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GS450 rear drum brake question

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    GS450 rear drum brake question

    Well I spent about 4 hrs. yesterday replacing the chain and sprockets and greasing the swing arm bearings, cleaning etc. - Thought I was running stock 15/45 gearing, turns out I had a 16T on the front and didn't know - doh! - no way would I want a 15T with the 45 on the back, the bike is hi-revving enough as it is on the freeways and quick enough accelerating once above 5k. Anyway, using the stock 104 links of 530 chain with the 16/45 gearing the axle had to be moved forward in the swing arm about two index marks, from 1 behind the large "center" index mark to 1 ahead of it. The one thing I didn't do was pay much attention to the rear brake since it had been working so well and has probably 60% remaining on the shoes. I did clean out the brake dust. So, I got it all together and adjusted the brake, etc. On my first test ride the rear brake seizes on and drags and by the time I get around the block and back in the garage there's smoke curling up from the rear brake!! So I backed off on the adjuster and squirted some lube on the shaft of the arm and worked it back and forth. It moves freely. Sitting in the driveway the brake works great but back on the road same problem. I have to come to a complete stop and roll the bike backwards then the rear brake will release with a loud snap. Not good! What's going on? The shoes are thick enough that no way am I getting the cam that forces the shoes apart completely sideways. I guess I have to tear it apart again and use some grease on the friction points of the shoes and actuator cam or whatever it's called. I have new shoes so I suppose I'll use them even though there's plenty of meat left on the old ones. After yesterday my legs and back are stiff enough to make that not sound like fun. That's what I get for being in a hurry to get a short ride in before dark. At least I did get to ride but having to avoid using the rear brake made it a slow careful ride and pointed out the lack of power in the single front disc. Time for some braided hose. I shouldn't be trusting that 25 yr. old hose anyway. It amazes me how some guys don't use the rear brake much. Not having it available showed me how much I do use it, especially in the twisties. I have trail braked into corners with the rear brake hard enough to create scalloping on the shoulders of my rear tire. My typical technique is to use both brakes entering the corner, release the front as I lean over, keep a light pressure on the rear brake thru the apex and roll-on, then release the rear brake and exit the corner. Sometimes if I find myself going a little too fast in a corner, rather than roll-off and transfer all that weight forward, I'll stay on the throttle enough to avoid that sudden weight transfer and use the rear brake to slow down a little. Much smoother and controlled that way. I have never had the rear wheel (noticeably) slide using that technique. The front wheel on my bike is more prone to slide than the rear. If I enter a corner WAY too fast, I'll get the bike vertical, grab a big handfull of both brakes while I'm heading for the side of the road, then let go the front and re-initiate the turn. This is all slow-speed riding in the tight twisties. I don't suppose there would be time to do that in a hi-speed corner. I don't enter corners at 60mph unless I can see all the way around and know I could probably have taken it at 70mph or more. Anyway, any ideas/tips/tricks for fixing the rear brake without tearing it down again? Ya right, I hear you all in my head. Just wave a magic wand! Or better yet, be more thorough the next time you have the bike that far apart...

    #2
    Did you remove The arm from the brake shoe cam ? Check & make sure it is indexed correctly

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      #3
      rear brake seizing on and dragging

      Originally posted by SqDancerLynn1
      Did you remove The arm from the brake shoe cam ? Check & make sure it is indexed correctly
      I didn't remove that arm and with the old chain the index was at approx. 65% of the shoe remaining. The brake worked perfectly with the old chain. The only things I can think of are 1) moving the axle forward that 3/8 in. or so changed the angle of pull or 2) loose dirt and brake dust are gumming up the works. In any case it's going to have to come apart again. Thanks for the reply!

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        #4
        I had the same problem - only when riding.
        Opened the drum. Used axle grease on the pivot cams (the ones that force the shoes apart). Problem disappeared.

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