MT motor has a 7 tooth pinion.

I raised the motor up as far as it would go underneath the bed of the Hummer, and filled the cavity below with foam, and hot glued it all in place. Everything fits as it should, including the PCB cover.

chilli_mp138 · #4 03-30-2005, 08:28 AM

Steve--

Does your MT even come close to moving?

I calculate a final gear ratio of 255.76:1 on your MT configuration. Here's how I computed it:

Gear Set One
input (motor gear--MT pinion) 7 teeth
output (MT red gear) 32 teeth
gear ratio = 32/7 = 4.57:1

Gear Set Two
input (MT red gear) 9 teeth
output (ZZ blue gear) 18 teeth
gear ratio = 18/9 = 2.00:1

Gear Set Three
input (ZZ blue gear) 6 teeth
output (MT green gear) 32 teeth
gear ratio = 32/6 = 5.33:1

Gear Set Four
input (MT green gear) 8 teeth
output (MT green axle gear) 42 teeth
gear ratio = 42/8 = 5.25:1

Total Geartrain Ratio
4.57 x 2.00 x 5.33 x 5.25 = 255.76:1

You could increase that ratio with two simple changes: use a 6-tooth ZZ pinion gear (enlarge the hole to 0.038-in dia with a no. 62 drill) and change the MT red gear to another MT green gear. That computes at 5.33 x 2.25 x 5.33 x.5.25 = 335.58:1. And a green MT motor would slow you down even more. You might even be able to pull the family dog!

I've used a 00-90 machine screw to hold the additional gear--what did you do? I also fabricated a plastic cover to enclose the gear box (paint it if you want to hide your secret from the competition, in case they haven't read this thread).

My black Hummer H2 body gives alot more room than the H1 body. You might, if that would be to your liking, check at your RS store to see what's been returned and scrapped; they might have an H2 in the junk box they'd be willing to sell cheap (look for other parts, too). Another MT green gear might be there, also.

I like what you've done. It shows really good imagination and construction. I've thought about a tutorial on my own website, but maybe you should write one for this forum.

zzmods · #5 03-31-2005, 06:13 PM

OMG Steve! Thank you!!!!!
I just did this to one of my monsters last night. I layed my gears out just as you have done. I used all green gears, a blue zz gear, and a green motor with 7 tooth pinion. It took me about an hour and a half to get all the gears to line up perfectly, but was well worth the effort. With all gears a aligned (sp?) correctly, my monster is quiet as a mouse. And speed? Well lets just say I timed how long it took my truck to go 10 feet, and are you ready for this? It took my truck 63 seconds to drive 10 FEET!

That's not all. My truck will climb a 55 degree angle! I put double sided tape on the tires and managed to peak at 60 degrees! I'm watching my truck climb this thinking to myself "I can't believe this is possible!". I'm sure if I was to put more weight in my monster, it would climb even steeper angles because I pushed it to the point where the wheels would spin. I don't think it would spin as easily if it was heavier.
I'm not sure what my total gear ratio is, but this thing is now a true monster. (all i have to do now is make it articulate)

Props to you Steve for sharing this information!

EDIT: Okay; I just used chilli_mp138's formula posted above to calculate my new gear ratio. I'm getting 287.73:1! Can somebody tell me if this is right? That just doesn't seem right. I think I did the math right. Again my gear setup is as follows and in this order using chilli_mp138's formula,

Gear Set One
input (motor gear--MT pinion) 7 teeth
output (MT green gear) 32 teeth
gear ratio = 32/7 = 4.57:1

Gear Set Two
input (MT green gear) 8 teeth
output (ZZ blue gear) 18 teeth
gear ratio = 18/8 = 2.25:1

Gear Set Three
input (ZZ blue gear) 6 teeth
output (MT green gear) 32 teeth
gear ratio = 32/6 = 5.33:1

Gear Set Four
input (MT green gear) 8 teeth
output (MT green axle gear) 42 teeth
gear ratio = 42/8 = 5.25:1

Total Geartrain Ratio
4.57 x 2.25 x 5.33 x 5.25 = 287.73:1
And if I had a 6 tooth pinion - 335.58:1

chilli_mp138 · #6 03-31-2005, 08:59 PM

zzmods--

Want to exchange TinyRC titles? I'll be a newbie and you be the pro?

I calculate a final gear ratio of 335.79 (I think you typed it in wrong, but your computations are in the style I was taught long ago). That should give you an actual ground speed of 0.078 mph with the green motor (4.992 mph scale speed) according to Rich Nagel's formula. You and Steve need to tell us how each of you did this!

Steve--

I picked up a tube of Loctite Threadlocker Blue and placed a TINY drop on each of the MT axle threads, then afixed the 2-mm hex nuts. It looks like they'll be even more secure now. It worked very well on one thread which had been cross-threaded by someone who must have been too excited.

