Replacing the brake pressure switch - Spanner rating anyone?

R

Rovertron

Member
Hi, it seems that my brake pressure switch has given up the ghost on me. It seems there's a large nut at the bottom of the junction, is this what I need to go for to replace the switch? There looks like a cut O-ring too right before the switch terminals. It looks a tight fit as part of the wiring loom running underneath it. Can I expect some serious fluid leakage?

I know that the workshop manual states bleeding the fluid on all four corners and a refresh.

I'm a bit wary of messing with the brakes and know that the rear bleed nipples are a pain to get to. The MOT is due in a few weeks, I was going to have a brake fluid refresh done as part of pre-MOT 'service'. I can jerry rig a manual switch to get me there.

Is it worth holding fire and getting the lot done at the garage as long as the replacement switch doesn't take too long in labour costs?

Cheers.
 
When mine packed up it took me more time digging out the right size spanner than it did to change it :p
once its off,there is only a dribble of fluid,I got my bruv to put very!!!! gentle pressure on the pedal as I tightened it up,this stopped any air bubbles and I have had no trouble at all!!
I have done this twice in 4yrs,easy job!!
tools needed,
a spanner that fits well!!
and a cloth + somewones foot :p
 
Many thanks for the info and tip, that sounds like my kind of job. It looks like a fair size nut admittedly.

Cheers.
 
where in uk are you?? maybe there a member who could possibly help just down the road!
 
Before you commit to changing it, just make sure you give the terminals a good clean and tap the switch lightly with a hammer, this often gets it working again.
 
Rovertron said:
I'm a bit wary of messing with the brakes and know that the rear bleed nipples are a pain to get to.
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Only one nipple on the rear & it's nigh on impossible to get a pipe & spanner on it. Often thought of trying to fit a metal pipe with the nipple on the end of it which would be far more accessible. Anyone else tried that? ???
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webmaster said:
Before you commit to changing it, just make sure you give the terminals a good clean and tap the switch lightly with a hammer, this often gets it working again.
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Hi,

Already tried whacking it as well as new terminal connectors and some emery cloth and it worked for a while. I was trying it out and needed more and more pedal pressure to get it to work and now it's completely dead. The fluid is clean and I'm only changing it on a two-yearly cycle regardless of condition because I'm a fastidious sort.

Thanks for the advice, the missus has gladly agreed to apply 'gentle' pressure at the vital moment.

It's the curse of the MOT I tell you, two days before last year's I had an entire rear light cluster suffer a mysterious 'no lights' problem.

As for the rear bleed nipple, I'm told one of the smaller 'flexy' ratchets can get to it but over-zealous tightening is a problem as there is less torque available.
 
I see there's a kit on the market to extend the 2 rear brake nipples on an E type Jag with 2 flexi hoses so I don't see why something similar shouldn't work on a P6

I find the hard part is getting the bleed tube onto the nipple
 
Well, the weather held off Sunday long enough to get this done.

I found out three important things.

The large nut part of the old sensor is around a 20mm or 21mm spanner (don't ask me in old money my AE spanners only go to 3/4''). I had a good quality monkey wrench, naughty, but offered up the best fit I had available.

The area around it is fouled by the exhaust manifolds, dizzy wiring and the odd copper brake pipe (yikes) there's about 1/4 turn play and choice of long armed spanner is limited.

WD40 is your best friend especially after 38 years of long distinguished service from the old sensor. A little tightening action followed by a loosening soon had the thing free.

Thanks for all the advice, one SWMBO's foot on pedal whilst tightening up solved bleeding the brakes.

I now have stop lights, MOT beckons.....
 
DaveHerns said:
I see there's a kit on the market to extend the 2 rear brake nipples on an E type Jag with 2 flexi hoses so I don't see why something similar shouldn't work on a P6

I find the hard part is getting the bleed tube onto the nipple
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Are the threads the same as the Rovers? If so, one kit should do 2 cars with us.
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I've notice a few people in trouble with this pressure switch.

