Morris Minor Owners Club

Is there a minimum bend radius for brake lines? I'm replacing some of the brake lines, as I'm not happy with the run I put in some years ago, in particular the line from the 4 way Union at the front of the car to the rear. I have a servo, so getting the line into the chassis leg as originally fitted is tricky.

Cheers N

If I was doing this, I would experiment to see how much the pipe distorted for a given bend, in other words use the minimum radius before the pipe showed any signs of narrowing of the diameter around the curve. There is a tool available to form a curve, whether it would give you the tightness you need I couldn’t say.

Cautionary tale
Do not buy those tools advertised as suitable for bending tight curves. They are only suitable for 5mm O.D. pipe and not 3/16" O.D. pipe as per the Minor.

I would not recommend the use copper pipe as it can harden and become brittle and crack. Use Kunifer which is a cupronickel alloy and is the most suitable material for brake pipes.

You can form quite sharp bends using your hands to form the bend but do it slowly. Use new metal pipe as it will be relatively soft and easy to form. Taking it slowly will eliminate any narrowing/flattening of the pipe I.D.. Make the tail longer than necessary and when formed trim the tail to length. I would recommend making the bend as large as possible. The pipe in question and the fitment allows quite a large radius to be made where it transposes from running alongside the chassis rail to entering the union fitted to the back of the master cylinder. Leaving the union slightly slack helps with aligning the pipe into the union. Tighten the union when the pipe is fitted.

Make sure that you form the correct union on the end of the pipe as there are concave and convex nipples on the braking system. You need to have the correct nipple to seal successfully.

Thanks gents. I'm fairly happy to make larger radius bends by hand, but I was wondering what the smallest allowable is? I've seen somewhere that the smallest bend radius shouldn't be less than 3 x the outside dia. of the pipe, but I can't find that page now. I won't be flaring the ends myself, I'll get the local friendly garage to do it, they've done it before.

While we're here, what's the view on re-using brake lines? As mentioned above, I have a servo, and the front to rear line runs from the front o/s corner, near the stop light switch, all the way past the starter, along the o/s chassis leg and to the flexible hose bracket above the back axle. It's a bit overlength, and has a couple of unnecessary bends in it-can I straighten it out carefully, then get it cut to length (about 10cm needs to come off) & get the ends flared?

I've always been of the view that brake lines are cheap enough not to be worth trying to salvage once they've been disturbed-or am I being overcautious?

cheers N

I have a CZ universal metal bender . If I want to bend anything special or different, I just make a new former if I don’t already have something suitable.

Bender cost about £30 delivered in 1985? Bends flat, round bar and pipes into all sorts of shapes in fairlly small sizes.

https://www.model-engineer.co.uk/sites/ ... bender.pdf

Everyone should have one

A bit more information and comments about the C.Z. metal bender.

https://www.model-engineer.co.uk/forums ... ?th=101230

I have and use one of the below:-

https://www.machinemart.co.uk/p/cht264- ... pe-bender/

It does the job but is not suitable for really small radius's.

For smaller radius I prefer to hand form the bend.

I like their hype.

How ‘unique’ can a ‘knock-off’ be, some 35 years after the original was marketed.

Back then the original was a just a plain universal metal bender. Now it is not only universal, but also multi-purpose as well.

I wonder what else it does. Possibly still good value at that price! Mine may have cost me as much as £15, in a wooden box with several extra mandrels, but will never be as cheap again, now! (OK, I’ve had mine well over ten years, possibly 15).

Hi,
Here's a kunifer brake pipe set for you. I have bought these before, they are good.
Includes a diagram telling which pipe in the set is cut to go where.
Best wishes,
Mike.

https://www.ebay.co.uk/itm/Morris-Minor ... SwaB5Xp1Eu

Thanks for the link, though I have just this evening bought a roll of kunifer brake pipe from Frost's. I will trial fit it, cut it to length, then take it to my local garage to get the ends flared.

Cheers N

On the subject of copper, has anyone ever actually seen a fatigue failure? All the magazines etc quote that it fatigues, I have been using it for 30 years and never seen a failure ( one car has done over 100k miles) . I have though seen steel both fatigue and rust through.

Yes copper pipes do fail especially where the copper pipe is exercised and is not supported or secured adequately.

