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MG TD TF 1500 - Brake line replacement

Hi all:

I'm looking to replace all the brake lines on the TF when I do a disc brake conversion later this year. I suspect the current lines are still the originals. I noted on several archived threads that folks have done brake line replacement for a variety of reasons. That said, given their age...would a full replacement be advisable regardless?


Jim Rice

I am still running the original brake lines in my car. I inspected them about 10 years ago and they were fine inside.

If you switch to synthetic brake fluid you will certainly have to flush them well.

I would think as long as your system did not get water in it that would cause rust, and the fitting seal properly (ie no evidence of leaking fluid) why replace them?

But lets hear from the experts.
Christopher Couper

There is no real way to inspect the inside for corrosion. Very common for the flares to be mushed in to the various fittings, making removing tough. At some point, I had a flare cracked and leak. Lines are generally dented, bent all over, etc. I would change them all for safety. George
George Butz III

I ran originals for 48 years. This restoration, I did change them out.

With a single braking system, any leak issue can cause a total loss of braking, and speaking from experience, pretty quickly.
Bruce Cunha

Thanks for the feedback. Bruce...good point. I had not considered that before. Moss carries a CU/NI brake pipe set. Comments on other threads seem to indicate they are well made and easy to bend/install, so I'll likely go that route. One question...does anyone know the fitting wrench size(s)? I want to see about getting a proper brake wrench for the fittings. I don't see any offered by Moss or Abingdon, but such wrenches are available from other sources. I assume the fittings are either metric or SAE...or heaven forbid Whitworth!! I don't want to mess up or round-off the fittings using regular wrenches.

I will do the swap as the car sits with everything it will be least in the engine compartment. Will straight wrenches work or should I look to buy some with swivel heads?


Jim Rice

To remove old brake lines I often cut them close to the fitting and use a box end wrench. Snipping them with diagonal cutters will give you an alignment reference to help make up the replacement. A six point box wrench is ideal...
J Stone

JS....My thought exactly if the fitting is really stubborn trying to remove it. However, installing the new ones I'll need the proper flare nut wrench. I tried a 10MM (too small) a 12MM (too big). An SAE 7/16th seems to fit well, but still a tad loose. (I was using an open end 7/16th wrench which may be why.) I'm surmising a proper 7/16th flare nut wrench is the proper size to use? That said, converting 7/16 (.437) to MM is a hair over 11MM (11.0998). So maybe a 11MM flair nut wrench is the correct tool to use?


Jim Rice

Jim, our cars were built in England in the 50s, so you will need Whitworth or BSF spanners to fit the nuts and bolt heads.
Originally the engine bolts had Whitworth / BSF heads with a fine metric thread.

Stuart Duncan

I went with the Moss lines. They fit well, you do have a little bending to do for the rear axle.

While moss offers nickel over copper, the original lines were spray painted black. I was unsure of this until I was able to document the black paint on Bill Chasser"s barn find from the 1960's

Bruce Cunha

Quality 6 point tubing wrenches, (with the slot), work very well. I replaced all the lines on the TF with Moss kits, not one fitting leaked. A tubing bender makes life easier. PJ

PJ Jennings

Hi PJ....nice looking frame! Do you recall what size tube wrench you used for the fittings?

Jim Rice

Jim, it's 11MM. I use an 11MM open-end wrench just to snug them up and the 6 point tubing wrench to tighten them. Does a nice job and doesn't mark up the fittings. PJ
PJ Jennings

Perfect! Thanks PJ. I noted a couple of the old fittings that have rounded flats and wanted to avoid repeating that when installing the new ones.


Jim Rice

just buy a cheap 11mm ring spanner and cut out a section the pipe thickness. The nuts are BSF size but 11 mm is near enough with a ringy.
Ray TF 2884
Ray Lee

Several original nuts were so mangled, vice grips were the best removal tool. Also good to get the ends out that were stuck due to smushed flares. The new lines are metric. George
George Butz III

This thread was discussed between 19/01/2022 and 22/01/2022

MG TD TF 1500 index

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