| Author | Message | ||
     Koby Millo New User Username: kobym Post Number: 8 Registered: 7-2011 |
Hi, I have 2 issues with my 1976 Silver Shadow and I hope to get some advice: 1. Steering wheel's vibration at 80-120 KPH. It happens only when the car is warm, and only on acceleration, not on constant speed. Things done already: Wheel balancing, replaced wheel bearings on all 4 wheels, rebuild driveshaft (new joints and balancing), replaced rear axle joints (all 4), replaced 2 front suspension ball joints. tires are new. Still have the same annoying vibration. Any ideas? 2. Strange clicking noise from the left hand side rear suspension ram. The ram was rebuilt 3 years ago with a new kit, and the noise exist from the start. When switching the car off, there are noises from the ram until the body sinks down. Any idea other than removing the ram and taking it apart? Thank you in advance for your help, Koby | ||
| h_kelly Prolific User Username: h_kelly Post Number: 254 Registered: 3-2012 |
Koby, in relation to point 2, the clicking noise may be air in height control ram?. I'm sure others will confirm/deny | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 2025 Registered: 5-2012 |
Hi Koby What a nightmare these vibration issues can be. Two other possibilities are worn propeller shaft hardy spicer joints and rear engine/gearbox mounts. | ||
| Martin Taylor Prolific User Username: martin_taylor Post Number: 139 Registered: 7-2013 |
Check for correct ride height, the drive shafts should slope down when standing so will be level during acceleration, if your springs are softer than usual you may need it higher to make this happen. Check also that the diff housing is secure to the boot floor and the reinforcing has been done. If not the diff will twist when the rear squats on acceleration and everything goes out of line. The car should not sink when left standing, if it does you have an internal leak in one of the levelling valves. The knocking noise is usually air as suggested previously. | ||
| David Gore Moderator Username: david_gore Post Number: 3016 Registered: 4-2003 |
Also check backlash on steering box: http://au.rrforums.net/forum/messages/17001/31084.html?1525423938  | ||
| Patrick Francis Prolific User Username: jackpot Post Number: 251 Registered: 11-2016 |
I concur with Martin. If my rear suspension is low, I get vibration which is worse under acceleration, and feels like it might be coming from up front. Initially I depended on my self levelling to keep her on an even keel unladen, but I eventually replaced the springs and packed her to a level ride height unladen. Now the self levelling only works with extra load or passengers. | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 268 Registered: 7-2012 |
Recently discovered what I consider the "Holy Grail" of info. If one goes onto Bentley Heritage site, under technical heading are all (most) Service Bulletins relating to Shadow. They list 1972 0n first, so need to scroll down for pre 72. There is a mine of information (and part no.s). Relative to this discussion under section H17 is how to adjust standing height, with graph of no. shims fitted- and what is required (assuming springs ok)Also is Service Info sheets and Shadow 1 Service manual. Maybe someone has seen the enormous work that you guys at RROC-AU have done and feel a bit guilty! Just another source of info, that can only help. reading bulletins is like reliving my youth! | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1969 Registered: 9-2004 |
"Strange clicking noise from the left hand side rear suspension ram" I set the ride height with LPG gas tank full. The springs [soft] settle when left over a period of days lovely! How can this be, With the ride height set correct and running levelling rams and shocks all the road uneven surfaces are compensated with the working rams working the diaphragm against the nitrogen pressure within the accumulators just like the Citroen system should work. Running the system infrequently causes many probs as does running the car on heavy duty springs. Car today ready for a 300 mile towing job to Worcestershire. PS important to check the trunnion oil levels with the car at ride height and the oil level plug at horizontal.   As for air within the rams that can make noises, running the system correctly after a bleed will let any micro bubbles to vent out of the reservoir caps. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 2017 Registered: 4-2016 |
Koby, I experienced a very high frequency vibration upon acceleration in my Shadow, yes this came quite bad through the steering wheel as well. You could even feel it through the floor and your feet. It ended up being a locked up viscous fan hub. Replaced hub and now 100% | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1971 Registered: 9-2004 |
Hub viscous shot, engine vibration, do check engine mounts! | ||
| Larry Kavanagh Prolific User Username: shadow_11 Post Number: 235 Registered: 5-2016 |
When accelerating the engine tends to lift at the front and drop at the rear, if the engine mounts are worn this movement may be exaggerated. I had a vibration in the steering wheel on acceleration and changing the engine mounts fixed it. On visual inspection the mounts looked good but when I removed them I found that the rubber on the front mount had almost fully separated from the metal plate. This allowed the engine to tilt and change the angle between the gearbox output shaft and the propeller shaft and I think that was the cause of the vibration. If the rams are creaking after shutting off the engine it's probably because the rear springs are weak and the height control valve levers have been set slightly high to keep the rear ride height raised. Once the engine is switched off the rear sags again and the fluid in the rams leaks slowly back to the reservoir as the weight of the car compresses the springs and the rams and shock absorbers. It causes an occasional groan as the rams and shock absorbers are settling back under the weight of the car. | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 269 Registered: 7-2012 |
