How to Build a 1/87 Scale RC truck a.k.a.TTTT
 

This is a long atricle. Please keep a copy of it for your reference when you are ready to build a 1/87 truck.

If you are serious about wanting to build a 1/87 TTTT, please read on......

For direction on my first TTTT project, I mostly used pictures from the German websites. Since I can't read German, I tried to use Bablefish as much as I could to translate, but that is only about 85% effective. Bablefish would give you results in English like, "make nice still depronplatten ergattert and a small carrier tinkered". Huh?! So allot was just guess work and interpolation. I did make email contact with a German guy who writes a little English, and he gave me some pointers.

At first I thought I had to somehow buy all German parts and electronics, but a little research showed I could get almost all of it here in the U.S. The only German parts I wish I had are some of the gearboxes from microantrieb.com. Their webpage is impossible to translate because there is no actual text. It is all in bitmaps. Go figure... I ended up using a U.S. gearbox made for model railroad applications and the ground clearance is not that great.

I would really like to see more interest here in the U.S. about TTTT (or whatever U.S. name we decide to give it) so I will share as much about my experience as I can, and eventually us non-German connected folks will have enough experience to help each other out without having to use bablefish. The problem is, that most young hobbyists in the U.S. are NOT MODELERS.

Our collective brains have evolved smaller and smaller until no one wants to build anything any more. Most kids just want their RC toys RTR (ready to run) right out of the box, and so no one is learning the skills of model engineering. This is evident just looking at a typical hobby shop inventory. Try to ask a typical hobby shop employee about anything other than a RTR T-Max, and all you get is a drooling "Rain Man" impersonation for an answer. But I digress. My point is that this hobby is not likely to take off and be popular because it is ALL custom fabrication and not likely ever be available in a kit form (though maybe RTR?).



HOW I DID IT...

Basically, the size of even the smallest off-the-shelf electronics prohibit building anything other than a truck with a covered cargo area to fit it all in. I have a special interest in Unimogs so I decided to use the Roco UNIMOG body.

Lesson learned: for a first attempt, the MAN 5t would be better, because it has more room than the UNIMOG.

I decided to build a frame out of brass, but it could have been done from a flat deck made of fiberglass or other composite. The problem with composite frames is that they are too light. This is one form of micro modeling where you want things to be heavy. I bent the frame rails exactly the same shape as the scale Roco UNIMOG frame rails were.

Lesson learned: No need to do that. A flat rectangular frame would have been sufficient and less work. Also the scale frame interfered with my servo placement and I hade to modify it later (see below).

The pieces of frame were soldered together using basic electrical solder. Silver solder is stronger but not necessary and requires too much heat for these little parts. All of your joints would melt as you tried to solder a new one.

The best way to design any custom RC model is to lay out the design of the chassis in the following order:

First, the motor and drive train. This is the most important system, of course.
Second, the steering geometry. (I blew that one when I made the scale frame. I am sharing this so others wont make the same mistake on their first truck)

Everything else has to be designed to fit around those two systems (especially the frame). The motor and gearbox are relatively tall and needed to stick up through the cargo bed of the UNIMOG. The steering servo needed to be mounted in the cargo bed. The Roco plastic is soft and easy to work with but after you cut all the holes in the floor of the cargo bed it becomes very flimsy and delicate. This is significant because you will be holding and handling this piece of the truck most of all during construction.

You will have to find a way to mount the bed to the brass frame. CA glue will be used when all the geometry is aligned but that is almost the last step of construction. I ended up tapping two 1.5mm holes in the rear corners of the frame so I could screw the bed down. The bed has to be attached and un-attached to the frame about a hundred times while you are working out all of the geometry, so gluing is not an option.

The only way to fit all 4 batteries in a UNIMOG is with 2 of them stuffed in the cab. Since the idea of TTTT is to be scale, you will need to carefully dissect the cab, bumper and fenders to be attached back in place on the brass frame later. I glued the fenders, bumpers and cab together, then screwed that assembly into the front of the frame with 1.5mm screws through the front bumper.

Wheelbase/Truck Height
I matched the wheelbase from the scale UNIMOG and made marks on the frame where the axels should be. This an important part of the overall geometry design. Also, the height or "lift" of the whole truck needs to be considered. I made my body 2mm higher than the stock. This allows for the
front axel to articulate without hitting the fenders.

