Post Number: 123
|Posted on Saturday, 19 January, 2019 - 01:12 pm: |
Noticed lately my newly purchased 79 Shadow makes a "knocking or rattling" noise in the rear when going over bumps. It sounds just like the noise when the shock bushings are bad. The bottom bushings look fine, but wondering about the upper bushings. Are the bushings hard to replace on the rear? Any suggestions/ideas appreciated!
gordon le feuvre
Post Number: 289
|Posted on Saturday, 19 January, 2019 - 08:35 pm: |
To confirm whether it is hydraulic system resrictors blocked or actual upper damper bushes you need to get to know the difference in sound. The restrictors are in the hydraulic line that feed the signal from the solenoid valve to each rear height control to allow rear suspension to level fast when in neutral/park or doors open. when in drive whatever oil is in rams at top of rear dampers is effectively locked there to maintain height of car. However, if restrictors blocked this leaves residual pressure acting on height control valves which manifests itself as fluid trying to get into/out of rams causing the knock. The best way to test is find safe slope and the go from forward to reverse on lock. As body of car moves, coupled with action of going from drive to reverse through neutral you can hear rear ram knock. After a few attempts, you will be able to tell whether this is your noise or not. Fix is to remove clean out restrictors, which are on rear cross member. If top damper bushes, need to remove rams for access to top damper nuts and then remove whole damper which is 60-70cm when extended from under car. There are lots posts already regarding restrictors and damper removal
Robert J. Sprauer
Post Number: 108
|Posted on Saturday, 19 January, 2019 - 11:44 pm: |
One of the signatures of the hydraulic ram knocking is that it may continue after the car is driven, sometimes for hours.
The rear differential carrier has 2 mounts/bushings on the top corners that are known to weaken (factory serv bulletin) and the triangular torque plate on the side has a bushing that mounts to the body pan (this get alot of movement).
There are also 2 control tubes on the rear suspension with bushings.
The exhaust hangers have alot of movement and weaken over time creating movement.
A loose jack has been known to make noise as well.
This will be a process of elimination and a lift will be helpful.
Post Number: 271
|Posted on Thursday, 24 January, 2019 - 10:30 am: |
On the subject, I seem to get a knocking from my right hand height control valve. This is evident when I move back and forth from neutral into either Drive or Reverse (slow to fast self level). It is quite a pronounced click or knock and definitely comes from the RHS height control valve only.
Although I have bled the system well,I was wondering if there might be some air trapped in the height control valve which is causing the piston within to click closed and open when receiving the signal pressure from the solenoid valve.
The other thought was the restrictors. This is because when I work the valve levers by hand, the LHS self levels much more smoothly that the RHS.
Also when I activate the levers with the gear in drive or reverse (slow levelling), I notice no movement at all, from either side.I am not sure how slow the slow levelling is?
I am thinking:
Clean restrictors, rebleed and think again if it still occurs.....
Ideal opportunity to change to YAK!
90% DOT 3 or 4, 10% Castor Oil - am I right?
What is the latest thinking on YAK? Can I mix it with existing, or better to bleed out as much of the old 363 as possible?
Post Number: 272
|Posted on Thursday, 24 January, 2019 - 10:48 am: |
Experience that I have had with knocking is that it may come from anywhere! (great help, I know)
1. I have a rattle and knocking which came from the horizontal torsion springs that open the boot. They go across the body between the boot hinges and sometimes have rubber hose that stops the springs knocking against each other, I put a couple of tie wraps and sponge to keep them tight.
2. Try moving from drive to neutral and back a few times and see if you hear any clicking or knocking and get someone to listen to where it comes from under the car. May locate something in the self levelling system. Foot on brake when doing this.
3. I changed the top bushings on my shocks. You have to remove the rams, undo the top nut on the shocks and then remove them downwards. The car has to be on a lift otherwise there is no room to remove the shocks. Mine were rattling, and I heard that by removing the carpeting around the rams in the boot, disconnecting the self levelling levers and convincing someone to lie in the boot whilst I drove around.
I hate to be negative, but after all that, I still have an occasional bl*&dy rattle.
Post Number: 215
|Posted on Thursday, 24 January, 2019 - 11:49 am: |
Likely the restrictors are clogged with debris from deteriorating hoses, dismantle and clean. Yes just add the new mix to the 363, unless the fluid in there is over two years old. 10% is close enough, use castor oil for remote control model aircraft. If you want exactly the same viscosity as 363 use 9.25% castor oil.
SRH8505 SCR18015 SRE22493 NAC-05370
Post Number: 273
|Posted on Monday, 28 January, 2019 - 05:30 am: |
Any harm with using cold pressed, unrefined Castor oil? I can get both, just that the cold pressed seems to be more available.
Post Number: 2756
|Posted on Monday, 28 January, 2019 - 06:39 am: |
I would not use unrefined, if that also means unfiltered. In any case, it would not be my preference.
I've always used pharmaceutical grade, which is available at virtually any pharmacy in the USA.
The refined stuff meant as lubrication for model airplane engines, which operate at far more extreme temperatures than our hydraulic pumps ever do, is available online from many sources. Here is one: https://sigmfg.com/products/sig-castor-oil
richard george yeaman
Post Number: 1044
|Posted on Monday, 28 January, 2019 - 09:15 am: |
I buy my castor oil from the pharmacy, I have to order it as it is not available over the counter, apparently it can be used in abortions.
Post Number: 274
|Posted on Monday, 28 January, 2019 - 08:10 pm: |
Thank you Jim, Brian, Richard for your advice. Will keep you posted.
Post Number: 3122
|Posted on Tuesday, 29 January, 2019 - 06:27 am: |
A hobby supplier for model aircraft flying enthusiasts should be able to supply suitable refined castor oil as this is widely used to mix suitable fuel for the engines.
Post Number: 325
|Posted on Tuesday, 29 January, 2019 - 06:53 am: |
I get my pharmaceutical grade castor oil from my local pet store. He buys it in 5 litre plastic cans and pours out a 1/2 litre for me whenever I need it. I reckon he's cheaper than a pharmacy but I don't know.