There are TWO different standing height adjustments. 1. With no hydraulic pressure in system (warning lights on and having bounced rear of car with ignition on/doors open/selector in park) the car stands on it's springs only. This is referred to in workshop manual as mechanical standing height. the rams will be empty and not extended at all. An easy guide is to look at tread of rear tyre, should just disappear towards top wheel arch on rear of car when viewed horizontally at top of arch. 2. When hydraulics powered up and car running, if weight added (passengers etc.) height control valves will sense this and direct fluid to ram(s) to lift body off road spring back to a level position. This position affects vibration as diff is bolted to underside of body, and affects drive shaft angles. When in park/door open a solenoid opens to allow fast levelling. When in drive/doors closed this solenoid restricts fluid movement to rams. This system does NOT operate like Citroen cars nor Silver Spirit Models onwards, which DO use the sphere with nitrogen as damping medium. Shadow models rely on road spring and separate damper. The ram is only to lift body off road spring when this is compressed with weight. The nitrogen/sphere is only to supply reserve of pressure to stop car should engine stop running, it has no function on suspension apart from supplying pressure for rams when needed. However, if road springs are weak, this can often be compensated by height control valve arms being adjusted, effectively "jacking" body up to level by using ram piston. This of course then reduces the amount the ram can then lift body when weight added as some of it's movement (3inches) has been used up. This is why some cars "settle" when not used as ram pressure is exhausted with engine off, and car is sitting only on it's road springs. | ||
| Koby Millo New User Username: kobym Post Number: 9 Registered: 7-2011 |
Thank you all for the detailed information - It's very helpful. Two issues I noted and will be tackled soon: 1. The engine mounts look OK, but I'll take them out, inspect, and probably replace. 2. I surely need to look into the issue of ride height - the car might be sitting too low and maybe the rams are working too hard... Thanks again, Koby | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 270 Registered: 7-2012 |
Koby, I think I need to expand on how the fast/slow solenoid actually works. When energised a port is opened that directs high pressure fluid to each height control valve. This moves a fast/slow restrictor valve within each height control valve that will allow the free flow of fluid to the rams. but only if this passage has been opened by the arm of the valve being moved by weight being added to car. Once the body has been lifted off road spring the height control valve returns to it's neutral position trapping what fluid is in ram. When drive engaged, doors shut solenoid is de-energised and therefore signal pressure into the height control valve is removed. When car again in park etc. when weight removed, height control arm moves the other way allowing fluid trapped in ram to exhaust back to reservoir, again until neutral height. The solenoid valve will be energised, allowing free flow of pressure through height control valve. Whilst all this is happening, the engineers at Crewe decided to put two line restrictors in system to avoid "plumbers knock" similar to turning a tap on/off fast at home. There is one on high pressure line from solenoid to height control valves and one on return line to reservoir. When these (moreso low pressure one) become clogged up, they have effect of partially keeping the fast/slow restrictor valve in each height control valve open that has effect of the rams trying to alter caused by the movement of the suspension under normal driving. This is the knocking that can be heard from rams, This is normal if going from reverse to drive quickly with steering turned etc. or on slope, but not normal driving. Hope I have shed bit more light and not more confusion! | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1975 Registered: 9-2004 |
Gordon did the factory do any testing with towing in the Shadow development? you say "The nitrogen/sphere is only to supply reserve of pressure to stop car should engine stop running, it has no function on suspension apart from supplying pressure for rams when needed" I would say with towing, pressure to the rams is a must. More on the towing at speed later! Imo after thinking what I carried out years ago, the memory may be fading but the car with the weaker springs with the sagging rear end was over come with rubber helper spring assisters and for running loads the trim height correctors were set engine running and full petrol tank and LPG tank with drive shafts level. After todays towing thought I would check the 363 fluid level all ok but feeling the tank, boy was it hot! I think a run down to Portugal [no trailer] would be fine as IMO the car drives far better now its had a long drive, long to me but some on here probable do more miles in a day. Will ckeck the rear brillo mounts as the road noise from the car loaded can be quiet on some surface and noisey on others! Call me daft but after trips I open the oil filler to let any condensaion out or to see any crankcace vapor, todays trip none, would hate to have a camshaft job.  BTW Sagging rear KPI will be effected! | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 271 Registered: 7-2012 |