Front Axel
The most time consuming part of the process is the design and creation of the front axel. I managed to find on one of the German websites a PDF plan for a front axel. It was not exactly what I needed for the UNIMOG, because it has a smaller width, but I used it as a basis. I did everything in millimeters and found it really easy to do. I used a Sherline mill to make the main axel housing but if you don't have access to a mini mill, you can
fab all of this stuff using razor saws and files. The knuckles are just 3x3mm brass blocks with 1/16" holes drilled vertically for pivot pints and 2mm holes drilled horizontally tapped to accept the 2x5mm axle screws.

Wheels
I used 2x6mm bearings for the front wheels. The Roco tires fit right over them and a 2mm screw into the mini steering knuckle worked as axels. Really simple and very effective!

Suspension
I decided to make only the front axel articulate for my first project, and this is pretty common on most of the German trucks I have seen pictures of. Keep it simple. I just used a single pivot point in the middle of the axle, sandwiched between a pair of brass angles suspended from the frame. For the pivot, I used a 00-80 screw and nut, so I could remove the axle as it was
constructed.

Steering
At the beginning of the design, I knew where the servo had to be, but I was not sure what the linkage geometry would look like. You almost have to have 90% of the rest of the design done, including how the body will be mounted, before you can tackle the linkage. I had dreamed up all kinds of complex control horns pushing and pulling etc., but when it came down to it, I found that the UNIMOG was so short, I could just link the servo control horn directly to the knuckle. Simple is always better. I used 1/16" brass wire as control rods. For the control points on the knuckles and soldered pieces of bent brass with 1/16" holes for the rods to the knuckles. I had to angle the control points on the knuckles in about 15 degrees to avoid hitting the inside of the tires.

Receiver
I am a criminal. I am forced to use the aircraft 72MHZ frequency for the radio because no company makes a 75MHZ or 27MHZ reciver small enough. If you know of one, LET ME KNOW! I cut off all of the pins where the servos connect and soldered all contacts. It barely fits around my gearbox.

Speed Control
I tore apart a HiTec HS-55 micro servo, and used that as a speed control. I removed the pot and replaced it with a mini adjustable 5k ohm resister. This makes it easier to find the neutral point and is much smaller. I mounted the resistor facing down through a hole in the bottom of the cargo bed so I could adjust it from the bottom of the truck. Note: If you have never used a servo as a micro speed control, email me and I will tell you all about it.

The rest is just assembly and fitting and re-fitting as you go along. If you don't have a blueprint or manual to build from, you have to try to design as much as you can at the beginning, then play it by ear the rest of the way. It's like playing chess alone; you have to consider if placing a piece in a certain location is going to effect another critical piece further towards the end of construction.

If your eyesight and nerves can hold out, you CAN build one of these little things! My German penpal says a little red wine sometimes helps.

Parts List
All prices are approximate.....

Servo - Cirrus CS-10 BB $26
Reciver - GWS GWR-4P $24
Rx Crystal - GWS micro $14
Speed Control - converted HiTec HS-55 micro servo $25
Batteries - four 120mAh NimHs $24
Transmitter - JR 4 channel $130 (another freakin' radio set with a receiver I didn't even use on this project!)
Gearbox - NWSL 172-6 50:1 w/ 60 tooth brass flywheel on input shaft $30
Motor - some little motor out of a micro servo I found in one of my junk parts drawers w/ 9 tooth pinion. $??

Total gear reduction - I dunno, you do the math. I got 50:1 to start with, then I add the 60:9 teeth ratio for the motor and flywheel. Whatever that is. I should have stayed in school and learned more math............ If someone can figure this out, please let me know.

Other materials:
Two 2x6mm bearings for front wheels $8
micro adjustable resistor
1/16" square brass $1
1/8 x 1/8 brass angle $1
some more brass $2?
nerves of steel $priceless

Done....
 

Ready to roll...:p

you have made your homework .
i hope that you find some modellers who build their trucks to make competitions . sorry for my weak english

Language
 

Danke Hally!

Your English is excellent! Please stay involved with this thread!

