New steel idler for XV-01, etc.

[Big Jon 686]

Looking at Tamiya’s new releases, I spotted a steel idler for XV-01 and other cars that use similar transmissions like the TD4/2. Although replacing the NN4 spacer with aluminum is cheap and easy, this should be a permanent fix for the drive pin wear on the idler, and the gear is already available.

Edit: Part number 22087

[ChrisRx718 4701]

Ah, I hadn't noticed this was cross compatible. For others looking, this is Part #22087 Steel 33T Idler Gear For BB-01 

I'll pick a couple up next time I do a mail order from Japan 

[Kowalski86 4274]

Huh, its pretty reasonably priced too, just $8 for us in the States. It's nice thst it's steel too, vs cheezy aluminum.

[smirk-racing 254]

This is a small part but a big deal! XV-01 owners have talked about this part for years and years... probably overkill (a little care with shims / spacers can do the trick) but I think this might be popular. I'm grabbing a few.

[Tamiyastef 2727]

i'll get me one of those for my XV-01 rebuild. It's getting a brushless system so a stronger idler might be a good "investment"

[Andreas W 2510]

It's a shame I didn’t know about this before. I have waited too long for parts I "needed" after I in reality was finished to build up the XV-01 again. 

 

Luckily It's not that much dismantling to retrofit it. I'll wait for Samirc.no to get it in stock again (together with the Yeah Racing diff for the M-08,  which also is temporarily unavailable).

[echobase 5]

I was just about to begin an XV-01 build. Could someone clarify exactly how this idler gear would be installed when assembling each gear box? Is it an addition? Is it a replacement? Is it a total solution?

[OnTheTrail 1239]

If both (front and rear) idle gears were replaced with this new steel one, do you still need to replace the NN4 plastic shims?  In other words was the shims and the original plastic idle a combined issue that played on each other?   With the new Idler being steel, I can't imagine the shim material having an effect either way?   Or am I not thinking this through...???  

 

[nockiboo 13]

For the XV-01 do you need 1 or 2 idle gears?

[OnTheTrail 1239]

4 minutes ago, nockiboo said:

For the XV-01 do you need 1 or 2 idle gears?

Two.   One for the front gear box (Step 2 of the manual) and one for the rear (step 8).

[echobase 5]

Also worthy of note is that Tamiya 22087 appears to be a fraction of the width of the BG1 idler gear depicted in steps 2 and 8 of the manual.

[nockiboo 13]

7 hours ago, OnTheTrail said:

Two.   One for the front gear box (Step 2 of the manual) and one for the rear (step 8).

Thanks for the detailed info. Appreciate it!

[skom25 2179]

During my build, I checked play and I suggest to shim it even with steel gear. Pin sticks out so much, that I have feeling that with steel gear, Pin can be weak point.

There is something wrong with design, because it is not normal that in edge case, you can see around 3/4 of Pin sticking out from gear.

Second thing is fact, that everything starts from weak NN4 part and gear is just "victim". In that case, you will have the same issue but probably, as I wrote, Pin will be damaged instead of gear. Even if not, at some point you will loose drivetrain.

[smirk-racing 254]

FWIW, the old solution of using aluminum shims for NN4 and removing excess play has been 100% reliable for me over long periods of time with strong brushless systems. I do like this new steel gear but it isn’t strictly necessary and I agree that allowing the pin to stick halfway out of the slot (which is what happens without shimming) is likely to be problematic. 
 

In short, shimming is cheap, easy and effective and probably still the right solution. The only hard part about shimming is taking the time to order the right shims (thoroughly detailed many times in TC posts including over the last few years so links to vendors should still be good). Also, I recall having to reassemble the gearbox at least 3-4 times as I tested the right number of shims. I was pretty obsessive about getting it precisely right (down to the level of a .1mm shim). That only took maybe 15-20 min per gearbox though. 

[Big Jon 686]

8 hours ago, smirk-racing said:

FWIW, the old solution of using aluminum shims for NN4 and removing excess play has been 100% reliable for me over long periods of time with strong brushless systems. I do like this new steel gear but it isn’t strictly necessary and I agree that allowing the pin to stick halfway out of the slot (which is what happens without shimming) is likely to be problematic. 
 

In short, shimming is cheap, easy and effective and probably still the right solution. The only hard part about shimming is taking the time to order the right shims (thoroughly detailed many times in TC posts including over the last few years so links to vendors should still be good). Also, I recall having to reassemble the gearbox at least 3-4 times as I tested the right number of shims. I was pretty obsessive about getting it precisely right (down to the level of a .1mm shim). That only took maybe 15-20 min per gearbox though. 

Agreed. I haven’t had an idler fail since I installed an aluminum spacer, and that was a very, very long time ago.