TOPIC:

Hello everybody,
I'm building a new re-release Bruiser (58519) and so far I really enjoyed everything.

I have problem with the transmission:
top and second gears are quite ok but I have problem with the low (4wd) gear... it does not enter correctly. I tried to switch manually by hand (without the servo) but is very hard to trigger. I had to push back and forth many times before let it enter correctly but is very hard.
I already completely disassembled and reassembled the transmission but same problem.

Any clue?



Thanks a lot for your help and sorry for my English...

Welcome Micom. I don't know if the gearbox is the same on the rere and the original but I had the same matter than you. My error was that the 2 springs were inverted. The short in the place of the long one.

It's been a long time since I built a Bruiser gearbox, but 4 things come to mind:

- I don't know if I'd expect the gearbox to go neatly into each gear every time, while it's sitting stationary on the bench, the gears won't line up every time. This gearbox is meant to cope with shifting while moving, is it any better with the motor running? Try a 1.5v D cell directly to the motor wires so it's spinning slowly;

- did you perform the adjustment shown in step 34 - including removing the temporary G2 & G4 spacers?

- I remember the gearbox being a little noisy until it had been running for a while to get the grease moved around & smooth the sharp edges off the gears;

- step 19 in the build manual (main shaft) is ambigous about how many shims to use, and where to put them - my gearbox works fine, according to my build thread (tamiyabase.com/...mitstart=0) at the time:

jonny wrote:

The was a _really_ helpful note in the manual - "Use shims (BC 16 (0.5mm), BA19 (0.3mm)) for clearance adjustment"... well, duh! I know shims can be used to adjust the end float, but what is it _supposed_ to be?

I reckoned there was about 1mm extra float once the shaft was together, so put an extra 0.3mm shim between the two plastic gears & two more 0.6mm shims between the 1150 bearing in the 22T gear & the circlip on the "left" end - so now there's no extra float anywhere on the shaft & everything still turns freely ... it feels right but I have no idea if it's correct

Hi,
I never faced such issues with my old 3 speed gearboxes.
The first thing to do is identify if the shifting is still hard when the motor is powered with a small battery as suggested by Jonny.

Have you lubricated the gearbox? If yes what did u use?

What also can help a bit, is performing something like a running in procedure (I’ve done that with my gearboxes and I helps lots) by letting it run on your bench at low speed for a while. Shift the gears from time to time so the gears can adjust to each other.

Keep us up to date

hello Stingray, thanks but in the re-release there are not springs...

Jonny wrote:

It's been a long time since I built a Bruiser gearbox, but 4 things come to mind:

- I don't know if I'd expect the gearbox to go neatly into each gear every time, while it's sitting stationary on the bench, the gears won't line up every time. This gearbox is meant to cope with shifting while moving, is it any better with the motor running? Try a 1.5v D cell directly to the motor wires so it's spinning slowly;

Yes of course, I powered the motor and I was trying to shift with the motor running

- did you perform the adjustment shown in step 34 - including removing the temporary G2 & G4 spacers?

Yes I did

- I remember the gearbox being a little noisy until it had been running for a while to get the grease moved around & smooth the sharp edges off the gears;

- step 19 in the build manual (main shaft) is ambigous about how many shims to use, and where to put them - my gearbox works fine, according to my build thread (tamiyabase.com/...mitstart=0) at the time:

jonny wrote:

The was a _really_ helpful note in the manual - "Use shims (BC 16 (0.5mm), BA19 (0.3mm)) for clearance adjustment"... well, duh! I know shims can be used to adjust the end float, but what is it _supposed_ to be?

I reckoned there was about 1mm extra float once the shaft was together, so put an extra 0.3mm shim between the two plastic gears & two more 0.6mm shims between the 1150 bearing in the 22T gear & the circlip on the "left" end - so now there's no extra float anywhere on the shaft & everything still turns freely ... it feels right but I have no idea if it's correct

Thanks for your help, I will try

Hello,

today for the third time I rebuild the transmission....

A lot better thanks to the suggestion to add shims on the main shaft to avoid movements.

Top and second gear are very smooth, only the low gear (4wd) still a little bit hard... it enter immediately (different from the other times when was quite impossible to engage) but after a few second of running on this gear I hear a "tic" and the shift rod move a little bit more meaning that the gear was not fully engaged.

In any case a lot better than before but I still don't know if keep it as it is now or try to rebuild it again...

Thanks a lot for your help...

Hi I'm having the same problem, stripped the gearbox for the third time. I shimmed out the gears so there is no play. Cleaned everything & put on new Tamiya ceramic grease & I get that same click into 4wd. I've set end points & trim. Rebuilt it to the letter.

Same here, this is a bit of trouble for sure. Now I know why they give you extra plastic gears!!!!

Getting ready to have another go at the 3 speed trans to see if I can get it to shift smoothly with stripping the plastic gears, luckily there are a few left in the kit...
First a total disassembly and a good cleaning.

Going to use Johnny's notes at the start of tis thread to try and dial it in better, if anyone has tips or suggestions a 3speed expert I am not.