Brake problem

[Guest]

This is my new bike, a 1980 GS850G. I bought it two weeks ago and am really happy with it.

It's not perfect, as you can see in the photo. It's missing those two side plates and the previous owner removed the faring that was installed and, having no headlamp housing, put in place a new aftermarket headlamp. Which is OK. I can live with that.

It runs well, but clearly was not loved it's whole life.

I have a couple of issues I'm dealing with that I haven't seen in other postings. One thing troubling me are the front brakes. Sometimes, it seems they are really tight so that the front wheel doesn't easily roll. Once, after riding maybe two miles, I stopped and the rotors were already really, really hot.

If I'm coming up on a red light and kick my bike into neutral, it doesn't just roll on as I would expect, but instead comes to an almost immediate stop at times. Plus, at these times, the front brake handle has almost no give to it. In other words, I can't squeeze it down at all, as if the brake pedal on a car were all the way up.

I haven't worked on bikes much, but the problem I am having reminds me of the time the master cylinder started going out on an old VW bus I once owned. It would just lock up the brakes on me when it got hot, then release them when it cooled down. I had to replace the master cylinder and then it was fine.

I've been told variously that the problem on my bike might be that the calipers need to be rebuilt, that I simply need new brake pads, that I should try releasing some brake fluid, or that the rotors are warped.

The pads look low anyway so I was going to replace them regardless, but could an old and crankly caliper cause this kind of problem?

Any thoughts on the most methodical way to approach this problem?

Thanks! - Hector

p.s. Here's my new baby. Oh, and this is an absolutely fantastic website and I should add my thanks to BikeCliff's website, who I see is a frequent contributor.

[tkent02]

This is my new bike, a 1980 GS850G. I bought it two weeks ago and am really happy with it.

It's not perfect, as you can see in the photo. It's missing those two side plates and the previous owner removed the faring that was installed and, having no headlamp housing, put in place a new aftermarket headlamp. Which is OK. I can live with that.

It runs well, but clearly was not loved it's whole life.

I have a couple of issues I'm dealing with that I haven't seen in other postings. One thing troubling me are the front brakes. Sometimes, it seems they are really tight so that the front wheel doesn't easily roll. Once, after riding maybe two miles, I stopped and the rotors were already really, really hot.

If I'm coming up on a red light and kick my bike into neutral, it doesn't just roll on as I would expect, but instead comes to an almost immediate stop at times. Plus, at these times, the front brake handle has almost no give to it. In other words, I can't squeeze it down at all, as if the brake pedal on a car were all the way up.

I haven't worked on bikes much, but the problem I am having reminds me of the time the master cylinder started going out on an old VW bus I once owned. It would just lock up the brakes on me when it got hot, then release them when it cooled down. I had to replace the master cylinder and then it was fine.

I've been told variously that the problem on my bike might be that the calipers need to be rebuilt, that I simply need new brake pads, that I should try releasing some brake fluid, or that the rotors are warped.

The pads look low anyway so I was going to replace them regardless, but could an old and crankly caliper cause this kind of problem?

Any thoughts on the most methodical way to approach this problem?

Thanks! - Hector

p.s. Here's my new baby. Oh, and this is an absolutely fantastic website and I should add my thanks to BikeCliff's website, who I see is a frequent contributor.

Stop riding it, it is close to locking up and dumping you on your head!
The return port in the master cylinder is blocked, or the hoses are blocked preventing fluid returning to the reservoir.
Get new lines, go through the entire system and get it right.
Simple stuff, but it must be done.
Brake fluid should be replaced every year or so, as it absorbs water and causes metal parts to rust, the rust flakes off and blocks things up.
Lines should be replaced routinely too.
I bet your bike still has the original brake fluid in it and a bunch of water and rust.

[salty_monk]

& fit twin pot calipers whilst you're at it





Will fit the 850G - goes fine on my 1000G anyway

[Silverhammer]

Brake fluid, over time will absorb moisture out of the air.. Then when it heats up,the moisure expands and forces the calipers to brake.. (this condition is actually pretty dangerous) Bleed the system to get all the old brake fluid out and it'll be good...

Silverhammer

[oldgsfan]

You're right, the brake fluid is pretty dark and I wouldn't be surprised if it was quite old. I'll try installing new brake lines and new fluid while I'm replacing the pads.

Thanks! I'll post again after I've done the work.

[tkent02]

You're right, the brake fluid is pretty dark and I wouldn't be surprised if it was quite old. I'll try installing new brake lines and new fluid while I'm replacing the pads.

Thanks! I'll post again after I've done the work.

You still need to remove the blockage from the return port.
Just clean the whole system, brake problems aren't to be taken lightly.