I need some advice on creating an HO trials park. I have never made a plaster mountain berfore:D

Looks great Overlander!!!

I have a third truck now........maybe I should start converting them!! Soon.

overlander
 

your skills are unmatched!
i believe you've inspired me to give it a try. i found a truck that i think will offer enough room. i'll attach the picture. thanks for the detailed "how to".

again, great job

Yes, Arch2b.

That is the MAN 5t truck I refer to in my article. It is very poular in Germany and is what most of the pictures of German trucks seem to be.

There is a lot of room in them. My next truck will likely be one of those.

overlander
 

there is aslo a double rear axle model of the same truck. which do you think would better?

hey overlander, nice truck! wish i was dedicated enough... (or if i had the supplies, brains, etc.):rolleyes:

Scuba Dude,

It doesn't take many brain cells. Your right about dedication, though.

I'ts more true to call it Obsessive Compulsive Disorder.

Only treated with copius doses of beer.

-Todd

Arch2b,
I have seen pictures of the 6x6 MAN 7t trucks. I can only tell you about the pictures I've seen, but it looks like most of the 6x6 out there use the middle axle as the drive axle. The rear one is just an ideler.

Maybe on your second TTTT project?


However, I have also seen actual 6x6 and 8x8:eek: 1/87 trucks. The 8x8 I'm talking about has the first two axles driving AND steering!

Here are a few pics of multi drive axles.....

More of the 6x6 MAN 7 ton
 

This thing is awesome....

6x6
 

Both of the rear axels drive, and articulate:eek:

I hope my next truck will be as nice as these German modelers can do.....

Incredible 8x8
 

I am truly not worthy.......

8x8
 

Just amazing....
Remeber, those tires are only 8mm diameter.

how to contact you?
 

Overlander

I am very interested in trying to build something of this nature and I clicked in your profile to email you but it said you don't accept, and would LOVE to get in contact with you with some questions and for some guidance on the servo/speed controller..

How can I get in touch with you via email?

Hello Overlander,
your instruction is realy very good. In germany it's like a sickness to build the 1/87 cars.

My english pages of www.mikromodell.de are still under construction, but I try to translate my pages from german language to english. Maybee one day there is also a instruction availible.

It's realy dont't nessesary to build a brass driveline, but it's nice to have one. So you can better fix the frontaxle and the gearbox on a robust frame.

best regards

Thorsten

www.mikromodell.de

Hey Overlander, cute baby!

Those trucks look awesome.

I have a third truck to build. It has tandem rear axles. I am going to build the Ford C-cab as a 2wd. The second truck as a 4wd. The third as a 6wd. I just have to finish my NASCAR first.

I am going to school for work for the next month. I'm not at home during the week so it is going to take a while.

Thanks for all the help and info. Now I just need to find a MAN Paris to Dakar truck.

i would love to get a few of the paris-dakar service trucks. watching them in the rally was very interesting.

Here is a pic showing the differnce in size between the Unimog and the MAN 5 ton. The MAN has about twicw as much room as the Unimog and will be the perfect truck for someone to build first.

Where can you get the bodies to begin with?

overlander
 

where did you get your truck, roco minitank? i can't seem to find any at my lhs's.

Buy the front axle...
 

If you can't or dont want build your own front axle, find a "Faller Car System" vehical by a German company called Faller.

These little HO scale cars have a steering front axle that is perfect for a beginners to make an off road truck out of.

See a later post below for the link........




Binary Terror,
Bodies can be found at most HO train stores. Ask for manufacturers like:

Roco
Wiking
Faller
Etc.

Where to get the bodies
 

Go here for just about ANY body made for HO:

http://www.reynaulds.com/

Remeber, this stuff will only fit in trucks with cargo beds....

Faller Car System
 

The Faller Car System vehicals have many of the parts you need to build your first TTTT.

A steerable front axle
A 6mm diameter motor
Worm gear set
On/Off switch

Here is a link to learn more:
http://www.reynaulds.com/faller/car_system.html

The gear ratio is vey high so they are better for street driving than for off road trials. But you can add gears to increase the ratio.

They are NOT remote control!:(

they charge what looks liek a flat $8.00 sh, ouch.:eek:

discount trains online has a flat $6.95 sh. still high but better than $8.
discount trains online

i would suggest looking at lhs's first. i already did with no luck:mad:

you could do a group buy maybe.

