Here's one for you - Front brakes seizing but then worked

[Guest]

Hey Guys,

So, I'm new to the forums, new to riding, and a new GS owner. All in all I love it.

But, I've been having some tough time with my front brakes. Particularly tonight coming home from work.

I have a 1970 GS 850 I bought used. When I picked it up, the previous owner said the front brakes were having some trouble. Namely, they were seized. We got it home, slowly, but could definitely tell the brakes needed work.

So, we pulled the calipers off, cleaned them out, re-installed, replaced the fluid, and all was good. The only thing we didn't clean though was the piston inside the caliper.

I took it out the other day and rode it for 5+ hours. Also, rode it today to work. Both times, no problem.

However, like I said, on my way home from work there was a bit of traffic. Sitting at a light and ready to take off, I killed my bike. Stalled it. So, I restarted and tried to get going again, but killed it again!

Basically, I had to rev it up to about 4,000 RPM and SLOWLY ease out the clutch just to get it to move any. Pulled up to a turn lane and some guy offered to help me out. Both of us together couldn't push the thing!

Well, finally was able to get it moved (using the high rev and slow going). Went to dinner for an hour and half, came back to pull the calipers off, but didn't need to because it worked totally fine!

So my question
What would cause the brakes to seize but then fix themselves after a hour and half?

Could it be connected to anything else? I did notice that it was smoking a bit and I'm thinking I need to change the oil. Could this have anything to do with it?

Would the caliper pistons remedy themselves with time like that?

Anyway, I am totally confused, and a total newb. Really hoping someone has some compassion on this guy and might have some advice.

Thanks all!

Nate

[tkent02]

You didn't take the master cylinder off and clean the inside, including the return port, did you?

Very common for bikes that have sat to have a clogged return port, the fluid can't return from the caliper to the reservoir, so the brakes can't release after being applied, or after they brakes get warmed up or hot. When they cool off, they release as they should. This is very hazardous, the brake can lock up at speed even if you never use the brake at all.

This could also be a problem with blocked brake lines, but that's not as likely.

Read all about it on Cliff's big website, along with all of the other neglected maintenance that must be done to ride an older bike safely.

[7981GS]

What year is your 850? (It is NOT a 1970 BTW )
Where are you located?

Eric

[natejelovich]

You didn't take the master cylinder off and clean the inside, including the return port, did you?

Very common for bikes that have sat to have a clogged return port, the fluid can't return from the caliper to the reservoir, so the brakes can't release after being applied, or after they brakes get warmed up or hot. When they cool off, they release as they should. This is very hazardous, the brake can lock up at speed even if you never use the brake at all.

This could also be a problem with blocked brake lines, but that's not as likely.

Read all about it on Cliff's big website, along with all of the other neglected maintenance that must be done to ride an older bike safely.

THANK YOU!

No... didn't clean the cylinder within the caliper. That's what I was thinking of doing next, given my current situation. And, I think you just confirmed it.

It did seem like my bike was getting hotter than normal too. But that might be an entirely different post...

Do you happen to have a link to Cliff's website you mention? Or, is it this: http://members.dslextreme.com/users/bikecliff

I read some stuff from him and it was super helpful.

Thanks again.

oh, and yes, it's a 1979. Sorry, missed a key!

Seattle (Issaquah), Washington

Nate

[Larry D]

He's talking about the master cylinder (the one on the handlebars) not the calipers. The master cylinder, that he's referring to, needs to be cleaned out as well.
Please be careful on the bike until you get this sorted out. *I* wouldn't ride it until it is. Having the front brake lock up at speed is a very, very bad thing.

EDIT:: ....and yes, that's Cliff's site.

[natejelovich]

He's talking about the master cylinder (the one on the handlebars) not the calipers. The master cylinder, that he's referring to, needs to be cleaned out as well.
Please be careful on the bike until you get this sorted out. *I* wouldn't ride it until it is. Having the front brake lock up at speed is a very, very bad thing.

EDIT:: ....and yes, that's Cliff's site.

Ah, got it, thanks for the clarification. And yes, agree, I hear you, I need to get this sorted out first... Thanks a lot for your help.

[spyug]

Would the caliper pistons remedy themselves with time like that?

No they would not.

