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Discussion Starter · #1 ·
I'm doing some restoration work on my '79 SSII, and have noticed over the past few days that the rear suspension is unlevel. The car goes downhill in the direction of rear passenger side. Measuring to the rear bumper from the ground, there is a difference of about 1 - 1.5 inches between the driver and passenger sides of the car (in the rear only).

I'm completely baffled by this, because I replaced the rear leveling valves, shocks and springs about a year and a half ago. They should all be fine. I can, obviously, get under the car and adjust the rear suspension levels, but I have no idea why the supension would suddenly decide to go out of level in the first place. I see no traces of a hydraulic leak of any kind.

Does anyone have any ideas on this? Ever seen this before?

Thanks!
Kevin
 

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Kevin,

Other than a hydraulic leak or adjustable perch moving it would be hard to say. Am not familiar with the rear leveling valves system and maybe that could be it but again, am not sure how that specific system operates and being a 1979 have a feeling it is more 'mechanical' than computer/electronically controlled. Other than having the shocks and springs dyno'ed to ensure close matching it would be hard to say. Again, not sure if there is an adjustable spring perch on the car and, if so, if that has come out of adjustment.

Do you have any pics of the system in question?
Is it controlled electronically?

Apologies, if my questions seem basic, yet am not familiar with that system and doing very basic diagnostics.
 

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since it is only a small difference I would suspect that the ride height adjustment valve is a bit off. Have it readjusted.
 

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This is most peculiar, that's for sure.

The height control system should never be activated in an unladen car. If you've not got people in the rear seat and/or a lot of heavy stuff in the trunk it should not ever kick in. This suggests a failure of something that keeps the system in its normal "static" state.

For an excellent overview of the height control system (and, for that matter, everything Shadow related) see Marinus Rijker's Rolls-Royce Silver Shadow site and, specifically, the pages related to hydraulics. On his diagnostic pages for rear height control, here, he has several possibilities listed for your situation. If you have had an internal height control ram seal failure it could cause the car to sink and the system would be unable to repressurize the height control ram to its default state when inactive.
 

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Discussion Starter · #5 ·
Unlevel rear suspension

guyslp said:
This is most peculiar, that's for sure.

The height control system should never be activated in an unladen car. If you've not got people in the rear seat and/or a lot of heavy stuff in the trunk it should not ever kick in. This suggests a failure of something that keeps the system in its normal "static" state.

For an excellent overview of the height control system (and, for that matter, everything Shadow related) see Marinus Rijker's Rolls-Royce Silver Shadow site and, specifically, the pages related to hydraulics. On his diagnostic pages for rear height control, here, he has several possibilities listed for your situation. If you have had an internal height control ram seal failure it could cause the car to sink and the system would be unable to repressurize the height control ram to its default state when inactive.
Thanks a lot to everyone who offered their thoughtful input on this thread. I finally broke down and consulted with a Rolls-Royce mechanic who clarified things for me. He said, for one thing, that the rear suspension is shimmed differently on the left and right sides to compensate for a full tank of gas, and it has possibly always been slightly off without my noticeing. (This is possible: I had the car stored under a car cover and tarp for good while before I got underway with my restoration work.) He also said the other possiblity is that the levelling valve on the low side is leaking internally. The symptom of working just fine, and car levelling out perfectly, when the car is running and the self-levelling system is engaged, but then the car settling out slightly low when the car is turned off is symptomatic, he said, of an internal leak in the valve. On the upshot, he said I don't need to fix this right away, if I don't want to. He said it doesn't really hurt anything and that one side will simply settle out about an inch lower than the other when the car is not runnning. He said I can live with this issue for a quite a while, so I'll get to it when I'm done with my painting, leather, and wood restoration. :D

Thanks again to all that helped!

Kevin
 

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I think your mechanic does not know his business. A Silver Shadow is designed to be level in all circumstances. The rear suspension is not shimmed. The fuel tank is slightly offset but the weight of fuel is insignificant compared with the weight of the rest of the car.
With the car unloaded, the hight is established by the rear springs only. The hight control self levelling valve and rams are only utilised if the back of the car is too low. It can be too low a) because of weight of rear passengers and/or luggage or b) the rear springs have started to sag - in which case the self levelling will be in continuous operation (not good).
If the car is permenantly low on one side, it is possible that one self levelling ram (not the valve) is jambed - holding that side of the car up or down. A visual chech is to stand away from the side of the car and eye the stainless steel lower side strip with the rear wheel disc. The strip should lead your eye to the centre of the disc. If not it is at the wrong height.
 

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Olaf,

The rear springs are (or should be) shimmed to the correct standing height.

This should be done with the hydraulic system disconnected. See workshop manual for instructions.

Once shimmed to give the correct and an even standing height, the hydraulics should be adjusted.

Front springs need to be shimmed and even as well.

Why it should have changed - perhaps it was evened up on the hydraulics instead of shimming?
 

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Discussion Starter · #8 ·
Paul Yorke said:
Olaf,

The rear springs are (or should be) shimmed to the correct standing height.

This should be done with the hydraulic system disconnected. See workshop manual for instructions.

Once shimmed to give the correct and an even standing height, the hydraulics should be adjusted.

Front springs need to be shimmed and even as well.

Why it should have changed - perhaps it was evened up on the hydraulics instead of shimming?
Thanks Paul (and all others)! Both levelling valves were rebuilt about a year and a half ago, but I can't really vouch for the quality of work that was done here. A friend of mine has a lift in his personal garage, so I'm going to run the car over there when I have the opportunity, and we'll take a closer look. We'll, hopefully, get the issue figured out.

Changing the subject...

One NEW problem the car has developed over the past 2 to 3 days, however, is a brake fluid leak. It appears to be dripping from what looks like a pressure regulator valve near the accumulator sphere on the drivers side (RHD). A puddle forms about one foot to the right of the dirver's side front tire. I'm thinking I can de-pressurize the brake system, then remove this valve and possibly install a new seal kit in the thing, but I'm not really sure.

I have maintenance records for this vehicle that demonstrate regular changes of hydraulic fluid and other hydraulic system maintenance, but I am beginning to wonder about the general health of this vehicle's hydraulic system. Are the Silver Shadow's hydraulics normally this troublesome?

Thanks!
Kevin
 

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Kevin,

The hydraulics in older Shadows, particularly ones that have not been routinely used (most important) and meticulously maintained (very important if the things are not getting "routinely exercised") are, without question, typically this problematic.

Once sorted out, they're really not that finicky, but you're dealing with a car the newest of which is over 30 years old now. The hydraulic hoses are supposed to be replaced every six years, if one follows the Crewe specified schedule. There are now aftermarket replacement hoses, available from a number of sources, that are entirely compatible with OEM specs. There is also a company, Hose Man, Inc. that can produce hoses with stainless steel armored teflon cores that should last far, far longer than originals since RR363 does not react with teflon, and it does with rubber, causing the hoses to break down from the inside.

If you want a comprehensive list of hoses for the Shadows and derivatives please download the file I've posted under the "Finding a good service shop" thread.

Good luck. You can do this. I've been sorting out my hydraulic system in bits and pieces for four years. Next are the accumulator and accumulator control valve rebuilds. I have also acquired most of the EPDM O-rings necessary to put together the majority of the seal kits, e.g., brake pump, height control valve, accumulator valve, etc. I am more than willing to put together kits at nominal cost ($5 to $10, depending on the kit) if you need/want them.
 
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