brake drum torque arm question

[Grinder]

I have a 77 that I'm putting a rear 81 drum mag on. All the spacers from the 77's spoke wheel seemed to work well. The problem is the brake torque arm as it hits the tire(130/90-16). Did they use different shaped arms or was the swingarm mount different? My arm is nearly straight.

 

[xjwmx]

I'm pretty sure the arm on my '81 has a beat-in area a few inches long to help clear the tire. It isn't a round tube its whole length. Other than that, no offsets or anything in the arm that I recall.

 

[Grinder]

That's what I might have to do is heat that area up and flatten it for clearance. Does yours look like a factory job or home mechanic with BFH? Mine is round the whole way with these little clips that need to be ground off. Would the clips have been for the brake lining sensor wire you think?

 

[gggGary]

I think XJWMX is right the later special arms have a factory "crease" to ease tire clearance.

 

[TeeCat]

On my '73, the torque arm is flat, with a center "spine" for reinforcement, but it's very slightly bent to ease tire clearance. So, a dimple or crease seems in order.

TC

 

[littlebill31]

Yep, my '81 has an area that is shaped inward to clear the tire.

 

[5twins]

Yes, the Special torque arms were dimpled to clear the tire .....

Yes, those clips were for the wire running to the rear brake wear sensor although I don't think it was present on the '77 model. Your torque arm may be from an even older model.

 

[Grinder]

Thanks for the replies. I took the arm to work today and heated it up on the inside area where needed and flattened about a 3" long area with an arbor press. Worked great, plenty of room now. My arm is stock 77 as I bought the bike new.