So what does the Faller Car System do? But, please I would pay anything for on of the but with a 1/87 scale Hummer.

Canadian guy
 

If you follow the link you would see what the faller car system does.

Quote from the link:

The Faller Car System is the name for a fascinating technical innovation for modellers! The integral motor drives the vehicle along, powered by rechargeable batteries, while a steerable front axle guides the vehicles through the streets, using a specially strong magnet mounted on a triple steering link on the front axle, to actually steer the vehicles along the roads.

Oh I didn't read that part correctly. Can you fit one of these devices in a 1/87 Hummer?

for those of you, like myself, in awe of overlanders amazing little rc...
 

...and who would like to try your hand at it yourself, i have found a good place to get the roco minitanks. the online stores tend to have high sh charges so i looked further. i found a nice person on ebay who sells these little trucks;
48vw or Rudolf Zerr @ rzerr@dccnet.com
he has a large stock, much more reasonable sh charges and has promply replied to several emails. i will be getting two trucks very soon (one in case i really f things up on the first one) so i can try my hand at making one of these little wonders.

Canadian Guy,

The front axle from a Faller car will surely fit in a hummer. Unfortunately, getting the rest of the stuff in there is very difficult. I'm not saying it can't be done, just that it would be a challege.


arch2b,
Aww, shucks:rolleyes:

Yes, I have purchased from him before on eBay. In fact that is where my orange unimog came from.

It is a good idea to buy a couple for the reason you mentioned.

One of the things that I did not like about that guy was that one of the trucks I bought from him had peices already glued on the truck, and very poorly too! I just chalked it up as eBay "Buyer Beware" and used it for parts.

If you order something from him, make sure you ask if it is NIB!

-Todd

oerlander
 

thanks for the warning, i will be sure to do so.

i can't tell from the pictures, do they come with rubber or plastic wheels? yours appear to be rubber.

also can you give a detailed list of the electronics you used. i need to start hunting and saving!

arch2b,

Most of the modern Roco trucks have rubber tires.. There are different sizes and tread patterns which is why I bought several. I took tires off of one to put on the other etc.

Which model did you order? I can tell you what tires are on it.


I listed a detailed parts list on the orriginal post on this thread. If that is not enough, let me know specifically what you need. Everything I got from the LHS except the gearbox.

-Todd

overlander
 

i will be ordering 2 ROCO MINITANKS GERMANY MAN N4510 4X4 and one ROCO MINITANKS GERMANY MAN N4520 6x6.

i'll go back and read it again, sorry for forgetting it was there. i will be getting under way in early feb. there is only one train/hobby shop nearby and a few rc/hobby shops. last time i was in any of them, i don't remember seeing any of the materials needed. i might have to drive to a couple of shops in springfield about 20-30 min's away. this cann only be done on the weekends as i don't get home from work till about 8pm. not to mention i have to ask the wife to watch the litle monster while i go driving around, i dare not take him into a shop with small, breakable things.

arch2b

Monster?
This is why they make strollers and duct tape.


The MAN trucks come with what is called a military tread. They come in two sizes; 12mm and 15mm. The MAN trucks have the 15mm tires.

They are rubber, but not really off road treads.


This is a pic of the 12mm military tread tires. The off road tire pic will follow:

This is a pic of the 15MM off road tread tires:

overlander
 

sometimes i wish i could get away with that.

what models have the 15mm off-road tires?

arch2b,

Thats not an easy answer. For example: some of the UNIMOGs have them, but most don't. :confused:

All I can suggest is that you look at the online catalogs from
http://reynaulds.com/
and
http://www.discounttrainsonline.com/

and look closely at the pictures, now that you know what the different treads look like.

Another example:
This one (see pic) Roco#554 has off road tires. LOOK CAREFULLY

BUT THIS ONE DOES NOT HAVE THEM
 

Go figure.....
They look the like the same truck, but Roco# 569 (see Pic)
does not have the off road tires. LOOK CAREFULLY

Yes! Now that that Faller Car System can fit in a 1/87 scale Hummer I can get one or another 1/87 scale S.U.V at my local train store and the system and start work!