Replacing NS Rear Wheel Cylinder

[xpress]

ah man, thank you, that's really nice. i am based near kew, richmond, surrey, close to west london and putney. i would be happy to buy someone a few tins and give them something! i don't have the pipe bending and flaring kit, but i would be grateful for a hand!

[charlie_morris_minor]

if you can wait a few weeks (and it would be a few) I would be more than happy to pop up to see you one weekend and lend a hand

[xpress]

No problem, thanks for the offer. I am around most days, if anyone in the meantime wants to pop round and see another moggie then give us a shout!

[xpress]

Hi there, can anyone tell me how many ft of pipe i will need plus a bit extra to be on the safe side for each side of the rear wheel cylinders to the four way union/flexi hose? I am going to go and pick some up!

thank you.

[xpress]

Hi,

Is there anyone around right now to tell me how long both the back brake pipes need to be, the ones from the flexi hose/four way union to the wheel cylinders? I am going to pick a couple of lengths up from someone's roll of kunifer.

Thanks!

[bmcecosse]

As per PM - 3ft will be plenty!

[xpress]

I have taken off the nearside brake pipe. ordering new ones right now to go from the t union to the pattern wheel cylinders.

i just measured the brake pipe length from flare to flare from the t union to nearside rear cylinder = 74cm.

I will edit and add the size of the other side here. i think these pipes are original.

Hope this helps someone else when ordering.

[bmcecosse]

Too short = useless, too long, the extra length can be easily lost!

[taupe]

The rear brake pipes F & G in the diagram are 22" and 32" long overall respectively. The ends are 3/8"BSF assuming you have a standard set up.

Ive posted this before but here is the Moprod catalogue for the minor 57-71 models - its all 3/8" bsf ref SPN on the diagram except the front brake cylinder link pipes 'D' ref SPA on the diagram which are 3/8" unf.

The only thing you need to check is are your fittings double or single flare as there is some variation in this (or perhaps non standard fittings may have been fitted).

The numbers after are the overall length in inches eg SPN 52 = 3/8" bsf both ends, 52" overall pipe length.

[bmcecosse]

So - 32" is more like 82 cms - NOT 74!

[taupe]

I made mine to the Moprod sizes and routed as in the diagram M2 in the manual. The length was just right and left plenty of 'slack' for the slight movement at the wheel cylinder end. If you routed the pipe tighter to the axle you could probably loose 3" from the pipe length and still fit it ok.

[xpress]

thanks for the feedback guys, yes 82 cm but if you route it tighter to the axle and cable tie it, it's more like 74cm that you need, but 8cm isn't that much more so the moprod sizes are probably quite right.

i have just checked my new cylinder that i am to fit ..

it's an LPR. i am only going to replace the one cylinder at present and i will order another LPR and i will have the kunifer pipe ready to do the other side. it is certified by the DNV and ISO 9002 compliant. i believe that the brake pipe i pulled out has the coarse bsf threads on either side. i thought that this pattern cylinder will need USF universal (fine) threads, but i tried the old brake pipe thread into the brass union then the brass union into the wheel cylinder and it fits, so the new pattern cylinder seems to take BSF. if it was USF it wouldn't fit in the cylinder. it all seems to be bsf.

one problem i am having is that i can't seem to slacken the bleed nipple union on the top of the nut. it's all old and brass, and i see no problem with reusing these bits as well as reusing the copper washers by waving a gas lamp across them a bit and annealing them and allowing to cool before i refit.

should i soak it in diesel then try to slacken off the bleed nipple? or try to use some heat on the barrel?

also, when you are screwing the pipes back in the unions and then into the wheel cylinder, do you add some copper grease to aid in taking apart in the future and protecting against the brake pipe threads rusting into the brass union or do you actually think it's a good idea for things to seize into each other a bit in order to hold together and become part of each other?

[bmcecosse]

Don't put copper grease anywhere near the brake system threads- perhaps just a dab on where the cylinder slides. Don't make the pipe too tight a fit lengthwise - the cylinder has to move. Yes - apply a bit of heat to the nipple! The fine thread used elsewhere on the brake system is 3/8" UNF.

[xpress]

thank you. i expect it's no grease on the flared ends because you want them to be as secure as possible? i don't expect the have to change the cylinder again for a good while and i can always route another piece of pipe. i am starting to see cylinder replacement as pipe replacement at the same time. i do intend to copper grease the bleed screw thread, because i don't want the trouble of backing that off and finding it seized again in the future. btw the t union end of the pipe was relatively easy to unscrew and the pipe stayed in one piece, just used a bit of plusgas.

ok, back pipes are ordered and coming this weekend and i am working on getting that bleed screw unseized now.

ps .. i noticed inside the wheel cylinder brass union that there is a hole there, do the holes in the union threading into the brass union need to be lined up i take it for the bleed screw to work properly? i haven't seen it written up but should this be lined up when tightening or does it make no difference since air will rise to the top anyway?

[bmcecosse]

Don't worry about it - there's room for the air to escape ok!

[xpress]

yay! ok, just waiting for the kunifer to arrive now.

[xpress]

kunifer all present and correct, great service and arrived the next day.

now i am trying to undo this bleed screw. i have tried some heat and cold, heat and cold. now going to try some releasing agent and might leave it in some diesel. i need to get a crack on it to unseize it.

question: is it possible to bleed the whole braking system through one bleed screw?

[bmcecosse]

No - each line needs to be bled locally. In 'emergency' it's usually possible to bleed it by simply slackening the pipe nipple slightly.......

[xpress]

i have undone the bleed screw. this was not an easy task. i took a piece from an old bmw toolkit, put it through the banjo end and pivoted it on an iron gate and kept on shocking and turning, shocking and turning the bleed screw, with penetrating fluid, and heat, and eventually it turned out, and the threads are perfect. i will brush some copper slip into the threads. i was just wondering, is it preference, could you please explain to me why you wouldn't want to put a bit of slip into the brake pipe threads in case something needs to be undone again?

won't this be good when this thread has a good ending to it, with the words ALL DONE !!!

[bmcecosse]

Just the risk of contaminating the brake fluid with the copper slip. You need to hope (check!) that your method hasn't damaged the part you put the bar through! If the faces are damaged/distorted in any way - it may not seal.