As many Tamiya enthusiasts I too wanted a bruiser for a long time, I especially liked the transmission and how it resembled the real thing. When I got my bruiser transmission I just had to modify it with ball bearings, but I heard of nightmare stories about people who tried it and never been able to reassemble the transmission.

Carefully I used kope instructions (www.kope.com/bruiser/TrannySvcManual.pdf) and eventually made my way with the bearings modification. Even though the build is a little bit tricky, it was fun just like any other Tamiya build, The only thing that was missing was a proper manual to take you step by step. So I decided to 3D model the transmission and create an instruction manual that any Bruiser owner can use and benefit from it, I hope you all enjoy it...

If you want to modify to ball bearings I recommend to replace only the 1150 bearings, the flanged bearings are too fragile and one even broke to pieces in my transmission causing damage to one of the gears. Even though you all know it, when you disassemble the transmission make sure you don’t lose any parts, they are not replaceable.

Before reassembling clean all metal parts with engine degreaser, I bet all those years of use with different lubricates left quite a mess inside.

Step 1 - I recommend inserting the 2nd speed countershaft and gear unit first and then the shift fork assembly (pictures & )

Step 2 - Make sure you use the proper length screw, there are three different length of screws in the transmission. Do not over tighten the screws so you wont destroy the thread in transmission case
(pictures & )

Step 3 - The dust cover must be in the correct orientation or it wont do it’s job, watch the pins molded on the dust cover, the side with 4 pins should face the screws. Use small amount of silicone sealant to hold the dust cover in place during the assembly (pictures & )

Step 4 - Insert the 1150 metal bearing (or ball bearing) to the motor housing first and then attach with the proper screws (pictures & )

Step 5 - I recommend inserting the low speed countershaft and gear unit first, then the shift fort assembly and finally the main gear cluster
(pictures & )

Step 6 - Not much to say about this step except remind caution with over tightening the screws (pictures & )

Step 7 - While inserting the shift ring make sure the teeth align with the cluster gear properly (pictures & )

Step 8 - This is a simple stage, just do it and keep on to the next one
(pictures & )

Step 9 - Nothing special here, just screw the threaded shaft first and then the front drive countergear assembly (pictures & )

Step 10 - This step is a little tricky since you need to align and insert three axles to three holes. Take your time and do it gently until the rear transmission end fits properly. To insert the rubber caps just twist them a little and push into the transmission (pictures & )

Step 11 - The motor usually slides in with no problem but pay attention to the notch on the motor housing that should fit into the slot on the motor (pictures & )

Step 12 - Ones the transmission is assembled There are four areas to be sealed with silicone. Even though the original Tamiya manual indicates five sealing areas the one in the middle of transmission Is redundant since it is the mold line of transmission case C. So save yourself some work and seal only four areas, it will also look better. Do not forget to lubricate the transmission before operation and from time to time between drives (picture )

Transmission case C disassembly - This step is not a must but If you really want to go into the transmission insides then go ahead, just remember that this is not your usual assembly with screws or cement, it takes a more aggressive method to complete. Also if you don’t intend to replace the metal bearing with ball bearing there is no reason for doing this step. locate the transmission so that the gear is not interfered and has room the get out (pictures & ) the screwdriver should hit the shaft and not the gear so it will push the shaft down (picture ) don’t go mad with the hammer, start easy and increase the power slowly until the gear assembly is out of the transmission case. This is what you will end up with after completing the step (pictures & )

Transmission case C assembly - Well if you chose to disassemble the transmission case I guess you have to do this step. Start by locating the shaft and bearing in the table clamp (pictures & ) Then put the transmission case on to of the assembly (pictures & ) and finally put the gear on top (pictures & ) When you hit the tamiya tool with the hammer to tighten the assembly make sure you don’t lock the gears completely. The gears should revolve smoothly with a minimum of play in the transmission case. This is how it looks when completed (picture ) If you lock the gears to much just go back to the transmission case disassembly method until the gears go free.

A big thank you to Shai (Zeppelin) for this amazing article and his hard work! Below you can download his manual for FREE...