Tamiya Stug IIIB 1/35 Track and Drive Sprocket questions

Hello Everyone,
I am asking, more for a friend, but I am curious as well. I am trying to locate what aftermarket tracks fit the Tamiya Stug IIB drive sprocket. I have tested two sets of tracks I had and neither one fit. I tested the T-rex Type 3a (which states for a Stug IIIB after 41) and a R-model Type 2 (38cm) type.
I am not sure what it is but the Tamiya sprocket seems a bit wider than it should be. The T-rex tracks would be for a 40cm width sprocket and the R-model for a 38 as I said before. So I am not sure what tracks would fit it. I believe Tamiya shows a Type 3a fitted on the box art.

I tried the R-model on an Dragon Pz IVE sprocket I had and they fit fine.

Any ideas, my friend would like to get a set of aftermarket tracks for his and I am just a bit stymied by this.

Thanks all in advance for the help.

Best,
Walter

Would it be possible for your friend to modify the Tamiya sprockets?
Use a razor saw to make a cut at right axles to the axle?
Are the sprockets too wide or are the teeth too thick or is it both problems?
The StuG III B should have the 40 cm tracks.
There was no such thing as 38 cm tracks.
When the allies measured the 40 cm tracks some took the measure outside the bolt heads
and some measured the width of the track link. The link is 38 cm wide and the boltheads add 1 cm
each side for a total of 40 cm.
The early narrower tracks were 36 cm (total width)

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Hello Robin,
I went and retried the T-rex tracks, Type 3a and another set of R-model Type 7. I know the Type 7 were the wider tracks. The Type 7’s fit the Tamiya sprocket fine, the T-rex Type 3a, do not. I thought that the Type 3a was the first of the “wider” 40cm track.
You would think that being both 40cm, they would fit. Also, it seems the Tamiya “teeth” are a little thick as well. I am just a little perplexed by the poor fit of the T-rex tracks.
Lastly, I honestly think cutting the sprockets is way beyond both of us. Wouldn’t even have a clue how to due it much less do it correctly. But thank you for the idea.

Walter

Thank you Fernando. Will let him know.

Can you measure the width of the tracks accurately?
Preferably with vernier calipers.
40 cm / 35 = 11.43 mm
I suspect that the Tamiya tracks could be a little on the wide side

How about just using drive sprockets from a dragon kit if they fit. Sounds like the Tamiya ones are off scale.

Hello Robin,
Here are the measurements I got. Used a digital caliper from Harbor Freight-not sure on the accuracy.

Tamiya Sprocket; Measure from outside of tooth to outside of tooth- 8.36mm

T-rex Type 3a w/o track pin measure 10.70mm wide
and 7.31mm in the center of the open part of the drive sprocket( for the tooth) to other side

R-model (they say 38cm type) it is an type 2
10.38mm wide w/o track pin and 6.49mm center (open hole to open hole)

R-model Type 7 40cm measure like this:
11.08mm wide without track pin and 7.67mm (open hole to open hole)

The pictures are the T-rex in tan and the R-model with 1 link on the drive sprocket. The T-rex can fit just needs pushing to fit on. The r model does not.
The r model on the sprocket is the Type 7, not the type 2 which did not fit. I think its a 36cm with 2cm for the pins type.Not a 38cm and 2cm for 40cm.
Hope I have done well. I tried.

Walter
P6071993
P6071995

I think the gap indicated by the red arrow could be causing your friends problem.

In the lower image the sprocket teeth are pressing against the outside sides of the sprocket holes in the track links. Check how the twoo teeth indicated by green arrows fit in the holes.
Check if you can press the two wheel halves tighter together.
If you use Tamiya Extra Thin (actually a pure styrene solvent) you may be able to soften the glue and the plastic in the joint so that you can squeeze that gap tight.
Also check that the teeth are aligned, otherwise the track link will get twisted sideways.
Maybe the photos are tricking me but I get the impression that the teeth on the right side of the photos
are a fraction of a millimetre to far forward (away from the camera).
You may also need to get rid of the mold flash, use needle file to file across the teeth (left-right motion in the photos). This little ridge could lift the track links and effectively increase the diameter of the sprocket wheel. This can cause fit problems since the assembled track will be too short and have problems fitting over the last tooth.

Edit: When I write You I obviously mean your friend, sorry about the misunderstanding …
:grin: :wink:

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The tracks on my Pz IV’s show the Tamiya lengths beings ~12mm while my Dragon lengths are ~11mm. That 1mm can be enough to make things start going awry.

Hi Robin,
The sprocket you see was glued together by me. The halves are “keyed” where they meet. I think Tamiya did this to prevent “misalignment” which I could see easily happening. The two halves are were pressed together as best I could.

I would love to hear if anyone has used aftermarket tracks with the kit sprockets. If you did, which did you use? Will pass the info on.

I never built this kit and I don’t own one either.
Experience from other kits lets me suspect that there is a small amount of “wiggle”
where the parts meet.
What you could do is make the teeth narrower

I have a bit of a blog going for this kit, although it’s currently shelved. I have also had issues with aftermarket tracks, and can confidently confirm that Masterclub MTL35015 tracks also DO NOT FIT :crazy_face::crazy_face::crazy_face:

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Hello David,
Thank you for writing and linking your blog. It will be most helpful to my friend. I hope you found a suitable set of tracks for your Stug. Can’t wait to see it when its done!

Best Wishes,
Walter