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MG MG Y Type - Shock absorbers oil change


Some two years back, before putting my YT on the road, I completely overhauled the four shock absorbers (new seals etc.) and filled them up with new damper oil (of un-specific viscosity). Since the dampers feel a bit soft, I plan to do an oil change during the dark winter month and have the following questions:

1. How do I best get the old oil out of the dampers - will a hypodermic syringe, with a thin plastic hose fitted to it, do the trick?

2. What oil viscosity should I go for to improve the dampers firmness?

Kind regards
Anton


Anton Piller

Anton,
I used a syringe as per your image to remove the fluid from my front dampers as I couldn't get them off without removing front guards.

I use motorcycle hydraulic damper fluid in mine. Not sure of viscosity. Have you checked in the TD/TF BBS archives,as the TDs had similar dampers.

cheers
Stuart
Stuart Duncan

Anton
I renewed my front shocks a couple of years ago and found a good oil designed for lever type Shocks.
Penrite
Shocker Oil 2
500ml Product code SHOK2005

If you search Penrite products you will see this is recommended.

Thanks
Royston
R T LLOYD

The following is information about Armstrong lever dampers, Peter Caldwell of World Wide Auto Parts (USA) is very well respected for his better than new exchange service on LA dampers, some years ago he posted the following in the Midget & Sprite section of the BBS.

And IF I remember correctly he put to work the oil in but leave and a bit of an air gap for expansion of the oil, but I would have to check on that for exact wording and suggest you do the same.

"Stick with the 20w oil recommended (AW [ISO] 68 spec). At most use 30w (AW [ISO] 100). Best are synthetics like Silkolene or Redline suspension oils. They hold up under heat waaaaay better than standard hydraulic oils.... and these shocks get hot."

[AW just means anti-wear as far as I can tell.]

"The SAE figures give a good guide to relative oil viscosities, however, the ISO figures, related to the true viscosity at 40°C, give a more accurate assessment of damping capabilities."

[ISO 68 / SAE 20w]
[ISO 100 / SAE 30w]

It depends where in the world you are as to which make of oil you might chose.

https://www.silkolene.com/motorcycle/suspension-fluids/sf-20/

Redline looks like you need to blend down to get 20w. - https://www.redlineoil.com/heavyweight-30wt-suspension-fluid


Nigel Atkins

Thank you Gentlemen, much obliged
Anton
Anton Piller

Anton,
I meant to put up my usual viscosity chart but forgot, I have also added brown horizontal lines to show 32 and 68 ISO.

And I have found Peter Caldwell's advice on oil filling. -

“Unlike a differential or transmission, the oil should NOT be at the level at the threads, but … below”
“The danger of overfilling is you will cause a future leak by displacing the air space necessary for the expansion of hot oil and force the oil out of the shaft packings.
The only reason you would want to add or top up the oil is if you are certain oil has leaked from the shock. Oil otherwise does not get consumed. Adding oil thusly is only a remedial repair.
Peter c.".

You can get different valves (kits) to alter the stiffness or adjustable valves (for some?) LA dampers but original damper in good condition with the correct oil in good condition would be fine for standard road use.

For the once in donkey's years fill I would strongly recommend a better quality oil to better withstand use and abuse and maintain its integrity for longer.

Silkolene SF 20 Fork & Suspension Fluid - https://www.opieoils.co.uk/p-89690-silkolene-sf-20-fork-suspension-fluid.aspx


Nigel Atkins


Nigel

Thank you for the viscosity chart, Peter Caldwell's filling advise and the Silcolene address.

I am not ready yet to tackle the dampers. Before I start, I will find out if the Silcolene is silicon based. If so, I would not use it in a system that was initially filled with a non-silicon type of oil.
I would be scared that a mixture of the two different sorts of oil might destroy the rubber seals (as it would do in a brake system....)!

cheers
Anton

P.S.: your chart will come in handy in finding substitutes of other suppliers - if needed.
Anton Piller

Anton,
I did wonder if you might be thinking of brake fluid rather than suspension oil with silicone.

Oil companies tend to be quite guarded about their formulas and particularly Fuchs but I'd have thought they wouldn't mind saying if their oil doesn't have silicone. Obviously I have no real idea but I've seen nothing to suggest it.

As with any oil change the thoroughness is important for better effectiveness. For oil that has been in the component for a very long time and/or harder use then best for a cleaning and flushing to remove as much old oil and contaminants (and cleaning and flushing agents) otherwise the new fresh oil and its effects are diluted by whatever isn't replaced.

