The MULE.... My tester Yokomo 870C

[hondaman]

Well I have been gathering parts for this car for a little while as I have been tossing things around on it but decided to get on this.. Here are the parts I am staring with:



870C Chassis
870C Arms
Yokomo Long Front Axles
Yokomo 3.5MM hubs (ZD-433)
Unknown Composite hub carriers (look like Yokomo Parts)
RPM Bulk Heads
Black Yokomo Rod Ends (ZM-400)
AE Steel Turnbuckles
Kyosho King Pins (92635)
Ofna 3MM inner hinge pins
Composite Craft Wing Mounts
Robinson Racing Spur gear with 1-way
Kyosho Gold Shocks
Trinity Wheels (yellow) 2.0"
Schumacher Tires

This is going to be a test Mule for 3d Printed parts I am going to be making in Nylon.. I've already begun to 3d model parts like the body posts, bulkhead caps, and arms.. I have bulkheads drawn up in 2d but far from finished.. I also am drawing up shock towers and top decks.. So this will be fun..

Shawn

EDIT: I added some of the part numbers that I used.. S

[stickboy007]

3D printed parts? Somebody's about to get real popular

[hondaman]

@stickboy007: Hahaha.. Well I bought a 3d printer a little while ago and have been using it for work and decided to do some parts that I want for my RC's mainly the Yokomo's as certain parts are hard to come by like the battery posts and bulkhead caps.. One of the ones I have is cracked at the bolt hole to attach it to the bulkhead but they go for like $80.. Not worth it for a runner-ish car.. I got lucky and got one from a parts lot a while back but I know this will come up again.. Not to mention I am missing one black battery post for my 93... If they turn out good I'll happily offer them to those on here.. That is what this little yoke is for..

Well I did a little work on the Mule.. I did some modifications for the suspension mounting holes as the plastic interfered with the attachment to the rear shock tower and for the turnbuckles I am using for the inner hinge pins.. Going to do a little cleaning up of this and make it look pretty.. Already rebuilt the diffs and had them assembled and put on some nice belts I had.. I was annoyed with the Tough Racing belts as the front was way long so I need to figure out if the tensioner will still work but I need my top brace first.. I need the bulkheads in first to check fitment of my top brace before I send it to have it cut.. I'll post up pics later.. Time for food!!

Shawn

[hondaman]

So I got some work done on the assembly of the roller..

I installed the Robinson Racing spur and some used belts.. I had a Tough Racing belt on there but it was way loose.. For now these belts will do while I try to figure out a tensioner but I needed it this far to test my top deck... Here is it with the RPM bulkheads on:



In the front I am currently using the magnesium hub carriers until I get some nylon parts.. I was looking for some king pins one day and decided to try out some Kyosho (92635 King Pins) parts and they fit great... Cost 1/3 of the Yokomo parts.. I do have another set of king pins so those will be saved.. The front hubs are Yokomo 3.5MM hubs and the larger stock hubs in the rear as I have the long universals in the front.. I will either try to source some hub carriers from RPM or go with Optima parts later.. I used the other plastic hub carriers in the rear since the hole for the king pins were a bit stripped.. You can see the turnbuckles on the inner hinge pins and I have those front and rear.. Here are the control arms attached:



I used AE turnbuckles and black Yokomo rod ends for the MX4 for the upper links and RPM ball cups for the steering ends..





I still need to attach the shocks and wheels to make this a rolling chassis.. I may decide to make a couple changes but I will see as I go on.. That's it as for now.. Going to need to figure out a shell soon.. Maybe I'll go with the Protech shell..

Shawn

[rccars4sal]

I like the look of the rpm bulk heads. Makes for a clean appearance. Ive been working on a 1 pc top deck that would cover everything front to back, and not require bulk head caps, just for those rpm bulk heads. Hopefully will give it that solid monolith style, and not look like an ad on. Thats on the back burner right now though.

[stickboy007]

That's looking pretty good...

As for the belt tensioner, I figured out a little trick that's basically an adaptation of the Works approach to belt tension. As you probably know, rccars4sal has been designing some repro 870c towers, lipo trays, top deck, etc. in carbon fiber. I have an earlier version of his 870c upper deck. On the particular chassis that I mounted it (I'll post pics eventually), the chassis was actually too long (I recall this being a problem for one of you guys earlier in another build?), so I had to extend the screw holes on the upper deck with a Dremel and a router bit, so that the screw holes are really slotted holes. The '91, '92, and '93 Works had slotted holes on the upper deck. You loosen the rear four screws (two for the bulkhead cap, two for the motor mount) and push the upper deck forward from the rear, and then re-tighten the screws while holding the upper deck in place. It requires some manual dexterity to pull it off, but it's certainly do-able, and what it does is flex the front of the chassis to tighten the belt tension.

