Front/Rear Dampers Oil Change

for those with Series MM sidevalve cars produced between September 1948 and February 1953
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alanworland
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Front/Rear Dampers Oil Change

Post by alanworland »

Removed the valves from the front dampers today to allow them to drain, and with much pumping up and down, not much came out!
I then removed the top covers and syringed out the remaining old oil replenished with new, re fitted the cleaned valves and bounced the car up and down - this moves the new oil into the 'working' chambers.
I then removed the valves to drain the flushing oil.
All fitted back together now with all that 57 year old oil removed!
I guess the original oil was the correct Armstrong product which I now have in a jam jar and boy does it stink! - far worse than EP gear oil!
I will have a go at removing the rears next which will also include removing one (or more) leaves from the spring assembly.
Last edited by alanworland on Tue Oct 27, 2009 11:16 pm, edited 1 time in total.
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mike.perry
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Post by mike.perry »

But does it make any difference to the performance of the dampers?
My MM fronts have never even needed topping up. All I have ever done is unscrewed the cap occasionally to check them
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alanworland
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Post by alanworland »

No difference what so ever! It's just nice to know they are full of clean oil!
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mike.perry
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Post by mike.perry »

The rears should be easy as you can remove them and clamp them in the vice.
What springs have you got? Original 7 leaf, Traveller 7 leaf or saloon 5 leaf? Mine has 5 leaf springs.
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alanworland
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Post by alanworland »

Have now tackled the rears. Offside ok drained and pumped through new oil - once again very dirty. Nearside oil very, very dirty, looked like a light metallic paste! and when I turned it upside down to drain the oil in the top chamber, nothing came out!
There must have been just enough oil in there to allow it to function as a damper (it felt ok as a damper) There is some wear in the main arm bearing and I can assume that the oil has leaked out from there.
I wondered if the proximity to the exhaust had anything to do with it?
Anyway I have topped them up as required and I am quite sure the left one will leak! (but only till all the 'excess' oil is gone!)
Any ideas as to how these come apart? it looks like the arm is welded to its shaft?
With regard to the springs I have the original type 7 leaf with the thinner leaf (7/32 I believe) and they seem very firm - will start dismantling soon!
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alanworland
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Post by alanworland »

Well, the rears are now bolted back and as I thought the left one leaks! In fact it had produced its first drip before I had both the bolts in!
I think what it will do is leak until it doesn't leak any more (there's a surprise!) but there should still be enough in there to enable it to funtion as a damper.
Think I will make some enquiries about replacements.
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pgc520
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Post by pgc520 »

What grade oil goes in the dampers ?
mike.perry
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Post by mike.perry »

It depends how firm you want the front suspension. About 30 grade seems to be normal. There is a thread about it on the main website
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