GB-01 Ball Differential Wanted...

[nintool 4]

Hello - If anyone has a Ball Diff set that they want to sell please contact me. I have also been looking for the metal diff cups that were offered up back then too and can't seem to find anything that could get my buggy back up and running with a ball differential. I have purchased the gear diff that was in the GB-01S model, but I'm not sure i have all i need to make that work as it needs the BA14 pin for it all to ride on, but I'll search my parts bin and hopefully find one. 

Side note-- I called Tamiya and was told that the gear diff and subsequent any upgraded diffs for the SW-01 or mini LunchBox, might work. He wasn't 100% but thought they would. I found on Aliexpress a HOT Racing TTDR125AL ball diff assembly and picked it up in hopes that it'll work. Looks identical to the one in the original GB-01 so maybe the Tamiya tech was spot on! 

Anyone with the same issue that may have solved it this way, please let me know, It would take the stress off trying to keep this lil frog running. 

thanks any input is much appreciated.

 

[gt6++ 29]

On 11/14/2022 at 11:13 PM, nintool said:

I have purchased the gear diff that was in the GB-01S model, but I'm not sure i have all i need to make that work as it needs the BA14 pin for it all to ride on, but I'll search my parts bin and hopefully find one. 

What is this BA14pin you mention?  I had the same idea as you and replaced my busted ball diff with the GB-01S gear diff.  I have installed it with seemingly no issues, but I have yet to actually run it in my GB-01.

I don't think I ever found a manual or exploded view of the GB-01s chassis, but to me the gearbox is identical minus the bal diff.

[SlideWRX 785]

What is the part number for the GB-01s gear diff?  My GT-01 ball diff is broken, and the replacement parts are impossible to find.

[taffer 948]

https://manualzz.com/doc/4665687/tamiya-gb-01-off-road-model-benutzerhandbuch

 

There's the manual

[SlideWRX 785]

That is the GB-01, not the GB-01S.  The GB-01 uses the same ball diff that my GT-01 does(Edit:It doesn't? see below)  The S is the updated TamTech that came out last year, that uses a gear diff.  I haven't been able to find a replacement ball diff (40106), the metal drive cup upgrade (40509) That is in the picture above, or the new gear diff (#???) for the GB-01S.

Edit:  After some more digging, rcjaz has the parts numbers up at least, even if none of them are actually available.  https://www.rcjaz.com.au/spares-tamiya-gb01-gb02-t-48_103_122.html?tPath=48_103_122.html scroll down past the GB-01 stuff to some S stuff.  51685 is the part number for the gear set.

The gear set looks like the same one as the SW-01, but I thought the SW-01 gear set was wider.  You guys have installed these into original GB-01 or GT-01 transmissions?

[No Slack 454]

Is this the partnumber you are looking for? (Sorry it is not for sale as it is my last set)

 

[gt6++ 29]

3 hours ago, SlideWRX said:

You guys have installed these into original GB-01 or GT-01 transmissions?

Yes I purchased the SP-1685 GB-01S spare gear set and installed it in my GB-01.

Everything seems to mesh but I haven't tested it.

[SlideWRX 785]

On 12/8/2022 at 11:10 AM, No Slack said:

Is this the partnumber you are looking for? (Sorry it is not for sale as it is my last set)

Yep!  I thought I had found one in Australia but it was not actually in stock. This would be the ideal fix, as it would be metal and should last a long time, but I can't find one anywhere.

On 12/8/2022 at 2:32 PM, gt6++ said:

Yes I purchased the SP-1685 GB-01S spare gear set and installed it in my GB-01.

Everything seems to mesh but I haven't tested it.

(Edit: This is wrong, see below) Ok! I can get part #9006746, which is 1 set in black for ~$6, or I can get part #54930, which is 2 sets in yellow for ~$7.   I guess I am getting a spare!

[SlideWRX 785]

On 11/14/2022 at 5:13 PM, nintool said:

 I have purchased the gear diff that was in the GB-01S model, but I'm not sure i have all i need to make that work as it needs the BA14 pin for it all to ride on, but I'll search my parts bin and hopefully find one.

BA14 is a 2x13mm shaft.  The pin on most hex adapters is 2x10.  It is probably enough to hold things together, but I suspect it isn't really needed much anyway.

[SlideWRX 785]

Edit:Original below, but I am digging into this more.  Online, there is nothing to distinguish the SW-01 gear diff from a GB/GT-01 gear diff.  Obviously, when beside each other they are different.  more to come.

Scratch that.   The GB-01 gearbox appears to be significantly different from the GT-01 gear box.  This thing from the SW-01 wont fit.  Since they share other components I was hoping the gearbox would be similar, but no. Hmm...  I really don't want to buy more random parts but maybe the single part mentioned above is different?

Back to the search for a fix!

[SlideWRX 785]

Soo.... The diff in the SW-01, as seen above is bigger than the GB/GT diff.  The MudMad SW-01 uses two black diffs (2x part #9006746), while the MiniLuchbox uses one set (1x 54930), colored yellow, but the exact same thing.  The SP-1685 GB-01S gear diff looks identical from online pictures to the black MudMad gear diff, but they are different.

SW-01 Diff: 0.6 mod gear size, 41 teeth

GT-01 Diff: 0.5 mod gear size, 39 teeth

Yeah.  Virtually identical design.  Argh. I had found a pic somewhere of the single MudMad black set, and saw the GB-01 set, and could not tell them apart, so I thought they were the same.

Well, mystery solved.  It looks like SP-1685 is only available in Japan, so while it only costs ~$3, Shipping is $23.  So I'm going to get a couple (just in case), and see what else I can add to my shopping kart to help offset the high shipping cost.

[SlideWRX 785]

Follow up just to make everything clear as mud!    I ordered and received the SP-1685 from Plaza Japan.  As you can see in the pic below, it is the same size as the original ball diff.  The yellow SW-01 part is too big.  I installed the gear diff an everything seems to work - I ran it on the desk a bit, but not yet outside (snow on the ground at the moment).

As for part BA14, a 2mmx13mm shaft to align the drive cups through that hole in the middle, I didn't have that.  I do have 2mmx10mm pins for wheel hex adapters though, and since I wasn't using the ball diff, I had 2mm balls...

All together ~2mm x18mm "shaft".  The balls keep the shaft part in the middle to align both drive cups.  Everything fit without issue.  I don't know if it is really needed, but it is there...

[gt6++ 29]

Is the BA14 really needed? 

I never was able to find an exploded view or instructional manual for a GB-01S.

 

Let us know how it goes!

[SlideWRX 785]

So it is a 2x18.4mm shaft - I found a exploded parts diagram for the GB-01S.  BA14 is from the SW-01, listed at 2x13mm.

I haven't actually run it yet though. My guess of 18mm was close!

[gt6++ 29]

21 hours ago, SlideWRX said:

So it is a 2x18.4mm shaft - I found a exploded parts diagram for the GB-01S.  BA14 is from the SW-01, listed at 2x13mm.

I haven't actually run it yet though. My guess of 18mm was close!

 

I see.... thanks!
My son ran the my GB-01 for the first time since I installed the gear diff (without the 18mm rod) and it seemed to have run OK using a 6V graupner motor.  Although I did note that it does not have as good traction on loose surfaces and gets stuck easier.  Maybe I have to put some heavier grease in the diff...

 

[SlideWRX 785]

After a couple weeks of Blegh from Covid, I got my GT-01 out on the driveway to see how things were.  I didn't seem to have any problems either.  I also added oil shocks, springs & new tires so I can't tell you what affected what, however the diff seemed to operate correctly.