Rear height control problem: RR SS 1

[varsas]

Hi.

I'm making fair progress with the hydraulic systems on my 1969 RR Silver Shadow 1. The brakes now work, which is an improvement, so I'm trying to fix the rear height control suspension. The front doesn't work either, as it has been disabled, but that's for another day

The situation was that the rear height control did not work, the car seems to be resting on it's 'normal' suspension. The offside ram would bleed (opening the bleed valve sent a jet of hydraulic fluid squirting out, this would grow in intensity if someone pushed down on the back of the car, and reduce if someone lifted it) but the offside would not. I determined there was feed to the nearside valve (loosening the appropriate pipe fitting would cause fluid to leak) but none at the ram. The actuating rod seemed to be about right. Because of this I decided to change that heigh control valve, which I have now done. Most of the pipes/hoses looked pretty grotty, so a lot of those were renewed too.

The situation now is that:

The accumulators bleed and hold pressure (brake pump test)
All brake bleed points bleed
No suspension bleed valves admit any fluid and there is no feed to the height control rams (disconnecting the puipes to the rams does not result in a boot full of hydraulic fluid)
There appears to be feed to both rear height control valves (again, fluid seems to be present at quite high pressure at the inlet ports)
There appears to be feed to/from the solenoid valve

Anyone got any idea's? I have tried disconnecting the control rod from the 'new' valve and actuating it manually, with the bleed open to no avail.

Am I right in thinking that if:

The height control valve is functional
and
It has a feed
and
The control arm is actuated

Then

Fluid will be emitted from the outlet, regardless of the control inlet and return?

My car does have a solenoid valve and a roll control valve however my understanding is that these affect the rate of operation of the valves, but would not stop the valves letting any fluid through. Is this where I am mistaken? If so I assume one or other of my roll restrictor valve or solenoid is faulty...

Thanks in advance!

[ADP68]

I cant help at all other than asking if you've seen this
http://www.rrsilvershadow.com/ETechn/Hydr/Menuhoog...
Or perhaps the Australian RROC site?

[ecurie]

There is an interesting animation on the hydraulic system which you can download following this link.
It really helps to understand how the system works.

http://www.samag.no/silvershadow/

[varsas]

Thanks for the replies.

More reading to do then! Not a bad thing.

Sadly that model isn't quite accurate to my car, must be for a car after the deleted the front system and roll restrctor but before they removed the connection to the doors. It also suggests the self levelling and brakes do not work with the engine off, which I very much doubt is true, and certainly is not on my car (the brakes at least work with the engine off). Neverthless it is interesting, at the very least it rules out the solenoid as being the issue.

[ecurie]

The brakes will indeed work with the engine off, but only for a limited amount of time.
The hydraulic spheres still hold some pressure but by using the brakes the pressure will go down.
Just keep pumping the brakes and in the end you will have none left.

[varsas]

ecurie said:

The brakes will indeed work with the engine off, but only for a limited amount of time.
The hydraulic spheres still hold some pressure but by using the brakes the pressure will go down.
Just keep pumping the brakes and in the end you will have none left.

Thanks for confirming, that's as I have experienced on my car.

Do you know if the self levelling suspension works with the engine off?

I always assumed it does but that model says not. The workshop manual states the engine should be run before (not during) bleeding so I have been bleeding with the engine off but if that stops the suspension working (how?) that would be the source of my problem!

[ecurie]

I always bleed the system with the engine running as I read it differently.
You run the engine for at least 4 minutes to make sure the hydraulic system is fully pressurised and then you keep it running during the whole bleeding process.
Only when bleeding the front pressure switch, you must turn the engine off as that is dangereously close to the front belts and fan.
Make sure you remove the gearbox thermal cut-out that sits in the fusebox under the glove compartiment. That way the car cannot be put in gear by accident.

When I bleed the rear suspension I put a few hundred magazines in the boot to make sure the levelling valves have to work.

Edited by ecurie on Wednesday 18th March 10:46

[varsas]

OK, thanks for the input.

It's certainly easy to try bleeding with the engine running so I'll give that a go. I hope that's all it is! I've seen you can get hydraulic pressure gauges from eBay for £10 or so, that'll be my next step...just work backwards through the system.

[olnmfc]

Bear in mind you need the brake pedal pressed to bleed with the engine on. This bleeds the high pressure system. Only open the bleed nipple slowly and a little due to the pressure. A 69 Shadow should have the low pressure brake system too which works on the lower rear calipers only. This means you do have brakes with the engine off even when depressurised albeit only very light brakes. A sort of fail safe system. The rear suspension bleed is done with car on ground rather than on hoist with weight in boot, in neutral and door open engine on, revs tweaked up... so much to remember. You can check if it's working by starting engine and looking at tyre to arch gap and if its increasing. This should take a few minutes and only be 1 or 2 inches on a car with old springs. Also bear in mind that in 69 RR decided that the front suspension levelling would be disabled at the factory as it was not making much of a difference. Much of the apparatus was still left on the cars however of that date. So your front may not work cos it's not supposed to