sticky brakes ...ggrr

classicalgreen

Active Member
having changed both front calipers..was driving to club meet when found they were binding ..luckily i was near enough to get into car park and let them cool off ( bit smelly and smoky), borrowed a scanner and released pressure after servo. it behaved on way home but started binding again later when trying to park. no changed master cylinder and servo assy plus most front pipes and all Flexi pipes.
trying to get ready for MOT ..bled brakes ( no softness) then found front brakes still gripping!
at a loss how to get round issue so would be grateful anybody come across this or have suggestion where to go next apart from wifes suggestion to start breaking it or setting it alight!
so far huge money pit so hard to justify further expense ( gearbox also leaking so needs work -auto box) sigh
at moment trying to avoid shooting self but it is a bit depressing and moving soon so need to get it back on road as trailering is v expensive. away this weekend but will hope to start rolling up sleeves again monday..might be holding either a spanner or a sledge hammer. :(
 
Hi, sorry but I can't decipher what you have and haven't changed. But the usual culprits are
front flexible,s have collapsed and acting as one way valve, or there is possibly a fault with
air valve on the servo allowing the servo to operate unwanted.

Colin
 
If releasing the pressure after the servo releases the brakes, then that rules out the flexibles and narrows it down to either the master cylinder or the servo. If it happens again, then try releasing the pressure between the master cylinder and the servo first. If that doesn't work then it's the servo, probably the air valve as Colin suggests.
 
Re: sticky brakes

update. sorry current status is, replaced both front callipers. all flexible hoses.most of fixed pipelines. refurbished rear callipers. exchange master cyl fitted . exchange servo unit assembly ( complete unit) fitted . system then bled. pedal is high with no sponginess ( good). problem being front ( as far as I can tell) brakes not releasing now ( this was an intermittent issue before replacing servo and both hydraulic cylinders e.g. master and servo ones ) so its not collapsing hose lines, unlikely dirt in system ( 2 litres pumped through) would be odd if both new callipers were faulty! so it leaves the servo vacuum valve ( but would that not have held All brakes on?) or I think...the joining block on inner wing where brake pressure sensor is fitted as well as the other brake lines.
thinking about removing the block and blowing through with air line checking for dirt etc. refit and bleed ,try again but likely to try pulling out servo vacuum valve first and see if that removes pressure retention in lines..if it does ( apart from being bleeding expensive to replace) well and good as can get part shipped in from wins international by post and sort out much needed MOT test later next week.
so far cars done around 300 miles in 20 months due to issues of one sort or another. (sadly bought lemon I think) and still has poor running issues when cold.( fuel I think despite new filters.carbs refurbished etc) would like to get at least 300 more done this year if possible! working out at around nearly £100 a mile so far . so halving mileage costs would be nice. wife very unhappy with rover and would rather I sold it off at a massive loss to keep sanity and peace in house lol . so other than engine cutting out after a run when starting off again ( fairly sure thats air bubbles in line due to heat evaporation in fuel system) and list of other issues that I can live with IF the brakes start working correctly .its still a car that gets good comments from public. who knows maybe in a year or two I can think about looking round for power steering upgrade. have nice day all and happy ownership. :LOL:
 
You need to diagnose the problem at the time that it happens, so when the brakes bind, jack up and turn each individual wheel to either confirm or discount that it's all four brakes or just the fronts. If it's just the fronts you have to investigate there. If it's all 4 then carry out the following:

suffolkpete said:
If releasing the pressure after the servo releases the brakes, then that rules out the flexibles and narrows it down to either the master cylinder or the servo. If it happens again, then try releasing the pressure between the master cylinder and the servo first. If that doesn't work then it's the servo, probably the air valve as Colin suggests.

If that indicates the servo that's where you focus your attention. If it points to the maste cylinder, check there.

The one thing you've written that concerns me is:

classicalgreen said:
pedal is high

If the pedal height is too high it will hold the brakes on because the piston won't be able to come back far enough to release the fluid back to the reservoir.
 
pushed car back and forth with handbrake off and in neutral after weekend away. car moved freely. then tested brake pedal , hard and high ( not checked distance its supposed to be from carpet yet) started engine with foot on pedal..pedal sank about an inch or so .indicating servo working ok. checked brakes again with engine now off and pushing car ..front brake(s)? now sticking .appears to be the front offside mainly.until i can jack each wheel up and try spinning by hand ..(will do so in week) can't confirm exactly. popped out servo vacuum valve after pumping pedal with engine off. can hear gas escaping with each pedal press until it goes quite (4-5pumps) am guessing thats the vacuum being purged .
with vacuum valve removed..car still not pushable. seems clear an hydraulic lock occurring in at least front off side and likely both front wheels. get impression rear wheels not sticking but without spinning individually can't say for sure.
thinking about removing the brass 'splitting' block with the brake light switch in it from office inner wing. wondering of a bit of crud is in it?
 
classicalgreen said:
( not checked distance its supposed to be from carpet yet)

It's the distance from the floor, not the distance from the carpet.


classicalgreen said:
seems clear an hydraulic lock occurring in at least front off side and likely both front wheels. get impression rear wheels not sticking but without spinning individually can't say for sure.


