Replacing Brake Cylinders

[Napoleon Boot]

Hi all,

I've got leaking brake cylinders on the n/s front and rear, while the driver's side brakes are dry as a bone. Obviously I'll need to replace the leaky ones, but should I be replacing the 'good' cylinders now as well? I know it's probably good practice, as if one side has gone the other side will probably go soon as well, but I'm trying to limit my spending having just shelled out for new shoes and drums all round (the old ones were worn down to the rivets and the drums were deeply scored ).

Thanks! Seb

[jagnut66]

It's up to you but if the 'good' drivers side cylinders are as old (or of an unknown age) it might be a 'false economy' not to.
You would also end up having to go round bleeding the brakes twice over.
Remember though to fit a good known brand at the front, the unbranded pattern items out there are only good enough for replacing the rear cylinders.
You are right though, they're not cheap.
But this is you're safety we are talking about here.......................
Best wishes,
Mike.

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[Napoleon Boot]

It's up to you but if the 'good' drivers side cylinders are as old (or of an unknown age) it might be a 'false economy' not to.
You would also end up having to go round bleeding the brakes twice over.
Remember though to fit a good known brand at the front, the unbranded pattern items out there are only good enough for replacing the rear cylinders.
You are right though, they're not cheap.
But this is you're safety we are talking about here.......................
Best wishes,
Mike.

Thanks Mike, I had a look through the pile of receipts that came with the car, and both front brakes had new cylinders in 2012; no record of the rear cylinders having been replaced by the previous owner. I ordered OE cylinders for front passenger side and pattern ones for both rear wheels, but now I'm having second thoughts; having got new Mintex shoes all round and new drums, I might as well do the job once and do it properly; will order a couple more cylinders and do the driver's side as well. It's a bit of a shock when you see the total in the shopping basket, but do I really want my last thoughts to be "I wish I'd spent a few more quid on the brakes cylinders"...?

Unfortunately one of the rear drums I got today has a big splodge of gritty paint over the braking surface, so I've had to email the supplier about replacing it. It's a pattern one - the proper ones are currently out of stock - needless to say the more expensive original drums I've got for the front wheels were perfect....

image0.jpeg (85.08 KiB) Viewed 2221 times

[kennatt]

can you not just clean it off,fine wet and dry if thinners won't shift it. save on time and return postage

[Napoleon Boot]

can you not just clean it off,fine wet and dry if thinners won't shift it. save on time and return postage

Hmm - if it'll come off OK; will wait to see what the suppliers say; I was expecting pattern parts to be a bit shonky but didn't expect to have gritty paint over the braking surface.

[kennatt]

It should all clean off,even if there is still a trace the shoes will soon clear it after a few applications, shouldn't effect the braking,You'll probably get the same advice from suppliers .

[Napoleon Boot]

It should all clean off,even if there is still a trace the shoes will soon clear it after a few applications, shouldn't effect the braking,You'll probably get the same advice from suppliers .

Supplier has kindly offered to send a replacement out; it might not look it from the photo but it's a gritty bituminous gloop, and I don't really want to go to all the trouble of replacing shoes etc if one of the drums is contaminated from the start! I would have ordered the OE drums but they don't seem to be available at the moment.

Anyway, should have everything I need tomorrow and look forward to getting stuck in; have read every thread I can find so fingers crossed...

[oliver90owner]

Over the years, I have found that there is not a lot that resists the application of a wire cup brush wheel in an angle grinder. Concrete can be a but tough but most things succumb very easily.

[kennatt]

if they don't want the drum back there will be plenty on here who will take it off your hands

[les]

Yes, my thinners soaked cloth is ready!

[Napoleon Boot]

Les, you've got a PM...

I'm pleased to say that after a long day's work yesterday, the shoes, drums and cylinders are replaced, I bled the brakes today and Peggy is back on the road! I used a Gunston Eezibleed and I'm glad I did, it made it very simple and no need to rope in a helper to shout 'up! NO, up!' at. As others have said on here, the kit doesn't come with a connector which will fit a moggy master cylinder, so I made one with a spare unvented master cylinder cap - drilled out with a step drill, and made airtight with some Sugru.

