Technical Rear brakes

[Jockcl500]

I have to say I'm with you on this Jock. I might remove the hub to make fitting the shoes easier but don't think any advantage would be gained if just doing a cylinder - As you can see in this picture of Becky's rear brake, although I haven't tried it yet, it looks like the cylinder can be removed without having to disturb anything else:

View attachment 208615

(I suppose also there's always the slight chance of the inner bearing hanging up on the stub axle and getting damaged, although that's probably a small risk) I would be reluctant to risk breaking the back plate retaining screws - which I think are Allen Hex Screws? - I'd rather mechanically attack the wee bolt holding the cylinder even if it had to be destroyed to remove it.

I've read before on here about using a blow torch on the brake pipe tube nut and how it melts the coating on the pipe. I'd rather just cut the pipe off the nut so I can get a socket or 6 point ring key on it and make a new pipe up. (I have great hopes for my new Vibro Sockets on jobs like this). This shot of the back of Becky's back plate shows how it will easily come out with the cylinder if you were to cut the pipe off:

View attachment 208616

Of course then you've also got to get the tube nut out of the flex hose at the other end. I wouldn't ever put a flame anywhere near a flex hose fitting. New vs old nuts/bolts/setscrews on a job like this? For the negligible expense I'd always just use new ones. As I said above, if you are going to make a new pipe then just cut the old pipe off at the tube nut and forget about undoing the tube nut at all, it'll just come out with the old cylinder. In fact even if you are not replacing the cylinder - maybe just doing the pipe - if you cut off the old pipe and remove the cylinder complete with the tube nut still in it, you can then grip the tube nut in your workshop vice and unscrew the cylinder from it thus saving the cylinder for reuse. I've often found a stubborn tube nut which I can't shift with the cylinder still fitted to the backplate is relatively easily removed in this way. Even at the flex hose end cutting the tube off means you can then get a single hex socket on it which makes removal much easier.

You are correct the cylinder is removable without disturbing anything else, the back of the cylinder looks fairly good and clean, a spray of lube and should be removable without too much trouble, I suggest some lube on the handbrake shoe lever pivot too, it looks like it needs it.
a brake spanner is the best for removing brake pipes, they fit perfect and never round off anything, looks like a ring spanner with a bit missing, I bought mine from the snap-on van 30 years ago and they still look like new, the worst that can happen is the pipe snapping, but I always try to remove without snapping them.

 

[koalar]

having the rear brakes apart 3X. Once for the Bosch linings falling off. Once for weeping cylinder and once for a sticking cylinder.


First time I worked around the hub but its not that easy to fit the springs. From then onwards I have undone the hub. Its so much easier to fit the pre assembled shoes and springs.


one car has 200K the other 100K all four cylinders came off without damaging the pipe

I normally only take the very minimum apart. But for the sake of one nut it really is worth working around it

 

[Jockcl500]

having the rear brakes apart 3X. Once for the Bosch linings falling off. Once for weeping cylinder and once for a sticking cylinder.


First time I worked around the hub but its not that easy to fit the springs. From then onwards I have undone the hub. Its so much easier to fit the pre assembled shoes and springs.


one car has 200K the other 100K all four cylinders came off without damaging the pipe

I normally only take the very minimum apart. But for the sake of one nut it really is worth working around it

The linings only normally fail when soaked in brake fluid from a leaking cylinder, if checked regularly and replaced when it is a weep, rather than a leak, this can be avoided.
The cylinder is easy enough to change without disturbing the shoes, so there's no benefit removing anything else.
But I agree if you are replacing the shoes it makes things much easier to remove the hub, and is the sensible thing to do.

 

[Pugglt Auld Jock]

You are correct the cylinder is removable without disturbing anything else, the back of the cylinder looks fairly good and clean, a spray of lube and should be removable without too much trouble, I suggest some lube on the handbrake shoe lever pivot too, it looks like it needs it.
a brake spanner is the best for removing brake pipes, they fit perfect and never round off anything, looks like a ring spanner with a bit missing, I bought mine from the snap-on van 30 years ago and they still look like new, the worst that can happen is the pipe snapping, but I always try to remove without snapping them.

