Results 1 to 7 of 7

Thread: D4 Brake Pedal travel and 'softness'

  1. 25th August 2017, 02:44 PM #1
    Ghost-Who-Walks's Avatar
    Ghost-Who-Walks
    Ghost-Who-Walks is offline Master Supporter
    Join Date
    Jan 2009
    Location
    Perth, WA
    Posts
    195
    Total Downloaded
    0

    D4 Brake Pedal travel and 'softness'

    Hi

    I've recently noticed a change in the feel of the brake pedal. I left the car at the airport for a few days, and drove other cars whilst away - when I came back, the brake pedal felt decidedly soft, and required more travel to get the same braking affect. Originally, I thought it was because I was driving other cars, and wasn't used to the 'feel' when I got back in my D4....

    For context, I changed the discs and pads about 3-4mths ago, so should all be good. Also bled/changed the brake fluid at the same time (for the first time in it's life I think!).
    I also washed the car the day prior to going to the airport, and it was extremely wet the whole time I was away (sitting in the rain, for 3 days).

    There are no leaks (fluid), and have never had any problems with air in the lines.

    So, my question(s):
    Any ideas what might cause this?
    Could water/rust on the discs cause some sort of 'glazing' effect on the discs, to reduce their effectiveness?

    I ask this, as it basically feels like the rear brakes are almost ineffective. I assume the rear brakes operate more at the 'start' of the pedal travel, with additional brake force coming from the front as you push harder/the pedal travels further (just my assumptions there!)...
    When I first push the pedal, you can feel a small retard/brake force, but then there's not much more for about 1/4 of pedal travel, before the real braking effect comes in (which I assume is the front brakes)...

    Anyway, I could go on trying to describe it - grateful for any ideas...

    BTW - discs are RDA rotors, front pads are Pedders Trakrider ceramic, rear pads are Akebono's

    Any help appreciated!

    Thanks

    Rob
    D4 3.0L SE, MY10, Arctic White
    ARB Colour-coded bullbar, Safari Snorkel, Traxide DBS, LRBT1 BT audio module, trying out some 19" Maxxis Bravo 980A/T's (ex Cooper Zeon LTZ's)
    ex D1 2.5L 300Tdi, MY97 - loved it, gone to a better place.
    Reply With Quote Reply With Quote
  2. 25th August 2017, 04:12 PM #2
    DieselLSE's Avatar
    DieselLSE
    DieselLSE is offline Wizard Subscriber
    Join Date
    Nov 2015
    Location
    Black Rock
    Posts
    1,228
    Total Downloaded
    0
    Very hard to diagnose this way, Rob, particularly as you have changed discs, pads and fluid at the same time. My first thought is to ensure the fluid is flushed properly and there is no air in the system. I'd be surprised if the fluid hadn't been changed before by the dealer as part of routine maintenance. Being hygroscopic it needs to be changed every couple of years or the booster will get gummed up.
    I think my first action would be to flush the system again with a different coloured fluid.
    I can't see how leaving the car standing in the rain for a week or two would matter. I once left the brake system alone for a full year whilst I worked on the rest of the car (Rangie LSE). The surface rust on the discs wore off in minutes and the brakes were fine once I was mobile again.
    2013 D4 expedition equipped
    1966 Army workshop trailer
    (previously SII 2.25 swb, SIII 2.25 swb & lwb, P38 Vogue, 1993 LSE 3.9V8 then HS2.8)
    Reply With Quote Reply With Quote
  3. 28th August 2017, 01:11 PM #3
    Ghost-Who-Walks's Avatar
    Ghost-Who-Walks
    Ghost-Who-Walks is offline Master Supporter
    Join Date
    Jan 2009
    Location
    Perth, WA
    Posts
    195
    Total Downloaded
    0

    Brake softness

    Well, took it in to get it looked at by my mechanic - they said they've never seen (felt?) anything like it before on a D4.
    Don't think it's air in the lines, nothing wrong with the pads/rotors, nothing electronic...
    Only leaves the mechanical bits (booster, master cylinder etc)...
    So, booked in for 'investigative surgery'...

    Very strange.
    D4 3.0L SE, MY10, Arctic White
    ARB Colour-coded bullbar, Safari Snorkel, Traxide DBS, LRBT1 BT audio module, trying out some 19" Maxxis Bravo 980A/T's (ex Cooper Zeon LTZ's)
    ex D1 2.5L 300Tdi, MY97 - loved it, gone to a better place.
    Reply With Quote Reply With Quote
  4. 7th September 2017, 01:26 PM #4
    Ghost-Who-Walks's Avatar
    Ghost-Who-Walks
    Ghost-Who-Walks is offline Master Supporter
    Join Date
    Jan 2009
    Location
    Perth, WA
    Posts
    195
    Total Downloaded
    0

    Wrap up

    To tidy this thread up...
    My good friends at Rovertech replaced the Master cylinder (~$330, plus couple of hours labour).
    Good as new. Nice, touchy brake pedal, high up in the travel. Just like it was.

