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I must have air trapped somewhere


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On my 87 Brat. The pedal just isn't getting as firm as it should. I replaced the master cylinder not long ago with a brand new one, and I just rebuilt the hill holder the other day. But I still don't have a rock hard brake pedal. About half way down, there is a "soft" spot that can be felt.

 

Suggestions on how to get the pedal back to the way it should be?

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Drum brakes in the back leaking and you can't see it?

 

I haven't noticed any leaking in the rear. However, I have had issues with the right rear locking up before the other tires on gravel/dirt roads. So my wheel cylinder might be bad back there. Wouldn't hurt if I changed them out, along with the springs and such in the rear.

 

Rubber lines: well, they are original and have exterior cracks. I've been wanting to replace them with braided SS lines, but haven't had the cash yet.

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Rust! On the caliper pad brackets, especially if the car has been sitting, will hold the pads from moving freely and feel very similar to air in the lines. Pull everything apart and clean off the rust. Take a file to the pads and face off the areas that contact the brackets from rust and even thick layers of paint and sharp edges that come on most aftermarket pads. Make sure the pads slide into the brackets freely with a little room to spare. Worse that can happen if they're too loose, is you might hear a little pad rattle if you have the windows down and no tunes playing :D. Better than too tight! Then, to flush and bleed the system. Open one bleeder at a time, starting with the furthest from the master cylinder, right rear. Pump all the old fluid out of the master cylinder, then, add new fluid and continue pumping till fluid runs clear. Don't worry about bleeding yet. Just flush all wheels, one at a time, with a good stiff pumping of fresh fluid. Nearly ALL failures of calipers and wheel cylinders is the cause of dirt, and especially water, getting into the system and going (where does water go in oil?) to the bottom, and easily corroding the unprotected cast iron, which then causes the seals to fail. Just because the fluid in the reservoir looks clean, means nothing. You probably have GLOP at the wheels, just pump it into a clear container and take a look! :eek: Now to bleed: ALL old Subaru's will GRAVITY bleed (I can't speak for newer ones cause I haven't worked on any made since 96). That means open up the bleeders one at a time, starting with the right rear, letting it run till all the bubbles come out (keeping the master cylinder topped off, of course) and that's all you need to do, two people are not necessary... I've done it hundreds of times like this. If you perform this flushing about every 4 years, you will most likely NEVER have to replace a caliper or wheel cylinder ever again!

Edited by Subaru Scott
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contrary to the rest of the automotive world; proper bleeding procedure on old soobs is as follows. RF, LR, LF, RR.... im not saying that doing it the normal way cant work, especially given the attention payed with the rest of the job, but this is how it should be done.

 

 

source unsighted as I have forgotten where its from. All I know is I read it and wrote it down on a card in my wallet where i keep stuff like that. (and wheel bearing PO etc..)

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the order is passenger side rear -> Drivers side front -> Drivers side rear -> passenger side front. I double checked in my haynes.

 

If you didnt bench bleed the master cylinder enough when you installed it there could easily be some air stuck.

 

id double check the connections and wheel cylinders on all tires for leaks first, check the adjustment on the rear, then bleed everything in the above order. see where your at then

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jack up the front, as high as you can. and hold the clutch in while you bleed them, should help.

 

also the rear proportioning valve may be sticky.

 

I have thought about that a bit, since I just had the hill holder apart. I see no reason keeping the clutch in should help with the process.

 

How does one know if the rear prop valve is sticky? And is there a resolution to such a thing?

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Does fluid come out of one of the rear brakes faster than the other?

If it does then you may have a sticky rear proportional valve

now as to how to fix it, I have no idea how it works, so I cant say, but tapping on it comes to mind.

 

 

My brakes were really squishy till I did some off roading in snow, they are better now, not perfect, but better. I don't think the snow had anything to do with it, but Subaru's do work magical ways.

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