Patrick, You must think of the way the system on a Shadow works as opposed to Citreon/Silver Spirit/Mulsanne. When weight added to car, passengers, luggage in boot, tow trailer. In a Shadow the heIght control valves will send fluid to the rams to level body up as far as they are able (3in max extension). Once on the move this fluid is effectively locked in rams. The suspension operation is then controlled by the road springs and dampers. the rams have NO effect on this, just levelling body up, even when they are fully extended. I never remember any one at Crewe talking about tow bars in the 60's/70's. I do not recall Crewe offering one. Spirit/Citroen operate differently where fluid is pushed into the sphere on the top of each strut/damper unit by the action of suspension movement on the road and pushed against the diaphragm in the sphere that squeezes the nitrogen on the other side of the sphere diaphragm that acts as a damping medium. That is why when on Spirit/Citroen the nitrogen permeates away the suspension (rear on Spirit) goes hard and the ride becomes "choppy" | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1985 Registered: 9-2004 |
Gordon, thanks, to clarify with the rams traveling up to 3" travel, lifting the body against the floating spring shock assembly, so fitting spring assisters years ago will have stopped sagging if the loading made the rams stop in their fully extended position without running on the bump stops. I wonder what the total noise weight on the tow hitch would be before this would occur. So, we must have a slow height compensation on route to allow for the weight of loss of LPG and petrol? | ||
| Larry Kavanagh Prolific User Username: shadow_11 Post Number: 240 Registered: 5-2016 |
I would be concerned if the fluid reservoir feels very hot, that usually signifies an internal leak in a valve - more than likely an accumulator control valve. If the fluid gets too hot it can cause seals to wear and then the internal leak becomes worse. Too much heat can also cause the hydraulic fluid to become too thin which can also result in wear on valves. I would recommend that you do a pressure test on the accumulators to verify that they are working within normal limits. If the ACV is holding pressure correctly you could test various hydraulic components e.g., height control valves and solenoid valve with a laser thermometer to see if one component is producing more heat than the others and hopefully narrow down the problem that way. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1988 Registered: 9-2004 |
Thanks Larry. Should of checked the temp however the whole engine bay was hot when the bonnet was opened. Pumps sat on top of the engine will have some bearing on fluid temp with more braking in the every day high density traffic now a days. If it an't broke don't fix it!!!!! Well unless it comes under service time items IMO. | ||
| Larry Kavanagh Prolific User Username: shadow_11 Post Number: 241 Registered: 5-2016 |
Hi Patrick, You may be right when you say "if it ain't broke don't fix it". These engine bays tend to get hotter than most ordinary cars. It's a big lump of a V8 with 2 exhaust manifolds fitted into a tight space. The viscous fan plays a very important part in drawing cooler air through the radiator and circulating the air through the engine bay also. Maybe if you do a laser thermometer test on your thermostat housing it will give you a clue as to whether or not the viscous fan is doing its job properly. I recently replaced my viscous fan coupling as the temperature gauge was rising more than usual in traffic and the temperature in the engine bay has reduced noticeably since. With the new viscous coupling the temperature at the thermostat housing has reduced from 205F to 185F when hot. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1989 Registered: 9-2004 |
Larry yes I thought I would do some checks to-day, that was a no go re starter motor. New thread on that. | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 272 Registered: 7-2012 |
Patrick, did not wish to complicate things any more than necessary, but even when solenoid valve de-energised so that the fast/slow level valve in the height control valves are in the slow level position there is a certain amount of "leakage" designed into system to allow for alteration of fuel load etc. over a trip. Can't remember the actual numbers, but they are in manual. This is so the car does not end trip "jacked up" at rear as fuel tank goes from full to empty. clever of them at Crewe! | ||
| John Rowney Experienced User Username: johnrowney Post Number: 40 Registered: 2-2015 |
I had vibration problems for some time on my Corniche DRH32489 between 90 and about 100 kph. I did the usual things wheel balance, alignment etc. All to no avail. Steve Sparks of NBS Services in Brisbane related to me that his father, Barry, had a similar problem years ago with a Shadow(?) years ago and fixed it by running the tyres a lower pressures. I then ran the Corniche at the factory recommended pressures and the problem went away. |
