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TR4A Armstrong Shock absorber oil


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Hi Guys,

As the oil in my Armstrong shock absorbers is of unknown vintage, I thought I would drain and refill. But what oil?

The original Armstrong oil is NCA. I have heard that motorcyle Fork oil  is suitable, but what grade?  Also hydraulic Jack oil?

Presumably the stiffness of the shock absorber will be affected by the SAE number.

Any recommendations appreciated.

Thanks 

Rich

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Thanks Roger, yes I know Moss have it, but I don't like paying Moss delivery cost when E-Bay have lots of suppliers of probably suitable oil for less price with postage included. :rolleyes:

Interestingly, the Moss description states also suitable for motor cycle forks.  Just need to know the best viscosity for the Armstrong Shocks.

Regards

Rich  

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Rich,

Curious about this myself I did a Google search and found this:

“It is a common practice in the construction and mining industries to use engine oil SAE 10, SAE 20 or SAE 30 with the lowest API rating as a substitute for hydraulic oil ISO 32, ISO 46 or ISO 68, respectively for hydraulic systems of heavy equipment. Is it a problem to use these? What integrity or lack of it does it give to the machine and to the people working around the site?"

BUT…

The ISO oils seem to be specific for use in hydraulic systems (Like the dampers). SAE 30 might be the same weight as ISO 68, but it is not the same chemically. (Anti frothing aditives etc.)

For the sake of a few quid more I’d go with the correct oil for the purpose.

Maybe search eBay for ISO 68 oil.

 

Charlie

Edited by Charlie D
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It's a hydraulic application, so a hydraulic oil is appropriate. Jack oils and fork oils are hydraulic oils.

I think ISO 46 is around 20 weight, and close to stock.

Ed

SDC11585a.JPG

Edited by ed_h
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I’m sure that Alec P suggested 30wt oil to me when he was talking me through competition improvements. 
 

motorcycle fork oil was the right stuff and I think specifically Harley Davidson dealers were a source as they need a heavier oil to deal with the weight. 

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2 minutes ago, Hamish said:

I’m sure that Alec P suggested 30wt oil to me when he was talking me through competition improvements. 
 

motorcycle fork oil was the right stuff and I think specifically Harley Davidson dealers were a source as they need a heavier oil to deal with the weight. 

Are you saying Harley riders are fat?

 

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1 minute ago, BlueTR3A-5EKT said:

Are you saying Harley riders are fat?

 

no no no the bikes are just big boned  I mean heavy 

:ph34r:

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It is common to use thicker oil for the levers. For racing purpose it is a good idea, for street use not in my opinion.

 

The reason is that race track often is flat but street has bumps. I found out that levers have very small valves that make car jump and uncomfortable on bumps and uneven roads. The thicker oil makes car stiffer in good roads but bad on bumpy roads.

 

Swapping to modern sports shocks showed to me what comfort ist possible with big valves, opening on bumps. You get smooth riding comfort and good roadholding.

 

So my recommendation for street use ist to use very thin fork oil for levers and beware of SAE30.

Edited by TriumphV8
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What ever was in, I top them up with "Bel-Ray MC10" motorcycle fork oil SAE 10 from time to time, 

which I have in my oil storage container from my BMW motorcycles.

This works lovely, me and my wife like comfortable driving.

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Hi all

My experience has been that thicker oil also can make the seals in lever shocks fail very quickly. Essentially the shock heats up inside as a result of continuous actuation of the piston, so the heat is transferred across the body, oil gets very hot and thin and the seals fail. Worse still the piston seizes. This is why a so called ‘upgrade’ with thicker oil Is only a partial solution and there is obviously a limit to the thickness of oil you can use and how long you can use the shocks for with thick oil in them.

You can revalve shocks, change the springs in the valves or shim the existing valves out a little, but you need to be able to test the effect, which is why you need someone who knows what they are doing or learn how you do it properly yourself. I have destroyed a pair of NOS adjustable DAS9’s on the back on my TR4 as a result of trial and error so not recommended .... they worked beautifully until the pistons seized chewed a hole in the body. Once one side goes, the other rapidly follows. Beware.

Regards

Tony 

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52 minutes ago, TR4Tony VC said:

Hi all

My experience has been that thicker oil also can make the seals in lever shocks fail very quickly. Essentially the shock heats up inside as a result of continuous actuation of the piston, so the heat is transferred across the body, oil gets very hot and thin and the seals fail. Worse still the piston seizes. This is why a so called ‘upgrade’ with thicker oil Is only a partial solution and there is obviously a limit to the thickness of oil you can use and how long you can use the shocks for with thick oil in them.

You can revalve shocks, change the springs in the valves or shim the existing valves out a little, but you need to be able to test the effect, which is why you need someone who knows what they are doing or learn how you do it properly yourself. I have destroyed a pair of NOS adjustable DAS9’s on the back on my TR4 as a result of trial and error so not recommended .... they worked beautifully until the pistons seized chewed a hole in the body. Once one side goes, the other rapidly follows. Beware.

Regards

Tony 

Good trick here

http://www.sebringsprite.com/shockabsorbers.html
 

Did you ever try the twin valve units that the racers of the 1960s and 70s favoured?

cheers

Peter W

 

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OK Guys,

Gone off topic now,  so I will just buy from Moss and pay the £5.45 postage :rolleyes:

Rich

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