Rear Brake Reline and wheel cylinder Replacement

[Lin1952]

Just had rear brakes done (not by dealer). They also replaced wheel cylinders although when I checked a week ago they were not weeping, advised this is normal procedure when replacing drum brakes. Expensive items at $88 a side which turned the job into $433.

Is it standard procedure ?

[biggibbo]

1st set on mine they replaced the wheel cylinders, second time round they didn't.

[Cowboy Dave]

There was a guy on the forum a while back who worked at a brake place for many years. His advice was that it was good practice to change wheel cylinders at the same time as the brake pads. It was the first I'd heard of it at the time, and I didn't follow the advice because I was doing it myself and had never changed a wheel cylinder before - but he did seem to know what he was on about and seemed pretty genuine about it.

[Calblitzen]

Drum brakes being old school, you would check the wheel cylinder seals/boots and piston for scoring and change out as required. Sometimes cylinders would fail prior to the drum replacement, however the brake fluid usually stuffed the pads.

[Lin1952]

Thanks fellas.

[leonbee]

Rule number 1. If it ain't broke don,t fix it.

[Tony]

Rule number 1. If it ain't broke don,t fix it.

This theory is all well and good but as this thread was alluding to, if you disturb drum brake slave cylinders, (meaning pistons move to a new position when shoes are replaced) they can leak for several reasons. They also may be seized on on one side and you wont even be aware of it.

I must admit, I rarely replace on the newer vehicles here, but the older on older ones they seem to fail 80% of the time when disturbed.

[AnOldFart]

Problem is that brake fluid is 'hygroscopic' meaning that it absorbs water from the atmosphere and because the rubber seals on the pistons in the brake slave cylinders are not -perfect- seals this then results in -some- fluid escaping past them and setting up rust occuring on the -outer- side of the pistons. Then when new brake shoes are fitted the pistons are compressed backwards into their sleeves along with the rust-pits residing on that part of them that was previously on the outside of the piston seal. End result....?? Leaking brake slave cylinders....!
Back in the 'good old days' when dinosaurs, and I, roamed the Earth, and -stuff- was expensive and hard to come by, you used to be able to re-condition/re-sleeve them, but now, when -stuff- is cheap, and (talented) labour is expensive and hard to come by, it's far cheaper to just throw them away and replace them with new ones from China. ....

[Homer]

^^ this

[leonbee]

Lin1952 never mentioned how many km was on the clock. If the cylinders today are more prone to faults I would have to agree, its in the best interest of the mechanic and the customer to change them and save the grief.

[biggibbo]

Just got my rear shoes replaced again today. Wheel cylinders did not require replacement this time either (@220,000km)