K.O.M.'s Full Independent Suspension 1.55

[K.O.M.]

It's been a long time, but now that the younger of my two kids is now 7 months old and is a little more independent, I finally get to build again.

Before everyone gets too excited, I'll just say that this will be a B.A.B.O (Buy And Bolt On) build, so there will be little or no fabrication planned. However, that doesn't mean that it won't be at least a little fun, and hopefully if I can inspire someone to use one of my ideas, then the build will be more than a success.

On to the pics!

Well, it would not be in this section if it weren't for these wheels:



Next up is what I decided to wrap them with--RC4WD 1.55 Mickey Thompsons, measuring 3.3" in diameter, scaling up would put them up to a 33s in real life, so this will be more of a street/stock rig:



So, to get you guys somewhat excited here's one thing that is interesting, RC4WD 4:1 GRU (Gear Reduction Unit). I'll need this to lower the final drive ratio of from the stock 11.27 : 1 to a still reasonable 45.08 : 1. With 1.55" wheels and tires, it should be plenty low and produce the scale effect and not the stop/start jerkiness associated with too high a gear ratio on something that was not really meant to crawl:



Next up is something interesting and RARE: a vintage unused Tamiya Acto Tuned M-Special motor! It's a "520" can motor, and the photos below show it with a standard motor for size reference. I'm using this motor mostly to see the crawling qualities it had when paired to the RC4WD GRU as I have another I was planning to use in a future 1.55 build.





A little bit about the motor: as far as my research can tell me, it's a 23 turn single armature, is fully rebuildable in that you can take the endbell off to remove the armature so the comm can be cut, yet it has bushings instead of bearings. Tamiya originally released it to improve the weight distribution of their rear-drive M-Chassis cars back in the 1990s. Sadly, TCS rules dictated sealed motors shortly thereafter resulting in a very short production of these motors.

So that's what I'm able to share so far, if anyone has any guesses on the chassis, or any more info about the M-Special motor, feel free to post here.

Cheers and see you all in a couple of days.

[K.O.M.]

Updates!

I killed about six hours during the weekend doing something I really dread--painting and detailing the body. I really would be happy if I could just pay someone to cut, paint, and detail everything for me and all I did was bolt the thing on, but the last time I did that, they just did not live up to my OCD standards--overspray, not trimmed right on the cut lines, misplaced decals, and didn't even bother to clean off the plastic shavings before shipping the body back to me. Worst thing is, this person/company actually charges quite a bit of cash to paint bodies--I won't publicly say who he is, but thankfully, he only details on-road machinery and will hopefully stay far away from the off-road forums. PM me and I will share the info.

Enough of me complaining, here are the results. Excuse the bad lighting in my garage.



I also had a chance to get the tires mounted, so, like a dork, I mocked everything up to the ride height I'll hopefully be able to get.



I LOVE Tamiya bodies; I HATE Tamiya decals. Freaking things are so tiny yet add so much to the detail of the body that I HAVE to put up with it and just spend the time to cut the decals and stick them on. Snorkel, side mirrors, light bar, and wing really add to the detail on this Porsche. I wish that this thing came with light buckets and pre-cut masking for the headlights/tailights to complete the package. But for now, I'm pretty much done with working on the body, maybe once I recover from the shock, I'll add a functional light bar in place of the plastic one.

[OSRC]

Nice find on that motor! Perfect for adding a GRU to that chassis. Really like those Porsche bodies myself, they have very nice lines.

[K.O.M.]

Time for a quick update.

Locking the differentials. I have decided to lock both the front and rear differentials as I really only intend to run this rig slowly.

As many of you know, there are many ways to go about locking the diffs, but I settled on the following:

All the diff parts laid out. I ordered two extra sets of bevel gear sets in order to lock the diffs.



After some test fitting, I settled on using 5 bevel gears without the carrier. This was done to improve clearance once everything was assembled. I also ended up using only one of the wide washers for the same reason.



This is how the motor and GRU all come together. I had to source much longer motor screws (18mm longer to be exact) in order to bolt the entire assembly together.



All assembled with the Tamiya eccentric motor mount. Holmes Hobbies motor for size reference.



Motor assembly mounted to the rear gearbox.



Rear gearbox assembled with suspension arms and dogbones.



That's it for today. Will be a couple of days before I get a chance to work on it again. Thanks for reading.

[OSRC]

Perfect set up for a TA chassis. Again, very nice find.

[K.O.M.]

Originally Posted by OSRC

Perfect set up for a TA chassis. Again, very nice find.

Thank you! I found a domestic seller on Ebay that didn't really sell too many RC related items, so when I saw it was for $40 shipped, I jumped on it and just bought it.

I was actually researching what the best way to fit a GRU in a CC-01 chassis would be with the least amount of chassis trimming. One of the builds I saw used a short out runner motor with the HPI GRU and that gave me the idea to search for a shorter brushed motor and that's when I happened upon some Tamiya Club posts about a "520" sized motor.

Holmes Hobbies actually makes a custom 520 brushed motor, but $120-$140 seemed a little high for something I was going to dunk in some water. John also has a brushless out runner that is the same size, but I didn't commit because I wasn't sure of the fitment at the time.

Anyways, I had this DF01 just sitting for the past year, so I figure I could at least test how the motor and GRU would work out before I start my CC01 project. I'm really excited about that build, but that might be about a month or so out.

[K.O.M.]

Big push to finish up this evening.

Front Gearbox assembly.





