Front brakes holding pressure?

[bjrpkr]

Weird thing lately...in morning when leaving for work, brakes work fine. In afternoon when leaving for home, front brakes are holding. I have to open the bleeder, let off the little residual pressure and then OK. Does sun's heat build pressure that isn't releasing? Is master cylinder bad or caliper(s)?
1979 GS800 38K miles
tx
Mark

[Nessism]

Most likely a master cylinder problem but it's a signal for a full system tear down and clean out. Replace the lines also if you still have the stock junk on there.

[BassCliff]

Greetings and Salutations!

Hi Mr. bjrpkr,

Please click here for your mega-welcome, chock full of suggestions and links to vendors and other information. Then feel free to visit my little BikeCliff website for lots of GS lovin'. Thanks for joining us. We like pictures, especially of your GS800. (Do you mean the BMW?)


Thank you for your indulgence,

BassCliff

[chef1366]

Either your caliper pistons are freezing up or the return port in your master cylinder is blocked. My moneys on the master cylinder.
I'd go through and clean the whole deal like Ed said.

[Steve]

My money is also on the return port in the master cylinder. It is a tiny little hole in the bottom of the cylinder that needs to be cleaned out with a paper clip.
(Why do they call them paper clips when they are made of metal? )

I had similar problems with my son's Yamaha. I went for a ride around the block (6-mile ride) and couldn't make it the last 1/4 mile home. Full throttle in second gear on a 1300cc V-4 was not enough to overcome the brake pressure, so I had to bleed it just to get home.

.

[psyguy]

Full throttle in second gear on a 1300cc V-4 was not enough to overcome the brake pressure

now, did you really have to try THAT

trying to have the disc melt, were you?

[Steve]

Well, it was slowing down gradually and I did not realize how much throttle I was adding until I tried leaving the stop light.
Yes, I tried to get it home because it was so close, but had to stop.

Not necessarily proud of what I did, just not afraid to admit it.

.

[psyguy]

Not necessarily proud of what I did, just not afraid to admit it.

.

i once left the shop where they "fixed" my brakes with the similar prob - the brake pads were seizing... what i did is i tried to break heavily in an attempt to brake the calipers free... the only thing i broke was the indicator when i lowsided on my FIRST attemp at "heavy braking" idea

NOT proud either

[Colin Green]

i once left the shop where they "fixed" my brakes with the similar prob - the brake pads were seizing... what i did is i tried to break heavily in an attempt to brake the calipers free... the only thing i broke was the indicator when i lowsided on my FIRST attemp at "heavy braking" idea

NOT proud either

Hehehehehehe

Sorry.. mine was on gravel.. so was quick and hurtful Lol

[bjrpkr]

Thanks for the input, return port sounds like the culprit. But I don't think I'm going to try overcoming it in 2nd gear...I'll do 4th, always wanted to see my discs glow red! Ha!

[cromwell1234]

they are very easy to rebuild, a friend of mine (not me of coarse ) drove on a sticky caliper for one season, the tire got so hot on a long ride that it completely blew of the rim, lucky this person was taking off from a red light--so dont wait----

[cowb0y]

I am havin the same problem on my '80 GS1100.You guys got any suggestions on where a fella could find a rebuild kit for the calipers and master cylinder?? Checked ebay and a few other places. Only found one rebuild kit for the calipers and its $30!! Sounds spendy to me, is that the goin rate these days??

[psyguy]

I am havin the same problem on my '80 GS1100.You guys got any suggestions on where a fella could find a rebuild kit for the calipers and master cylinder?? Checked ebay and a few other places. Only found one rebuild kit for the calipers and its $30!! Sounds spendy to me, is that the goin rate these days??

www.z1enterprises.com

[oldgsfan]

yeah, z1enterprises is good, but I've had some good luck with these guys:

http://flatoutmotorcycles.com/

They offer all the same parts as bike bandit, but I have found them to be less expensive and their customer service is really good. They're based out of Indiana, so expect the merchandise to take a few days.

By the way, the earlier posters I think are spot on about taking a look at the brake system when this problem comes up. I had my bike a week when I noticed it wouldn't roll up to a stop and the roters were becoming blazing hot.

I pried open the brake reservoir and saw the inside just full of junk. The fluids hadn't been replaced in the bike's lifetime.

I ended up rebuilding the master cylinder (kit from z1enterprises), replacing the brake lines, rebuilding the brake calipers (z1) including new pistons (flatoutmotorcycles) and putting in new shoes. I'm not a mechanic and still found it very feasible.

You should do a search on replacing brake lines with ss lines 'cause there's a great posting here on how to do that.

Good luck.