CR01 Bronco Trans Problems

[GrndLvls Brain]

Started building my Bronco the other day and finally got to the point of building the transmission/planetary gear setup. Fought with it for a good hour with no luck and need some help. I don't have any pictures for reference points as to what I need help with cause I'm at work and didn't think to take any before hand.

Here we go:
Build the whole gear setup, case and all to spec as the instructions lay it out. Went to put the motor plate on the back to close it up and the bigger gear that comes in contact with the motor, isn't sitting all the way down like it should. Took it apart about 5 times completely and rebuilt it all with the same issue. Finally I got it to close up like it should but now with all the screws tightened like they should be, the gears are really tight and hard to turn. Took a small screw driver through the hole for the pin to the drive shaft to turn it and that was hard. But once I loosen the screws just a bit, it frees up a little bit and turns a little easier. But I think its still to tight then it should be. And I should point out the motor isn't even contacting the gears yet, its slid to the opposite side still.

Any ideas as of what could be wrong? Thanks guys!

[timmy85]

i had to keep my case screws loose so the trans was easy to turn. i think there is a spacer that goes between the two bearings in the big gear. i forgot it on my bulid and had the same issue. i done have my manual in front of me so this is all i got.lol sorry but hope it helps.

[GrndLvls Brain]

I've got the spacer between the bearings like it said, which i wouldn't think something that tiny would have that affect on it. Gonna mess with it some more tomorrow when get off work.

Haven't had a chance yet really to mess with the motor at all. Don't plan on running that one long as it is, upgrading to a brushless crawler motor.

Thanks for the help guys

[860Crawler]

The large bearings inside the trans is not seated all the way down on the shaft of the gear. It takes Herculean strength to get it to seat properly then the whole tanny will go together right and the case will be able to be tightened down.

This part trips up nearly everyone in the build. I couldnt figure out why my trans wouldnt close together and it kept binding.

[GrndLvls Brain]

Yeah I had that problem too with the large bearings. Ended up putting it all together and used a vise to help push the motor plate down to seat the bearings all the way down. Still binds but about to go tear it down for a 6th time and go from there

[GrndLvls Brain]

Got it fixed and its working good now! Ended up taking a deep well socket and popped it with a hammer on the big bearings and they finally seated all the way back. The little bit of a 1/16th of an inch was what was giving me hell.

Thanks for the help and just glad to know it wasn't something I did that cause the problem at first.

[860Crawler]

I recently replaced my spur gear, the bearings are just as fun to remove as they are to get on:-(

[GrndLvls Brain]

Thats the part I'm going to be afraid of when I have to do that. I'm almost debating ordering another set of gears/bearings and just build a new setup instead of fighting them to get em off

[Thump Wallop]

Yep, good idea. The gear set is cheap, and your local bearing supplier will easily match those bearings without having to buy Tamiya stuff.
Additionally, reduce the need to replace the spur gear by fitting a hard steel pinion. The alloy ones are RUBBISH, and when they wear unevenly, they screw the spur as well.
I am unsure why Tamiya needed 2 of those huge bearings, they are bearing a load, but I thought it was a bit of overkill...the planetary design and functionality spreads loads well, so you should not really need to rebuild this gearbox much, unless you insist on TRYING to destroy it..

[GrndLvls Brain]

I figure just order all new Tamiya stuff and build a new one. Doesn't cost me that much to do that, and not that I really care bout cost as it is. I don't plan on destroying the transmission in it but never hurts to have a back up in the work case possible.

But yeah when we were rebuilding it for the last time we were trying to figure out ourselves why they needed 2 of those big bearings.

[Teamsherman]

I had no drama's whatsoever with my transmission case. The only thing i found that did bind, was the diff locking pin if i screwed it in too far. When that was backed off an bit, no problems and still no problems. My bearings during the build literally fell into place.

[860Crawler]

Originally Posted by Thump Wallop

Yep, good idea. The gear set is cheap, and your local bearing supplier will easily match those bearings without having to buy Tamiya stuff.
Additionally, reduce the need to replace the spur gear by fitting a hard steel pinion. The alloy ones are RUBBISH, and when they wear unevenly, they screw the spur as well.
I am unsure why Tamiya needed 2 of those huge bearings, they are bearing a load, but I thought it was a bit of overkill...the planetary design and functionality spreads loads well, so you should not really need to rebuild this gearbox much, unless you insist on TRYING to destroy it..

This.

It was my pinion that was just ever so slightly moved out of mesh and it wore the teeth of the pinion into a sawblade shape and ate the spur teeth at the same time. So I ordered hardened Robinson Racing pinions through my local hobby shop. They had to order them in, since they don't carry metric.

[twisted concept]

i had the same issues as well...so you guys are saying the first of the larger bearings in the case has to be seated against the spur gear in order to be seated correctly?

[860Crawler]

yes, it has to go down as far as possible. It seems like its seated but usually it can go another few mm.

[twisted concept]

whats the best method for seating the larger bearing in place? Ive read that ppl are using hammers and deep sockets to seat the bearings tight but is that safe?

[UFCSam]

I'm having this same issue with my new Land Cruiser; I used a deep socket to knock the two big bearings down, but everything is completely bound if I screw the motor side on.

Any updates/tips?

[UFCSam]

Nevermind, I found the issue. The metal motor-plate was apparently backwards. I didn't notice that one side had a groove around the circular opening (which lets the plastic piece sit flush). The Tamiya instructions are written so well on the other steps, I'm surprise there isn't a little blurb about paying attention to which way that plate is, because it definitely matters.

[OSRC]

It says "Note direction" and points at the little notch.

S'ok, I mounted mine in the wrong set of holes in the skid and the motor hit the front upper links. Could not for the life of me see what I did wrong..swapped out the motor to get it to work and only realized it about a year later.

[UFCSam]

Ahhhh, well it was user-error then . I was just frustrated as hell at that step in the build (and everything else until then was going really smooth)

[carried away]

Well there ya go, I got frustrated with the binding and just installed an axial trans and driveshafts. Works great now haha