Tamiya planetary gearbox set question

[str8axle]

My question is what is the ratio of the stock white planetaries? Are they 4:1? I know the blacks are 5:1. If the whites are 4:1 then you could swap a Tamiya 5:1 in right. I know it would not make a huge difference in gear reduction but I'm only looking for a little bit lower crawl ratio with my 2.2's. I'm worried that with my hobby grade stuff it might be too low if I add a Tamayia 4:1 or 5:1 planetary. With my set up like it is now I can go down really steep rock ledges and the gearbox will spin up and help it crawl down in control. It seems like if I added a planetary that it would not spin up but lock up and slide. I'd hate to cut up my axle housings to add a planetary and find out that it's too low!

[mazdaparts]

From what I have figured out, the stock low range ratio is 125:1and 25:1 for high range. I added a second black plantary set and it is now 625:1 for low and 125:1 for high. I could be wrong but I think each planetary set is a 5:1 reduction.

[str8axle]

I read this cool article on the Tamayia planetary gear box that I found.http://www.du.edu/~jcalvert/tech/planet.htm

Then I took apart a stock planetary and found that the first white one is 4:1 - 16 tooth sun gear/(16 tooth planet gear + 48 tooth ring)= 4:1, and the black and the last white one are 5:1 - 12 tooth sun gear/(12 tooth planet gear + 48 ring)= 5:1, so 4:1 x 5:1 x5:1 = 100:1. It looks like it would be no problem to put a 5:1 in place of the 4:1. You would just replace the stock motor sun/spur gear with a 12 tooth one and put the 5:1 in place of the stock 4:1 but the Tamiya kit only comes with one 12 tooth sun gear! From what I found it is a 48 pitch with a 5/64's center hole nylon gear. I just need to find another one and I can try it. To bad the stock steering motors use a 10 tooth gear or I would just take it off one of the many spares I have lying around!

I would end up with a 125:1 ratio, 20% lower. I would think that it would be noticeable, obviously nothing like adding a planetary but better than stock and simple to install!

I'll let you guys know how it works out. Can anyone recommend where to look for a 12 tooth nylon spur gear? I wonder if good hobby shops would stock these?

[str8axle]

Originally Posted by mazdaparts

I could be wrong but I think each planetary set is a 5:1 reduction.

Yes I think you are wrong but thanks for replying!

I am sure the first set of plan's is 4:1 and that I can put a 5:1 Tamiya plan set in place of the first 4:1 stock set and lower the reduction from 100:1 to 125:1 in low and from 20: to 25:1 in high range. That's 20% lower! This should be awesome for hobby grade and larger than stock tires, kinda like going from 4.10's to 5.29's in scale. All without having to cut up the axle housings.

I found another 12 tooth 48 pitch gear at the hobby shop that is a Losi Mini-T pinion gear set for $3. Just need to trim it length to make it fit. Soon as I get my Tamiya Plan set I'll see how it works.

Somebody else must have tried this before??