P6 Brakes,advice.

P6 Brakes,advice.

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Discussion

Old Merc

Original Poster:

3,490 posts

167 months

Wednesday 18th April 2012
quotequote all
My mate has a nice 1964 P6 and has asked me to help!! (but I`m clueless)All the discs and pads are in good condition, have been taken apart etc etc (its the type with separate hand brake and foot brake calipers at the rear),brakes bled over and over BUT! on first press of the pedal there is excessive travel,second press perfect solid pedal and it does NOT sink so I`m not thinking m/cylinder,right or wrong??.I`m thinking of the hydraulic servo ? what do you P6 experts suggest? thanks lads.

tonys

1,080 posts

223 months

Wednesday 18th April 2012
quotequote all
If no joy on PH, best bet is to post on here, very helpful forum for P6s.

http://www.classicroverforum.com/

Old Merc

Original Poster:

3,490 posts

167 months

Wednesday 18th April 2012
quotequote all
Many thanks, that looks the best place for advice.

jith

2,752 posts

215 months

Friday 20th April 2012
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Old Merc said:
Many thanks, that looks the best place for advice.
The original Rover P6 had Dunlop calipers similar to the MK2 Jag. If not already tried, use a pressure bleeding system that attaches directly to the master cylinder. This guarantees that all the air will be displaced from the system.

If you still have lost travel it is almost certainly in the servo valve. The primary seal in the servo used to fail on these cars and weep fluid into the vacuum chamber. When it got to the level of the vacuum take off pipe to the inlet manifold the engine would suck the brake fluid into the manifold and you would have awhite smokescreen from your exhaust to rival a steam engine!

Hope this helps.

J

Old Merc

Original Poster:

3,490 posts

167 months

Friday 20th April 2012
quotequote all
jith said:
The original Rover P6 had Dunlop calipers similar to the MK2 Jag. If not already tried, use a pressure bleeding system that attaches directly to the master cylinder. This guarantees that all the air will be displaced from the system.

If you still have lost travel it is almost certainly in the servo valve. The primary seal in the servo used to fail on these cars and weep fluid into the vacuum chamber. When it got to the level of the vacuum take off pipe to the inlet manifold the engine would suck the brake fluid into the manifold and you would have awhite smokescreen from your exhaust to rival a steam engine!

Hope this helps.

J
Many thanks J,I was thinking servo,its been bled many many times and as I said 1st pump is crap 2nd solid and does not sink,so makes me think its not air,we will go for the servo.A similar fault occurred on 60`s Peugeot 404`s with hydro vac brakes,they would fill the vac tank with fluid and then suck it into the manifold.