Hi,
I'm expecting some waving arms in response to this question so first can I please say that I do NOT want to compromise safety - but this is an exercise in bangernomics, so I want to know what I can do without compromising safety.
I need to replace a leaky rear wheel cylinder on a Mk2 Golf. I have heard that I "should" replace both wheel cylinders and also the brake shoes.
I can understand replacing both cylinders - if one's leaking, the other probably won't be too long. I don't usually replace central locking motors in sets of four, though. Is the other one really likely to fail next week? Do we know this by trying it (How? That's never done...) or do we just think it probably will?
Just as important, would it affect the brake balance (MOT testable), having one new one and one old one?
Then the shoes. Of course on one side they've been covered with brake fluid. I will clean up the drum with brake cleaner (and garages have done this for me with previous cars so I presume it's standard practice). Can this not be done with the (otherwise good-as-new) shoes? Do they absorb the fluid somehow? Or it it always done like that because it's better value for a garage to replace them while they're in there and now it's become folk lore?
The cost of the job could vary between £4.50 and £40 depending on how much of it I do. Again, not going to break the bank, but it's bangernomics. If it ain't broke, don't fix it.
Thanks very much!
-Mark
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no expert, but economics vs safety-hmmm, no contest! Besides if you factor in your time I expect you will indeed find it cheaper to replace both cylinders now, than it would to have to take it all apart again later. Besides so far as I know friction linings soaked in brake fluid kind of fall apart, well mine did. Besides what's £40 for peace of mind in the integrity of your (rear) brakes?
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www.bayingbasset.com
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I have frequently replaced just the one wheel cylinder and this is perfectly safe and MOT-able as long as its opposite number is not leaking (peel back the rubber gaiter to check for leaking fluid) and not stiff or seized (try moving the pistons backwards & forwards). If in any doubt at all, replace both. Regarding the shoes, they absolutely must be replaced, as an axle set. Once contaminated with fluid you will never get it out again. There can be no compromise here. When I was a student, I used to save the uncontaminated pair, and then the next time a cylinder leaked I had a spare pair to replace them with, but this is not really to be recommended as unequally worn sets could cause some imbalance, but it's a ruse that served me well when I was impoverished.
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The changes are that there is more to this jom than meets the eye. I, from experience on may VW would suspect that the meter pipe is corroded into the fitting so although you may be able to undo the compression fitting it will rotate on the pipe. This means new slave cylinders and some pipework. Yes with older cars the other cylinder will probably alrready weeping and peeling back the out dust seal will reveal fluid. No you can not recover contaminated brake linings and no you can not heat them up in the oven to boil the oil off this just cause a bond failure between the lining and the metal backing. The old oven trick applied to rivited shoes 40 years ago. You can only buy shoes in pair to change both and both cylinders as well. At the age of your car I would get someone to stand on the brake, engine on, whilst you closely inspect the rear flexi's for sights of bulging or ballooning as that is what is attached to the other end of the replacement pipework. It's always nice to now that your brakes are in great nick and safe. Regards Peter
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mark a set of shoes is £18.00 approx, for mintex, wheel cylinders are about £7.00 each is it worth compromising? clean the drums up remove the lip on the edge of the drum and you have cracked it, as for the brake pipe if it snaps it snaps! clean up the pipe end were the nut is and lube it first, wind the nut back and forth it should come out ok, if not a garage would make them up for you at about £10 each have a go!!!
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Thanks very much for the answers and extra information, everyone. The point about the brake shoes absorbing the fluid is fair enough - so they'll be replaced. Since both sides have to come apart anyway I'll also check the other wheel cylinder and decide whether to replace it depending on condition and how easily the other one comes off (with corroded pipes etc.).
Editor - you might want to re-read the massive disclaimer at the top of my post :-) I do NOT want to compromise safety. Absolutely not. (Will you be replacling all the brake parts on your vehicle today, just in case? ;-) )
Thanks all!
