Gun Tech

Well, I picked up another old Tamiya King Tiger (one motor, twin clutch) that was in great shape for cheap and it didn't need too much to get it running. It still had a 75mHz radio, but no charger and the LHS couldn't find one hiding anywhere in the store. So I sucked it up, bought an ESC and headed home. I took out the old RX along with the old school analog speed control. I had another 2.4 RX for my DX6i and after some trial and error, got it working. The turret is the old style without elevation and I had to find a constant hot to supply power to the traverse switch. This is my brief clip of this thing zinging along at what I strongly suspect is not scale speed. I put on a set of Imex metal tracks last night and it runs just as fast, but it exaggerates that one of the clutches slips at low speed tight turns. In the video, I am not intoxicated, I am holding my phone in one hand and driving with the other. The odd noise in the background is a weedwacker, not the tank. Enjoy a bit of old school.



Mark

cleong

You could easily install a 540 crawler motor to slow the thing down.

Old MSgt

That is like the early Tamiya KTs I first built when I was stationed on Okinawa in 1992. The Tamiya supplied 'speed controllers' were just a plate with brass contacts with a lever for a servo and linkage to turn for speed.

The FIRST time I tried the KT after I'd built it was 'EXCITING'! I sat the tank in the yard, turned everything on, the eased the speed up and IT TOOK OFF LIKE THE STARSHIP ENTERPRISE!. I kept messing around with it and in no time had stripped the pot metal 90 degree gears. Went to the hobby shop and ordered a new trans and tried it again... BAD, ALL BAD!

Being new to 1/16 r/c Tamiya tanks, I did some asking around and realized I needed to get a decent electronic speed controller. After that things got better...

But even with the new speed controllers it seemed that the speed was still WAY TOO HIGH. So I spaced the two clutches out as far as they could go, drilled a hole and put in another gear between the motor drive gear and the clutches. This helped a LOT! Here's a pic of the old down geared trans.

I wrote a letter (it's around here somewhere in my old 'files') to Tamiya and sent'em a drawing and description of the geardown I'd did and how I'd stripped a couple of transmissions with the old setup.
A couple of weeks later I got a letter from them saying they were investigating it

and a brand new trans. I still have the new unused trans...

After I started using ESC and the geardowns my two KTs accompanied me on MANY 'After-A-6 Pack' patrols around the housing areas on weekends.

And while we were stationed in Utah Tamiya came out with the 'new' trans and electronics so I ordered those and updated my old clutch drive KTs and tanking life got a LOT BETTER!

Mike in Kentucky

Gun Tech

cleong,
That is a 540 motor, I don't know if crawlers have a lower RPM, but the answer will be to set it up with twin motors. I have another KT like this and I already gutted it and have a pair of the Mato brass boxes for it, but I haven't done anything yet because I am planning to lengthen the hull for a Jagdtiger build somewhere down the road. I have a Leopard 1A4 that uses the same drive system, but it seems a bit more docile for speed and drivability.

Mike,
Neat idea, but I doubt I will implement it. This was just a case of being cheap and wanting to get it running for a quick thrill. Eventually, I will go through and bring it around to modern running gear, but keeping it a runner for now makes the most sense.

Mark

cleong

Yes, I know it is a 540 - you get a lot more aftermarket options in that size. A stock motor is 27 turns, you can get 540 size crawler motors of 40 turns or more that have lower maximum rpms that is a drop-in fit.

Old MSgt

Yeah Mark, those old style clutch trans were a 'pain' to mess with. Slipping clutches, clutch adjustments, gears stripping, etc. I definitely prefer the new systems BUT those clutch drive really 'FELT' different to run. They had that 'slow jerky' to turns that makes the tank look and drive REAL. They sometimes didn't totally stop the other track and there wasn't any 'neutral steer' with them. They also didn't have that quick positive change in steering that the new system has.

I remember seeing film footage of Tigers, Panthers turning and how the hull slowly lunges around in jerks and that's how the old clutches made my KTs move. With the new TUs/ESCs it's pretty dead-on and positive... I drove my old ones a LOT so I'm just being 'nostalgic' of how they moved.

BUT, then again, the new system is easier to control and mess with... and I LIKE IT!

Mike

Gun Tech

I took it out for another run today and I will see what I can do for the clutches, it just makes low speed turns too much trouble. It is way too easy to be applying power for a turn and it slips. I have another set I can disassemble and see if I can beef up the clutch units. By the way, the tracks I got from Imex work like a dream, they are a perfect fit and even getting a bit rough in a fast turn, they stay put. They also give the tank a better sound than the plastic tracks.

Mark

Old MSgt

Take the cork clutches out and make sure they don't have grease on them and the pressure plates. I used to stretch the pressure springs out a little for more pressure. I even got new cork and made new clutches but don't get too thick cork. And check the little cork dampeners between the locks cause if they get grease/oil on'em then they won't help stop the shaft when throw out pressure is put on.

I work on the old trans a LOT for the three years we were there... I didn't have our motorcycles or firearms to work on and I needed something mechanical to do. It may have saved my liver a little bit...

Mike

Gun Tech

Mike,
Cork!!!??? I would not have seen that as a pick for a friction material. As for springs, I have bags of coil springs in every imaginable size from my gunsmithing, so I have that covered. I may tune up a set from the other drive unit and get them ready for a swap later.

Mark

P.S. Liver is evil, it must be punished. (at least that's what I learned in the Navy)

Old MSgt

Here's a pic of the clutches and pressure plate. Those little cork dampeners at the ends of the drive shafts are suppost to help put drag on the shaft and stop the track when the big clutch hub is pushed in and it puts pressure to tighten'em. Sometimes those little dampeners gets soaked with grease/oil and then I'd have to clean'em.

The large cork clutches over time gets smooth and don't want to grab the pressure plates enough. I tried roughing up the plates with sand paper but that didn't help much. I stretching the springs just a little helped too.

But it was the pot metal gears that gave me the most trouble. They liked to start spinning on the copper hubs they ride on SO I took each gear and used a hammer and chisel to put an 'X' on the copper end to bind'em. That helped, but years later I found a gear company that had those gears made of steel and I order some, soldered'em on the copper and they haven't slipped yet! AND, just my luck, right after paying big bucks for those steel 90 degree gears, Tamiya came out with the NEW trans and electronics. So I ended up upgrading my KTs to that....

A fella can get very creative when he's stuck on a little island for three years and didn't have all of his tools that had been put in storage! I was using a new drill and a file/hacksaw blade for a 'lathe'!

And, yeah, I did a LOT of clutch trans 'engineering' and 'modifications' after a 'few' cold ones... wasn't much to do off work there. Didn't play golf or scuba dive (cause there were Great Whites in that ocean that would have LOVED to eat a sweet little sergeant of breakfast!)

Mike

Max-U52

Which Imex tracks did you use, the older ones from the Porsche turret or the newer torro set?

Gun Tech

maxu52,
The tracks are TAG120277, I just ordered them through Erik and they fit without any binding. I have a set of HL tracks that I also ordered and they don't match the Tamiya sprocket, but they do come with their sprocket when you order them and they will probably be for my Jagdtiger build since I will be making so many changes. I have gone a bit nuts with my collection and I am creating a backlog in no time flat. I knew this would happen, but the heck with it, I am having fun!

Mark

Max-U52

Hey Mark, have you had any trouble with the pins trying to work themselves loose?

Gun Tech

No, the pins have knurled ends and so far have stayed put, but I don't have a huge amount of time on them so far (less than an hour).

Mark