Them's the brakes -- again

[Darrell]

My 250SL runs out of rear brake adjustment well before the linings are significantly worn. Logically, it seems the drum is oversized, though I don't have a device to properly reach inside and measure it.

To compensate I wrapped the brake cam with copper sheeting and JB Weld previously. After that the brake never worked better, until the modification came apart one day down the road.

Recently I installed new shoes again (929278R) and measured their diameter on the backing plate. My caliper read 126 mm, which seems appropriate for a 130 mm (specified) drum. However, with these new shoes the brake lever will rotate 360 degrees without the shoes making any contact with the drum.

This time I'm thinking of building up the cam/flat end of the shoes with pieces of sheet metal JB Welded on. Has anybody taken this route to rectify this situation before? This method seems like it would be more durable than my earlier cam buildup. This topic has been discussed but I don't think it concluded with a definitive fix.

Darrell from Nanaimo

[matt glascock]

This doesn't sound quite right. Could an incorrect cam have been installed previously? Is the cam worn and thinned out at the points of index?

[BrianZ]

I'm seeing the same thing with the rear brakes on my Road Toad. The linings are too small diameter, but not to the extent you are seeing. I have tried two different drums with pretty much the same result; too much lever travel before the shoes make contact. I have tried some aftermarket grooved shoes but they seem a little bit worse than the stock shoes. I think that it's a combination of too much slop in the original design combined with a drum that wears quickly, but I am not 100% sure. I'll have to take some measurements of various drums (Toad, Ace, Wombat, etc) to see if there are any differences.

I was going to try building up the cam as you described but haven't got around to trying it yet.

Brian

[olddogs]

Cycle dealers will have an appendix to their brake shoe catalogs that will list shoe width and total diameter. There are dozens of options. I used to order a shoes a couple millimeters larger in circumference and modify the round end to fit the Hodaka post and grind the flat end to custom fit my drums. Vesra and EBC both had standard and grooved shoes that I made work. Now if I could only remember what the part numbers were I could be more helpful. I think they were meant for a Yamaha.

[Al Harpster]

I believe Matt G has provided the most likely answer.

I've got a '76 Suzuki 130 mm brake assembly in my basement.

Calipers measure over those worn shoes is 129 mm.

You're starting about an 1/8" low with new shoes.

The brake cam, maybe not stock-replaced-by-somebody, is a prime suspect.

Or the wrong shoes.

Wear on the cast iron break liner pressed into the REAR hub, the one that works less, is not so likely.

If you can get to 129 mm, or just under, that's a good starting place.

That's where I'd look.

[matt glascock]

Also, you could increase adjustability of the brake actuating rod by running a half inch or so of the rod through a die to give you a bit more threaded length of the rod to work with if all else fails and the brakes work otherwise. That really shouldn't be necessary if the correct parts are present and/or are not worn out.

[taber hodaka]

You will always hear me say everything about hodakas is great. Well the brake issue has always been a concern to me even the early models. ------------------------- Clarence

[MTrat]

Rather that adding threads to the brake rod, you might just change the position of the cam lever on the splines of the brake cam. Besides shimming the cam you may also shim the pivot point at the other end of the brake shoe.

[Darrell]

Thanks for all the think-tanking over this issue!

The brakes have been this way since I got the bike at 830 miles so I'm assuming the problem doesn't stem from worn parts -- unless there are pre-existing manufacturing deficiencies (wrong cam?). Brake action has always been spongy too, except for when I built up the cam and then it was great.

This might be interesting: I remember that the shoes that came with the bike had the Suzuki 'S' brand cast into them, or a trademark that certainly looked similar. I never got to ride the bike with these shoes, the linings had rust welded themselves to the drums and had to be chiseled off. It was a long and tedious restoration that I wrote about for the Resonator Revisited.

In the meantime I think I'm going to try building up the flat end/cam follower with metal shims on the brake shoes this time until superior replacement shoes are identified. Since brake lining is adequately adhered to the shoes may JB will bond the shims satisfactorily. Will also measure the drum diameter too even though there's no discernible wear, or ridging, to the eye or touch.

