tomhugill

Well I bought some replacment tamiya tus for my KT and after two days of use one has chewed its self up, same gear as the ones i was replaceing so I cant even canibalise the old boxes.FML! Have ordered some impact tus so will see how the steel gears in them get on!

mergen

I just put those in my tiger they are awsom, and they deliver in about 3 days, and they come from singapore, maybe those other guys should use FEDEX insted of pigions.
Mergen

sevoblast

I would suggest that you have a problem somewhere besides the transmissions, as many of us have used Tamiya transmissions for years with no problems, including me personally with many competitions at Danville.

You need to check your tracks and running gear for binding and proper alignment, and make sure all road wheels and idlers are free wheeling and in alignment. Also check your track pins to make sure one or two are not walking out. Also check to make sure there are no bolts or screws in the area of the track travel against the hull that could momentarily jam the track.

Was this the same side of the tank that the TU failed both times?

tomhugill

Well servo, I thought like you so the second time round Ihave stripped off all the mud guards and checked the alignments, the tank was running sweetly upto yesterday. I run the tank on pretty rough terain as such some times I get stone jamming the tracks but I never force them.
The boxes have gone in the same place but on a different sides. Strangly the first sign of trouble was a knocking noise I took the box out and found one of the teeth had bent slightly. The rest of the box was 100%perfect. So I canibalised one of my other boxes and replaced this. It was only then the rest of the box got chewed up in pretty short order.

RodgerB

Check the diameter of the original gear and the replacement gear with a caliper to make sure the clearance is identical? It doesn't take much to cause the situation that you describe, especially under load condition?

danlrc

It's time for a timing belt drive instead of gears.....

tomhugill

Well if you do need any tamiya frames or drivetrain bits send me a pm , id be happy to contribute to the project

sevoblast

Are you using the stock tracks or metal, and if metal, whose?

tomhugill

Im using a set of closed pin kenny kong metal tracks currently

sevoblast

Hmmm. All I can go on then is my 17 years of experience with Tamiya. Now, the original Type 1 TU's were a bit weak. The Type 2's were better, but way too fast, as were the Type 1's. Type 3's, which have been extant for quite some years now have given me zero trouble in this rock garden we call home. However, you may want to invest in a spring loaded idlers system, as the stock 'spring loaded' system is pretty week. DP offers them through etoarmour.com. They work well and can probably solve your problem. I have them on one KT, but the other KT and the JT run in the same mess and do fine....so far.

Also, even one stone caught momentarily in the tracks can pop a gear tooth, and then it's all over. Here's what you can to to hardened steel gears in Type 1's if you jam the tracks with the charming mud we have here.

tomhugill

Ouch looks nasty. Are you able to get replacments for the individual gears or are you also having to replace the whole gear box?

manchu9inf

Sev,
I never get tired at looking at that mud and stripped gears! All I can say is; WOW!

sevoblast

I build from time to time extremely strong transmissions for Tamiya. I used to go to Danville Meets when I was in USA, and the combat is pretty hard on the tanks. I use the original Type 1 TU's, and gears from HPC in UK. However, HPC has gotten outrageous in their prices for gears of late.

sevoblast

Manchu, that deal was a lesson in what not to do, IOW don't leave a 12 year old running a tank in our famous mud while you answer the phone. It was an expensive lesson.

tomhugill

How much are you paying per box for gears from hpc?

sevoblast

HPC's price per small steel gear is $45.00. There are 2 small steels in each TU, ergo 4 small gears total, $180.00 per set. Carriage was quoted at 55 pounds to either USA or Krimea. Go figure.

Panther G

I'm not convinced you will be happy with the Impact TU's. The only ones that ever held up where the ones completely reworked by Willy or Sevo, so their quality has ALWAYS been a question mark. The only reason they are still making them is due to all the redesign work done by Willy and sevo to make them reliable.
Willy would go through upwards of 50 sets to get ten he could sell. I'm not sure but Sevo had probably expierienced much of the same.
Tamiya gearboxes are great pieces with the proper set up and lubrication.
How you run the tank has a HUGE effect on the life span of any TU so you may need to adjust slightly the way you run them
Remember these act VERY MUCH like thier full size counter parts and are very vulnerable to break downs depending on use and abuse. which is the major cuase of premature failure. Not always so it's not totally fair to generallize like that but it does happen on a regular basis.

tomhugill

Ah, this will serve me right for jumping in and buying straight away :/ The main reason I went for them was that you can get hold of the replacement gears. Its such a shame tamiya discontinued their overhaul kits as these would have saved me so much money.

I have to say its a pity Im not able to adapt the asiatam 3:1s I have spare from my jagdpanther. The other set Ive got on seem to be bullet proof, the motors have burnt out before any damage to the gearing theyre that strong

tomhugill

Quick update, it would seem that the output shaft diameters on the asiatam 3:1s are exactly the same as that on the tamiya boxes, so Ive managed to adapt them to use the KToutput shaft. All i need to do is adjust the standoff positions to fit and the job should be a good un