Sanity check on soft brake pedal - Defender Source
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Old April 10th, 2016, 01:39 PM
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Charles Galpin
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Sanity check on soft brake pedal

My 2a brakes have degraded over the years from being able to lock them up on a single push, to double pump, to now double pump and then slowly going to the floor which can be rather terrifying. I need to get this sorted in general, but also plan to do a few things to the D90 which will require me to daily drive her while that's going on, which could take months at the pace i move

I just checked all the wheel cylinders - no leaks, and adjusted the shoes, but it doesn't change anything. The soft lines look ok.

There seems to be some leaking from the reservoir cap, but nowhere else that I can see, including the master cylinder.

So I'm thinking master cylinder (internal leak) at this point since it doesn't have a booster.

Anything else I should do before looking into the dorman replacement?
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Old April 10th, 2016, 01:45 PM
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Park on a steep incline with the nose up the hill. Apply your brakes and hold it (don't re-pump) with your truck in neutral. If you start to roll back it is more than likely an internal leak in your master cylinder.
I learned this from a LR zen master in Orlando.
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Old April 10th, 2016, 01:47 PM
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It's pretty flat here, but I know it will roll without even trying it. I've been driving it like this way longer than safe :D
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Old April 10th, 2016, 01:48 PM
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Come to think of it's it's flat in Florida too. Sounds shady. j/k. lol
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Old April 10th, 2016, 05:25 PM
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If the pedal slowly goes down when you are holding it and there is no fluid dripping underneath, you have an internal leak in the master cylinder.
If you have to pump to get the brakes to apply, you don't have them adjusted properly or it is one heck of a leak in that master cylinder.
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Old April 10th, 2016, 05:29 PM
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Charles,

If you have the orginal style(rubber) flex lines clamp them all off and see if you get a stiff pedal. If so then release them one at a time whilst trying the pedal between unclamping. This will tell you where it is. All clamped and still soft= MC, front clamped and rear unclamped and still hard=rears good. Unclamp the fronts one at a time and check.
Most likely air in the system or old fluid with water absorption issues. replace and bleed.

WARNING; don't clamp stainless steel lines the teflon liner will crack.
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Old April 11th, 2016, 09:04 PM
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Charles Galpin
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Thanks Gene

Yes, I have the rubber lines so I'll do the clamping test to be sure, but will get my parts order in anyway just to be safe. I think this is way beyond bad fluid (although it does look terrible)
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Old April 11th, 2016, 09:25 PM
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Quote:
Originally Posted by javelinadave View Post
Park on a steep incline with the nose up the hill. Apply your brakes and hold it (don't re-pump) with your truck in neutral. If you start to roll back it is more than likely an internal leak in your master cylinder. I learned this from a LR zen master in Orlando.
That is exactly the problem a LR zen master in Orlando fixed on my truck.
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Old April 12th, 2016, 05:57 PM
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Can't soft lines degrade and expand under pressure? I always use braided lines to prevent any expansion ... Don't know if it's voodoo but seamed to make my motorbike brakes better.
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  #10  
Old April 12th, 2016, 08:00 PM
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Charles Galpin
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I'm sure new braided lines are better than ancient rubber ones, but I think rubber ones in good shape should be fine.

I clamped off my lines, and the pedal still goes fairly swiftly to the floor. The only difference when clamped was the pedal was initially hard at the top of the pedal. New master on order.

Thanks all
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