Hi Guys,
I'm afraid that neither the Armour Concepts "Trans Mod Kit" & the Applied Effects Gear Reduction is available anymore. The people who manufactured them did it soon after the kit was released and only in small batches. I guess that they found it non viable commercially and hence stopped producing them (it was only a sideline/interest for them). It is a shame.
The trans mod kit was simply a gearbox bracing kit that also strengthened the output shaft area. No-one makes a straightfoward copy/replacement of this but I believe that Daryl Turner on the armornuts website http://groups.yahoo.com/group/armornutsrcarmorhut/ makes a gearbox brace that sits under the boxes instead of the hex standoffs.
So as far as I know there are only a few options left for gear reductions and no real definitive and commercially available, affordable solution...
Willy's (good luck and don't hold your breath!) but supposedly exellent.
Also Wecohe in Germany do a complete gearbox rebuild that reduces the speed in half and massively increases the torque, also including a top brace. I can honestly say it's awesome but it is expensive! I think this is a case of "you get what you pay for." I paid for it and was emailed by Uli at wecohe who said that they normally do the rebuild as part of the deal – no extra – and run them in and adjust if needed. Just send us your gearboxes. Result: One fantastic set of gearbox es, nicely lubed and unbelievable torque. If you can afford it, go for it! https://www.wecohe.de/shop_eng/index.html Also available in Nth America via a couple of places but I dont think they will do the rebuild for you. PDFs of the rebuild available at the wecohe site.
Also from Germany is a company called Jamara that makes a gear reduction set. I don't know if it was designed for the Tiger kits and cannot comment on its effectiveness but I know that Panzerpabst has installed one. Have a look at his site for a pic. I did stumble across a german site that had details but didn't bookmark it (drunk again). I guess you can google for it. Perhaps Panzerpabst can supply some details?
Alternately you could try adapting some thing you find elsewhere like CT_Mazi but a word of warning... unless you really know what you are doing and all about gears/ratios/etc etc you could actually do your gearbox a lot of harm by stripping all the gears etc see... http://groups.yahoo.com/group/armornutsrcarmorhut/message/3698
Another option posted by WW is "use a diode jumper to solve the problem" (previous page). The guys at Danville came up with this as a quick solution I believe but for some reason don't recommend it long term. Because it reduces torque? I think its posted here http://www.sead.us/technology.html (at the bottom of the page)
Also WW mentions "A final option is finding someone that can get Kyosho parts. I've seen a reduction on eBay that loosa a LOT like willy's at about $13 each, no motor. Next time I see it, I'll log the part #." Worth investigating...
I also read somewhere that the Bandai motors run at about half the rpm that the stock Tamiyas do... thoughts anyone...? I'm just guessing but people may have gone down this route previously. Mmmm...
I guess that overall, there are very few realistic, proven, available and affordable solutions available at the moment. Anyone want to address this... are you listening aftermarket manufacturers?
Did I forget any WW?