Yamaha Part number 3GH-25151-00, the shaft with the cam on it that that spreads the brake shoe when it rotates.

Considering that I can't seem to find a new one to purchase anywhere (not available...), has anyone ever modified one? By modify, I mean take a mig welder to it and add some material to the lobes on the cam to make it a little larger, making the brake shoes spread open more sooner.

I have a suspicion that the one in the rear of our 98 Timberwolf is worn down so much that it's not actuating the brake shoe like it is suppose to. Brand new shoes on it, and it still has to rotate so far before it engages that the cam is going perpendicular to the surface on the shoe that it mates too, making the shoes not spring back and disengage, leaving the brake locking up every time you let off...

I had a thought about taking my mig torch to it and adding a little material to the ends of the cam lobes to make them a little larger (grinding down and rounding them off afterwards obviously). I would much rather do it to the shoes on the surface that the cam rides on, but I'm fairly certain it's cast aluminum, and I don't have a tig welder...

Thoughts?

Or am I just crazy? lol




Picture of the front, but same general idea... On the fronts I flipped the cams 180 to make them start waring on a more fresh surface, could see where they were worn down some on the side they had been riding on before, and it did help a little.

 

Are you sure you have the right shoes? As those don't seem to "sit" right on the pivot pin. I mend all sorts of ATVs and if I need a set of shoes I don't have in, have tried others that I do have, surprising how many look identical but are a slightly different radius or pivot pin diameter. Check the drum diameter, as an over-skimmed drum will cause this problem. I have known people fit shim plates on the shoes, to compensate, note the dove tail steel plate fitted to the lower one on your picture, but brakes are a safety feature so any mod must be well done. I wouldn't modify an "unobtainable" brake cam unless it shows obvious signs of extreme wear.

 

Well they're suppose to be lol. They're not OEM, but when held up they matched the old ones dead on (except for having shoe material on them). The drum seems pretty smooth and flat. There was a little ridge on the side when I first removed it, but it was just a build up of junk that I was able to chip off and scrape away with a flathead screwdriver. It wasn't a ridge as in a grove cut by the shoes wearing into it.

Now that you mention that steel insert on the shoe that rides on the cam, I never noticed that before... even stranger that it's only on one side... I will have to pull it back apart and investigate that further!

I can get a used one of those cams on eBay, it's just getting a NEW one that seems like it would be impossible. Luckily they're the same on the rear and both the fronts, so that opens options up a little for searching for one.

 

Wearing pad only on one shoe and the top shoe appears to be the wrong radius on it's pivot, I think you have got some wrong shoes mixed up with right ones. It is extremely difficult to tell if they are nearly right. Honda rears do the "over centre" trick when only slightly worn, put a worn out shoe against a new one and there is only a mm or two of difference.