Tamiya Geaboxe Mods old type

[971wright]

Hi Guys Have started my Sherman and being a bit short of funds have had to mod old gearboxes so they wont strip the final gear (apparently they are prone to this )so first thing was to change the bushes on the final drive the originals are the to ones made of some kind of alloy with a split in them dont no if they come with this.
                           The final drive shaft with the sprocket on wobbled about 5 mm so completly stripped  the gearbox (dont strip both down at the same time leave one assembled for referance)the bushes fell out so out with the micrometer and started measuring the bushes made the replacement bushes from the one in the picture it was the right size for the shaft so only had to turn the out side took about 20 minutes to make 4 of them assembled them and tested all the wobble was cured .

        regards pete

P.s also fitted gearbox brace across the bottom of gearboxes to stop hull flex see lower Photo

[971wright]

Hi  The next stage for upgrade was outer gearcase the original gearbox dosnt have any support for the shaft see First picture this is how it looks from Tamiya Tony (tiger 205) took some pictures of a resin gearcase with aa rule along side for scale  see photo .
            From these Photos made a gearcase for each side from aluminium with a brass bush to fit the final drive shaft see photos of home made gearcase before fitting .Next stage was to drill and tap the gearcases to the side plate see photos and then try them see photo with the screws in didnt put all of the screws in because they have to come out to final assemble them .The last 2 photos are before and after Im sure you will agree they are less likley to wobble or fail now.
    The Next part of the upgrade is to change the motor drive pinion which as 15 teeth will fit a 10 tooth pinion this will give the gearbox a 33% reduction.Does anyone know what speed the the 380 motors run at may change for a slower one but need to what the standard ones run at 


      regards pete

[grompix]

Brilliant work Pete. Thats the kind of mod Tamiya should have done to these gearboxes in the first place. The 380 motors on my old gearboxes ran very fast so I think your Sherman would benefit from some slower ones - perhaps hi-torque HL motors?

Cheers
Chris 

[971wright]

Hi Chris at the moment have a good selection of motors white cap black cap Heng long motors Speed 400 7,2 volt speed 400 6v speed 400 4,5v also Jamara 480 I know the speeds of all of these motors but dont know how fast the Tamiya motors are is there someone who does know the speed .Or it will be a case of trial & error trying them all out to see which works the best .probabley 7,2 volt speed 400 or Jamara480 will need a rx18 or 14 with fan for both these.


    regards pete

[grompix]

I don't know what the revs on the Tamiya 380 motors are Pete but I tried tamiya motors on my HL StuG and it ran WAY faster than the stock HL motors. So it looks like the HL motors in their StuGs are low speed hi-torque. Incidentally I couldn't see any colour caps or markings on the HL motors - they are just plain.

Cheers
Chris 

[971wright]

Hi Chris Thanks for the speed comparison will try Standard Heng Long motors with 10 thooth drive pinions will save me having to remove them off the motors an refit to Tamiya motors Just to find out they are to fast any way will save these motors for fitting to a 3:1 reduction gearbox .

      regards pete

[971wright]

Hi Chris found out how fast rs 380 motors are 16200 rpm thats has fast as a Speed 400 7,2 v motor

regards pete

[grompix]

Hi Chris found out how fast rs 380 motors are 16200 rpm thats has fast as a Speed 400 7,2 v motor

I wonder how that compares with the HL Hi-Torque/Low Speed motors.

Cheers
Chris

[971wright]

Hi Chris the motor speeds are these as best I know white cap motors 8,500rpm
                                                                          black cap motors 16,200rpm
                                                                          speed 400 7,2v  16,000rpm
                                                                          speed 400 6v      19,200rpm
                                                                          speed 400 4,8v    32300rpm
                                                                          permax 480        17,000 rpm
                                                                Tamiya rs 385              16,200 rpm

all these have been calculated for 7,2 volts so it all depends on the gear ratio and sprocket size to work out the speed required for each tank ,if you want a racing tank or one that will climb the side of a house I prefer the later not to botherd if it is a bit slow as long as it dosnt stop at the first sign of a lump.The only draw back with low speed is the battle system after a couple of hits on my tiger its down to a turret battle because it dosnt want to move this has 3:1 gears and 7,2v speed 400 motors may try it with speed 400 6v to give it a little more speed but still have the torque.A little trial & error

      regards pete

[971wright]

HI GUYS Next part of gearbox upgrade the original gearbox is 30:1, so have built my own reduction box to add on First 5 Photos are the righthand the next 4 are the lefthand. At the moment with a 10 tooth gear on the motor it works out at 150:1 whoops overdid it a bit have ordered 15 tooth gears for motor so it will be 100:1, so far the cost of doing these mods is very cheap £5,67 for the gears that I orderd today still have to finish off the lefthand mith motor mount and a little bit on the righthand .The righthand works have had a battery on it for a short burst to check gear alinement and its as quiet as a mouse compared to heng Long all metal gears.After fitting the larger drive pinion will post photos of them finished and fitted ,No doubt will have to do a little cutting to get the motors to clear each other I know there is a mod to do on the lefthand where the motor touches so will do this when I drill for motor mount when the new gears arrive.


  regards pete