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Brakes: Nothing, then Everything!

Discussion in 'Brakes' started by Tom Rymes, Mar 18, 2017.

  1. Tom Rymes

    Tom Rymes New Member

    I recently purchased my first P6, an early 2000TC NADA. It is early enough to have a generator and a single-line brake system. I haven't been able to get it out on the road much, due to snow and salt, but while I was out, the brakes seem weak at first, but when you press further, they seem to come on all of a sudden. The car stops well and in s traight line, and the brakes do not seem to be sticking.

    I presume that the brakes are Dunlops (I have yet to be able to check), and the servo is a Lockheed. I have reasonably recent invoices for work on the calipers and the servo, but I'm not so certain where to start with troubleshooting.

    I was looking at a photo I took (attached here), and I noticed what looks like an unusual setup for the servo, where a hose exits the rear section of the vacuum chamber. I will have to have a look at where it goes, but I have only seen photos online where that hose should go to the white plastic air valve on top of the cylinder. It looks almost like the rear plate was rotated. I will have to go have a closer look and see what is up with that, but I don't see hoe that could cause an issue unless the hose is kinked.

    I'm certain that more information will be needed, but does anyone have any thoughts based on what's here?


    Attached Files:

  2. Vern Klukas

    Vern Klukas Member

    Your car should be Girling, not Dunlop, unless your serial number has a A suffix. If that was the original servo rebuilt, then it is almost assuredly a Girling car, the Dunlop cars used a different servo except during the transition to Girling, when you'd get a mix of bits.

    As for the odd hose, the servo has been assembled incorrectly. Properly, the air valve (white plastic bits on the cylinder) and the outlet the hose is attached to are aligned, and there is a short hose between the two. The air valve is meant to point upwards when installed.

    Can't comment on the sticking brake action, but the servo being put together wrong suggests some incompetence at worst and amateur ignorance at best. So there may be other things amiss.

  3. colnerov

    colnerov Well-Known Member

    Hi, Yes indeed that hose should go to the air valve and as said is usually only as short as possible, not halfway round the engine bay. The unpredictable operation of the brakes does point to an air valve problem, so correct the plumbing and alignment first before proceeding further

  4. Tom Rymes

    Tom Rymes New Member

    Vern: My car's serial does have an "A" suffix.

    I made it over to where the car is, and that hose does connect to the air valve. It looks like the rear of the vacuum canister was rotated to allow the air valve to be placed in this position while aligning the mounting studs with the bracket. I had an MGC with a pair of Girling Mk2 servos, and this is certainly not one of those, and it looks to be a Lockheed, or perhaps more likely a PowerTune.

    Based on this thread on a Lotus Elan forum, the powertune is a Lockheed knockoff. Then, based on the image on page 5 of the PDF linked in that thread (too big to attach here - I tried....), the cylinder should be installed as it is in my car, namely tilted upwards with the air valve rotated off-center, too. Does anyone have photos of other P6s with Lockheed servos installed?

  5. Tom Rymes

    Tom Rymes New Member

    Another item of note, which led me to my guess that the rear was rotated, is that the rear of the servo has only two studs, not three. Of note is also that those nuts are loose and need some tightening before I go back on the road!
  6. Demetris

    Demetris Well-Known Member

    DSC00084.net.jpg DSC00085.net.jpg It definately looks like an incorrect servo assembly. At least.
    This is what mine looks like. Apparently only two of the 3 studs are used to bolt it in place.
  7. Tom Rymes

    Tom Rymes New Member

    It looks to me that it's clearly not original, but looking at yours, it sure is nice to see that it is mounted with the cylinder in the same orientation.
  8. colnerov

    colnerov Well-Known Member

    Hi, If you do a Google image search for 'Rover P6 engine bay' It seems 4 pots have them below the centreline and the V8s have them above. They're ostensibly the same servo, just different sizes. Earlier I did some research and both ways can have quirks, above they can give bleeding problems, the solution was to dismount the servo off its brackets and have the hydraulic part pointing more upright. Oriented below, fluid can get between two 'O' rings and lock the air valve piston up, Lockheed's answer to that was to remove one of the seals. So I think its a case of 'you pays your money and makes your choice'.

  9. Hairyrover

    Hairyrover New Member

    The fluid outlet from the servo should be pointing up and the air valve down. There is a very short rubber pipe between the air valve and the rear casing of the servo. The powertunes do not get a very good right up,being a cheap copy of the Lockheed units.

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