# rear brake drum cylinders leaking



## TITT4TATT (Nov 20, 2006)

I' was just told that when you remove rear brake shoes,you should make sure the brake "cylinder pistons" isn't allowed to extend out IE: you must spring load the cylinder pistons to prevent them from going outwards to far or this will crack the internal seals? not the dust cover seals.

anyone ever herd of this?


:4-dontkno


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## TITT4TATT (Nov 20, 2006)

*replacement of the cylinder*

when tightening the new line onto the rear brake cylinder,how tight should the brake line be tightened?


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## 8210GUY (Aug 29, 2006)

Not heard of that myself, not put that way anyhow, it is true you should keep the pistons inside or you will get air in the system which will need bleeding and you run the risk of scoring the cylinders, you should bleed it afterwards anyway but you can minimise what you have to do, and you should check them for any leaks while you have access, if there is change them first or they will contaminate the new shoes rendering them useless.
But if you remove the reservoir cap and put some cling film over it to make it airtight it will slow down the amount of fluid loss :wink: 
Be careful when tightening it, you will easily strip the thread if you use to much force as they are only aluminium from my experience, it's not easy to explain, they should be tight, but not the sort of tight you would do with a wheel nut, I would say when you start having to apply pressure your about tight enough if that helps.


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## crazijoe (Oct 19, 2004)

When you remove the brake shoes, the pistons wll not just come out. There are four seals in a wheel cylinder. Two on the inside (cup) that seals the pistons and two on the outside that protects them from dust. Usually there is a spring on the inside of the wheel cylinder that keeps the pistons apart, but the tension of the spring is not enough to push the pistons out.

You should tighten enough to make it seal. Remember, the threads do not make the seal, the flare on the end of the tube makes the seal.


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## dai (Jul 2, 2004)

we always tied them with tie wire around the cylinder to make sure they did not pop
with new cylinders the same price here they were 40yrs ago,i would consider renewing them as well


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## 8210GUY (Aug 29, 2006)

Although the pistons wont spring out as such, they can\do come out due to the remaining pressure left in the system if theres nothing to stop them like the shoes, hence removing the reservoir cap will help a small bit by letting some pressure out, and sealing it with cling film creates a vacuum therefore minimising the escape of fluid, it wont totally stop it, but it can make a lot of difference to the job depending on the circumstances, and find out the bleeding order as well, because you have to do it in a specific order otherwise you may as well not bother, so it's VERY important to get that right.


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## dai (Jul 2, 2004)

the bleeding order is from the wheel furthest from the master cylinder working in to the closest


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## Midnight Tech (Dec 31, 2001)

If it's an antilock system , you may want to refer to a shop manual for bleeding instructions-some of them don't bleed like a normal system.


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## Spacemonkey6401 (Jul 27, 2006)

On a car I did brakes on, the line had a hole in it that had to line up with the brake line, too tight and it didn't work, too loose and you had brake fluid all over the place.


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