Aye Jock, although it looks a bit corroded (never been touched since leaving the factory I suspect) I'm hoping it'll all come apart ok. I'll be giving it all a good soaking with Plus Gas and a good few "nudges" with my air hammer before I try to loosen them. I had previously, in the above post, been considering a worst case scenario. I do like my pipes to be A1 though so may change them, I'll just see what they look like when I get it stripped down, might just do the flexes too, I'll just see.

Also completely agree with you that "split ring keys" are the way to go if you want to save the pipes. Here is a wee "pick and mix" I've collected over the years:



The three on the left are fairly recent purchases from Machine Mart bought when one of their VAT free events were on. The middle one is an old Britool I bought second hand to work on diesel lines. It's bi hex (12 point) which makes it easier to use in tight corners but for brake pipes you definitely need single hex (6 point) Then there are my two trusty old Williams Superslims which I've had since they were just wee baby ones and have seen the bottom of many a Mini, 1100, Marina, Maxi, etc, etc. The last one, on the right, was given to me by one of my students when I taught classes. It's a very poorly made tool with no maker's name, simply says "India" on it. I kept it as part of my "horrors" box of tricks which I would use to illustrate and enliven shop talks. Right at the top of the picture you can see my two home made pipe bending formers. the one on the right does a radius about half that of the more "De Luxe" one on the left with the handles. In fact I tend more to just bend pipes round my old wooden handled screwdriver handle but the bending tools make a neater job if I'm wanting a "super de luxe" look to the job.

I agree with you too about the lack of lube on the shoe pivots. As the hand brake has worked properly, and she's sailed through her two MOTs since I've had her, I've been concentrating on sorting other "stuff" - Big service, timing belt, leaking front shocker, etc first. Looking at them I doubt if the brakes had been looked at in years. The rear drums were a real pig to get off due to the size of the lip on the inner edge, even with the brake cable disconnected. I'll be doing a complete job on the rear brakes as well as the cylinders.

 

[DaveMcT]

I always clean all the bolts, before covering with copper grease, then refitting them. If I have taken it off, it will come off next time easily.
Copper grease on the back plate before fitting the wheel cylinder too.

I was thinking that because the hex heads get corroded, you are better to use socket heads. But they must be high tensile and plated. Stainless are almost certainly too weak and non plated will rust very quickly.

 

[Jockcl500]

Aye Jock, although it looks a bit corroded (never been touched since leaving the factory I suspect) I'm hoping it'll all come apart ok. I'll be giving it all a good soaking with Plus Gas and a good few "nudges" with my air hammer before I try to loosen them. I had previously, in the above post, been considering a worst case scenario. I do like my pipes to be A1 though so may change them, I'll just see what they look like when I get it stripped down, might just do the flexes too, I'll just see.

Also completely agree with you that "split ring keys" are the way to go if you want to save the pipes. Here is a wee "pick and mix" I've collected over the years:

View attachment 208625

The three on the left are fairly recent purchases from Machine Mart bought when one of their VAT free events were on. The middle one is an old Britool I bought second hand to work on diesel lines. It's bi hex (12 point) which makes it easier to use in tight corners but for brake pipes you definitely need single hex (6 point) Then there are my two trusty old Williams Superslims which I've had since they were just wee baby ones and have seen the bottom of many a Mini, 1100, Marina, Maxi, etc, etc. The last one, on the right, was given to me by one of my students when I taught classes. It's a very poorly made tool with no maker's name, simply says "India" on it. I kept it as part of my "horrors" box of tricks which I would use to illustrate and enliven shop talks. Right at the top of the picture you can see my two home made pipe bending formers. the one on the right does a radius about half that of the more "De Luxe" one on the left with the handles. In fact I tend more to just bend pipes round my old wooden handled screwdriver handle but the bending tools make a neater job if I'm wanting a "super de luxe" look to the job.

