jad Posted February 23, 2010 Share Posted February 23, 2010 Hi everyone This weekend my brake pedal started to sink slowly. as in when the brake pedal is pumped it becomes very hard but slowly sinks. Before this started happening the brakes were sometimes hard and sometimes a bit soft but mostly stopped the vehicle well and didnt pull. The callipers discs and pads are all fairly new. Before I start replacing anything i was wondering what peoples thoughts were on what it could be? My first thought would have been master cylinder. Any ideas on things to check first would be helpful Thanks Jad Quote Link to comment Share on other sites More sharing options...
hicapster Posted February 23, 2010 Share Posted February 23, 2010 Have a look at master cylinder, than work your way through the whole system ie, all break unions and cylinders i think you have a leak just look for signs of weeping at all the break unions and pipes. good luck Quote Link to comment Share on other sites More sharing options...
Crofter Posted February 23, 2010 Share Posted February 23, 2010 I had the same problem, sometimes the brakes worked and some times they did not, after a short while they got worse and could not be trusted so after checking the usual suspects, I replaced the Master Cylinder this solved the problem, but I did not use a genuine part and the problem returned after 3 months, so now I have fitted a Lucas master cylinder. If you buy a master cylinder buy a genuine part, and would advise anyone else to do the same, because it's not a nice feeling when approaching a junction and the brake pedal goes to the floor, fortunitly one circit still worked in my case and I got away with only a fright. Regards, Ronnie. Quote Link to comment Share on other sites More sharing options...
markyboy Posted February 23, 2010 Share Posted February 23, 2010 Have a look at master cylinder, than work your way through the whole system ie, all break unions and cylinders i think you have a leak just look for signs of weeping at all the break unions and pipes. good luck You won't necessarily find a leak if it's the master cylinder, although there may be one behind the dust seal, if there is it will run down the inside or outside of the bulkhead. Certainly sounds like fluid creeping past the master cylinder seals to me. I'd replace it with a genuine one, don't use Br*tpart!!! Mark Quote Link to comment Share on other sites More sharing options...
boy Posted February 23, 2010 Share Posted February 23, 2010 i have just got a new genuine one for my truck not a bad price and the parts man said not to go for a br*tpart one because there are a lot of greif!! Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted February 23, 2010 Share Posted February 23, 2010 Mine does a similar thing, I've just ordered a new master cylinder for it. £20 of eBay delivered, genuine Lucas! Bargain! Quote Link to comment Share on other sites More sharing options...
defender dave Posted February 23, 2010 Share Posted February 23, 2010 worth checking the wheel bearings its a common thing that will make the break peddle soft Quote Link to comment Share on other sites More sharing options...
jad Posted February 24, 2010 Author Share Posted February 24, 2010 who did you buy that from and does he have more? I saw them on there for 60ish worth checking the wheel bearings its a common thing that will make the break peddle soft my wheel bearings are fine ok wasnt told anything about them at my last scruitineering anyway.... but how would the wheel bearings cause your brake pedal to be soft? Quote Link to comment Share on other sites More sharing options...
western Posted February 24, 2010 Share Posted February 24, 2010 my wheel bearings are fine ok wasnt told anything about them at my last scruitineering anyway.... but how would the wheel bearings cause your brake pedal to be soft? if the bearing were slack, the hub/disc will run out of line & push the pads back into the caliper, therefore next brake application, pads have to move out further giving the feeling of a soft pedal. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted February 24, 2010 Share Posted February 24, 2010 http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110497684117 If anyone else needs one, get one while they're available this cheap! There were 9 available yesterday evening, so they're going quick. Don't know why they're so cheap, but the listing says it's brand new and the proper Lucas/Girling item. No connection, just want to help others get a deal if they can! Quote Link to comment Share on other sites More sharing options...
