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Post by roversmark on Jun 10, 2021 14:59:07 GMT
I wonder if anyone can help me?I have a 1966 Rover 3 litre mk111 saloon -my mechanic tells me i need a new Control cylinder for the brakes that bolts on to the vacumn chamber.
I already have fitted a new Brake Master cylinder but i gather another cylinder exists?
Can anyone help me
Thank you, Mark
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Post by Phil Nottingham on Jun 10, 2021 16:08:17 GMT
He may mean the vacuum tank under the wing?
This is not required if you convert to the P5B Lockheed servo under the manifold? Spares for the original obsolete and unreliable Girling unit are not worth the hassle so its best to convert. See Wadhams website
David Green may have a secondhand vac tank
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Post by harvey on Jun 10, 2021 16:21:09 GMT
The cylinder on the right in this pic.
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Post by Phil Nottingham on Jun 10, 2021 21:14:11 GMT
Not aware these are available now separately?
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Post by enigmas on Jun 10, 2021 23:17:29 GMT
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Post by harvey on Jun 11, 2021 10:25:53 GMT
Not aware these are available now separately? I don't think so, but easily sleeved and resealed. |
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Post by MK IA Norway Viking on Jun 11, 2021 11:54:24 GMT
Hello Mark. I have an MK IA and think the MK III have the same design on the braking system.
Be proud, for you have in what some people see as the ultimate P5, since you have the most developed Rover that retains the original engine design cooked up by the Wilks Brothers with their mechanics in the 'thirties.
In essence, the braking system is a single circuit hydraulic system consisting of a master cylinder (brake pedal acts on this), a brake service unit and a vacuum reservoir.
The only purpose of the reservoir is to have power assisted brakes without the engine running.
Energy for the brake servo comes from the intake manifold, where vacuum from the combustion chambers is the source of power for the braking system.
The number one culprit when there is a failure on the braking system is the brake servo. It is seldom that the master cylinder is faulty. If the vacuum reservoir is faulty it will have no consequence whatsoever as long as the engine is running.
The brake servo needs to be in use, otherwise it will dry out and the vacuum on the brake servo vacuum side will suck braking fluid into the "big" end of the servo. From there the fluid mixes with fuel/air and enters the engine and out with the exhaust fumes, making hte exhaust white.
You can either send your servo unit to JRW for overhaul / exchange or you can DIY with a servo kit that JRW will sell to you. JRW's kit is superb.
It is easy to fix the problem - take off the cover on the big end of the brake servo, slowly release the pressure of the spring & take out the piston.
Drain the brake fluid you will find in there, gently remove traces of brake fluid and grease.
Re-lubricate / replace the soft rubber ring on the piston, lubricate the walls of the vacuum chamber (the big end, about 15 cm across) in which the big piston travels (so it is not a "dry fit" and replace the original o-rings with those that come with the service kit.
Replace also the gaskets etc. that comes with the service kit.
Excluding building the servo out and into the car, the overhaul of the brake servo should take between 1 and 6 hours depending on degree of skill and experience. Your brake-systems workshop could do it as well.
The worst thing that will happen if you do this wrongly is that the power assisted brakes will either not have any power assisting at all or that brake pressure comes "not evenly". I once did an overhaul that caused the brakes to jam on.
Good luck, mate !
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Post by Ken Nelson on Jun 11, 2021 15:24:36 GMT
Very educational explanation. Thanks for that. I do recall trying unsuccessfully to rebuild my original Girling unit 20 years ago and then finally obtaining a used Lockheed unit (from a later P5 I believe) that seemed much easier to rebuild and that has worked fine ever since.
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Post by roversmark on Jun 12, 2021 16:21:13 GMT
Thank you for this helpful advice ,Mark
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Post by roversmark on Jun 12, 2021 16:23:04 GMT
Such great advice - im very grateful ! Mark
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