Brakes stuck, gunk?

The front brake pistons on both sides of this old bike won't retract. Bike has been sitting for a long long time. Could it just be gunk down in the sides of the pistons? if so, whats best way to clear it out?

TY in advance...

 

Sounds like you might have to rebuild your brakes. Bleed the brakes first and replace with fresh DOT4 until the fluid clears up.
See where that gets you and if the pistons are still seized you will want to pull them out and check for corrosion. If they are fairly corrosion free clean out the inside area of the brake with a soft brush getting all the gunk out and change out the piston seals and dust seals and put the piston back in with a little brake assembly lube on the seals and pistons (I wouldn't recommend using the brake fluid for assembly lube). Stick the piston back in and bleed the brakes and they should be good as new.

 

One of my least favorite things to do but you need to pop them apart and inspect the calipers for damage and corrosion.

 

Got one piston out, looks clean inside. gonna clean em and put it all back together. Can i get away with reusing these piston seals?

 

No, you will need to buy new ones, odds are these are original to the bike and well worn out.

 

Now that I'm for sure buying them, any advice on best source? (price)

 

It is hard to beat their prices on OEM.

OEM motorcycle and ATV parts from Honda, Yamaha & Polaris – Cycle Parts Warehouse

 

are you sure it is the pucks sticking? It could be the slider pins the caliper slides back and forth on. I've had that happen.

 

I am sure he had a chance to inspect those if he tore them down to getting the pistons out.

 

had to be one of the more satisfying jobs working on the viffer. Gunk builds up behind the seals and prevents piston from retracting. Trick is to use the brake lever to get both sides of the calipers to push out their pistons. I have a nice set of internal cir-clip pliers that I grabbed with from the inside to pull one pistons out. Otherwise pretty straight forward. Too bad they dont anodize the inside of the calipers, this might not happen. By the way I have re-used seal and dust seals on my own bikes and other peoples with no re-precussions. Now, I got a proper stopping bikie.

 

When you go to that much trouble to get them out and they are what- 2 bucks a piece and after 20+ years they are usually pretty distorted and worn out. Get new ones and you won't have to sweat it for another 20+ years.

 

I did the job spur of the moment and if they were messed up I would have ordered them from my local stealership. You know the main seals are made out of tough rubber, once I scraped the crap off with my finger nails they infact looked brandy new. One dust seal was a little distorted but not a big deal. Just food for thought. Some things you can get away with, some you cant. I used a special anodizing liquid thats used in the aviation industry thats highly caustic inside my calipers, they looked amazing clean after I spent 2 hours with scotch bright pads and a handy little Snap On pick cleaning out the mug. Cheers

 

thanks all for all the info. those prices are better than I've found elsewhere, Dukie. Cant wait for tires, and then this old things good to go!