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MG TD TF 1500 - Brake Problem

I have rebuilt the brakes on my TD project, including replacing all of the brake lines. I am having a problem getting one of the banjo fittings on the front brakes to seal - I have used new copper washers of the correct size, made sure the both faces of the banjo fitting are flat, and that the area under the banjo bolt is smooth. It still leaks from what appears to be under the banjo bolt head. So, what am I missing?
don scott

Don,

You don't say if you are using DOT 5 (silicon) or DOT 3 fluid, but DOT 5 is harder to seal.

Also, you have new copper washers, which is good, but it is possible to have a bad washer. Did you try smoothing the washer too? Or heating it up to dull red and letting it cool to anneal (soften) the washer?
(no need to dunk it in water, but you can, it won't make a difference)

warmly,
dave
Dave Braun

Don, similar problem years ago, evidently the banjo bolt had a crack. Replaced it and leak gone. George
George Butz

Hi Don,

I am going through the exact same thing you are. This past weekend I installed my freshly resleaved cylinders and new brake lines and DOT 5 fluid and can't get a couple of the banjos to seal. I tried new washers and annealing to no avail. They appear just to weep under heavy brake pressure. In the archives there is mention of a product called Gasoila to use, unfortunately I can't find it here. I searched out another product made by Permatex that I would like to try.
http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/Permatex_Pneumatic_Hydraulic_Sealant.htm

Although designed for threads I figure it should work if I put an extremely thin coat on each side of the washers before installation. Any comments from anyone about this product? I have some on order and it will be here tomorrow. I will give it a try as long as there are no major concerns brought up here. Good luck! Tim


Tim Mayor

I had a similar problem with my brake rebuild a couple of years ago. I slowly tightened the banjo bolt a very small amount once a day or two or three and kept track of the small weeping (DOT5). If I recall correctly, I drove the TD during this time, too. After a couple of weeks the weeping stopped. I thought it possible that the malleable copper washer might take a little while to conform to the shape of the banjo.

I did not heat treat my new, carefully smoothed washers, but would do so if performing the work again.

To keep the bleeders clean, I also placed snug rubber caps on them (NAPA) to aid future servicing.

Larry
Larry Shoer

I use Gasoila sparingly on my TD. It can generally be purchased at a good plumbing supply house. The specific Gasoila product I used is non-hardening.

In doing my full brake rebuild I used Gasoila on certain pipe fittings, leaving the first goodly number of threads free of Gasoila.

I debated long and hard the use of Gasoila on the copper washers and decided not to do so. I was concerned that the Gasoila could squeeze into the brake line and brake fluid. I wanted to avoid at all costs contaminating the brake fluid. Gasoila has fine grained non-soluble solid particles in it (talc, if I remember correctly).

When used cautiously on pipe fittings, I think Gasoila is fine. I know others have used it on the copper washers. I wanted to see if I could first stop the DOT5 leaks without it, and did so as described in my previous post.

There is more information in the archives about Gasoila.

Good luck. Be patient...

Larry
Larry Shoer

Thanks everyone - it helps to knoe I am not the only one experiencing this. I will try heating and smoothing the washers and report back.

Don
don scott

Don,

Not sure if this is the best way to do it, but I taped a piece of very fine grit (1500?) sandpaper to a piece of glass and, with my finger, wet sanded the copper washer until smooth and flat. I used a scrap piece of inner tube about 1/2" square to prevent the sharpened edges of the washer from cutting my finger.

Larry
Larry Shoer

An update:
I went to pick up the Permatex sealent fully expecting to pay $10-$15 and just about fell over backwards when they told me $44.00! Whoa..need to think this one over especially when I need to use only a few drops! I left it at the store for now.

Maybe I'll try fiddling some more with what I have. Unfortunately I suspect my problem is with the sealing surface on the cylinder itself, and they are already installed on the car. I'm not sure how to go about smoothing it without contaminating the cylinders with filings or grit without taking everything apart. Think I'll sleep on this one. Tim
Tim Mayor

So, I heated the washers to dull red, then let them cool. I then sanded on a flat surface to make sure they were absolutely flat. I also did the same to the wheel cylinder after blocking the hole. After all of this, I put everything back together and the leak was still there. So, I have tried tightening the bolt a little each day, and it is remarkable how you can keep doing this for several days. After 3 days of this the leak has slowed considerably so I think I am on to something. Hopefully, a few more days and that will be that! Thanks again for all the suggestions and advice.

Regards,

Don
don scott

Don,

I didn't even have to tighten the banjo to stop the very slow final leak. After about a week or so it just stopped on its own. I suggest you hold off for awhile and see if yours does the same. Even driving the MG may help. The heating and cooling of the brake line and vibration generated while driving may work the mating surfaces so as to close up any small leaks.

Larry
Larry Shoer

Interestingly, copper work hardens. i.e Small stress areas from working the copper makes it harder. Next time you probably want to smooth it with sand paper and then anneal it.

warmly,
dave
Dave Braun

Larry - unfortunately, it will probably be a couple of years before driving is an option - I still have the tub to finish and then reassemble everything.

Dave - I should have thought of that, but of course, I was in a hurry to solve the problem, as usual!

Thanks,

Don
don scott

Don,

My leak stopped before my first drive after rebuilding the brakes. I check periodically and all has been tight since then (two years). I hope your leak stops on its own, too.

Larry
Larry Shoer

hello, there is a potential problem with sanding the washers...even using a glass plate. depending on how you do the sanding, you may not end up with parallel faces. regards, tom
tom peterson

Tom,

While each side needs to be flat, I'm not sure they also need to be perfectly parallel. Just so the washer makes a good seat with the banjo on one side and the brake cylinder on the other, for example, you've accomplished what you need.


Larry
Larry Shoer

larry, don't ask me how i know, but they do need to be reasonably parallel. there is only so much even soft, annealed copper can take up. (again, don't ask me how i know.LOL! ) regards, tom
tom peterson

This thread was discussed between 13/07/2009 and 26/07/2009

MG TD TF 1500 index

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