Brake ?'s

[RossL]

I have a couple of questions about the brakes in general. First off I had to replace the brake line because I damaged it.

I've owned the car for 3 months and I don't have much windshield time..... My car has factory power brakes.

I noticed (before I replaced the line) the car would slow down as I approached a red light and lightly applied the brakes, BUT.................when I wanted the car to "stop moving", I had to use a lot more pressure and the car would stop abruptly.

1) Do you have any idea what would cause that last extra pedal pressure required to stop?
2) When I'm bleeding the rear it seems like a lot less fluid comes out when I open the bleeder compared to the front. Is that normal?

The car was totally restored about 15 years ago so all the lines and hoses look "recent"

[ward 57]

Odds are that the booster diaphragm is leaking. In restorations I'm sure if the system is working properly they aren't touched. Thankfully if the booster fails you still have brakes that act like the booster was not there. A booster rebuild may be in order.
For several years I drove my car with a failed booster as I only went around the block or just moved it. It wasn't until I retired and sold my classic boat I started driving it more that I noticed It wasn't right. When rebuilt it was full of crud & brake fluid. It works great now.
I admire you people who take on the job to replace those lines. I'm lucky enough to have had my car for a long time and used it enough to keep all those lines and tank clean.

[RossL]

Odds are that the booster diaphragm is leaking. In restorations I'm sure if the system is working properly they aren't touched. Thankfully if the booster fails you still have brakes that act like the booster was not there. A booster rebuild may be in order.
For several years I drove my car with a failed booster as I only went around the block or just moved it. It wasn't until I retired and sold my classic boat I started driving it more that I noticed It wasn't right. When rebuilt it was full of crud & brake fluid. It works great now.
I admire you people who take on the job to replace those lines. I'm lucky enough to have had my car for a long time and used it enough to keep all those lines and tank clean.

Is there any indication to know if the booster needs a rebuild?

How difficult is it to rebuild?

[willcarter]

Thankfully if the booster fails you still have brakes that act like the booster was not there. A booster rebuild may be in order.

Maybe. When the booster failed on my ‘57 a couple of years ago, it resulted in the braking being completely gone. Fortunately, it was at the shop for something else when this happened rather than it happening while I was driving. The shop called me to say that while they were moving the car, the pedal went all the way to the floor and had no braking at all. They discovered that the booster had failed, resulting in the brakes failing completely. I had assumed that the booster failing would just mean you would still have braking, but it would just manual; but apparently that was not the case.

Now: maybe my brake system is “plumbed” in such a way that a failure of the booster causes a complete loss of brakes. I have no way of knowing and I’m too much of a novice to figure it out on my own. But I just wanted to add my contrary 2 cents from my own experience.

Also: immediately after getting the car back with a new booster installed, I noticed that, similar to what the OP described, applying the brakes normally would only slow the car down, not stop it. In order to stop it fully, I had to push the brakes really *really* hard; and even so, it still wouldn’t come to a sharp stop. (I think I may have posted a thread about this a couple years ago). I have at various points and for various reasons driven my ‘57 with properly working power brakes; with properly working manual-only brakes; and with malfunctioning power brakes. They are not at all similar, so I knew that this wasn’t a “the booster failed again and you’re just not used to manual brakes” thing. In my case, it turned out to be that the shop hadn’t adjusted the brakes properly after installing the new booster. I took it to another shop and they adjusted the brakes; problem solved. (Can’t remember if the issue was that the first shop had set the brakes “too high” of “too low,” but it was something like that). This may not be the cause of your issue - among other things, you said that your car will eventually stop abruptly, whereas mine would not - but I just wanted to mention it.

Edit: here’s my earlier thread that I mentioned: http://vintagethunderbirdclub.net/phpBB ... d6ae0c9e15

[Rusty57]

Unless you have recently replaced them, replace all 4 brake hoses.

The internal liner will absorb brake fluid over long periods of time. This will restrict the flow of brake fluid until the pressure gets high enough to make the brake hose swell and let the fluid go through the system. Then the brakes come on strong.

When we bought our ‘57 the brakes worked like you described even after a lot of work on the system. The previous owner and his mechanic (they have a private collection of over 100 cars) had replaced all the wheel cylinders, installed a new master cylinder, installed new brake shoes, had the booster rebuilt, and replaced the 2 front wheel hoses and the hose to the rear axle. We had agreed on a price to buy the car based on them fixing the brakes. Because the brakes were still not working properly he discounted that price and we took the car.

After we had agreed on the discounted price I asked the mechanic if he had replaced the hose from the booster to the connector on the chassis. You should have seen the look on his face.

That hose was so swollen shut that I could not blow compressed air through it. There was one other issue because the mechanic had not moved the plastic tip on the end of the brake pedal rod from the old master cylinder to the new one. So I could not properly adjust the pedal free play.