Shocks built. I decided to run the limiter inside the shocks as per the instructions. I know that a lot of the TA/DF based builds do without the spacer, but the front arms only droop down so far that the mounting points are exactly the same length as the shocks. I will have to grind the C-Hubs and lower A-Arms to get the same extension out of the front to match the rear. That might be in the future, but for now, I just want to get the car assembled. I'm running them without the preload collars as the springs seem a little bit stiff.



Front and rear end coming together.



I've got a roller!



I couldn't resist, so I skipped ahead and mounted the body. Some teaser shots:

[K.O.M.]

Finishing up Phase I of the build!

Electronics setup and ready. No fancy connectors, or ESC, not a lot of current being provided or needed for this thing. Servo is just a Savox metal gear to get started. Receiver is a KO Propo, IMHO, one of the fastest systems available, not that it's needed on a crawler/trail rig.



Wasn't happy with the amount of slop in the axles, so I had to shim it before going for a drive.



More than just poser shots, the car actually made it up this, with a bit of body rub, so I'm ok with it's performance so far.







Video will be coming up shortly.

[K.O.M.]

First Run!

[K.O.M.]

Phase II Begins!

So, I may have been just a tiny bit misleading when I said this was going to be a buy and bolt-on affair.

Trying something small with the Tamiya TA/DF platform that is just a small variation of what they could be. I see the potential.

Fabricating a new chassis! Awww yeah! I don't know if this will end in tears, but I'll give it a good college try.

First mock-up attempt.







Any ideas, comments, or suggestions are welcome. Please fire away.

[K.O.M.]

More slow progress, but progress nonetheless.

I originally thought that I would do a few things with the first chassis design: get more clearance and make the car slide off the rocks better by boatsiding and narrowing the chassis, have the chassis wide enough so I can screw the sides of the lexan body to it so the body is protected (and more importantly, it reduces the unrealistic shaking on bumps--spoils a good video shot), and finally, get a new bellcrank system for the steering with zero ackerman and more throw.

Well, in the interest of time, I'm settling for all of the above, but I will stick with the stock steering mounting points for now. I have enough material to build about 4 different variations of this chassis, or I can simply re-drill mounting holes.

Chassis design 2 is therefore a bit wider to accommodate the stock servo mounting position and the stock bellcrank mounting position.





Chassis 1 (brown) vs. Chassis 2 (green)

[K.O.M.]

This is all I got done tonight.



I think I may have been too ambitious with the 16 ga T304 stainless steel sheet. My Dremel Saw Max cut the section I needed in about 15 seconds, much faster than I could have done it on a band saw, but it sure did use up a bit of that abrasive disc.

I'm thinking of bailing on the stainless sheet since it is is a PITA to drill.

[eddievedder]

I like the box art look of the body. Maybe paint those wheels orange???

Very cool ideas. Nice work.

[LoneRanger]

16 guage? I dont use that shit on my 1:1 what do you think your building a scale military vehicle that requires defense against roadside bombs?

go pick up some 22 or maaaaybe 20 guage. By the time you bend and bolt it all together that will be plenty strong enough.

L.R.

[chino63]

Originally Posted by LoneRanger

16 guage? I dont use that shit on my 1:1 what do you think your building a scale military vehicle that requires defense against roadside bombs?

go pick up some 22 or maaaaybe 20 guage. By the time you bend and bolt it all together that will be plenty strong enough.

L.R.

Agreed, 22 is what I use, much lighter and plenty strong for abuse.

[K.O.M.]

Looking back upon it, this "scrap" 12" x 36" sheet was probably not as cheap as I originally thought. I just picked it up during lunch and was in quite a rush, that I just eyeballed grabbed what I thought was 18 ga mild steel. The gal at the counter couldn't care less and said $10 and it's yours.

After I used up half the life of a Dremel roto saw metal disc in just two cuts to get to the point where it is above, I took out a magnet and some calipers, and yep, stainless and it was just over 0.06".

[K.O.M.]

And because I am a glutton for punishment, I keep going with the metal stock I have

After another roto saw cut off wheel, one carbide jigsaw blade, and one small Dremel cut off wheel and sanding drum, and some potentially pissed off old folks next door from all the noise, this is where I stand:



Center punched all the holes I'm dreading of trying to drill tomorrow:

[OSRC]

I like where this is going, I've modded the heck out of these chassis over the years. Thought about going with a flat chassis, but never actually did it. I usually put the flat plate up top and bent plates to connect the lower points on the gearboxes. Gains center clearance, but really loses out on COG.

[K.O.M.]

Originally Posted by OSRC

I like where this is going, I've modded the heck out of these chassis over the years. Thought about going with a flat chassis, but never actually did it. I usually put the flat plate up top and bent plates to connect the lower points on the gearboxes. Gains center clearance, but really loses out on COG.

I've looked at a couple of builds that were done that way, and I think if I had a hardbody, then I could just use aluminum angle and a mild steel to connect the lower mounting holes like you mentioned. I still would have to solve the steering issue, but I think I could use the standard Slash bellcrank or something similar. I really liked one of the Landrover LR3 builds by one of the guys on the Spanish crawling website, Addiccion Crawler.

His video:

[K.O.M.]

Happy Friday! Chassis is bent into shape, holes drilled.



Just a few more things and Phase II should be done shortly:

-Lexan or Delrin top plate
-steering bellcrank mounts
-some body trimming
-shimming/spacing the bulkheads so it is aligned