Many think all oils are the same and that's correct only to a certain extent but the quality of the base oils and the quality of the additives packages makes a difference in use.

I usually put up the viscosity chart to demonstrate that the weights are a range. For example one particular SAE 30 oil may be close to being the same as another oil at SAE 40 in the same way a person in their 30s may not be that much younger than a person in their 40s as one could be 39 and the other 41 – or the difference could be a lot more, they are 31 and the other person 49.

What one company calls x weight (say 20) might be very close to what another company calls y weight (say 30).

I am a big believer in high quality oils for their additional protection qualities and that they maintain their integrity under even arduous conditions for longer, perhaps more important for engine oils where many additional stress can occur but also relevant to gearboxes, back axles and even dampers. The additional margins better oil can offer help against faults to the components and loss of oil level, with often high levels of heat to guard against, as with the dampers as Peter Caldwell explains.

HTH.
Nigel Atkins

ETA: I meant to put, some customers buy different weights of oil to blend to a weight of their own preference, bearing in mind many of these are bike owners and/or racers rather than road use classic cars owners.
Nigel Atkins


Nigel

You are right in assuming that I was referring to brake fluid. If the mixing silicon oil with non-silicon stuff affects the rubbersin a brake system, it surely would also do so in a shock absorber system.

I also put just the best oils into the gearboxes, diffs and engines of my cars.

I will talk (probably next week) to my local oil supplier who is "very knowledgeable andprofessional". He is representative of Liqui Moly oils:

www.liqui-moly.de

I'll keep you posted :o)

Kind regards
Anton

P.S.: the damper oil that I am using at present in my YT was given to me by a MG Mate. He described it as "the very best" but it was not in the original canister anymore...
Anton Piller

Anton,
all good stuff, I don't know of any silicon in Silkolene and I'd have thought Peter Caldwell would have mention about mixing different sorts when recommending it - but never trust an assumption.

I would be interested to hear what your supplier suggests. I am sure there is a selection of very good ones to choose from all over the world and I would be interested in your choice anyway.

I must be honest and put that I had thought Liqui Moly was Americain as it is not a brand I have ever really noticed over here.

I try to support a local oil blender myself but have often recommended other more international companies even if some buyers still think they are British. My engine, gearbox and rear axle oil blender of choice - Millers Oils - https://www.millersoils.co.uk/

I put the following many times but I see I have yet to put it here, I am not an expert in anything, certainly not oil, I am not technical and not a very competent DIY mechanic, I only pass on the very little I have read and even smaller amount I understand. I can admit to having and giving my own opinions and beliefs (many times) as they are regularly repeated here, and often disagreed with, which is fine, especially as I often make mistakes and even more often forget what very little I thought I knew.
Nigel Atkins

Nigel

I am not at all patriotic when buying oils and stuff - it just reassuring that my local dealer knows and shares a lot about the oil he offers. In addition Liqui-Moly has a superb website :o)

Re.: your remark about the "little" knowledge, you have is wonderfull. I like it too much

Anton
Anton Piller

Anton,
I am very happy to buy local if I can but only if it is good enough and I can acknowledge faults in local products.

In my lost post I did actually write and then delete about dealers recommending products they do not make the most profit on or even products they do not sell so send a customer to a competitor so that the customer gets what they want or really need.

Thinking Liqui Moly was American I noted they were German and I think that I will actually continue to remember that as it surprised me.

As for knowledge, thank you, but I am really not being falsely modest, I know very little about oil and understand very little about it, and that is without what I forget.

Generally classic owners tend to be very conservative about products like oil and do not seem to recognise that even if they stick with the old brand names that the product has changed and improved from the decades ago when first introduced and it is even harder to to promote the idea that up to date modern products can be suitable and better.

I usually give links that support what I belief but also links against so that some can make up their own minds one way or the other.

I am at the age now where I realise that what I thought I knew was sometimes wrong or very wrong and that I knew and know so much less than I thought I did and do - and that is not even allowing for what I have forgotten and forget. I also have always mixed things up like left and right, up and down, etc. - but apart from that I am always spot on. :)

As an example on engine oils for classics I often gave three examples, but one disappeared, of different views. -
http://www.kewengineering.co.uk/Auto_oils/index.htm

http://www.mgb-stuff.org.uk/enginetext.htm#oils

Cheers.
Nigel Atkins

This thread was discussed between 25/11/2020 and 29/11/2020

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