-Mark
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did indeed read your disclaimer the 1st time around, dear boy, but since you asked for my opinion, I gave it to you. I see that a number of other posters think similiarly.
Yes I would indeed be replacing brake parts TODAY, if I had reason to believe they weren't up to standard, or very shortly about to be. Not becuase I'm anal about this-more because I'm lazy & if I've got in pieces anyway, might as well replace then.
Bangernomics though-I've always liked this approach! Have we a thread on Ultimate Bangernomics & Bodges??
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www.bayingbasset.com
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>>but this is an exercise in bangernomics, so I want to know what I can do without compromising safety.
bangernomics does not include brakes, steering, or suspension,Not in my day anyway.the bad leaker of wheel cylinder being replaced also involves replacing brake shoes as well.
if the other wheel cylinder is leaking,its best to replace both, As being a leaker it could fail at any time,fraid no one can specify how long it will last(depends on braking habits) so to remove the *I have no idea how long it will last*...best to replace as an axle pair,safer that way!
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Steve
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When you say pair, you mean one on each wheel, not two inside one drum?
I think the consensus is right - replace the whole axle set. I used to think it would save money by only replacing the leaking cylinder (but checking the other carefully) but experience shows they really do last about the same length of time.
If you are only doing two wheels it is worth isolating the fluid one wheel at a time (mole wrench and old carpet) so that you don't have to re-bleed the whole system. When you get the union undone, stuff a golf plastic thingy into the end.
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Over the years I have replaced one wheel cylinder only at rears .. after checking the other side is OK. Never had any problems. I have also re- sealed one front disk caliper only - same comments.
Disks and pads or brake shoes: always in sets.
madf
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In the past, I have put such brake shoes via at least a couple of saucepans of boiling water to get them back to being serviceable.
My assumptions were (a) brake fluid is water solvent and so it should dissolve out, (b) the shoes must have been designed mechanically not to fall apart when splashed with brake fluid, as no one knows when this is likely to happen, and (c) they were likely to have got at least as hot as the boiling water in normal use.
I did this at least a couple of times either because the shoes had lots of life left or because it solved the lack of transport problem while my car was jacked up.
Usual disclaimer, if you do it, it is at your own risk.
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Usual disclaimer, if you do it, it is at your own risk.
Yes, and who else is at risk when your brakes fail.
Is it worth saving a few quid on new parts, compared with all the other potential costs? Your life, the lives of others........
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Only three weeks ago I removed a set of shoes that had been wet with brake fluid for two or three weeks and the adjusters where past there limit as the both top edges of the shoe where down to 1/3 the thickness and the drum and assembly was full of mud generated by the disintegrating shoes. The other side was dry but the outer seals where full of fluid that had weeped past the pressure seals. The car past it's brake balance MOT test 5 weeks before so they were fairly dry them. I can see your boiling water logic but when the shoes warm up again the hydralic fluid bleeds out of the shoe and contaminates the surface and the drum. On safety grounds this is not advisable. Regards Peter
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If it was me then I would change the leaking cylinder and leave the good one alone. It is true that if one fails then often the opposite one is not far behind, but if it is okay then why fix it if it isn't broke, you are after all trying to save money. I have replaced one cylinder a good few times and it is perfectly safe to do so. As for the shoes then if they are soaked in brake fluid they are scrap. If your cylinder is only weeping and the shoes haven't soaked up the brake fluid then you might get away with scuffing the linings up and refitting them but if they are covered in fluid then replace them. It is also perfectly safe to replace only the linings on the affected side, although not particularly advisable. They come in a set of four anyway so you will have them to fit, but if you don't want to do the other side then you don't have to. Just remember that one set of linings will be worn out before the other side. As far as the MOT goes there will be no problem with imbalance due to one side having older components. As long as the older components are all working correctly and are adjusted up correctly the brakes should be fine.
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I see false economies here.
You replace 1 wheel cylinder at £7.00 and a set of shoes at £18.00. \total: £25.00
The other cylinder lets go soon after as predicted, so thats another £25.00 if the shoes are contaminated again and they only come as an axle set. So all together thats £50.00.