For example: the pipe serving the Minor rear brake cylinders where it moves with the cylinder and is secured to the axle - between the wheel cylinder and the securing strap holding the brake pipe to the axle the copper pipe can move, vibrate, work harden, then get brittle and fail usually where the pipe is screwed into the wheel cylinder.

Knowing how copper pipes can work harden, crack and fail I would never fit a copper pipe to any part of the brake system that carries any safety critical fluid. For me Kunifer every time.

Hmm. Thanks for that insight Phil, I'll have to check the rear axle pipes. Is there a foolproof way of determining whether an old pipe is copper or kunifer?

Cheers N

A friend of mine had a copper pipe go on the front brakes on his Humber Super Snipe. He was just pulling off the motorway, luckily there was a fairly long slip road for the hand brake to slow him down

I had a rear brake pipe fail on a 1275 Midget a number of years ago - fortunately i was on the M1 at the time, so was able to slow down and stop safely on the hard shoulder. It was copper and failed on the pipe from T piece to the brake cylinder. I put it down to fatigue due to not being strapped to the axle properly, but the fact that it was copper and not Kunifer probably didn't help.

On bending small radii, I bend copper steam pipework for miniature steam engines using a former made of a stack of washers bolted together - the smaller diameter are the radius you want and the number required to equal the pipe thickness, with a couple of penny washers on the outsides to prevent the pipe distorting and flattening when you bend it. I've also used the same technique on copper brake pipes successfully.

Remember if you use copper pipework it will work harden very quickly, so bend once only - if you go back and try again it will be noticeably harder to reform, and may need annealing before you can bend it again, although i'm not sure if annealing copper brake pipes is a good idea, as they operate at a higher pressure than steam engines, albeit a bit cooler

The stack of washers is a good tip, thanks!

The line from servo to rear axle t-piece failed shortly after I fitted discs. I was on the A420, just approaching the dual carriageway section immediately before the A34 at Oxford. Fortunately I was able to pull off, on to the uphill slip road, and brake using the handbrake. Another 2 miles and I would have been approaching the A34 roundabout at 60mph, which could have been nasty.
That happened because I had overtightened the union on the t-piece. I cut the pipe short, had a new flare put on it, and refitted it, had no problem since.
I make sure the pipe is secured using pieces of old rubber hose wrapped around it, and large cable ties going around the back axle and piece of hose.

Ok, so I did what I said I wasn't going to do, and bought a brake pipe flaring tool from Halfords.
Has anyone got any experience of these? Because, despite following the instructions to the letter, I haven't been able to get a decent flare in about 20 attempts, using a piece of old brake line.
I'm cutting it using a small adjustable pipe cutter.
Link to the tool:-
https://www.halfords.com/workshop-tools ... g-tool-kit

Cheers N

Should have read the warning label on the box!

Personally, I wouldn’t pay washers for that type. Sorry to be so blunt.

One of mine is a SIP, I think. The other was good quality but I can’t remember the origin - both were second hand from auctions/sales. I needed some larger hydraulic flares, at one point, for agricultural use so the second was picked up when the opportunity arose. They are both ‘buried’ somewhere in the garage as they have not been used for some time, but I know where to look if I were to need one...

I bought a similar item and it was no good at all so invested in a good quality UK made item.

https://www.frost.co.uk/professional-br ... ring-tool/

There are several of the below on 'e' bay and they are good having used them extensively when in the garage trade.

https://www.ebay.co.uk/itm/Sykes-Pickav ... SwAfVeNY00

ndevans wrote: ↑Thu Feb 06, 2020 11:09 pm Ok, so I did what I said I wasn't going to do, and bought a brake pipe flaring tool from Halfords.
Has anyone got any experience of these? Because, despite following the instructions to the letter, I haven't been able to get a decent flare in about 20 attempts, using a piece of old brake line.
I'm cutting it using a small adjustable pipe cutter.
Link to the tool:-
https://www.halfords.com/workshop-tools ... g-tool-kit

Cheers N

I've got one of those type flaring tools that I brought some years ago and I used it to replace a load of brake pipes on a more modern car. Mind you it was the modern soft bend-by-hand copper pipe, so perhaps that made a difference?
Did about 14-16 flares on it. Did eventually break the little die thing that stopped the pipe from collapsing.