[Suzuki_Don]

BTW Hector you are also missing the cam end covers off your valve cover.

On your brakes just wait till Dan has the CBR Honda conversion finished that he is working on.

Dan. BTW I have had a new set of brackets made up from 10mm aluminium plate (I could not get any 8mm over here). The setup on the bike looks really good with the 310mm CBR900RR disc and the twin pot caliper. Just the setup for the smaller GSs with single disc as original.

[jbharley3]

Had the same problem. Naturally the brake fluid and rust particles were the culprits. I bled each brake line while "pumping" new fluid through the lines. Took almost two cans of new fluid to get clear, clean result. The removed fluid was like coagulated blood or jello consistency, loaded with fine rust particles. With the lines cleaned out and the new fluid, the brakes work just fine. As a result, I did the same thing with the rear brake even though I was not having the same problem. The brake fluid cleared much more quickly since there is less brake line. Both systems (front and back) now respond like new. Make sure that once the fluid runs clean that there is no air in the lines. This will cause spongy, non responsive brakes. Just keep working the brake lever and you will eventually clear all of the air out. Good Luck.

[thezmann76]

I'm pretty new to motorcycles but have been around cars my entire life and hydraulic brakes are roughly the same concept across the board. Everyone is absolutely right, the fluid has to be changed regularly and the lines flushed and inspected. As far as the rotors go, if they were warped you would get a pulsating or severe vibration while braking. Your problem seems to be narrowed down to the mastercylinder or the caliper(s). Rebuilding them is pretty straight forward and can be done on a basic workbench with a good repair manual. Best of luck and be careful while testing your work, we'd hate to see you get hurt or dump your new girl end over end! Matt

[Suzuki_Don]

& fit twin pot calipers whilst you're at it





Will fit the 850G - goes fine on my 1000G anyway

Dan nice setup with the stainless braided lines. Do you have both lines going direct from caliper to MC. And if so, did you make them up yourself and do the banjo connections on both end of both lines have any angle on them or are they straight fittings.
Thanks again.

[salty_monk]

They are Goodridge from Z1 entreprises.

If I did them again I would run one line down & loop the 2nd over the mudguard to the other caliper looks much neater at the bars.

Looking forward to seeing pics of your setup. 10mm will be fine, not sure why I went with 8mm I think I measured something similar in as store & just went with it.

Dan

[greg78gs750]

i gotta agree with the calls for a complete brake overhaul. i just went through this with mine, had the intention of just changing the lines. i figured, well, i might as well see what the inside of that rear caliper looks like, and, well, it was grotty to say the least. after taking everything apart, i would say it was a MIRACLE i have lived this long. seriously. do both calipers, both m/c's and replace the lines too. it really is not hard at all. the whole shebang only cost 200 bucks for me, and thats with stainless lines from earls, rebuild kits with pistons for both calipers, m/c cup sets front and back, and new pads from z1. and i dont have to worry whether it's going to stop now.


greg

[oldgsfan]

i gotta agree with the calls for a complete brake overhaul. i just went through this with mine, had the intention of just changing the lines. i figured, well, i might as well see what the inside of that rear caliper looks like, and, well, it was grotty to say the least. after taking everything apart, i would say it was a MIRACLE i have lived this long. seriously. do both calipers, both m/c's and replace the lines too. it really is not hard at all. the whole shebang only cost 200 bucks for me, and thats with stainless lines from earls, rebuild kits with pistons for both calipers, m/c cup sets front and back, and new pads from z1. and i dont have to worry whether it's going to stop now.


greg

A rebuild is what I'm doing know. The caliper pistons had some pitting, and the fluid was like yesterday's coffee.

I have already ordered the caliper rebuild kits for both front calipers, and already have my new fluid reservoir cause the old one was warped and practically folding in on itself.. but I'm kind of stumped with what to do about the brake lines.

I know I can order OEM replacements for the bike, but I've seen a lot of people recommend going with stainless steel lines. So my question is, if I do that, does it require getting new banjo fittings for all the lines?

And is there a simple explanation of a way to install new lines while doing away with that splitter that sits over the front fender?

As always, thanks ..

[salty_monk]

I got mine from www.z1enterprises.com I ran two down from the master, 1 to each caliper. Used the double banjo bolt from the splitter. Cost around $35 a line if I remember rightly.
If I did it again I would run one down from the master to the right caliper & loop a short line over the fender to the left caliper. A little cheaper, possibly easier to run the lines & much cleaner at the bars.

Dan

[J_C]

To answer don's question, at the MC I used one straight and one 30 deg. Not sure if you can use two straight there and still have everything fit the way it's supposed to... Dan what'd you do?