19.02.2003
Donor Clod...
Here's a picture of Project StockClod... she ain't much to look at but she was fun to put together... now she's destined for greater things!

Locked Differentials
The first thing I did was to open up the gearbox and lock one of the differentials. This was done using metal epoxy - the one I used is called PC METAL by PC-Products. After mixing the epoxy together, it was mashed between the differential gears. Care was taken to keep proper alignment of the gears and also to keep the epoxy off the main gear.

This locked diff will go into the rear to power the truck over obstacles. It's important for crawlers to run locked diffs because otherwise, wheels that lose contact with the ground when going over rough terrain will "unload" - i.e. it will spin while the opposing wheel on the other side will not - because of the differential action.

For starts, I will run the locked diff in the rear and see how it performs. Running locked diffs will increase turning radius and will also require a very strong servo to steer. By running only one diff in the rear, I hope to still get a decent turning radius. 4-wheel steering will also be used to improve steering.

I then worked on the steering setup. I like the setup on my Ripper Clod but it isn't a great setup for crawling because It places the servo in front of the gearbox. This may actually get in the way when approaching obstacles head-on. The servo in this setup is placed on the side where is can't possibly get in the way of things. Although it places more weight on one side of the axle, I think the effects are insignificant on a low-speed crawler.

A heavy-duty steering link was also fashioned from 6mm thick aluminum rod and polished to a high-sheen. Special mention has to be made about this link because even after all the projects I've done, this is my VERY FIRST LINK made. I was never able to find the rod needed locally until now, and it's good to know I can now fashion my own custom links as needed.

While on the topic of steering, the steering stops on the knuckles have also been filed off so that I can maximize the steering of the truck.

I have to give credit where it is due - the idea for mounting the servo in this position and manner came from clodman on CLODTALK. Great idea dude!

Here's the lower links that will be used for the suspension. They are machined by Eric Beach of Team Tweaked and are special in that they have a ball machined out in the middle of the rod. This ball will allow a shock to be mounted directly on the lower link. I have chosen this method because I've used cantilevers before and have found that direct link mounting has less slop and also allows for very good articulation. Cantilevers are heavy, contain more parts to break, and also require more careful design otherwise the truck's tires are prone to hitting the cantilevers/chassis before the shock is fully compressed (hence not allowing full articulation.

I intend to use an inverted upper link setup but haven't exactly decided how I would do this yet...

The future awaits!

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21.02.2003
Had some time to work on Hoof today and the next step was to work on the upper suspension mounts. The Clod has always required innovative solutions to mounting links on the top of the gearbox because it doesn't have any screw-holes on top to work with. With this in mind, I used a piece of 1.5mm thick aluminum to make a mounting platform above the gearbox. Bending the aluminum was tricky to ensure that everything fit just right, but it worked.

Why 1.5mm aluminum and not something thicker? Well, I don't really have any special equipment to bend the aluminum so using anything thicker would have posed problems when it came to bending the aluminum. However, using such a thin piece posed a potential problem - the force of the upper links might actually bend the aluminum when running the truck hard. To solve this problem, I went into my spare parts box again and found 2 old SASSY USA-1 servo mounts. These things are nicely machined and pretty much useless since I sold my USA-1, so they became the backbone of the upper mount. By attaching them lengthwise to the aluminum, they should eliminate any possibility of anything bending - only true testing will tell. :)

Ripper Testing
I have a bashing session tomorrow with some MT guys - it's the first gathering of our unofficial rock-crawling club in Singapore. As such, I really wanted to bring Hoof out for a run. But without a chassis and suspension links, it was impossible. Then I thought of grafting the Hoof gearboxes onto my TXT chassis - that would be COOL! But I'd have to find some way of mounting the cantilevers to the gearboxes and it was already too late to customize anything else... so the Ripper came to mind. After some wrenching, here are the Project Hoof gearboxes mounted on the Ripper chassis!

As you can see, everything fits quite nicely! The stock Ripper setup tilts the gearboxes to add castor for better racing performance. However, with the Hoof setup, the gearboxes are level with the ground, raising the motors up and out of harms way. I will be testing this setup without wheel wideners tomorrow to see how it performs.

Ah, the customary articulation picture. The Ripper sway-bars were removed for full articulation capabilities. 4WS is achieved with a futaba S9402 servo in the rear and a Sanwa (airtronics in the US) ERG-VB servo for the front - the VB servo boasts an impressive 13kgs of torque. As it is, the truck can turn all 4 wheels while stationary.

Someday someone might try this same setup with a 2-channel radio and realize that the rear-steering turns in the wrong direction - resulting in crab-steering rather than 4WS like in the picture above. The reason I could do this that my rear servo is controlled by the third channel rather than the first. Using my 3PJ radio, I am able to mix both channels so that I can get as much or as little rear steer as I want.

Testing begins tomorrow!

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23.02.2003
Took the truck out for a spin and to be honest I was pretty disappointed - the locked rear diff was causing a lot of steering problems. Not only did I not have proper rear steering, the rear was sometimes going the *opposite* of where it was supposed to be going... either the servo was too weak to steer it (111oz torque!!!) and/or the servo saver was giving due to the stress. Unless I find a solution to this, I am going to lock the rear steering.

On the upside, I did manage to complete the basic chassis today. It's loosely based on a Ripper design, but the battery is now in a flat orientation - this is to allow me to cut a second battery hole above the current one for a second pack if I want to. If during testing one pack is enough (I intend to use 7-8 cells) then I will cut some more holes in the chassis to reduce the weight. Cutting the side plates was a tough job as the was 6061 aluminum... sore hands now.

Here are pics of the chassis. The left and right sides are joined by 8 crossmembers - the two center top ones (silver in color) will also be where the radio plate mounts. The multiple holes on the chassis were cut just like on the Ripper chassis for 2 reasons... (1) the multiple holes allow me to try various configurations and (2) if I decide to use a Ripper suspension in the future (i.e. lower suspension arms), I can just order the arms and bolt them right on. In any case, the chassis still has an abundance of space to drill more holes and test more mounting positions.

The upper suspension links are still not completed so in the pics you see a mock-up of the truck with the lower links installed. At current configuration, the length is just shy of 14".

Here's a side view of the chassis. I would probably set it up with slightly more ground clearance in the middle so that it can better crawl over objects better. The second pic shows a close-up of the lower link installed - as mentioned earlier, these are steel heavy duty links with Kyosho 6.8 ballends. The motors are currently Sapphires with 13tooth pinions but I have a pair of 11 tooth pinions and TTR adjustable mounts to install later.

Just for fun I mounted my 1/8 SAVAGE shell on the chassis to see how it might look when completed. I think the 1/8 shell is just about the right size for this truck... looks pretty cool!

Probably take a break for a couple of days to let the sore hands heal. Still to do - upper suspension links, shocks, rear steeromg lockout, body mounts... did I miss out anything?

On to page two!

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