Has anyone out there tried abandoning this switch in situ and replacing with a spring operated pull switch off the brake pedal? If so any guidance on where the components came from etc?

Regards

Chris
 
This crossed my mind, I have the Workshop manual containing the then NADA car (confusingly referred to as 3500S) and my Series 1.

The NADA car has a pedal operated switch and it looks a bit complicated to remove and refit. I don't know how difficult it would be to source a NADA brake switch and then fit it. I'm making a big assumption that the NADA/Series 1 componentry is sufficiently common.
 
I have had repeated problems with this switch on my 3500S - I then bought a "stock" of them a while back (having had 2 failures in 2 years). Most recent one has worked for the last year and a half so fingers croissed.

However - when I asked about this a while ago another member of the forum mentioned that he had had so many failures of this switch in the past that he had converted to a "mechanical" switch. Might be worth asking him what he did. I think it was John Larkin - but not 100% sure
 
A friend of mine in UK and Austin 1300 owner (they use the same switch) went through a switch about every 3-4 months.
There must be something with a batch of faulty switches.
 
I have problems with the pressure switch too, in that it only operates with extreme pedal force. Replaced it with new switch from Scott's Old Auto Rubber (Australia) but to no avail. I am looking at the alternative of a micro switch, possibly accessed from an instrument supplier here in Cairns. Have just spent $1800 on brake overhaul but now, after two attempts by the brake shop, still have no rear or hand brake. Ideas?
 
Harry said:
Have just spent $1800 on brake overhaul but now, after two attempts by the brake shop, still have no rear or hand brake. Ideas?
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Are you confident they know what they are doing with p6 rear brakes?? have they got a piston re-setting tool!
If you have no rear foot brake,;- you either have a collapsed flexihose or line blockage somewhere,caliper pistons put in upsidedown! transfer strut missing,self adjusting mechanism is knackered!!
hand brake not working;- cable streched,can lever tappet pins in caliper dropped out of grove,transfer strut missing,self adjusting mechanism is knackered.
if they bleed well with good pressure though the nipple,no blockage. if the pads only just do move when foot or handbrake is applied,its the self adjusting pawl or ratchet on the pushrod. I adjusted mine when my self adjust was knackered,by screwing the adjustment so I could not get the pads in,then screwing the adjuster piston back till they only just went in with a little persuasion 'lightly tapping with small hammer' starting with the innermost 'bigger' pad first!!,coz its easier to get to and tap the outer one in/out last.
if you get a good blown up diagram of the calipers that will help in knowing how it all works.
good luck
 
Pilkie O,
No, I am sure they don't know what they are doing when it comes to P6.Took them 3 months the first time. I really think it is a problem with the adjusting pawl. I even gave them copies of relevant manual pages. Thanks for your tips, I may have a go at it myself but I would really prefer them to fix it. Harry..>>>>>>>>>>
 
Hi Harry,
I agree that they should fix it.as they have charged you for something that does not work!! you could always find a specialist and get them to sort it and send the bill to the other garage,or get a big chunk of your money back
 
Harry said:
Have just spent $1800 on brake overhaul but now, after two attempts by the brake shop, still have no rear or hand brake. Ideas?
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Doesn't really matter how much it cost you, if whoever did the job didn't know what they're doing they'll never get it right. Although there are dozens of things they could have got wrong if they overhauled the calipers, if they bought in recon units chances are they have not adjusted the calipers properly, and then have tightened up the cable to compensate, which just makes the calipers not work, giving the problem you've got. (I've fixed more than I care to remember after so called "experts" have done the job)
Personally my view of the girling pad tool (for winding back the piston) is that it's worse than useless, but there you go.

If you can post a picture of the handbrake quadrants (with the handbrake OFF) I can tell you if it's incorrectly set up.
 
Hi from Australia
I have had problems with the brake pressure switch; waste of time replacing them. the best solution is to fit a microswitch on a bracket above the brake pedal (AUD$13) and wire it to the light circuit. Works perfectly and also emits a little "click" on operation to let you know it's working.
Regards, Harry
 
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