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MG MGB Technical - Brake lines replacement hints?

Hello all,

For Fathers Day I got an Automec brake line replacement kit for my '71 B. Before I start tackling this job are there any hints or things that you learned the hard way?


R Gallagher


I put one in last year.

Even though the pipes are soft enouch to bend by hand, I still used a small pipe bender to make the tight turns.

I had the engine out while removing the old pipes and installing the new pipes. It was quite easy especially when putting the pipe clamps back on the body,

But they can be installed while the engine is still in. You will just have to do some bending while under the car

Removing the front left pipe will be very difficult without cutting it as it runs along the cross member and is not very flexible.

I worked from the front to the back starting with the master cylinder. I found it more easy to remove the entire brake and clutch master cylinder system.

When tighting the nuts, don't be too rough. The softer pipe will start to twist. I used a little brake fluid on the nuts and flanges to lubricate them while attaching to the flexible lines and the rear brakes.

I also routed the rear line between the left and right wheels a little lower than the originals to help prevent it from being crushed if I have to have it towed. I hope this helps.

I also replaced the entire brake system, rebuilt master cylinder and rebuilt from auto. (Life time garentee) and new rear cylinders from Moss. Gravity bleed the pipes first then using my lovely assistant, we used the pump system and I have a very solid brake system. No leaks etc.

I hope this helps

Cris DeYoung


Awesome! Thanks for your experience!

R Gallagher

Rob, I just replaced the lines in my '71 as well. Double check the connector for the two brake lines that feed the rear. The one I recieved only had good threads in one side and the other side was all chewed up. I didn't find that out until the job was almost done, and the soft brass fittings don't work well with the short replacement couplings you'll find at the local parts store.
Remove the existing brake lines and reproduce them out of the car. Fitment will be easier. If you have to cut a stock line to get it out, that's better than bending it. It will be easier to reproduce that way, unless you only make bends in otherwise straight sections.
You may have to adjust your rear brakes 2 or 3 times to lose the soft feeling in the top inch of brake pedal stroke. I thought I had air trapped in the lines, but after repeatedly pumping the brake pedal and readjusting the brake shoes, it went away.

Are you replacing the clutch line at this time too? You may as well...
Jeff Schlemmer


Funny, I started looking at the two lines from the master to the distribution block and thought exactly about "Why didn't I get the clutch line".


R Gallagher

Just a hint in case you cut your lines to remove them. Scribe a line lengthways where you cut to align the mock up on the bench. Not a big deal, but might save you trouble.

I just did the entire car using a few incomplete Automec kits I bought cheaply and it was fairly easy to bend the lines by hand or by using a tube bender. For the tight turns I used a bender and for the rest I used my hands. I also used a sheet metal tool to get all the straight parts straight and it looks quite good. I did however bend the pipes to none factory placements as I was replacing every line in the car.

For the clutch line I ran the tubing below the reservoir and got rid of the hump that traps air. Several people told me it won't work but having restored several other cars and noting the placement of the clutch lines, they all ran below the reservoir.

The 5/16 fuel lines were a bear to bend.
Mike MaGee

I did this a very long time ago and tried to take off the old pipes without too much distortion.I then fixed the start of the new pipe parallel with the same end of the old one with a strong fabric tape and progressed with my pipe bending little by little matching the shape of the new with the old and securing with tape as needed.Once the complete shape of the line was recreated I removed the tape and fitted the new pipe which worked quite easily since it matched the form of the original.This method worked particularly well with the fuel pipe.
sam christie

I agree with Mike on the clutch line. It bled very easily that way and works great, but I had to cut and reflare the line since there was plenty of extra from rerouting. I bent ALL my lines by hand. The tubing benders just got in the way.
Jeff Schlemmer

Consider using steel wool to shine them up and a spray of some clear coat.

Well, I finally put some fluid in the brake system and bled the entire system using a power bleeder which worked quite well. I only had one small leak which was taken care of pronto.

The problem I did have was with the braided stainless flex lines. 2 of the 3 were plugged up and fluid could not pass through. I thought I crimped a line but that wasn't so. I loosened the fittings until I found brake fluid coming out and determined where the blockage was.

When I got the flex lines off the car nothing would pass through, even compressed air. I used a piece of wire and brake cleaner to clear the lines. Everything is new so I couldn't figure out where the gunk came from and I blew the lines clear after bending them. It was gunk not grit that blocked the lines. Go figure.

Now all is well.
Mike MaGee

Thanks guys for all of your help. I have bent the first line perfectly with my hands and it's much easier than I anticipated.

Just take it slow and it's very easy.

R Gallagher

I'm approaching the relining of the 1979 V6 conversion with a roll of 1/8 SS tubing and a couple handheld econo-benders ( Eastwood) and lots of optimism. I'll keep yall informed. I'm leaning towards a renewal of all couples to the AN thread, DC-ing the old existing ones creeping up the works now on the car. Anyone have opinions, pros/cons on relining the vehicle using the stock thread fittings versus the newer ( and pretty-colored) AN threads, Mike or Chris?
vem myers

Standard flaring kits will not last long w/ss tubing. SS is a tough material and it chews up flaring tools. I suggest you buy an additional double flaring. A friend who works for a hydraulic company told me that and having tried to drill through ss I can attest to how hard it is.
Mike MaGee


For the rear line running from the M/C to the brass coupler, be aware that there are 2 different fittings, even though they look very similar.

The fitting with the grooves on the hex goes to the M/C. Test fit the other end to be sure that it threads into the brass coupler properly.


This thread was discussed between 02/07/2005 and 12/07/2005

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