Daihatsu Skywing - Slow Brake Fluid Drop

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Thu 29 Mar 2018 07:58
Daihatsu Skywing - Slow Brake Fluid Drop - edlithgow

Might finally be a bit of substance to back up the criticism of my brake maintenance, since I appear to have a very slight fluid leak. Due a flush and a check on brake hardware anyway.

I put this wheel cylinder back on after cleaning it up about a year and half ago. It showed some wear from the corrosion, so that's prime suspect.

[url=servimg.com/view/18149521/220][img]i35.servimg.com/u/f35/18/14/95/21/th/img_6925.jpg[/img][/url]

Drum is mostly still grey with some light rust spotting, so its sunflower oil/aluminium treatment has held up quite well.

[url=servimg.com/view/18149521/365][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7840.jpg[/img][/url]

Lots of dust, but the hardware has only rusted significantly where I didn't apply the treatment, because I was concerned it might cause sticking, or where it was too much trouble, like on the brake shoe backing

[url=servimg.com/view/18149521/359][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7834.jpg[/img][/url]

PTFE tape used on the pivot point is still in place.

[url=servimg.com/view/18149521/360][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7835.jpg[/img][/url]

Re-treated the hardware more extensively this time. I'll rely more on grease and PTFE tape to prevent sticking.

[url=servimg.com/view/18149521/361][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7836.jpg[/img][/url]

Some sign of fluid behind the wheel cylinder dust boots, though some of that is water from washing the brakes down.

[url=servimg.com/view/18149521/362][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7837.jpg[/img][/url]

I applied pressure to the brake pedal for a few hours with rubber strapping. No leakage from the wheel cylinder, but of course it isn't moving in this static test.

url=servimg.com/view/18149521/363][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7838.jpg[/img][/url]

[url=servimg.com/view/18149521/364][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7839.jpg[/img][/url]

I think I'll still replace it assuming I can get one. If not I'll strip-clean and refit it, perhaps adding some PTFE tape around the seals.

I've had a crawl arlound and I can't see any leakage elsewhere, but its so slow (halfway to the min line in about 2.5 months that I probably wouldn't anyway.

Edited by edlithgow on 29/03/2018 at 08:01

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Thu 29 Mar 2018 09:44
Daihatsu Skywing - Slow Brake Fluid Drop - Bolt

If the master cylinder is bolted to the servo its possible the leak is going into the servo from the mc rear seal? just a thought

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Thu 29 Mar 2018 10:13
Daihatsu Skywing - Slow Brake Fluid Drop - edlithgow

If the master cylinder is bolted to the servo its possible the leak is going into the servo from the mc rear seal? just a thought

I should really strip the MC anyway, given the state of the rest of the system when I finally got around to it, but I won't do it unless I can get the seal kit.

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Thu 29 Mar 2018 15:50
Daihatsu Skywing - Slow Brake Fluid Drop - edlithgow

Appearance of the brake dust also tends to indicate that wheel cylinder, since it was heaped up on top of the cylinder like damp (volcanic) sand.

I wash brake hubs out with water and detergent when I first open them, catching the water in a bowl or bucket and then tipping it down a drain. Usually its blackened with suspended brake dust..

This time the brake "sand" settled to the bottom and the water was hardly discoloured. My guess is the particles were bound together with brake fluid residue.

How big an issue is it if the shoes are contaminated with brake fluid? I missed a trick in not boiling them when I took them off. Can't do it now because I've treated the backs with sunflower oil, but I've got an old spare pair of shoes somewhere so I could put them on instead.

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Sat 31 Mar 2018 08:58
Daihatsu Skywing - Slow Brake Fluid Drop - edlithgow

Oops. Looks like I got the wrong part.

I knew only one wheel cylinder had a bleeder, but assumed apart from that they were interchangeable.

Seems not, since one seat is a convex cone, the other, with the bleeder, is a concave cone.My fault

Only 380NT, so not too tragic if they wont swap them, but a waste of time and money.

url=servimg.com/view/18149521/366][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7841.jpg[/img][/url]

New one

[url=servimg.com/view/18149521/367][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7842.jpg[/img][/url]

Old one

[url=servimg.com/view/18149521/368][img]i62.servimg.com/u/f62/18/14/95/21/th/img_7843.jpg[/img][/url]

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Mon 2 Apr 2018 17:15
Daihatsu Skywing - Slow Brake Fluid Drop - edlithgow

Oops again,

Assuming the writing would be the right way up, I spent quite a long time installing the wheel cylinder upside down, cursing poor quality aftermarket parts the while.

Installing it upside down was VERY DIFFICULT, but I showed a lot of grit, determination and (last but not least) stupidity,

Fortunately I didn't do too much damage.

On the right way up now. Test drive probably Wed, but the leak was very slow so it'll be a while before I know if its fixed.

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