We have very good brakes now.

[ward 57]

That's quite a story. Swollen flexible brake lines are something many new mechanics don't understand. When I had my M/C rebuilt the new kits are designed that the plastic plunger tip is not required and everything worked without any issue, but they are available if needed for original equipment. From what I understand that plastic cap was unique to the T-birds due to the different pedal configuration from the sedans along with adjustments according to the shop manual.

[RossL]

That's quite a story. Swollen flexible brake lines are something many new mechanics don't understand. When I had my M/C rebuilt the new kits are designed that the plastic plunger tip is not required and everything worked without any issue, but they are available if needed for original equipment. From what I understand that plastic cap was unique to the T-birds due to the different pedal configuration from the sedans along with adjustments according to the shop manual.

What is this? the plastic plunger tip

[RossL]

I ordered new wheel cylinders and hoses, along with a booster rebuild kit.

When I tried to bleed the brakes I could not fit an open end wrench on the bleeder screw because there are too many obstructions. The only tool I could get on it to loosen it was a socket, very difficult to "bleed"..... Is this normal?

I will have to see what the new wheel cylinders look like. Maybe the bleeder screw needs to be longer???

[ward 57]

That's quite a story. Swollen flexible brake lines are something many new mechanics don't understand. When I had my M/C rebuilt the new kits are designed that the plastic plunger tip is not required and everything worked without any issue, but they are available if needed for original equipment. From what I understand that plastic cap was unique to the T-birds due to the different pedal configuration from the sedans along with adjustments according to the shop manual.

What is this? the plastic plunger tip

From what I understand the T-Bird brake pedal mount configuration is different than the regular cars. In those the throw of the piston plunger was adjustable but in the T-Bird it is not. The plastic cap was used to slightly extend the rod. The rebuild kits from CASCO have a different push rod to compensate so the plastic tip is not needed.

[Rusty57]

On our '57 I needed the plastic tip that fit on the end of the brake pedal rod. I ordered it from Concours. Without it the pedal would travel quite a distance before the rod started pushing on the piston in the master cylinder. There was not enough adjustment in the eccentric to compensate.

I can understand how a longer push-rod eliminates the need for the tip/spacer.

Whether you have the longer pushrod design or need the plastic tip you still need to make the proper adjustment at the eccentric. There needs to be a small amount of clearance/free-play in the pedal. That allows the piston in the master cylinder to retract completely. If the piston does not return to "home" the ports that allow the brake fluid to return from the wheel cylinder to the master cylinder reservoir are not opened. The brake shoes will not release properly.

[ward 57]

You explained it better than I. After I relaced the M/C I didn't even need to adjust it. Learned you can't bench bleed them. Has to be done in the car the leverage needed by the pedal due to a valve in there.

[Jimntempe]

I ordered new wheel cylinders and hoses, along with a booster rebuild kit.

When I tried to bleed the brakes I could not fit an open end wrench on the bleeder screw because there are too many obstructions. The only tool I could get on it to loosen it was a socket, very difficult to "bleed"..... Is this normal?

I will have to see what the new wheel cylinders look like. Maybe the bleeder screw needs to be longer???

I have often had to use a 1/4" drive socket for those. An ignition wrench set might work too unless it's so tight the ignition wrench can't handle it.

[paul2748]

I've always used a box end wrench for the bleeder. Tight, but not a real problem. Usually the longer the better clear obstructions and for max force (without breaking anything). Also helps in turning range.

uote=RossL post_id=136896 time=1706892445 user_id=10031]

When I tried to bleed the brakes I could not fit an open end wrench on the bleeder screw because there are too many obstructions. The only tool I could get on it to loosen it was a socket, very difficult to "bleed"..... Is this normal?

I will have to see what the new wheel cylinders look like. Maybe the bleeder screw needs to be longer???
[/quote]

[Rusty57]

I agree with Jim and Paul. I always use either a socket or a box end wrench on a bleeder screw at least to break them loose and for the final tightening. My preference is a box end or socket that is a 6 point.

If there are clearance issues I might use an open end to manipulate the bleeder during the bleeding process. You don’t need a lot of torque to seal the bleeder during the return stroke. In my case I do have a pressure bleeder so once I open the bleeder I leave it open until any air and old fluid are gone.

There is one other trick I learned from working on old British sports cars. If you ever look in the tool box of a mechanic who works on them for a living you will see lots of “unusual” wrenches. They will be shortened, heated and bent, and/or the open and box ends ground to fit into a restricted area.

Maybe that box end wrench will fit the bleeder if it is just a little thinner.

[ICON 1956]

At the time I bleed my brakes I bought a Harbor freight box wrench and I custom ground to fit the bleeder it worked....