Rear brake locked up?

[Steve]

Also, does anyone have a picture of the rear master cylinder with the lid off? Mine has a rubber housing but it appears to be dirty and is sitting on top of the brake fluid. Is brake fluid suppose to be in the rubber housing or under it?

Noob

The master cylinder itself does not have a "lid", but the reservoir does.

Yes, there is a diaphragm inside that somewhat seals the fluid from the air, otherwise the fluid would keep absorbing all the moisture out of the air, contaminating itself.

The master cylinder is the part that is at the lower end of the hose that comes out of the reservoir.

Usually, the only thing necessary on the reservoir is a good cleaning, unless it is physically damaged, then it needs to be replaced.
Any rebuilding" is going to happen in the master cylinder, where you will replace the piston, spring and seals.

You would probably be doing yourself a favor if you also got a rebuild kit for the caliper, but take it apart first, to see if you might also need to order a piston.

To answer your other questions:
Yes, you can get a new brake line from G&S Suzuki or any of the other vendors that we use.

A stainless line will also work, but is a bit more money.

Your issue with the brakes only working with the bolts loose is probably due to not having axle spacers installed correctly. If the spacers are not in the correct order, the brake disk will not be centered in the slot in the caliper, causing it to drag or bind. Find out which way the caliper needs to move, and how much, you will probably find a spacer that thick that you have in the wrong place.

.

[GS650E_81]

The master cylinder itself does not have a "lid", but the reservoir does.

Yes, there is a diaphragm inside that somewhat seals the fluid from the air, otherwise the fluid would keep absorbing all the moisture out of the air, contaminating itself.

The master cylinder is the part that is at the lower end of the hose that comes out of the reservoir.

Usually, the only thing necessary on the reservoir is a good cleaning, unless it is physically damaged, then it needs to be replaced.
Any rebuilding" is going to happen in the master cylinder, where you will replace the piston, spring and seals.

You would probably be doing yourself a favor if you also got a rebuild kit for the caliper, but take it apart first, to see if you might also need to order a piston.

To answer your other questions:
Yes, you can get a new brake line from G&S Suzuki or any of the other vendors that we use.

A stainless line will also work, but is a bit more money.

Your issue with the brakes only working with the bolts loose is probably due to not having axle spacers installed correctly. If the spacers are not in the correct order, the brake disk will not be centered in the slot in the caliper, causing it to drag or bind. Find out which way the caliper needs to move, and how much, you will probably find a spacer that thick that you have in the wrong place.

.

Thanks Steve. I think you are right. I forgot to take a picture of the caliper and rear axle before replacing the tire.

I have a Clymer manual but if I remember when looking at it, I got rather confused.

I will take another look at it.

[GS650E_81]

One of the pistons is fully erect, but I cannot get it to come back down. The other piston will go up and down freely. Is there a way to get a stuck piston to go back into the caliper?

I took off the rubber housing on the piston so I know its not stuck on the rubber.

[Steve]

This is in the caliper?

Take the piston completely OUT. Take out the o-ring that seals against it, clean the groove that the o-ring sits in. Also clean out all the gunk behind the piston. It might be best to change the o-rings, too, but you will have to decide whether you want money in your wallet or good brakes on the bike.

Yeah, if you just want to get the piston back in, you can use a c-clamp to push it in.

.

[Nessism]

One of the pistons is fully erect, but I cannot get it to come back down. The other piston will go up and down freely. Is there a way to get a stuck piston to go back into the caliper?

I took off the rubber housing on the piston so I know its not stuck on the rubber.

It's simple to get the piston where it belongs. Follow these steps carefully...

1) Remove both pistons from the caliper

2) Clean both pistons and look for pits in the chrome (replace if damaged)

3) Order new piston seals and brake line

4) Remove master cylinder and tear it down. Inspect cylinder bore carefully for corrosion damage and replace as necessary

5) Order a new master cylinder kit

6) Reinstall new seals in caliper and master cylinder, and reassembly everything with your new brake line

7) Bleed brakes and ride happy

[GS650E_81]

It's simple to get the piston where it belongs. Follow these steps carefully...

1) Remove both pistons from the caliper

2) Clean both pistons and look for pits in the chrome (replace if damaged)

3) Order new piston seals and brake line

4) Remove master cylinder and tear it down. Inspect cylinder bore carefully for corrosion damage and replace as necessary

5) Order a new master cylinder kit

6) Reinstall new seals in caliper and master cylinder, and reassembly everything with your new brake line

7) Bleed brakes and ride happy

Such a good helper!

[Steve]

Such a good helper!

True, but he doesn't make house calls.

.

[GS650E_81]

True, but he doesn't make house calls.

.

Boo! LOL

My father-in-law to be is coming over today to help me work on the brakes. I am going to have him help me clean them and then I am going to order replacement parts.

[GS650E_81]

I can't seem to get the allen head bolts to budge with my 10mm. Any suggestions on getting them out?

I have sprayed them with pb blast but no luck.

[Nessism]

I can't seem to get the allen head bolts to budge with my 10mm. Any suggestions on getting them out?

I have sprayed them with pb blast but no luck.

Get a set of allen head sockets. Then you can use a longer handle wrench for more leverage.

[chuck hahn]

Loosely refit the calipers back on the forks so theres something to hold them still..then youll get good enought leverage to get them to come loose. I always loosen everything before i take the calipers off the forks. If you dont have the allen socket set that goes on the ratchet, then put the allen wrench in and use the box end of a long wrench to make a extention like a breaker bar. Or if you have a small hydraulic jack you can use the pumping handle as a breaker bar too.

[GS650E_81]

Bolts are totally seized. Cannot get them off with brute force.

I will have to grind them off...

I can't seem to find the bolts online at any of the online parts sites. Anyone know if these bolts are replaceable before I tear into them?

[chuck hahn]

You are talking about the 2 allen head ones that are the pad carriers...right? Heat the casing up with a propane torch and drip a drop or 2 of old engine oil down in the recess and the heat will suck the oil into the threads. What kind of allen wrenches do you have? Regular bent at a 90 style or the 3/8 drive socket style? If you dont have the socket style, then go to Harbor Freight and get some..they are life and allen head savers. You can get plenty of torque with the socket type and its easy to add a breaker bar to the ratchet or the breaker bar itself. Between some heat, some penetrated oil, and the right tool they will come right out. Some like this is what i mean...AND like i said before..remount them on the forks so you can get some leverage on them.

http://www.gearwrench.com/catalog/bit_sockets/hex/setdetails.jsp?part=80580

[GS650E_81]

No go on heating up the threads.

I am guessing no one has pulled these apart since '81.

I am grinding down the heads, but a big PITA.

[chuck hahn]

Drill thats just slightly smaller than the OD of the head and drill them down till you can pry the rim of the head off with a flat tip screwdriver. Then seperate them.