@ rccars4sal, I don't recall if you made an exact Jammin' repro upper deck with mounting holes for the 870c tensioner pulley, but if not that, you could alternately make a Works style upper deck with slotted mounting holes. That would go over quite well for a project like this, and offers an option to adjust belt tension without adding a pulley which increases drag.

[hondaman]

@ rcarsforsal: I was thinking about that myself as I was designing my top deck (the one I pm'd you about) but I saw seabass's one his 870C (he sold it a while ago) and I didn't feel it for me.. don't know why, just my taste.. I like the add on look of the Yokomo top decks for some reason..

@stickboy007: gomachv had that problem on his with a new yokomo belt being too tight.. I did think about the Works style tension but the Tough Racing belt was way loose.. for it to get to where the stock 870C belt sat without tension, but still loose, I had to flex the chassis way too much.. not going to work on mine that way.. no biggie.. going to tinker with it after I get my top deck done.. for now the belt is fine so I will put on a tensioner later..

the top deck I drew out has the slotted hole for the motor mount as of right now.. in the future when I finish 3d modelling the bulkhead caps, I'm going to do a set like the 93 W.C.S. with a provision for a turnbuckle to do the adjustment.. solves the problem of needing two hands to get the right tension.. I'll draw out a chassis with the slotted holes like the 93-up when I get further along..

I'm working on a new set of arms soon to be able to use the longer axles easily but keep it within the 10.5" width.. thinking b44 c-hubs or tamiya stuff to be able to 2.2 wheels and get parts if they wear out or break and not break the bank.. I'll keep this updated.. If anyone has any ideas, I'd love to hear them..

Shawn

[stickboy007]

Gotta be a little careful here. Eventually it won't be a Yokomo anymore

[hondaman]

Gotta be a little careful here. Eventually it won't be a Yokomo anymore

I know what you mean.. but if it can keep it out on the track, I'm ok with that.. I still have my shelfers..

Shawn

[hondaman]

Well I got this into a roller.. Unfortunately I couldn't use the Kyosho Golds.. I forgot the rears were too long.. I thought that maybe they would be short enough but no go.. So instead, I slapped on a nice set of AE team shocks with the shorter RC-10T front shocks and buggy fronts.. I had these for the next 870C I was going to build.. Guess that means I just have to find another set or something else.. Maybe some big bores for this one down the line?? Well here are the pics with the Trinity FLORO yellow wheels and Schuey cut spike tires..







In that last pic, I notice that the springs maybe for the long shocks and not the truggy fronts.. All the screws are SS and I have the Composit Craft wing mounts on there.. I had to open up the mounting holes on the tower but that was alright since this tower was modified already and banged up.. Looks better in pictures.. So now all I need is a shell and electronics.. I'm going to go with vintage electronics for now as I have most of what I would need.. I'll order a shell next week (have some bids up on ebay) and decide on a paint scheme.. But that's it for now..

Shawn

[stickboy007]

Those Trinity yellow wheels are very cool!

If you're going to use this as a runner, then I'd recommend replacing the aluminum shock caps with V2 plastic caps. Better to break those than the shock tower, plus the bleeder hole makes rebound tuning much easier.

[rccars4sal]

I ran an 870c for a few weeks as my "going on a walk" car. It was super fast and efficient. One of the most efficient buggies ever I think. Boy did it injest a bunch of destructive little pebbles though.

The latest top deck Im cutting has the holes for the belt tensioner. Not sure how well a turn buckle system would work. It would basically negate the stiffening properties of the deck, and relegate it to a massive belt tensioner device. Perhaps slots for front screw holes, then a turn buckle going from the deck to the bulk head cap. So, tension could be fine tuned, then locked down.

[hondaman]

@stickboy007: thanks.. those wheels were somethin that just fell into my lap.. got the rears in a yokomo wheel lot including a set of NIP stock pink wheels that I put on my first yoke.. found the fronts on ebay 2 days later for a nice price.. I also have another set in orange and a pair of rears in pink.. these shocks are temporary but if I do keep these on, I will take your advice..

@rccars4sal: the turnbuckle system is used on the 93W.C.S. and is just for pushing the top deck to adjust belt tension.. you loosen up the mounting holes and motor mount just like you would do on a 93Works but instead of trying to push and pull everything you just turn the turnbuckle.. makes thinkgs easier.. you then lock it down and your top deck acts as both a support and a tensioner.. check out DerbyDan's or Charlie don't surf's build of their W.C.S. and you will get the idea.. that's how I did..

Shawn

[rcnj]

Hi Shawn -

Would you mind confirming for me that those Kyosho kingpins worked perfectly for you?

I cannot find any Yokomo kingpins for my own 870c restoration and it will be awesome if the Kyoshos are indeed a perfect substitute!

Do you know of any other substitutes?

Thank you in advance.

Brian

[upforit365]

Kyosho OT-4 King pins are a direct fit for the 870c