    Assuming 'something' (piston, valve??) had failed inside the unit.

    Not very common (read - uncommon, almost unheard of) fault. At least it wasn't complicated, or disabled the vehicle... And there was a part in Aus!!!

    Thanks.

    Rob
    D4 3.0L SE, MY10, Arctic White
    ARB Colour-coded bullbar, Safari Snorkel, Traxide DBS, LRBT1 BT audio module, trying out some 19" Maxxis Bravo 980A/T's (ex Cooper Zeon LTZ's)
    ex D1 2.5L 300Tdi, MY97 - loved it, gone to a better place.
    Reply With Quote Reply With Quote
  5. 9th January 2018, 03:19 PM #5
    Ghost-Who-Walks's Avatar
    Ghost-Who-Walks
    Ghost-Who-Walks is offline Master Supporter
    Join Date
    Jan 2009
    Location
    Perth, WA
    Posts
    195
    Total Downloaded
    0

    Finally finished??!!

    Quote Originally Posted by Ghost-Who-Walks View Post
    To tidy this thread up...
    My good friends at Rovertech replaced the Master cylinder (~$330, plus couple of hours labour).
    Good as new. Nice, touchy brake pedal, high up in the travel. Just like it was.

    Assuming 'something' (piston, valve??) had failed inside the unit.

    Not very common (read - uncommon, almost unheard of) fault. At least it wasn't complicated, or disabled the vehicle... And there was a part in Aus!!!

    Thanks.

    Rob
    So, about a month after having the master cylinder replaced, it reverted back to previous symptoms (soft pedal to about half travel, slight braking initially then full braking from half travel down).

    Went back in to Rovertech. Again, diagnosed as faulty master cylinder ("It CAN'T be anything else!").
    Apparently the first 'new' one they got from over East, but was likely it had been sitting on a shelf somewhere for quite some time.
    They ordered another new one from the UK (was guaranteed to be recent manufacture) - fitted it up, and has been like new since!!!

    I don't know about luck - good or bad - I get a problem that hardly anyone has heard of, and then it happens twice (to 2 separate units) in 3mths!!!

    Anyway, great service again by Kevin and the guys at Rovertech. And it does look like the problem has been fixed!
    The first 'new' (faulty!) master cylinder was sent back to supplier for strip... Not sure on outcomes from that.

    As an aside, there was a thread on the Disco3UK forum that mentioned seized calipers (not sliding on the bolts) that caused an issue with similar symptoms. It sort of makes sense (one piston engages, and then the other has to travel much further to engage the other side of the disc, assuming it is seized 'off-centre'). But the guys at Rovertech checked this and it was not the cause in my instance.

    Thanks.

    Rob
    D4 3.0L SE, MY10, Arctic White
    ARB Colour-coded bullbar, Safari Snorkel, Traxide DBS, LRBT1 BT audio module, trying out some 19" Maxxis Bravo 980A/T's (ex Cooper Zeon LTZ's)
    ex D1 2.5L 300Tdi, MY97 - loved it, gone to a better place.
    Reply With Quote Reply With Quote
  6. 9th January 2018, 03:52 PM #6
    letherm's Avatar
    letherm
    letherm is offline Wizard Silver Subscriber
    Join Date
    Oct 2013
    Location
    Old Toongabbie, Sydney NSW
    Posts
    1,273
    Total Downloaded
    0
    Quote Originally Posted by Ghost-Who-Walks View Post

    I don't know about luck - good or bad - I get a problem that hardly anyone has heard of, and then it happens twice (to 2 separate units) in 3mths!!!
    You have heard of Murphy's Law haven't you.

    Good to hear it's now fixed.

    Martin
    Reply With Quote Reply With Quote
  7. 9th January 2018, 04:35 PM #7
    PerthDisco's Avatar
    PerthDisco
    PerthDisco is offline ChatterBox Subscriber
    Join Date
    Oct 2012
    Location
    Perth
    Posts
    2,700
    Total Downloaded
    0
    Quote Originally Posted by Ghost-Who-Walks View Post
    As an aside, there was a thread on the Disco3UK forum that mentioned seized calipers (not sliding on the bolts) that caused an issue with similar symptoms.
    Everything that lives under the car seizes on UK cars!
    Reply With Quote Reply With Quote
« Part Ordering Confusion | Leaking D3 fuel tank »

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules

Search AULRO.com ONLY!
 Search All the Web!