Trans mount swingarm broken and how to fix it without removing the tranny

[Earl Upham]

I have noticed a lot of bike models have the swingarm pivot attached to the rear of the trans on rubber mounted models like mine. Trikes have this problem too. I have read all these crazy reasons why people think causes them to break. I disagree 100%. It is just a bad design plain and simple. An easy fix in my opinion is too have a machine shop turn a piece of steel round stock down to include the bolt hole through the middle and possibly have a bronze sleeze installed as well but make it stout enough and attach it to the front of the back frame downtubes. Use a carbide bur to grind down the broken transmission pivot. Make sure there is clearance for the rubber mounted trans to clear it. The swingarm mount on the back of the trans, in my opinion, contributes to wobble on cornering because the swingarm moves with the motor/trans assembly rather than with the frame and front wheel. What advantage is there to a frame and front wheel tracking in one direction while the engine/trans wiggling around with the rear tire throwing the track off? None!!! The swingarm should be hard attached to the frame, not the engine/trans assembly. Mine is completely broken off and the only good thing is the pivot is mounted to the front side of the rear frame downtubes preventing the whole thing from just separating from the bike. I haven't started on this project yet but I will be doing it in the future. Just curious what some of you think about my proposed swingarm pivot fix since I haven't seen this suggested before. I believe the fix can be done without removing anything but the swingarm and rear wheel.

 

[Jeff Klarich]

Good thinking, post some pics when work is done.

 

[liquid_wrench]

Welcome from Ohio.

 

[gator508]

Welcome to the forum from Gulf Coast AL

 

[dolt]

Can't say of a good or bad idea and would need to see pictures of the broken pivot and some drawings/sketches of the proposed modification along with a structural analysis to support the design of the attachment of the new hardware to the front of the back frame down tube. I don't believe the "fix" is an easy one. JMHO.

The '09 touring frame design went a long way in minimizing wobble while still leaving the trans and pivot as the rear motor mount and there are several ways to minimize the wobble on early and later touring models.

 

[K dobson]

Im not sure but i feel asif i have brought the bike you have been discussing

looks asif its taken a rear end smash and somone has replicated exactly what you are describing

would be a funny coincidence if this was the motor in question

If not did you by any chance have any success with the straight swing arm to frame conversion ?

my dad always says i need a new tranny case because the torque of the motor could potentially twist the motor in th frame ? I always called his bluff and that i thought the new design is pretty practical but im not so sure really on the fence about getting s new tranny the difference is £400+