I agree with you too about the lack of lube on the shoe pivots. As the hand brake has worked properly, and she's sailed through her two MOTs since I've had her, I've been concentrating on sorting other "stuff" - Big service, timing belt, leaking front shocker, etc first. Looking at them I doubt if the brakes had been looked at in years. The rear drums were a real pig to get off due to the size of the lip on the inner edge, even with the brake cable disconnected. I'll be doing a complete job on the rear brakes as well as the cylinders.

Good one Jock, Looks like you have all the tools covered to sort it out, I was wondering about the home made tools, I don't use a pipe bender always just done it with my hands, I do use a flare tool though got to get them neat, doing these jobs takes me back to the days when I did it for living in Glasgow, although it's a bit different on the ground, rather than on a ramp.

 

[DaveMcT]

When I first disconnected my rear brake hoses the flare nuts had seized on the pipes. To avoid damage, I cut the rubber hoses and spun off the fragment. Thankfully some heat from a gas lighter was enough to free them off. A smear of copper paste keeps the underlying metal from corroding.


That all said, I priced up replacing both brake pipes from ABS module to brackets by rear swing arms. I do not have a flaring tool (and good ones are not cheap) so running the whole length in braided hose was competitive.

 

[Jockcl500]

When I first disconnected my rear brake hoses the flare nuts had seized on the pipes. To avoid damage, I cut the rubber hoses and spun off the fragment. Thankfully some heat from a gas lighter was enough to free them off. A smear of copper paste keeps the underlying metal from corroding.


That all said, I priced up replacing both brake pipes from ABS module to brackets by rear swing arms. I do not have a flaring tool (and good ones are not cheap) so running the whole length in braided hose was competitive.

I never thought about the price of them, until you mentioned it, just had a search around there are a lot of cheapo rubbish tools on the market, mine is a Automec aft100 which is a great tool, probably best with braided hose, a much more reasonable cost option.

 

[DaveMcT]

Normally I will buy a tool and have it available for next time. But the last time I flared any brake pipes was a rusty Mini around 1882. I might have got the wrong century. That tool worked in copper pipes but could not handle steel. I priced up braided hose but in the end did not need them.

My custom rear axle hoses were £25 each side. A long braided hose from ABS to rear brackets would be about £35 (£25 for the first metre plus £10/metre thereafter). You "could" run a continuous line all the way to the brakes (race style) but I feel the joint under the rear floor makes more sense on a road car.

 

[koalar]

If the worst happens and you have to replace the pipe most motor factors will make them up for you. Last ones I replaced was a couple on a Susuki Swift. Some ends were bubble others double flared. Plus three different type of fittings. Used Wilco motor factor.

Unfortunately most are still shut

 

[DaveMcT]

The easiest option is a pair of 600mm long lines from HEL to run from the chassis brackets to the brake cylinder. These will replace the rubber flexible and the steel pipe and cost £25.50 per side.

Get them made with four grommets and suitable end fittings (from memory both ends are female flare nuts). Phone HEL and they will help you though the process.

Attach to the car with zip ties over the grommets.

https://auto.helperformance.com/custom-braided-brake-lines

 

[PAMIC]

Well, over the years I found it is often possible to loosen off the brake pipe a fraction and if the pipe is twisting with the flare nut then there is another option I have used on several occassions. I did this last week on my wife's panda 1.1 while replacing brake shoes & cylinders . ( The lining came off the shoe so the cylinder piston travelled too far & started weeping; given it is a 2005 car on original rear brakes, I decided shoes & both cylinders best bet) anyway, the bolts were removed using 10mm spanner - Snap-on about 40 years old - but with a slim profile which gets in that small gap very nicely. Undid the flare nut a fraction, then removed retaining bolts & pushed the cylinder with brake pipe attached through backplate just enough so I could rotate the cylinder & remove from brake pipe. No excess strain on pipe needed! Refitting is reversal of process, screw cylinder onto brake pipe, push back through backplate & then fit retaining bolts & tighten flare nut. The alternative is to undo brake pipe where it joins the flexible hose and remove cylinder & brake pipe as one unit & remove brake pipe with cylinder firmly held in vice or similar.