If you didn't have the pistons out, you haven't done a proper job and you could be endangering your life. It is very likely that the pistons and bore are rusted. Very possibly the piston was held in place by some rust and somehow your fiddling with it got it free again. The problem is that rust is still in there and overtime it will do it again. It probably looks like this:



That's all it takes to freeze a pistion. Often the skirt of the piston which is hard chromed gets attacked by rust and cracks or fissures occur allowing the rust to take a better hold. You need to get the pistons out to check for this and if you find any damage you need to replace the piston. The bore can be carefully cleaned out and reused.

As mentioned by the others, you need to clean the master cylinder too and you should change the hoses if they appear to be the originals. Changing to stainless steel lines will improve the feel and response of the brakes immensley as there is no expansion in the hoses as there is in rubber hose.

You should not do a half assed job with brakes. Remember your life can depend on them. If there is any doubt to their working and you are unable to sort it properly yourself you need to have an expert fix them......or park the bike. This is serious stuff my friend.

Good luck with it.
Spyug

[natejelovich]

Thanks spyug, that's helpful.

So, sounds like main things are:

1. check and replace pistons in calipers
2. clean master cylinder (brake fluid reservoir)
3. get stainless steel brake hoses

Is Parts N More the best site?

I'm not seeing stainless steel hoses on there. Any other good sites or is going to dealer the best?

Also, on Parts N More, it looks like they don't have parts for '79 specific...

[koolaid_kid]

For item 1.), check the pistons first. If they are corroded or appear damaged, replace them. If they can be cleaned up (and recall, spyug mentioned both the pistons and the bore) and everything is spiffy clean and not pitted, then you just need a caliper rebuild kit, which should contain all the seals and o-rings you need. If the piston is pitted, let'r'go. You will know once you get in there.

[natejelovich]

great, thank you!

[Nessism]

I strongly advise against aftermarket master cylinder and caliper piston seal kits. The OEM Suzuki parts are vastly superior.

[natejelovich]

Update

Hi All,

Thanks again for all your help, I really appreciate it.

I took apart the calipers (again) and this time checked the pistons. Good news, there's no real rust or other problems with them:





I also removed the main cylinder and it was looking pretty bad. I cleaned that out but am wondering how to make sure it's really clean inside the hoses.





I also removed the brake lines and am going to get some stainless steel ones.



I'm hoping these adjustments will take care of the problem...

I'm also going to change the oil. Then on to back brakes...

A couple questions:

1. Any tricks on cleaning out the hoses that lead off from the main cylinder?
2. Anything else I should be looking for in the brake situation? I don't want those locking/seizing up ever again...
3. Should I consider replacing the fluids in the drive shaft, etc? I see the bolt and drain screws and wondering how critical this is to change out.

Thanks again all. Here's a couple other pictures just for good measure:

[tkent02]

The return port, I believe it is the upper hole in this picture, the one that looks clogged. If the return port is clogged with rust particles, the brakes can't let go when you release the lever, and they can't bypass any pressure which has built up because of heat. The result is more brake drag, more heat, more pressure which can't escape, the brake stays on even harder, making even more heat. A vicious circle that ends with a locked wheel and a broken ass. Several forum members have fallen hard because of this.

Find a picture in a manual to make sure it's the correct hole, and open it up.
The brake lines must be replaced to prevent more rust particles from blocking this tiny port again.

By the way, the rust is caused by not changing brake fluid often enough. Change it annually and there will be no rust problems.

[natejelovich]

The return port, I believe it is the upper hole in this picture, the one that looks clogged. If the return port is clogged with rust particles, the brakes can't let go when you release the lever, and they can't bypass any pressure which has built up because of heat. The result is more brake drag, more heat, more pressure which can't escape, the brake stays on even harder, making even more heat. A vicious circle that ends with a locked wheel and a broken ass. Several forum members have fallen hard because of this.

Find a picture in a manual to make sure it's the correct hole, and open it up.
The brake lines must be replaced to prevent more rust particles from blocking this tiny port again.

By the way, the rust is caused by not changing brake fluid often enough. Change it annually and there will be no rust problems.

Sounds like I got more tubes to pull off.

Thanks tkent02, much appreciated.

[koolaid_kid]

Yes, you certainly have more work to do. It is highly recommended that you replace the 30+ year old lines with stainless steel lines. Far superior to rubber lines, and they look better too. There are lots of vendors that will sell you exact replacements (3 line system), although many prefer to go with a 2 line system instead. What did the pistons look like? Or are you going to replace them anyway?
You are doing the correct thing by taking everything apart, considering the amount of gunk you found in the master cylinder. You should also purchase an OEM master cylinder rebuild kit while you are at it.
Best of luck.