Find out for certain which ones are binding (rather than just guessing) and open the bleed nipple on those ones, if it frees of just that one there is fluid pressure being retained in that line and you need to find out how/why. If it frees off the whole system then the problem is further back in the system towards the pedal. If it doesn't free off then it's a mechanical fault at the caliper/s.
 
many thanks harvey. adjusted pedal to drop to lower level. able to bleed brakes fully. off for its mot Friday ( fingers crossed as handbrake is awful despite reworked callipers. :eek: new pads and discs)
 
classicalgreen said:
( fingers crossed as handbrake is awful despite reworked callipers. :eek: new pads and discs)

Did you set the pads final position with the disc in or out?
Though even if not done with the Harvey method of 'out', l wouldn't have thought that the handbrake would be 'awful'.
Again, Harvey is the man to assist. He did Bruiser's rear brake caliper replacement four years ago & the handbrake is as efficient now as the day he set it. A P6 handbrake if done properly is fit & forget & extremely powerful.
 
The Rovering Member said:
A P6 handbrake if done properly is fit & forget & extremely powerful.
When my car was tested a couple of months ago, the tester shouted "Woohoo!" as he locked the rear wheels on the rollers with the handbrake. :D
 
if i recall correctly rear pads were fitted after disc was in place but then calipers fitted over discs ( entire diff was dropped at time as it had a seized swing pin. ) checked as far as i could for correct set up using handbook and online pics and data ..hand brake is hard to apply and does not seem to affect good braking resistance. wife certainly would not be able to operate. well its going for Mot friday morning ..soon find out if it ok or rubbish. think a match and a gallon of petrol may be in order ...er that was a joke by the way..just in case ..it does catch fire during its mot...carried out too much work and too much £££ spent to write it off. just very tempting at times..( most of us will have been there) :eek:
my ford Kuga has rear discs and handbrake is a doddle to apply and works very well.. total opposites.
 
it passed MOT ..just .26% as single brake system. tester commented on lack of bite..invited me into inspection pit to check it over with him. seems cable is a bit loose leaving parking brake taking up excess slack before biting on rear discs. even when heavily applied was poor braking..the mechanism seems so good and he thought it was new!
as rear callipers were stripped and rebuilt last year I am confident the 'pin' was correctly in place on rebuild etc. at moment of opinion its possibly the pads ( new and new discs last year) are possibly not effective enough? both hinge pins were sorted and do swing very freely so its not a case of only one pad being used.
wish it has same effect as my Kuga .. sill will eventually ( moving soon so no time to explore properly) get round to full check on parking brake .cable and movements etc.
thanks to all who commented . advise always welcome.
 
If the quadrants are back on their stops when the handbrake is OFF, and there is slack in the cable, then the slack needs to be removed. If there isn't slack on the cable, but there is excess movement on the lever before the handbrake bites, then the calipers haven't been set up correctly.
 
checked cable when working under car . needed a bit of slack taken up on adjustment. now works reasonably well though would not trust it on a 1 in 3 slope. nothing seems wrong but 'grip' on the discs ( new ) with new pads only just run in ( 200 miles) is not exactly confidence inspiring. :(
 
classicalgreen said:
checked cable when working under car . needed a bit of slack taken up on adjustment. now works reasonably well though would not trust it on a 1 in 3 slope. nothing seems wrong but 'grip' on the discs ( new ) with new pads only just run in ( 200 miles) is not exactly confidence inspiring. :(

There's something wrong there then.
 
just had MOT .near side caliper not operating correctly so unbalanced braking . ( fail) rear handbrake yet again (fail) . so 2days chores is to check front caliper with wheel off and pads out . thin wood insert and operate. pedal.see if operation is ok or one sticking? partially seized? car. not used a lot at around 300 miles per year and. callipers all round changed about 2 years ago. so slightly. annoyed but. with a rover P6 learnt to expect issues . rear handbrake no idea what. to do next so its case of jack ups and sit on wheel ramps. start checking from handbrake itself ( free?). cable movement inner/outer sleeve? then. action on levers for brakes. back on pins. no excess cable or. too tight etc . assuming I can'y. sort ( likely) might have to try and find a local garage that is willing to spend time and effort having a go . I am missing something but c ant see what. I have found a guy whom used to own 5 p6 rover so he may be able to guide me ..will be having a chat. this evening. sadly can't work under cars ( long story) anymore . might think about hiring one of those 4 post lifts and having him have a look when up in air . with luck its going to be something really stupid .. though having had. about 10 goes over 4 years at handbrake and looked various pics etc on here . no joy. evermore annoying is I owned a zephyr mk4 once and that has almost identical rear brakes . that worked fantastic !! gggrrr
 
I think your main problem is lack of use. They start to seize up and dry out when left for long periods.
 
note lack go use . think your correct .will endeavour to put more use on car. possible do a run a week to next village and back as minimum and longer runs. to next town where possible . ought to get quite a few braking situations in local streets.
 
Back
Top