Thread: Spongey brakes

Great Thread,,having exactly the same issue after rotors,calipers,hard lines from Flexi renewed,and sinking pedal on slow application.
Starts off ok when cold,once run and brakes used a few times,the braking becomes soft with long pedal throw until biting.
Slow steady pedal application with engine running drops pedal close to firewall.
Brake booster rebuilt and seems to be perfect,hard pedal engine off,start and drops an inch,good vacuum in manifold line.


This is on an 81 two door Range Rover.
Replaced imperial calipers with metric and redid the hardline unions to fit at the caliper end.

No leaks,correct sized fittings used.
Wheel bearings replaced as well and no play.

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Bled these things 5 times now and no better.
Changed out master cylinder from new aftermarket unit,thinking the wife may have been a bit overzealous with the pumping,(not going there )… and ripped a primary or secondary piston seal on full travel.

Had a good look at Vetcar’s diagrams,got out the old handbook as well,and compared the lines on the old calipers with the new ones I’d installed.

Front passenger side was matching as per originals, but I’d incorrectly installed the lines on drivers side.
Missed seeing that the lower calliper line ran to the top Flexi union on the old lockheeds.
Solution?

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Reinstalled hard lines as per the originals,bled again using both nipples on the inner side,then the outer as per my autobooks manual.

I took a video of the top nipple bleed,here’s a snapshot,but upshot is I cannot get a bubble free bleed from this one.
Streaming air from this one,not fine micro bubbles but full on bubble bath.

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Wheels back on after much faffing,test drive,exactly the same..long pedal throw getting worse with more usage.

Whats going on here?
Same poor result but possibly different problem to Vetcars issue.
My thoughts are possibly the Aftermarket caliper on that drivers side has a decent air leak at one of the piston seals?
No evidence of brake puddles or drops noticed at all.

May have to take it to a brake shop for further diagnosis.

**Update**
Checked for wheel bearing play after only having renewed both sides 3 days ago..All was well at the time.

Watched the above trailfitters vid kindly linked by Towe,and after reading his similar experience(cheers for that,legend)
Thought I’d recheck it,,Sure enough,massive play on drivers side,,thought I had preset and seated the inner bearing enough,obviously not!

Reset wheel bearing preload and brake pedal now firm and exactly where it should be,no more fading away,,happy days.

Hope Vetcar can sort his with all the awesome input on here.

The top caliper bleed point has to be open to the air somewhere .... if your getting air in there, it has to be coming from somewhere.

A few weeks back I found a small car for my daughter, and figured before I tried the vacuum bleeder here on it .... I'd try in on the ****box range rover here first. I purchased the vacuum bleeder a year or so ago to bleed an old citroen. I had no success at all. It had weird bleed nipples that weren't standard ... and I couldn't pull fluid through from the reseviour (I'm thinking I need to pull its master down and check for rust/blockages in it).

Anyway, I followed the bleeding diagram in this thread. First I sucked all the brake fluid from the reseviour and refilled with fresh stuff. Two of the bleed points on the front calipers were completely blocked (I'll need to chase up some bleed nipple covers). Every bleed point had air in the circuit .... I just put some grease around the bottom of the bleed nipple thread so air wouldn't be sucked from here. The rears, I couldn't get a constant stream of fluid from. I think its not air in hte lines, rather you can't flow enough fluid through the length of line invovled for the bleeder to keep its suction hose full ... so the stream breaks up (so hopefully air isn't present, just not enough fluid).

The pedal now sits about an inch higher and is much harder. I still think randomly the pedal was sinking far enough before to activate the backup secondary circuit.

seeya
Shane L.

I think I heard of this once before a long time ago and the problem was that the master cylinder was faulty from new.
AFAIR the primary or secondary circuit seal was faulty.
Regards PhilipA

Originally Posted by PhilipA

I think I heard of this once before a long time ago and the problem was that the master cylinder was faulty from new.
AFAIR the primary or secondary circuit seal was faulty.
Regards PhilipA

Is the top bleed point for the secondary circuit? If so the brakes will probably work perfectly, but have no backup system if they ever fail. Is there a simple way to isolate the main brake system so it will not work? That way when you pressurise the secondary system, any leaks should become obvious ( wetness/leakage of lines .... or failure of the master cylinder on the secondary circuit).

Originally Posted by westy1

.....................

Had a good look at Vetcar’s diagrams,got out the old handbook as well,and compared the lines on the old calipers with the new ones I’d installed.

Front passenger side was matching as per originals, but I’d incorrectly installed the lines on drivers side.
Missed seeing that the lower calliper line ran to the top Flexi union on the old lockheeds.
Solution?

[/FONT]9ACFE250-3F58-4536-B339-D3B1D2E55D29.jpg C8FDB58B-EC47-4C84-8270-4BD0B5EA9DEE.jpg

Reinstalled hard lines as per the originals,bled again using both nipples on the inner side,then the outer as per my autobooks manual.

...................

Hi Westy,

If you still have your old Lockheed callipers I wonder if you could do a simple check for me.

If they still have the pistons in can you put a bit of wood or something in between where the rotor was, so they still seal.

Then give each hard line a squirt of air (top one goes to the bottom of the calliper at the rear, etc) while loosening each nipple in turn.

The aim is to confirm which line (or port) on the calliper is primary and which is secondary.

I've done this before but can't remember.


cheers, DL

Would happily do this test DL,alas I have no air compressor,sorry.

Originally Posted by westy1

Would happily do this test DL,alas I have no air compressor,sorry.

A push bike pump would do it, even blowing through a neoprene tube through each loosened nipple would indicate what is connected to what.

cheers, DL