 

[DaveMcT]

The steel pipes are zinc plated and plastic coated. The zinc just under the flare nut expands just enough to seize the flare nut. Where the nut must be turned simply heat the nut with a gas lighter. The softens the plastic and frees the nut. You will need to protect the bare metal as the zinc is already depleted.

I solved the back end by scrapping the swing arm metal and the rubber hoss (two per side on the 100HP). Cost for braided hose was similar or cheaper and with swivels at both ends very easy to fit.

 

[rmjbn1]

Replaced my rear wheel cylinders today, and as with @PAMIC above, I found it much easier to spin the cylinders off the brake pipe.

My brake pipes are copper, no coating, so maybe replaced at some point? Plenty of penetrating fluid and heat, could loosen the flare nuts a little but even taking it very gently could not undo them without twisting the brake pipes, both sides were the same.

Took the hub & back plate off, removed the two retaining bolts, prised the cylinder away from the back plate and it was very easy to unscrew the cylinders and screw new ones on this way.

One benefit of my daft white wheels - I could tell my left rear was binding slightly due to light dusting of black brake dust on that wheel.

I noticed both cylinders just starting to weep underneath the rubber covers this time last year during my pre-MOT checks (had been dry the year before).

Ordered new cylinders from Shop4Parts, shoes have plenty of meat left on them. In hindsight, I should have gone for a full rear brake kit with new shoes, springs and adjusters, Febi are available for £70 delivered.

One year on, left cylinder was dry but seized. Right cylinder leaked out a surprising amount of fluid when I pulled back the cover. I'm lucky it hadn't escaped and contaminated the shoes.

Following on from the odd bolt sizes reported above, mine were all standard metric, 10mm for the cylinder retaining bolts, 11mm for the flare nuts, 8mm for the bleed nipples.

 

[Pugglt Auld Jock]

Replaced my rear wheel cylinders today, and as with @PAMIC above, I found it much easier to spin the cylinders off the brake pipe.

My brake pipes are copper, no coating, so maybe replaced at some point? Plenty of penetrating fluid and heat, could loosen the flare nuts a little but even taking it very gently could not undo them without twisting the brake pipes, both sides were the same.

I think finding tube nuts seized to the pipes on any vehicle not in it's first flush of youth is pretty much a given. The technique you've used here can also be very useful when renewing flex hoses. Finding a pipe which is a little "iffy" due to rust but probably good for some time before really needing to be replaced if it has a seized tube nut is often the "trigger" which decides me to just make up a new pipe rather than waste time trying to free off the nut.

I use either copper or cupro nickel piping when making up new pipes and remember, quite a few years ago now, being surprised to find the problem you mention here. I was expecting the tube nuts to be easy to undo when used with the copper pipe, but not so. Often they proved to be as seized up as when used with steel tubing. I think the steel nuts "bite" into the copper more than the steel and probably a lot more distortion/reforming of the copper takes place due to tightening of the nut when compared to the steel. Of course, as they age, although the tubing doesn't corrode like the steel does, the nuts still do and, I suppose, there may be some sort of electrolytic corrosion "thing" going on too? I know there are a lot of arguments about using Copper grease because of the possibility of electrolytic reactions and other problems it can cause (and I'm now using ceramic greases on calipers, pads and brake shoes) but I do still coat tube nuts and bleed nipples with copa slip at every service because I find this makes undoing these components - especially when it's time to do a fluid change - much easier.

 

[DaveMcT]

I use Action Can CS-90 anti seize. It's a stiff paste that works well on anything from brake pipe ends (not the open end of course) to bolts running into aluminium or otherwise exposed to the weather.