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MG MGB Technical - reconnecting hydraulics

well I got the pedal box frame back into my GT with the master cylinders attached. What I need to know is whether or not I need to prep the ends of the clutch/brake lines that screw into the master cylinders. they're in somewhat rough condition, but I was curious if they needed any kind of coating, if teflon tape may help, etc. I'm worried that they are corroded enough to leak!
Chris

Ideally, the compression fitting should be enough. Are the threads clean and clear?

I'd think any thread sealer would have to be chemically researched for compatibility with your chosen brake fluid.

I'd guess that a wrap and a half of joint tape wouldn't hurt.

No warrantees implied or suggested.
glg

Use anti-seize on the threads or if you prefer some teflon tape w/antiseize. Teflon is inert and OK to use. I hate trying to remove rusted and frozen brake lines :(
Mike MaGee

The thing to be careful about is not allowing anything to get into the line itself. Teflon tape can wreck havoc with any kind of hydraulic system if it gets inside the system. For that reason it is universally recommended that it not be used in hydraulic systems and more suitable sealants are available, (check with Parker) but none at all is even better. A brake line is a slightly different animal in that the seal is independent of the nut and threads so it is possible to put the tape on the threads and not get it inside the system. The problem arises when you have to remove the line again because invariably a strand of the tape will remain in the female end of the thread and is extremely likely to find it's way into the system when the fitting is replaced. As long as you are aware of this and deal with it appropriately every single time this is probably still OK, but if you neglect it even once it can mean a total brake system failure. By appropriately, of course I mean that every single particle of the teflon tape has to be removed from the female fitting and the tube, perhaps by ultrasonic cleaning or similar method or new parts must be used. Your choice, but I would prefer having to fit new lines and fittings to taking the chance. If the old nuts are getting that bad maybe you should consider replacement anyway.

Jim
Jim Blackwood

Jim makes a good point, but overwhelmed it with the dangers of using teflon tape.

Thread sealant is unneccesary in a flare fitting. The sealing is done by pressure between the flare on the tubing and the female opening on the fitting. The nut is there to apply that pressure, not to seal the fluid.

I think I'd stay away from the anti-seize as well. I'd be afraid it would contaminate the brake fluid during assembly or later disassembly/reassembly.
Matt Kulka

I have to agree with Jim on the dangers of teflon tape. So does the nuclear Navy, finding teflon tape in the ractor compartment of a naval ship will bring everything to an instant halt. The reason? Teflon tape becomes transparent when imersed in liquid of any kind. You now have a contaminant in the system that can't be seen.

The threaded portion of the brake line is nothing more than a jam nut to keep the flaired line tight against the seat. All the sealant in the world will not keep that nut from leaking fluid if the flair and seat are leaking. No sealant or anti-seize is necessary or appropriate on these threads.
Good luck - Dave
David DuBois

Not that this is 100% related, but I'm a licensed gas fitter and I find that any time a thread sealant is used on a compression or flare joint, it only masks leaks temporarily. A good flare will seal without sealant and I always recommend NOT using any. Unless you want a slow destructive leak that's difficult to locate years down the road...
Jeff Schlemmer

What's a gas fitter? You specialize in gas lines? Around here, plumbers are the guys who work with gas lines, as well and water. Teflon has it's uses, flare fittings are not one of them. A bit of neversieze on the threads is all you need to use.
gerry masterman

I assumed Chris was concerned with the condition of the flare nut, not with the sealing of the fitting, because of rust on the threads, which is a common problem. And I agree, you'd hate to have to take it apart on down the road only to find the darned thing is siezed up and the corners round off instead of the thing turning. BTDT. So my advice was directed towards treatment of the threads to prevent that scenario, not trying to seal the fitting, which Jeff and others have pointed out is not only a bad idea but doesn't work anyway. Teflon tape would work for this purpose, but isn't a particularly good idea as mentioned. Anti-sieze would be better but a contamination risk still exists. Better still to replace the nut and re-flare the line, but best is to replace the entire line with a stainless one.

Jim
Jim Blackwood

Jim is right indeed. I'm more concerned with the condition of the nut as the threads are certainly fine, just a little crusty. it was definitely an experience trying to get it off. I had to unbolt the the pedal box frame and pull it out to get better access to the clutch line nut. brakes weren't TOO bad but clutch was the worst. I'm taking all this to say that the seal has nothing to do with the threads ont he nut, rather the pressure of thenut on the flare of the lines... in that case I think I should be just fine. thanks everyone.
Chris

This thread was discussed between 08/11/2003 and 09/11/2003

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