western Posted February 24, 2010 Share Posted February 24, 2010 http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110497684117 If anyone else needs one, get one while they're available this cheap! There were 9 available yesterday evening, so they're going quick. Don't know why they're so cheap, but the listing says it's brand new and the proper Lucas/Girling item. No connection, just want to help others get a deal if they can! a bit cheaper than here Quote Link to comment Share on other sites More sharing options...
jad Posted February 24, 2010 Author Share Posted February 24, 2010 http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110497684117 If anyone else needs one, get one while they're available this cheap! There were 9 available yesterday evening, so they're going quick. Don't know why they're so cheap, but the listing says it's brand new and the proper Lucas/Girling item. No connection, just want to help others get a deal if they can! I have a G reg 1990 90 from what i could work out i wanted part number NRC9529 which is this one http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=390123201116&ih=026&category=31348&ssPageName=WDVW&rd=1 can anyone confirm if the one I quoted from a previous post be used aswell? cheers Quote Link to comment Share on other sites More sharing options...
western Posted February 24, 2010 Share Posted February 24, 2010 NRC9529 is Correct for your vehicle upto chassis HA701009, from HA701010 the servo & master cylinder changed, so the later cylinder won't fit your servo, bolt holes are in a different orientation. Quote Link to comment Share on other sites More sharing options...
jad Posted February 24, 2010 Author Share Posted February 24, 2010 NRC9529 is Correct for your vehicle upto chassis HA701009, from HA701010 the servo & master cylinder changed, so the later cylinder won't fit your servo, bolt holes are in a different orientation. cheers looks like ill be paying a bit more then unless anyone knows of another cheap source for a NRC9529??? Quote Link to comment Share on other sites More sharing options...
jad Posted March 2, 2010 Author Share Posted March 2, 2010 Hi again Just wanted to ask. Is changing the brake master cylinder as easy as unbolting the old one bolting in the new one and bleeding the brakes? i had a search but could find anything. cheers James Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 2, 2010 Share Posted March 2, 2010 Just the master - yes. Bleed the master before attaching it to the pipes though - you can get air locks in a 'dry' master cylinder. Les. Quote Link to comment Share on other sites More sharing options...
jad Posted March 2, 2010 Author Share Posted March 2, 2010 Just the master - yes. Bleed the master before attaching it to the pipes though - you can get air locks in a 'dry' master cylinder. Les. Hi Les How do I do that? is it the same method for bleeding the brakes but just through the master cylinder? thanks for you help James Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 2, 2010 Share Posted March 2, 2010 Fit the master cylinder (2x17mm head nuts), fill the reservoir, get someone to press the brake pedal, put your fingers over the pipe outlets, release the pedal and then press it again, take your fingers off, then back on, press the pedal again, and so-on, until brake fluid squirts out of both holes, then attach the pipes and bleed the system as normal - front and back. Les. Quote Link to comment Share on other sites More sharing options...
Guppy Posted March 2, 2010 Share Posted March 2, 2010 Not wanting to hijack the thread but could my symptoms point to the same diagnosis? I currently always have to press the brake well over 70% of the way in order to get anything more than a minimal effect. If I 'pump' the pedal (press, release, then press again immediately) the pedal's resistance is reached within about 20% and the brakes are very effective. I ask only because i've had recently issues with a blocked breather on the front axle to the point where i've had one-shot grease pressure-burst all-over one of my front discs and not gotten around to cleaning it and replacing the pads yet. I should also add that my bearings should be sound as both front hubs have been rebuilt in the last 12 months. Sorry for the n00bie question! Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted March 2, 2010 Share Posted March 2, 2010 I have exactly the symptoms described above, I think the 'two pumps' problem is to do with the drums on the rear being either out of adjustment or very muddy/wet. As for the pedal sinking when constant pressure is applied, I think the master cylinder is in need of replacement. I have bought a new master cylinder, and am hopefully going to discs on the back soon anyhow. So when I change the axle I shall change the master too. Then I can re-build the old one with some new seals and keep it as a spare Quote Link to comment Share on other sites More sharing options...
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