Brake problems (still)

Hi,

Still got a problem with the brakes on my defender, have changed the master cylinder (twice) and it's now the case that when you drive forward at 30mph+ for any distance, hitting the brakes will cause the pedal to hit the floor. Pumping them will bring it back but then it just happens again down the road,

The brakes bleed up just fine now, but today I got it on axle stands and can feel a very slight play at the 3-9 position. There is also the noticeable sound of something binding in the wheel which pulses once every cycle of the wheel.

Is it possible that I've got a mildly warped disc pushing the piston back in meaning it needs to be pumped out each time?

Theres no vibration in the steering wheel but then again the steering is quite vague!

Cheers for any help,

Chris

Yes very possible, I assume you are talking about a front wheel? 3-9 could be down to worn TRE's if there isn't any 6 - 12 movement but that wont affect the brakes just steering. Take the drive member off and try spinning the wheel again, if you still have noise you have eliminated CV and diff issues and may be duff bearings or pads rubbing on warped disk. You could then whip the wheel off to have a good look at disks

Now track rod ends would make some sense as I heard a knocking today from that corner going over a bump,

How easy is whipping the drive member off? The diff is very worn, I can tell that from the backlash, but CV joints might be doing something.

cheers

Getting the drive member off isn't too hard. It's the thing in the middle of the hub held on by five bolts. There'll also probably be a circlip and a washer or two holding it onto the drive shaft.

Don't forget, a lot of air can hide in a Land Rover braking system. I usually find it takes quite a bit of bleeding to get rid of it all. It helps if you let it 'settle' for a few hours or overnight between bleeds.

Did you use a reputable master cylinder? Have you checked all the brake lines and unions for weep age. You can check the disc for warpage with a simple home make gauge. Maybe a pencil taped to an axle stand and touching the disc at one point ,then spin disc slowly and watch for any run in/out. (bit mcgyverish but should work)