XSeries-forum

it's hard to explain ..... i've never noticed it before but the pedal feels firm and consistant while braking but if you keep the pressure on after you've stopped the pedal starts to sink but it never feels like there is a problem or spongy

Hopefully getting mine back wednesday after the gearbox rebuild and will test it for you but tbh i have never noticed a soft pedal or it sinking to the floor. Surely would have noticed it at a red light

I think I know what you're describing Ian.  It's what was really noticably happening with mine but it seems to have improved in that regard.  Once stopped if you push quite hard it will go to the floor though, not that you would normally have cause to do that.  The sponginess and seems to be variable.  If I can try another next to mine I will.  I'll probably have you all wondering about your brakes now! 

[quote="Dan1502"]
  I'll probably have you all wondering about your brakes now!
[/quote]

YUP !!  ) ) ) )

YUP !!!  was stopped in traffic today and thought of your brake problem lol , and if i stop and keep same  pressure on the pedal it stays put  BUT if i push harder it will slowly go down to almost floor

[quote="COLIN"]
YUP !!!  was stopped in traffic today and thought of your brake problem lol , and if i stop and keep same  pressure on the pedal it stays put  BUT if i push harder it will slowly go down to almost floor
[/quote]
Could be bad master cylinder seals, one of the symptoms is the brake pedal slowly sinking to the floor when you keep your foot on the brake.

Mine's had a new master cylinder fitted amongst other things.

In terms of moving slowly to the floor, all cars I've tried seem to do it to varying degrees but moreso if you pump the pedal a couple of times at standstill then put constant pressure on though in the mini it takes a lot of pressure.

What I'm wondering about now is different in that once stopped if you just push straight down it moves a lot, and to the floor or virtually so, quickly but it does take more than normal braking force to do it.  I do really need to try another again but I'm so busy at the moment and it was in the garage for over two weeks.

I will talk to the dealer about it again shortly but just wanted to drive it a bit first.  I also had a parking sensor fault which was showing on the diagnostics as a failed sensor which was replaced but it's since been working intermittently, initially with a constant beep and now they act like they work but the front goes from nothing to constant with nothing in between.

Just checked mine, nope I have a hard pedal which doesn't drop at all, even with a lot if pressure being applied.

Thanks

[quote="Dan1502"]
Ok.  So I have it back now for a few days but it still doesn't seem right so it shall probably be going back in.  Could any X5 3.0D owners try this please?  Drive along then bring the car to a gradual halt as if pulling up then without taking your foot off the pedal, push it to the floor.  Will it go right to the floor?  If it does, does it do so quickly?  Does it do it under moderate pressure?

I now accept that with pretty much any car if you start the engine pump the brakes a couple of times then push very hard on the pedal it will slowly creep to the floor or not far off it but mine will do this under light to moderate pressure and after coming to a halt you can keep pressing straight to the floor once stopped.
[/quote]
Have you sorted your issue yet, or have BMW come up with a fix?

I have exactly the same problem as yours,
and mine is 3.0d (diesel) as well (2006) facelift e53.

All I did was change pads , didn't open the bleeder valves, except for loosening the master cylinder reservoir cap, pushed back the caliper pistons to install new pads  then...
low pedal.
(well, increased pedal travel, just not feeling the same as before.)

So, I thought maybe MC bad, I put a brand new master cylinder in (what an absolute pain in the..)-  no change;

Pressure bled using Motive bleeder and INPA to activate the ABS - no change.

Changed the pads and rotors (again) to a different brand - no change.

I haven't relented and taken it to BMW... yet,

I'm hoping you've got some ideas?

Please Help anyone?!

Mine's had a new master cylinder, new servo, new flexible brake lines, many bleeds with correct ABS unit activation, loads of bits bled on and off the car, testing with blanked off brake lines from the ABS unit etc etc etc.

The pedal does vary and sometimes it's pretty much ok but most of the time if you stop and witout lifting off the break push further it will push right down and it does the creepy pedal thing.  Sometimes before the engine is on it is solid and others there's some travel.  Also it feels like you want to pump it once first sometimes too.  Sometimes it feels more spongy than others.  It does brake fine though.  It's got me questioning whether I'm cracking up at times.  I'd like to try some others but I'm so busy and feel a bit cheeky going to second hand car dealers to try them.  It's due back in soon but I don't know what more they can do really.  Probably another bleed.  The ABS unit seems to be functioning fine though I did read of a Mazda with a similar problem which turned out to be an o-ring or two in the unit.  That would be an experiment with a £1,500 part.  I've also heard about vacuum leaks but it was fine as far as I know before.

Have you or BMW replaced the Brake Booster?
I'm starting to think it may have something to do with it;
BMW gave it back to you, not quite right?
I was hoping they'd get to the bottom of it,
I've read of a number of recalls of BMW where it seems to be related in that the same symptoms manifest themselves, -not e53- but e70 and e60/ e6x but some of the part numbers for these brake components are common,
so it may be same issue? 
https://www.recalls.gov.au/content/item ... ooster.pdf

And this:
http://www.carsguide.com.au/car-news/bm ... fect-21433

All work has been done by BMW.  As it's brake performance seems fine, I needed it and they didn't have a car available I agreed to take it away and try it for a while as there are stories of these things getting better themselves with use.    Applying logic to the system doesn't result in a solution.  A dodgy servo should really only make it harder to brake.  I'm not sure whether the vacuum hoses have been checked though.  In fairness to them as it's an old model they don't have new cars to compare and it's a while since they regularly worked on them.  I'm also struggling to find others to try (mostly due to lack of time) and description are open to subjectiveness and interpretation so I feel it would really be best if I tried a few.  I'll let you know what happens but you might wish to hang fire on throwing more money at it for now so long as the brakes work.

Yes, you're right I shouldn't really just throw money at it while the brakes work;
But I have high expectations! I expect them to work flawlessly I couldn't let anyone else drive it knowing that potentially the brakes are not 100%.
Yes , it may resolve itself if the cause is pad knock back, as that would increase pedal travel but once it engages full braking power;
I may try and look at that;
I just took the X5 to a brake specialist in the hope after he looked and drove it he'd just 'know' from experience what the likely cause is , but he seemed lost- what a let down, but he did agree that it just didn't feel right;
So now I'm tossing up what try next,
1. Change booster (I wish I changed it when I needlessly changed the master cylinder),
2. Try bleeding again;
3. Try and eliminate any chance of pad knock back, but removing one pad on one side, put a plate in its place to prevent Pistons over extending, then carefully push back to allow the pads to be reinserted...
Surely someone else has had a similar problem?
I'm still hoping someone will chime in with- " yeah, I had same problem and I / BMW / mechanic fixed it all by just doing ....????"

What does a rolling road brake tester show the brakes are actually doing?  What performance is actually being delivered by each corner?  Is it balanced across each axle?  Is it correctly balanced front/rear?