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Brake system experts, I need some help


Toucan

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During nats my brakes were a bit squishy, so the weekend after, I adjusted all the drum shoes and bled the system, was working really nicely, and I had been using the car to get me to work most weeks. Last Friday I was on my way to work, first time I had used the car in 4 or 5 days, I put my foot on the brake and the pedal went right to the floor, luckily I was only going slowly and could still use the handbrake to get me the short distance home.

The car in question is my 68 bellett, it has a single outlet 3/4" master, going to a remote brake booster, then into a splitting block thing which separates rear, front left and front right. All four wheels use drum brakes.

When I lost the brakes, the fluid in the master was right down, so I topped it up and bled the brakes from the furtherest line to the shortest, the brakes bled up a bit but were still squishy, and I realised I had done this procedure with the handbrake on, so I released the handbrake and bled them all again. Pedal felt better, and I went for a quick spin around the block, but on returning, we could see fluid on the road, so checked the master and sure enough the level had dropped.

Next day I bled it up again, this time bleeding the master, and booster before the wheel cylinders. I made sure each connection and bleed nipple was closed tightly and dried each one with a rag after I'd played with it, pedal feel was great. Today I looked at it and pedal feel is the same but master has lost almost all its fluid! No fluid is visible on any connection.

I know I need to check the wheel cylinders, but can only get one of the drums off, rest are stuck on the center hub, I have been hammering them and soaking them in penetrating oil so hopefully can get them off to check soon. Looking through the shoe adjustment hole they all look dry however.

What would allow me to get good pressure and pedal feel but still leak fluid?

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everything.

so there are no noticeable leaks?? its a bit weird that it is eating fluid but not showing signs of it. got any brake clamps? try blocking off each wheel (unless you can get the drums off) and see if that narrows down the problem, also somtimes the booster itself and poos itself, normally noticed by brake fluid in the cabin but they are pretty good and holding the stuff .

*edit* kk got there first

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If its leaking that badly, you wont have to have a drum off to see the leaks. But you could definately bleed the system and it could feel good but only until the system drained again

maybe its leaking into the diaphragm in the booster or something weird where alot of fluid could hide for a while.

As well as checking the cylinders, check all/any connections like hose to steel line etc, but leave it parked overnight somewhere where its possible to see anything that may have leaked out and check it in the morning, the fluid has to go somewhere

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What would allow me to get good pressure and pedal feel but still leak fluid?

A leaking wheel cylinder seal will do that.

Get those drums off and peel back the rubber dust caps on the wheel cylinders. Any fluid in those dust caps = a leaking cylinder.

I can't agree that the fluid would be visible on the ground

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What would allow me to get good pressure and pedal feel but still leak fluid?

A leaking wheel cylinder seal will do that.

Get those drums off and peel back the rubber dust caps on the wheel cylinders. Any fluid in those dust caps = a leaking cylinder.

I can't agree that the fluid would be visible on the ground

yea man but losing that amount of fluid wont be held inside a boot

also a prime indicator that a wheel cylinder is leaking or has started to is the brakes lockling up on that wheel all the time due to accumulation of the dust and shit *same thing as putting a little bit of oil on hands then rubbing will be slippery then become more and more tacky the more dirt and shit build up *

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^ The boot itself can't hold a great deal of fluid but you can spread a fair bit around inside the dusty backing plate and drum, rim and tyre before you start to see it on the ground.

A couple of table spoons of fluid would drop the M/C by a noticeable level

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No noticeable fluid underneath the master or around the firewall in the engine bay or in the cabin.

Not going to notice fluid on the floor of the garage, concrete is already wet mouldy/green.

Will keep going on the drums, needed to stop and ask for advice though, the stubborn buggers are making me rage

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^ A release thread on a drum is a semi modern thing I think KY.

Escorta, do the drums come part way off? If so they will be getting caught on the shoes. If they don't budge at all then ensure that they don't have locating screws before you get too violent. If fitted, the screws hold the drum to the axle flange to prevent loss of brakes when a wheel falls off. Those screws seldom get re-fitted but I though I would mention it just in case......... (I know you aren't dumb)

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Fluid can leak out of any component.

Your remote booster sounds like a it could be the culprit. Best to start with the wheel cylinders and work back from there though.

Do your drums have little threaded holes in them so you can wind a bolt into them to push them off?

Back the brake shoe adjustment off and give the drum a decent wack on its edge with a hammer.

Or you may not have slip off drums and you will have to remove the wheel bearings to get the drums off.

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also if there is no removal threads in the drums, U can drill and tap some yourself (easier if you know how the hub looks under it) just drill an 6.5mm hole then tap it with an 8mm bottoming tap, you can tell when you go from drum to hub as the drums are cast iron(Usually) and the drilling swarf will be a grey powder, the hubs should be steel so will get a normal swarf, u will need to drill into the hub a few mm's to allow tap to work

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I appreciate all the advice so far.

The drums have a small securing screw, but no release threads.

img1922go.jpgimg1927kr.jpg

Other three don't want to budge. I've backed the shoes off, don't think they are binding there, I think it is just the center, which is such a small surface, I don't know how it hasn't broken free after the abuse I have given it. No drills/taps in my garage, will just take it somewhere if I can't get them off

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Give them a good sharp thwack with a hammer on the edge of the drum - try a few times on the vertical flat face between the studs and if that doesn't work then give it a whack where the drum goes from vertical to horizontal is the sweet spot..

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master been resleeved?

get a lump hammer or small sledge hammer and place between the threads then hit the back of that also make sure you have nuts on the studs so if you miss you can retain a thread,

sounds like you shoes have worn a sweet groove inside your drum making them difficult to get off.

as for leak get it up on stands running and get someone to mash the brakes while you spotlight around.

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