So I have discovered today that has I’m driving after applying the brakes I can lift the brake pedal about an inch and feel the brakes coming off so there basically staying on but it’s intermittent. So I’m going to investigate what’s going on maybe it’s the brand new booster? How can I tell if it’s booster or is there a spring? Or maybe the pivot point for brake pedal is jaming? But I never noticed this with other booster, but then again I had to stand on brakes to make it stop! So I will take a butcher’s and see what I can find. If any one has any info on what to check has I will check the obvious pivot point ect. Anyone else had this issue. Or can a caliper hold the pedal down a bit of maybe it’s swollen resovire hoses??
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Check the return spring on the pedal - it lifts/balances the pedal. And of course the pivots etc, which may hamper pedal ‘retraction’…
Springs in the master cylinder does the pushback to open the reservoir - but deteriorated brake hoses to the calipers are causes for maintaining piston pressure…
Frank
xj6 85 Sov Europe (UK/NZ)
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Swollen brake hoses would be my guess as well - often undamaged from outside and totally unproblematic for quick brake action, but causing permanent drag (if one-sided, of course) and limited brake effect with slowly increasing brake action as typically on a roller bench. After 20+ years all rubber brake lines are prone to suffer from this effect - change is easy, cheap and even if the lines are not the cause of your problem will be good for peace of mind.
Good luck
Jochen
75 XJ6L 4.2 auto (UK spec)
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Frank I have checked pedal action and seems fine at start up depressing the brakes when cold no problem. Then on a drive has I pretty much drive this car everyday to work on a lot of up and down hills here in northern calofornia. It’s starts to happen going down hill applying the brakes heavily then pedal sticks! I stopped along the way and could smell my left hand from front of car getting hot also to touch but the brake lines and calipers are new! So have to inspect closer!
Jochen
I have replaced hoses and calipers. Has I explained to Frank I’m going to inspect further!
But raining today here so possibly on the weekend!
Besides checking the spring, make sure to lubricate the pivot point. My 420 has a similar issue and it was the pivot had no lube and would hang up now and then.
Brake components, including hoses, heats up during braking which softens hoses. I strongly suspect brake hose deterioration - and would change the hoses on plain suspicion…as the simplest and most likely cause…
Frank
xj6 85 Sov Europe (UK/NZ
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No way if the hoses are new?
Certainly not, David - but are the brake hoses new…?
Frank
xj6 85 Sov Europe (UK/NZ)
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And
So I would think so, and reservoir lines would be unlikely to cause sticking brakes…?
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Agreed, David…
To summarize; releasing the pedal, the master cylinder pistons move to open to the reservoir - to bleed fluid back. Brakes can only stick on either if the pistons stick in the bore - or fluid is not bled off the caliper(s). Fairly high pad pressure is required for braking effect - the odd thing is that it is heat related. which sort of complicates the search. There should be some disturbance in the reservoir when the pedal is released…?
And with brakes hot and scrubbing; opening bleed valve may be a clue for hydraulic locking…?
Frank
xj6 85 Sov Europe (UK/NZ)
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So I ordered yellow stuff pads and vented discs from ebc not slotted just street stage 5! And two new hoses will see once I install I have a warped rotor on drivers side so I’m replacing both will post my results. Thanks gentlemen for all your suggestions and help it is much appreciated! It’s a real bummer driving with brakes that have an issue!
So I replaced brake rotors and yellow stuff pads from ebc. The brakes work fine now no staying on now I have to drive easy for 200 miles. Then bed the pads in from 60 down to 20 mph. I noticed that my drivers side caliper had a lot of air when bleeding the brakes maybe this might have been a part of the problem! I purchased my parts from buybrakes.com for 215 bucks free shipping and a 10% of coupon so well worth the money will post an update after 200 miles! Thanks for all help and suggestions.
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Air sounds like a problem. But it means your brakes must have been very spongy in the first place.