The Loctite is expensive, there's enough for both you and me to keep our false teeth firmly attached when we're living in the home running our ZipZaps around our rocking chairs. Get the Blue version, it says mechanical force will break the bond. The red and green versions require heat to break the bond--and you know what that does to the wheels! I pickup up mine at Lowe's in adhesives/glue section.

zzmods · #7 03-31-2005, 10:59 PM

Gosh! A real Pro? I'm sure I'll earn the title someday, but until then...
Anyway, Steve's picture inspired me to do this for myself. They say a picture is worth a thousand words, so here is 4000 words worth of photos.

zzmods · #8 03-31-2005, 11:01 PM

Please excuse my numbness but I cannot figure out how to post more than one photo in a post.

zzmods · #9 03-31-2005, 11:02 PM

You can see here where I had to file a little off the body so the gears would fit and run smoothly.

zzmods · #10 03-31-2005, 11:12 PM

I don't mind writing up a tutorial to make this possible (that is if Steve does not mind. After all, HE inspired me.

). But tonight it is late so for now, here is one last tease frame. For this shot I should have placed a carpenters speed square in the shot but I leave my tools at work and didn't have one on hand. And yes, that is a 50 - 55 degree incline!

Sorry for the messy pics. I'm no photographer. The flash tends to white out close-ups and does not get bright enough for wider shots. Oh well, you get the idea anyway.

frizzen · #11 03-31-2005, 11:21 PM

You built a Crawler Box for your truck!!! Dude, that's wicked.

Do you have a trail or rock crawling diorama built up yet?

zzmods · #12 03-31-2005, 11:26 PM

Quote:

Originally posted by frizzen
You built a Crawler Box for your truck!!! Dude, that's wicked.

Do you have a trail or rock crawling diorama built up yet?

I have not built a obstacle course yet; I just did this to mine last night. I just used a box cause it was all i could find that was a good flat and stiff surface to try out my trucks new found powers.

Steve · #13 03-31-2005, 11:39 PM

You guys go nuts with your tutorials, won't bother me in the least. As for shaving the body, I had to do that also...make the side wall thinner and a little off the inside of the back bumber. However, I picked up a Dodge pickup body today from RS and it's thinner and doesn't require the shaving, still need to notch the bumber a tiny bit though. One thing you could do is put some kind of standoffs near the rear body mount tab to pull the body back as far as it will go, you might get away with no shaving at all on some bodys, I recommend foam here as it will allow you to compress it when removing the body. Looks great ZZmods, glad you had success, now get out the paper mache and build yourself a mountain to climb!

AND back to the original secret topic of wheel weights, I finally got all four done, and with the help of a wheel kit from RS, I'm back in business. The truck weighs a TON now, it's 3.7oz, no joke. The only downside I see of this weight is the stress on the steering and gearing. No problems yet, in fact I think it turns sharper now (weight on front wheels maybe?), and let me tell you, it's rock solid stable. The CG is so low, it's almost impossible to roll it over.

Chilli, I use the blue loctite stuff in the red tube as well, I bought the tube like 4 years ago and there's no sign of it running out anytime soon. A little goes a real long way.

Steve · #14 04-01-2005, 09:22 PM

Articulation: Diets did it a while back with an Xmods tranny bearing and some metal tubes that fit in the bearing and eachother. I tried to copy the concept and came up with some useful items for those looking to do it as well.

Antenna's. The telescoping ones. The last piece is usually solid and works great for a drive shaft replacement, and the section it fits into is exactly the right size for it's sleeve. As for bearings, I found a great source for those as well. Those little one inch chipset fans from graphics cards or motherboards are sometimes ball bearing instead of bushing, not all, but some, they usually have two in each, and they'll fit perfect over the solid shaft of the antenna. I'm going to use two bearings, one for each end of the drive shaft. Wish me luck.

Steve · #15 04-02-2005, 12:42 AM

Success! A whole new dimension to the MT. Mad props to Diet for showing us the way. I snapped a few quick pics, it still needs a little cosmetic love, but I didn't even expect it to work in the first place. For the curious, I just cut the rear end off, replaced the drive shaft, fit it in a sleeve, put the bearings on, and put it all back together, then glued the sleeve to the chassis. I moved the PCB forward a little and glued the cover on. It even fits on the stock charger. The motor is temporarily hot glued in place as the next step is a gear make-over to drop it down to about 300:1.

This mod is really only for the truly insane. The whole truck has to be taken apart and put back together again while attempting to line up the drive shaft, bearings, steering, axles, not to mention somehow hold onto the thing while it flops around in two halves.

Also, the twisting action of the tail end causes stress on the motor wires, which will eventually break off and require re-soldering, but of course, only after you've glued it all back together again. Getting to those tabs after it's together is tough. Might want to extend your motor wires to a different location so that they are more accessible when they snap off.