Rear brake cylinder

[Hondasp2]

:brickwall: I attempted to remove the brake line nut to the rear of the rear cylinder with a brake line spanner after soaking union in wd40 but the f@@@ thing rounded off still!! Any ideas as to how I can now remove this and will I have to buy a replacement brake pipe

[brodfather11]

You can sometimes loosen them with a pair of mole grips, if you get them loose the problem is can you tighten it up again ? . If not a flaring tool is needed to fit a new tube nut after cutting the pipe, which means you need some free play in the pipe to stretch it to fit again. As you have a new wheel cylinder it may be quicker to buy a new pipe and fit them together, if the pipe tube nut at the other end of the pipe comes out easy or you may have to use a pair of mole grips to get that tube nut out ! .
A ring spanner is the best with a small touch of heat if really tight which you can only do after cutting the pipe.

[Hondasp2]

Thanks I was thinking of applying a small amount of heat with it intact to try and shift it

[addo]

The hard lines are unlikely to be very dear. You might have access to prefabricated standard length lines that can be bent into a suitable shape.

Or, borrow a flaring kit and make a new one yourself. A good spread of options for this situation.

[geoff]

You will be able to apply plenty of heat without fear of damaging the seals. The cylinder end seals are covered by the backplate and the internal seals are insulated by the hydraulic oil. The elastomer should be capable of withstanding 200*C anyway.
When hot try tightening a little before backing off.
A mole grips may succeed if you have the access.
The hydraulic seal depends on a tapered fitting so the actual tightening force doesn't need to be huge so even if the nut is rounded you will able to do it back up correctly.
If you try and cut the pipe and put a joint in you will need a very good quality flaring tool which is expensive.
A cheap flaring tool is only suitable for copper pipe and as such you would need to replace the whole pipe run.
Have a try undoing it and see how you get on.

[polar]

sometimes corrosion sets in between the pipe and nut a small amount of heat will free it off.

[Barkas]

Wear goggles if using heat on pipes and unions, or working on overhead pipes with hot brake fluid that can squirt out into your eyes .