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NEW CRCM Gearbox for Tamiya tanks
I had this brain-storm how to fix this ongoing gear-problem on these new style Tamiya gearboxes...
as we know in the meantime one of these gears close to the outputshaft starts wobbling very soon
and eats up the other connected gears and soon after that = missing teeth's ....
1 more thing I always disliked on that setup is that there is a gear-up to the outputshaft ....
= large gear drives smaller gear .....
I think ( hope ) I found a solution for that without spending a million bucks for a setup like my heavy-metal-gearboxes,
or making complied new gearboxes....
I added 1 more shaft and 2 more gears to these gearboxes , but for that I did get rid of that gearclutter with these small weak gears
and I never gear-up , from gear to gear it's just gear-down , the way it should be ...
see here the gear-calculations ,
first the original setup :
and here the modfied gearing :
now there is 2x 5mm shafts on the outputside and a 1 piece clustergear on the bottom-shaft ....
the 2x 5mm shafts and all gears running on the 4 mm shafts have ballbearings now ....
the 70:1 gearratio ( vs 60:1 original ) together with the Big-Block-motors ( long can 400's )
should be just right for the Shermans
and may works okay for the Tiger 1's as well,
even thought for a 24 miles scale-speed
I should have a 78:1 gear-ratio
since the 70:1 calculates as 26.7 miles scale-speed
but this is just a calculation....
since with a lower gear-ratio also the available torque drops ,
the 70:1 may works ok for the Tiger 1 as well....
I will post here soon some test-results ...
King Tiger still would need a little higher gearratio / additional gearreduction ( mine has 85:1 and run's 22 miles/hr scalespeed )
parts needed to do this modified gearbox : ( per 1 gearbox )
busted gearbox and a new set ...prefared Pershing gearbox .
or just the needet gears from spares ?
1 brass clustergear ( is on all gearboxes the same , excepted the first Shermans had here a tripple-plastic-clustergear )
1 Pershing outputshaft with that small silver gear and both ballbearings ( the small silver gear , is on all gearboxes the same )
( a Tiger or Sherman outputshaft will work to , but needs to be cut a little differnt )....
2x additional gears ( not Tamiya )
10 ballbearings per gearbox for the gears
gears need to be drilled out to make ballbearings fit , no maschining on the 4mm shafts required
cutting a bigger slot in the bottom of the gearbox for that brass-cluster-gear
cutting of that Pershing outputshaft
drilling of the 2 additional gears to make them fit on the 5mm shafts and secureing them with pins ( drilling a hole gear/shaft )
if I get the second set done , I will test them during our practice run end of January ,
on our Danville Tankbattlefield....
and if they performe okay , I will calculate the cost's for these modfied gearboxes,
and will offer them as replacements ....
in case you are not up to the task with machinework on a mill and lathe ....
1/2005