frustrated!

[William G.]

After replacing the master cylinder, TWICE, with reproduction Master cylinders and new formed brake lines from it to the safety switch block, I have not had success in keeping them from leaking! The car is a 67, with non-power brakes. I live in the Melbourne Florida vicinity and am asking if anyone can recommend a classic car shop, or restoration shop in this area where I might be able to get some help.

Thanks

Bill

[Leif A.]

Re: frustrated!

Did you use stainless steel lines?? If so, they are known to be extremely hard to seal. I would try some copper "crush" washers to eradicate the leaks.

[Ryan S.]

[Mark E.]

Re: frustrated!

Where is it leaking? Photo please.

[William G.]

Re: frustrated!

Where is it leaking? Photo please.

The leak appears to be around the Master Cylinder. I installed the second of two reproduction Master cylinders a couple of months ago, when the first one leaked around the prebent/ formed lines between the MC and the safety switch block. The lines that were sent from ZIP Corvette with the first MC were on correctly bent, or were too long and did not fit. I did try to bend them and I believe may have caused the problem back then.
When ZIP warranty exchanged the MC a second time, they also sent me new formed lines. Those fit correctly as advertised! Because of the ridiculous heat here in central Florida, I did not immediately attempt to pressure bleed the new system. That was finally done three days ago. This leak is worse, as when I removed the bleeder plate, I could almost watch the fluid in the front reservoir dropping! I looked under the car the floor, covered with cardboard was soaked. Initially I thought it was the bleeder plate seal that had leaked, however, that was dashed when I could see the fluid dropping.
All of this started last spring when I decided to replace the four rubber brake lines, original to the car, and found the silicone fluid rusty. Then found a layer of fine rust in the bottom of the original MC. Rather than rebuild that, I ordered the reproduction MC.
All of the lines on the car are original steel. The fluid appears to be dripping down onto the left side engine compartment splash shield and then running off onto the floor and the left hand exhaust pipe.
I would consider buying the replacement steel lines running from the MC to the front and also the rear, but first I have to find out what is leaking. I sure hope it is not the MC and the seal at the rear of the main piston of the MC.

As far as attaching pictures, I have not done that on this forum and am now sure how to do that. Sorry!

Bill

[Gary C.]

Re: frustrated!

Bill,

This is what aircraft guys use to seal fuel and brake lines. https://www.aircraftspruce.com/catal...ezturnlube.php

Have used it for years on Corvettes brake and fuel lines and it works great.

Be careful to only put on threads.

Gary
....

[James G.]

Re: frustrated!

With stainless lines I have had luck "lapping" the fittings together, prior to installation.
With brake lines I use a little brake fluid on the flare, insert the line, tighten the flare fitting finger tight and then spin the line inside the fitting, when it freely spins I tighten with my fingers until it has some resistance, then spin it on the flare again, typically 2-3 times cinching the fitting by hand and it feels concentric and free of highspots.
Remove wipe the fitting and then install on the car,
I find the double flare is not as well formed when a hydraulic flare is done VS a spin flare.
I have done this on many stainless line flare fittings which I could not get to seal.

[Kent S.]

Re: frustrated!

Bill,

This is what aircraft guys use to seal fuel and brake lines. https://www.aircraftspruce.com/catal...ezturnlube.php

Have used it for years on Corvettes brake and fuel lines and it works great.

Be careful to only put on threads.

Gary
....

I've always thought the threads have nothing to do with leaks. The seal is at the flare (or not) - the threaded portion just applies the pressure.

[Ed S.]

Re: frustrated!

I've always thought the threads have nothing to do with leaks. The seal is at the flare (or not) - the threaded portion just applies the pressure.

It is not the thread - threads have nothing to do with the actual "seal". Threads allow you to apply pressure to the flared end so it seals against the preformed cone. It is the flare in the SS line that is likely the problem. SS is hard, does not easily conform to the opposite mating surface like carbon steel tubing does. That is where the leak is - once the fluid gets past the imperfect flare to cone mating surfaces it easily wicks around the threads and on to your garage floor or where ever.

[Duke W.]

Re: frustrated!

When ZIP warranty exchanged the MC a second time, they also sent me new formed lines. Those fit correctly as advertised!

All of the lines on the car are original steel.

Bill

So what is it... the replacement pipes or the originals?

Contrary to common belief flare fittings threads are not the seal. The seal is the the interference fit between the flare and the conical fitting. When one or both are new install them by tightening and loosening the B-nuts AT LEAST three times. This will "form" the flare to the cone and yield a tight seal.

When reinstalling previously removed mating pieces that didn't leak, it's okay to tighten just once and the joint should be leak free.

ALWAYS use a five sided "tubing wrench" when loosening or tightening B-nuts. Use of a plain open end wrench is a virtual guarantee that you will round off the B-nuts!

Stainless steel pipes can be quite difficult to seal because SS is much tougher than plated mild steel, which makes it more difficult for the flair to conform to the cone and seal.

The way most vintage Corvettes are used, plated steel brake pipes will outlive all of us, so take a pass on stainless.

Duke

[Michael H.]

Re: frustrated!

Buy some flare copper crush washers that will stop the leaks. Check with Grainger Ind. Supply.

Mike

[Doug C.]

Re: frustrated!

Flare gaskets can also prevent PS hose leaks. I keep 1/4, 3/16, 5/16 and 3/8 in stock.