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Discussion Starter #1
We've been having issues with brakes pulling hard to the left. As best I can tell the steering and suspension are tight. So it must be brakes, right?

Well, today I braved to 106°F heat and rebuilt the front calipers. New pistons and seals. Now I have no front brakes.

Did I screw this simple job up?

When test driven I barely had enough brake to stop from 20 mph. I couldn't even skid the rears. Seems I should have been at least able to skid the rears. I had a hard pedal.

The brakes gravity bleed okay, but won't bleed with the pedal. I get a hard pedal after an inch or so of travel, even with two bleed valves open. Master cylinder? Linkage?

A replacement master cylinder is a six hour round trip away. The show is on Saturday.

Mike
 

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Have you replaced the rubber brake lines?

It sounds like you have a blockage somewhere or maybe the mc is the problem.

Are you getting good fluid flow through the metal brake line by itself when you push in the brake pedal? How about through the rubber line?
 

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If you let the master run dry.. Then You probably have the M.C. Air Bound. soft petal Or you have a leak, fitting not tight, drawing air into system
Bleed the master Cylinder first, My method is to do it while installed in GT, Remove all the hard brake lines and plug, using the ends of old brake line fitting with 2' of hard line make three adapter for hoses, So now you can fill MC and pump the brake petal until the three hoses that are clamp to stay inside MC "" Are clear ,, solid fluid,,, Then one at a time remove the adapter and hose and reinstall each fitting back in MC..

Now master cylinder is Bled, you can easy bleed at each wheel now,,,starting at rear right..etc I also used a Power Vacuum Pump Bleed way. w/ side arm flask, see photo,,flask prevents brake fluid from entering V. pump, easy to find leaks. if you have a leak very hard to bleed system
Good Luck
 

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Discussion Starter #4
The pedal is not soft.

The only parts I worked on today were the calipers, and I just put air on them and the pistons moved, so I didn't screw that up.

I'll try air that the ends of the lines at the master cylinder.

Working alone on something like this is difficult.

I think I have a master cylinder rebuild kit. If not, I'll be up early heading to Opel GT Source.

Mike
 

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The pedal is not soft.

The only parts I worked on today were the calipers, and I just put air on them and the pistons moved, so I didn't screw that up.

I'll try air that the ends of the lines at the master cylinder.

Working alone on something like this is difficult.

I think I have a master cylinder rebuild kit. If not, I'll be up early heading to Opel GT Source.

Mike
Are the rubber flex hose old? if so I'd replace them.
 

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If I remember right, if the banjo/copper washer are put on in the wrong order, you end up with the symptom you describe.
 

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Discussion Starter #7
The flex lines are about 5 years old. They are the stainless steel type from Gil.

I disconnected the lines at the master cylinder and blew air through them. The pistons moved.

I took the master cylinder out and checked the pedal linkage. No obstruction.

On the bench I pressed the shaft on the master cylinder and it seemed to snag on something after moving less than an inch. I tried a few more times and it seemed to clear.

In the vise, I removed the c-clip and the guts will not come out. Is that normal? I have a rebuild kit and I don't see anything that would cause it to hang up.

If this wasn't the brake system I'd put it back in and see how things go.

Mike
 

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The flex lines are about 5 years old. They are the stainless steel type from Gil.

I disconnected the lines at the master cylinder and blew air through them. The pistons moved.

I took the master cylinder out and checked the pedal linkage. No obstruction.

On the bench I pressed the shaft on the master cylinder and it seemed to snag on something after moving less than an inch. I tried a few more times and it seemed to clear.

In the vise, I removed the c-clip and the guts will not come out. Is that normal? I have a rebuild kit and I don't see anything that would cause it to hang up.

If this wasn't the brake system I'd put it back in and see how things go.

Mike
There's a trick to removing the guts. I think there's a bolt that needs to be removed.

It's shown here

 

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Discussion Starter #9
There's a trick to removing the guts. I think there's a bolt that needs to be removed.

It's shown here

It's so late, but this was such great news I went out to disassemble and inspect my master cylinder. Frack. It does not have that bolt. My master cylinder is one or Gil's more recent designs.

I think I still have an older one I can rebuild. I'll look for it in the morning.

Mike
 

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It's so late, but this was such great news I went out to disassemble and inspect my master cylinder. Frack. It does not have that bolt. My master cylinder is one or Gil's more recent designs.

I think I still have an older one I can rebuild. I'll look for it in the morning.

Mike
If the rust or sand or crud did clear out, then the guts should indeed all pop out with the c-clip removed on the no-bolt type. Sounds like it has rust in there. PB Blaster in all opening, and setting a while, then smacking the open end of the MC down on a hard item like a block of wood is needed to make the guts move out. It can be a VERY little bit of rust and it will get stuck like that. I have one almost new inside but a bit of moisture in the c-clip end hung it all up. The rest of the MC was clean.
 

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Discussion Starter #12
I talked to Gil and he convinced me to go ahead, put this one back on. I could push the rod all the way in so it should work.

I put it back in and thoroughly bled the brakes, front and rear. The rear brakes work, but the pistons on the fronts do not move. The engine was on and I had power brakes.

I put air on the flexible line to one caliper and the pistons moved easily.

It has to be the master cylinder. It may have been slowly failing on us, causing our braking problems, and now it has completely failed.

It's 104°F out now, over 100 in the garage. I need a big Cobb salad break then I either fish around for a used one I am sure I have here or I'll tank up and make the 6 hour round trip to see Gil. I called earlier to confirm he has them in stock. I'm not giving up getting to this show. I might even trailer it if I have to.

Mike
 

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I agree, it must be MC. I will repeat my comment to the similar issue few months ago: MC piston(s) normally move only limited stroke keeping that area of MC swept and rust free. When pumping the pedal during the bleeding process, the piston(s) will slide much further and reach the area of the cylinder that is corroded. Rough surface will damage the seal.
 

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Discussion Starter #17
The car hasn't been driven in a while. The master cylinder could have corroded.

I have a bleeder I had not used in years, but used it today but just to pressurize the system. Very handy. Catherine came over to help with tonight's work. Very helpful.

300 miles later and I have a master Cylinder that works. Gil left it out on the grill by the shop for me.

The brakes work, but the problem of the pull to the left remains, but is not as bad, it seems, so far.

It's 2:30 in the morning here. I was planning to leave at 4 AM, 5 AM the latest. Let's see how I do. I'm partially packed but need showers and all the rest.

Mike
 

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Discussion Starter #19
The brakes work great. They do not pull left or right, worked correctly to and from Monterey, which included a side trip through hilly downtown San Francisco.

In a few days I'll take the old master cylinder apart to see what went wrong.

The show itself was good, definitely worth the 200 mile drive on 20 minutes of sleep. I had lots of visitors, people wanting to sit in the car, flip the headlights, all that. Now that I'm home I see we got a little press, a Facebook post by Classic Motorsports. There's a reasonable chance we got a little more.

Mike
 
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