Replace both cylinders at once + shoes . Thats £39.00 a saving of £11.00.
For me the bonus in doing the lot would be peace of mind, which is priceless, and not having to whip the brakes apart every so often to check for the leak thats almost guaranteed.
£7.00 - thats nothing. You wouldnt think twice about putting it into the fuel tank.
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Fullchat
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"Yes, and who else is at risk when your brakes fail."
The shoes showed no sign of brake fluid when checked later. On both occassions MY vehicle passed the MOT braking test.
We make safety judgments every day.
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No Comment. Regards Peter
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Having just changed a cylinder on one side only, I'll chuck my spanner in the works;
I too am paranoid about brakes to the extent that I look round them all as soon as I aquire a vehicle, which is how I found the offending cylinder, just a trace of fluid under the rubber, nothing elsewhere.
Naturally I carefully checked the other side only to find that cylinder was very much newer, but not brand new, obviously only one side had been changed previously.
Hmmm, re-reading, I don't know now whether I've made a point for changing one or both....
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One mans junk is another mans treasure
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I should have added they were back brake shoes which accounted for less than 30% of the vehicles braking power with the front engined vehicle.
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3 cars last 3 weeks all been checked over prior to mot all found to have good shoes but one had parted from its backing in every car,
car no.1 saxo
car no 2 clio
car no3 corsa
all three were perfect in everyway on the footbrake and handbrake and you could argue that they broke off due to the action of removing the drum,however they are serviceable parts and have also an unreasonable life to live therefore todays bonding adhesives may have taken man to the moon but for going to the shops it should be replace/replace/replace.
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\"a little man in a big world/\"
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Where they all on the near side per chance. Regards Peter
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Where they all on the near side per chance. Regards Peter
if that was to me Peter D then you are indeed correct as they were and usually are,what do you know?
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\"a little man in a big world/\"
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My 26yr old TR7 had a weepy rear cylinder one side 3 yrs ago, and the other side 1 yr ago. The ancient shoes are nearly down to the rivets.
I merely replaced the piston seals and cleaned up the cylinders with a touch of brasso. Both sets of shoes have been soaked in brake fluid but they passed the annual MoT and lock the wheels with ease. There are no leaks.
If you ensure you only replace shoes when you need to, i.e. as close to the rivets/backplate as possible, the pistons will be towards the end of their travel so there will be little opportunity for corrosion of the cylinders as they will be full of brake fluid.
This summer I shall replace the shoes, thus pushing the pistons back to a new operating position, and hopefully another 25yrs of life.
Incidentally, assuming the coefficient of friction at the surface of new and worn shoes is the same, it makes not a scrap of difference if one set of shoes is brand new and the others are nearly down to the rivets.
If it works, don't mend it.
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Yes, but:
IME shoes that are that worn are also pretty glazed. They may be braking adequately, but surely not as well as new ones (after initial bedding in)?
I thought corrosion of cylinders arose from dissolved water in the fluid, if it hasn't been changed regularly? Don't you smear a trace of brake grease on the exposed portion of the bores, just inside the dust cover?
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I can't belive this debate. Fullchat says it all beautifully. The solution is very simple. Pay £39 = a proper safe job. End of discussion.
If you can't afford £39, you honestly should not be running a car on safety grounds.
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Absolutely. What are some guys on. Regards Peter
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It's not that I can't afford £39, I just prefer spending it on other things than car bits. And yes, I change the brake fluid - every ten years or so. It doesn't seem to need changing more often than that.
If it works, don't mend it.
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Wow, I started a war..! :-)
Did the job on the weekend. Replaced one cylinder and all the brake shoes.
The cylinder on the other hub appears to have been serviced (not in the last 5 years as far as I can see from the receipts) and looks good so that's staying where it is.
All points about safety, economy, false economy and hassle duly noted. Thanks for everyone's input!
-Mark
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