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Alan Rowson
Yet to post message
Username: arowson

Post Number: 1
Registered: 4-2016
Posted on Thursday, 05 May, 2016 - 07:02 pm:   Edit PostDelete PostView Post/Check IP

Just completely rebuilt the hydraulic system, brakes and height control on my '79 SS2. It all operates perfectly.
Before the rebuild there were all sorts of strange noises coming from the height control system, and after the rebuild, it is just the same.
If the height control system is disconnected, by putting blank plugs in the connections to the rams, there is no noise.
All the major components have been reused, except for the RH side accumulator, which was replaced. New seals and flexible pipes were fitted everywhere.
Any ideas?
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David Gore
Moderator
Username: david_gore

Post Number: 2022
Registered: 4-2003
Posted on Thursday, 05 May, 2016 - 09:12 pm:   Edit PostDelete PostView Post/Check IP

Have you bled the rams - the bleeders can be hard to find under the car?

My first guess is trapped air in the rams/height control valves.

Another possibility but very remote is you may have sourced RR363 from a particular production batch in the 1990's that was renowned for causing noise problems from the ram pistons and height control valve pistons sticking instead of moving smoothly. If you search the Silver Shadow topic using "RR363" as the keyword, you should find a post by me that has photos of the containers Castrol used for this troublesome batch of RR363.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 108
Registered: 7-2012
Posted on Friday, 06 May, 2016 - 01:02 am:   Edit PostDelete PostView Post/Check IP

DID YOU 1.OVERHAUL/CLEAN THE HIGH AND LOW RESTRICTORS FOUND ON REAR SUBFRAME2. IF THIS DID NOT CURE, TEST OPERATION OF SOLENOID VALVE AFTER OVERHAUL. BOTH THESE CAN AFFECT THE SYSTEM BY "HOLDING" PRESSURE ON THE FAST/SLOW PISTON IN EACH HEIGHT CONTROL VALVE. THIS HOLDS THE VALVE PARTIALLY OPEN. THE CAR IS THEN TRYING TO CHANGE THE EFFECTIVE STANDING HEIGHT BY PUTTING FLUID IN RAMS DURING THE NORMAL UNDULATIONS OF THE ROAD. IF YOU GO QUICKLY FROM REVERSE TO DRIVE WHEN TURNING GIVES IDEA OF NOISES AND RAM KNOCK.ALL HYDRAULIC!
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Alan Rowson
New User
Username: arowson

Post Number: 2
Registered: 4-2016
Posted on Friday, 06 May, 2016 - 06:30 pm:   Edit PostDelete PostView Post/Check IP

I have bled the rams twice, on 2 successive days and a lot of air came out, each time. Initially, it looked like beer coming out of a tap, but then went clear with no sign of bubbles..
The original hydraulic fluid has all been replaced with Castrol DOT3 mixed with 10% castor oil.
The restrictors and solenoid valve were all removed and serviced.
When bleeding the rams, does the car need to be standing on its wheels, or is it ok to have it jacked up with the wheels removed?
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David Gore
Moderator
Username: david_gore

Post Number: 2027
Registered: 4-2003
Posted on Friday, 06 May, 2016 - 07:17 pm:   Edit PostDelete PostView Post/Check IP

I bled the rams on DRH14434 with the car on stands, the wheels removed and the height control valve actuating arms disconnected from the trailing arms to allow manual operation. I would run the engine to charge the accumulators then operate the height control valves manually on each side separately with a clear pvc tube attached to the bleed nipple until the fluid ran clear, then tightened the bleed nipple while the fluid was running and returning the valve to the neutral position as soon as the nipple closed.

I had no problem with noise from the rams afterwards although they were not overhauled as part of the full hydraulic system overhaul being undertaken at the time. The height control valves were overhauled as a preventative maintenance item.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 109
Registered: 7-2012
Posted on Friday, 06 May, 2016 - 07:25 pm:   Edit PostDelete PostView Post/Check IP

Alan, you need to simulate that there is some weight in rear of car because as the body gets lower with weight the height control arm moves upwards to allow fluid into ram(s) to pump body back up to normal height. If you disconnect height control arm link at lower end where it attached to suspension trailing arm, by pushing upwards from the neutral position i.e arm horizontal, you will feel the arm movement becomes hard. If you push against this you will "crack off" the plastic/metal disc that allows the hp fluid from inlet port into height control valve to port that feeds ram. Open bleed screw and it will bleed. You must take great care not to over extend arm one way or other as this will disconnect internal actuating eccentric, which means removal of height control to refit. If you go onto Marius Rijkers feed from main page of this site, you can see operation of height control and the disc that needs to be cracked off seat to put fluid to rams. I recommend that before bleeding you disconnect link and just get feel of resistance by pushing up and get feel of it cracking off. Sorry to dribble on, but putting what I have done for 45 years into words is not proving easy!
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Alan Rowson
New User
Username: arowson

Post Number: 3
Registered: 4-2016
Posted on Saturday, 07 May, 2016 - 12:25 am:   Edit PostDelete PostView Post/Check IP

Thank you gentlemen. I basically did what you have said. The bleeding was done with the arms disconnected and I could feel the arm movement become hard and the valve open as I continued to push it upwards from that point. I also well understand the operation of the valve because some idiot mechanic had previously set them with the shaft opposite to where it should be and we figured it out from first principles. This sure helps to remove the mystery. After bleeding, I set the valve position at the point of the resistance just starting and connected them to the trailing arms, with the car standing on its wheels.
Sounds like I may need to do some more bleeding, which can't be done for a couple of weeks as I am going away tomorrow.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1002
Registered: 5-2015
Posted on Saturday, 07 May, 2016 - 09:24 am:   Edit PostDelete PostView Post/Check IP

The noises are usually hydraulic hammer. Like water hammer. A slug of oil flies down the return line for the rear rams. And Knockes on the way.

The cure is to clean and bleed the restrictors. Also use 5% castor oil.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 110
Registered: 7-2012
Posted on Sunday, 08 May, 2016 - 06:15 am:   Edit PostDelete PostView Post/Check IP

The standing height setting is in 2 parts. The first, mechanical is set with the road springs and shims. The hydraulics should be depressurised, 150lbs on each front seat and 10 galls of fuel. Once this is set correctly within spec. the hydraulic or showroom height is set with links on height control valves. As Alan says the system should be pressurised and the valves and links from trailing arm to height control valve set so that valve is just at crack off point to allow fluid into rams. For all this to happen correctly height control arms need to be in correct position on valve. People "tweek" them and alter link length to allow rams to permanently extended to compensate for sagging springs. There is a factory bulletin that easily explains how to set height with springs/shims. Even clowns like myself who attended Shadow courses at Hythe Rd were struggling! Hence the intro of the bulletin, a copy of which I'm still trying to locate to post on this site. What hope for none factory trained guys 50 years down the road, I take my hat off to you.

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