Leaving it a day before bleeding the brakes allowed me to check that there were no more leaks. The front n/s wheel cylinder had been leaking brake fluid, so the new cylinder cured that, but the rear n/s cylinder seemed OK, and the leak seemed to be oil coming from the hub.

It seems that the screw holding the hub in place was missing, so I replaced it and cleaned everything up.
I was worried that the leak might return, and there was a tiny amount of oil this morning, though I hadn't been able to screw the brake drum back in place overnight so I'm hoping that may be the reason. I went round and tightened both the rear hub screws as much as possible as they were both a bit loose, will check periodically.

Went for a short test drive and the brakes are much more responsive than before, handbrake is better now as well. I've contacted a local classics garage about scheduling my overdue MOT now that everything appears to be working, I'd like the reassurance of knowing that they've checked the brakes on the rolling road. Here's a couple of pictures of my renewed brakes in case anyone is interested or spots a howler:
N/S Front:

IMG_8070.jpg (46.25 KiB) Viewed 1992 times

N/S Rear:

IMG_8079.jpg (46.74 KiB) Viewed 1992 times

[mobylette]

The screw is there to locate the half shaft. It's the wheel nuts when done up that pull everything up tight. Is the leak from the half shaft/hub joint or from behind the hub?

[Napoleon Boot]

The screw is there to locate the half shaft. It's the wheel nuts when done up that pull everything up tight. Is the leak from the half shaft/hub joint or from behind the hub?

Hopefully this “before” photo shows it best - as you can see, the screw to locate the half shaft was missing, and the oil was presumably flung out as the hub rotated. I replaced the missing screw with a spare brake drum to hub screw, it fits but I should check in case I should be using something different.

[kennatt]

as said in previous post its the wheel nuts that clamp the flange to prevent oil leaks,not the screw. Every time I took a wheel off my old ,I had a slight leakage,I eventually formed the practice of only jacking up the side I was working on so that the oil ran away from that side.Tried several gaskets sealants etc every leaked, later models had a rubber seal fitted into a groove,dont know if this solved the problem.

[philthehill]

Kennet is correct in that the wheel nuts are the final arbitrator as to the sealing of the hub gasket.
It is also important to note that the thickness of the gasket has to be taken into account so that the correct protrusion of the wheel bearing outside of the hub gasket takes place.
There has been in the past some considerable discussion on here regarding the required thickness of hub gasket - use search facility. Also see wksp manual regarding the hub bearing protrusion.
It is not just a matter of fitting a hub gasket and forget. The thickness of the hub gasket and the preload on the bearing outer race are related.
The fitment of the later hubs with sealing 'O' ring goes some way to reduce the incidence of oil leaking from between the hub and the half shaft.

Also it is most important that the axle breather is in place and functioning correctly; and the drain holes in the brake back plates are kept free of crud to allow any oil getting past the hub seal to escape and indicate to the owner that the oil seal is in need of replacing.

[Napoleon Boot]

Thanks both, I think I have a better understanding of what's going on now.
I'll have a search and read up about hub gaskets; to make life interesting the two rear hubs are non matching, the leaky one has MOWOG on it and only one threaded drum screw hole, the other has no markings and two threaded drum screw holes (which caused a lot of head-scratching when I tried to re-install the drums and couldn't get the screw to stay in!). Dunno if this means that one is later than the other, and whether they have different sized gaskets.
*edit* - I've had a look and they look the same size, the other one has a very very faint 'MOWOG' casting on so may be a pattern copy.

Still crossing my fingers that maybe the leak occurred when I had the wheel removed and both sides jacked up, allowing the oil to dribble out - I'll have a bit of a drive and check the leaky side again. If it's wet I'll need to renew the gasket.

Thanks!
Seb