Brake Drum Wear

[Canuck]

Hey all,

Got a brake problem, wondering if anyone has some insight..

I checked the manual to troubleshoot the brakes. all signs point to brake drum wear.
Now i took the rear wheel off checked the pads(seemed almost 100%), but the brake drum felt smooth as a new sheet of metal. Should there not be some abrasiveness to the drum as well as the friction caused by the brake pads??

If the drum has been buffed down to a smooth shine.. should i REPLACE or create a rougher surface to get some extended life out of the current drum?


The symptoms are as follows: Rear brake pressure applied with minimal stopping power... takes alot of pressure to get half the braking power? I thought if the drum is smooth... how is there any friction to create a decent stop coupled with the front brakes...

Thanks guys,

[Sarris]

The drum is getting constantly polished by the shoes, so mooth and shiney is OK. Are they adjusted properly? How old is the bike (assuming these are original)? How many miles? Is the wear indicator within range? Are there any grooves or cracks in the drum? Is the drum within manual specified thickness parameters? If not, replace it. The specs for the drum are on manual page "CHASSIS 5-32"

IMHO, I'd say it's probably cheaper to buy a good used rear wheel w/ drum than to replace it and re-lace the rear wheel.

[Easy Rider]

Originally Posted by Canuck

The symptoms are as follows: Rear brake pressure applied with minimal stopping power... takes alot of pressure to get half the braking power?

Don't panic! :cool:
Everything you describe is normal.

Typical of a drum brake. More noticeable if there is too much slack in the mechanism. Just look at the contact patch of the front disk; smooth and shiny, right?

The front brake does 70% of the stopping; rear only 30%......or to put it another way, stomping on the rear brake to a point just shy of locking the wheel, will give you only 30% of your total stopping power.

A LOT of GZ riders go through something similar to what you have; rear brake anxiety. Most find that they need to adjust the slack out of the mechanism and that it works much better after they do. In the process of doing that, you might need to adjust the pedal height too.....and then at the end, check the operation of the stop light switch.

More to follow if you need details of the adjustment proceedure. It may be posted here somewhere already.

[Water Warrior 2]

In some cases the rear brake shoes will loose their ability to create friction due to glazing. Years ago when off roading our bikes would totally loose their rear brakes after muddy water crossings and such. A great and very cheap fix was a very light sand blasting of the brake shoes and it was like new again. A little emery cloth on the brake drum removed the surface contamination.

[Canuck]

Thanks Water/Easy/Sarris

I've been told about using an emery cloth on the rear drum, ill give this a try...see if i can get the shoes blasted. If that isn't the solution than maybe a new brake drum is....

(My GZ has 34000 kms on it... 03' model)

All of my strength into the pedal should lock the wheel in my opinion... not that i want to put myself in that situation but... isnt that how brakes properly work if need be?

[Easy Rider]

Originally Posted by Canuck

If that isn't the solution than maybe a new brake drum is....

All of my strength into the pedal should lock the wheel in my opinion...

OK, you are going to do what you think is right regardless but I am here with 40+ years of riding experience to tell you that it is almost NEVER necessary to replace a rear brake drum on a small bike with as little mileage as you have.
AND......
The rear brakes on your bike are just NOT what you think they should be. Wish as you might, they just are NOT.

Even with the rear brakes in perfect condition, many GZ riders find that they cannot lock the rear, in a practice situation, no matter how hard they try.

In my opinion, you are wasting your time.

With your mileage, you might be due for new shoes and a corresponding roughing of the drum AND a careful linkage adjustment but certainly NOT a new drum.

[Canuck]

I replaced the front shoes today successfully, adjusted the rear brake linkage and will leave the roughing for another time...
IF 30 % is all the rear brakes have to offer than ill take your word for it and not worry about it.

Taking them off and giving the whole rear brake system a clean helped too and I'm satisfied with their performance coupled with the new front brakes.

[Badbob]

30% for a rear brake is very optimistic. I'd say its more like 10%. Of course this all depends on what your doing with the front brake.

I keep my rear brake adjusted so "I" just about can't lock it up.

[primal]

For what its worth, I locked my rear wheel several times during the MSF course.

[Canuck]

yeah primal i remember the same thing on the GZ i rode through the riding course... Definetely should have locking capabilities...

Maybe not after 34000 kms... but at least thats a starting point... ?

either way im getting 15-20% ...enough to displace even pressure to assist the front... so ill settle on it..