[Bullfrog]

Once upon a time, long, long ago - I built up the actuation cam by adding brazing material. By that method, there were no concerns about adhesive failures, and as I recall I made the cam both wider and slightly thicker. My main target was a wider cam for more "throw" on actuation of the rear brake for each degree of actuation of the brake lever at the hub.

[taber hodaka]

That is the solution needed. I would guess some old dealers made other improvements for racing ect. ----------------Clarence

[Bullfrog]

While the custom cam is one solution, simply having brake shoes which are properly sized for the drum seems better to me.

[olddogs]

Remember the round post does not move. Simply making the flat pivot point wider just tilts the shoes. You need to increase the post diameter also. This is why double leading brake hubs were the hot setup before disc brakes took over. This is also where a slightly over sized shoe comes in handy. It is always easier to make something fit by making it smaller than it is to make it larger.

I put some chalk on the pad material then would spin the wheel while dragging the brake. This will show you exactly how much surface contact area you are dealing with. You can then start arcing the shoe to increase the contact area. Stopping is as important as going.

[Darrell]

While the custom cam is one solution, simply having brake shoes which are properly sized for the drum seems better to me.

These "properly sized" shoes are elusive though. There are other makes/brands of 130mm x 25mm out there -- just have to figure out which are compatible.

But for all that, I put new rear shoes in my 94 Wombat (same p# but not the grooved ' R' version) and that brake works just fine.

[Bullfrog]

My "beef" is that it can take 30 degrees of cam rotation before the shoes contact the drum. There is plenty of braking power available, but the rear lever has to be cranked 20 degrees by the adjuster nut on the rod to keep from sticking your toe in the ground while applying the brake.

[Darrell]

Ed, did you ever find that "sticking your toe in the ground while applying the brake" is a kind of a braking assist? Sort of like the way Fred Flintstone stops his car with his heels

Anyway, here's my brake cam buildup solution. This time I attached the cam/shim wrap with Kesters "Metal Mender" solder, rather than JB Weld. I'm a little more confident that the soldered connection will be more reliable.

With this modification the slightly worn shoes measure 127.7 mm while attached to the backing plate. The drum is 130.1mm so that's pretty close to the 130mm factory spec.

Given that the drum diameter is fine then the Hodaka brake operation deficit has to be an undersized brake cam and/or brake shoes.

[Dale]

Darrell, If this works out for you it seems like a good subject for a Resonator article. This issue is so common. Thanks for sharing.

[Joe Ormonde]

Here`s the bottom line: the replacement shoes DO NOT FIT CORRECTLY. I bought the grooved Brake Shoes from Bill Cook and ran into the same problem with a Brand New Rear Drum. I put a Factory Backing Plate with 40+ year old Shoes from a 72 Wombat and the brake lever moved half as much for the Shoes to make contact the Drum. What does that tell you? The front shoes are new factory ones and the Brake Cam Lever barely has to move for the Shoes to make contact with the 47 year old drum on my 71 Super Rat. The Replacement shoes just don`t fit right. At least for me they don`t. Joe Ormonde.

[Bullfrog]

Joe, I think you nailed it.
Ed

[dirty_rat]

Didn't Capt. Eddie write up an article for Resonator Revisited a few years back dealing with brakes and ways to make them work better? As I remember, one of the methods was to wrap a shim around the brake shoe post to increase brake lining coming into contact with the brake drum.

[Joe Ormonde]

When you have to modify something to make a new part fit it shouldn`t be caused by the new part. When my Super Rat was new, the Brake Cam Arm both front and rear only had to move about 1/2 inch for the shoes to make contact with the Drum . Some replacement parts are Superior to the factory parts; others are not. Take my 71 Super Rat. The Factory Piston Ring was Iron and needed to be replaced before anything else. Then Poppy Piston Rings came out and lasted 3 times longer. They were Perfectly round and didn`t need to be filed down to fit. That`s what a replacement part should be like : as good as the Factory installed part or better with no extra time spent to make it fit. I just don`t want to modify something now and have to de- modify it later. UNLESS it`s a obsolete part . That`s a different story! Joe Ormonde.

[viclioce]

That’s a good point Joe! I like the “notion” of a replacement part being as good as or better than the original. Otherwise, why change the design? Victor