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MG Midget and Sprite Technical - Damper colour

Really technical issue - does anyone know the blue paint colour for this Armstrong damper?
It's the surviving original, refreshed with one of Malcolm's kits and I'd like to refit it.

I'm assuming the reservoir needs to contain some air (hence the filler plug being on the side rather than the top) and shouldn't be overfilled, otherwise the damper will lock solid and have the potential to explode?
I was thinking of drilling the filler plug, tapping a thread(!) and screwing in a grease nipple so the occasional oiling could be done using a grease gun filled with fork oil but there would be no way of knowing how full the damper was.


Jeremy MkIII

Yes, leave an air gap. I doubt it would explode, more likely just to leak out the shaft seal, but the air allows for expansion of the oil in use.

Not sure I would bother with a grease nipple. If you are losing that much oil that you need to regularly top it up, you have bigger issues!

As for ther colour, I don't know on that one.

How did you find the refresher kit?

Cheers,
Malcolm.
Malcolm

Jeremy,
from my previous post quoting Peter Caldwell in the Archives here -

Peter Caldwell on filling the dampers -
" ... That is the filler hole. Of course you can't see how much to add as you are filling the air reservoir. Unlike a differential or transmission, the oil should NOT be at the level at the threads, but a half inch below, which you can't see. So, just add some, if you must.
On the rear, the same size wrench opens the plug on the side of the shock just below the lid gasket. This is easier to not overfill.
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".

- And. -

"Peter Caldwell of World Wide Auto Parts (USA) who used to post on here and is very well respected for his better than new exchange service on LA dampers cautions about using thick oil, 30w max (I know you put 15w).

"Stick with the 20W oil recommended (AW68 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 I think means anti wear, AW68 would be AW ISO 68 and 15w is shown as ISO 46.

IIRC Peter said there were several ways of mechanical uprating (not oil) but IIRC for DIY heavier valve springs (but as always don't go on my memory)."

Malc is the man here for valving."
Nigel Atkins

Malcolm, it was easy to use, I only needed one of the seals as it's a later valve type. The gasket (and seal) were a perfect fit and don't leak.

I was fortunate as the original screws were able to be reused as they came out easily. However with them being cheeseheads I can see the need for replacements if they're corroded or have been butchered by previous owners. Like the fact your replacements are crosshead and in stainless steel.

I already had a supply of 20 weight fork oil so can't comment on the one you supply.

Very happy with the kit as you've sourced and supplied difficult to find hardware which enables older original parts to be refurbished and used again rather than buying poor quality 'reconditioned' replacements currently available from most major supplies.




Jeremy MkIII

Not sure about the colours. The only colours I have seen are no-paint and a metallic copper colour. I assumed no-paint was as supplied to BMC/BL (cheaper than the painted versions?) and the metallic copper were as supplied to Armstrong customers.
Not sure about metallic blue as I have never come across one.
All conjecture really.
Rob
MG Moneypit

I've just noticed a typo, I've copied & pasted a good number of times -
"15w is shown as ISO 46" - no, it's ISO 32.

ISO 46 is towards the bottom of 20 SAE with ISO 68 being towards the top of 20 SAE (see my obligatory viscosity chart below).


Nigel Atkins

Thanks Nigel,

so the reservoir is just for air no oil basically at all, interesting. I may need to siphon some out.
I thought the dampers were designed to leak a little to lubricate the main shaft bearing?

This was was completely empty. The filler plug was missing so I made one from a 1/2" bolt, I must have emptied it in the dark and distant past.

Thanks Rob,

I've seen the metallic copper colour you mention, some of the NOS obtained many years ago were that colour. As mentioned this came off the car and as it's been in our possession since 1977, I'm assuming it was an original fitment.
The colour reminds me of old Matchbox cars for some reason.


Jeremy MkIII

I always wondered why one of mine was copper in colour.

Thanks

James Paul

I bought a NOS set from BL many moons ago. They have still got the BL part number taped to them. They are both copper coloured.
Bob Beaumont

Jeremy,
as I put elsewhere I'm not sure which damper Peter Caldwell was referring to in that quote so exact details might not apply on your situation just the general principles.

I wouldn't bother to syphon any out as it'll leak out if you get them too hot for the oil, unlikely with your show car use, shiny combination spanners on show with boot lid lifted and extra bright boot light to make them sparkle even more.
Nigel Atkins

I have always filled mine up to the thread holes for the filler plug, using a syringe. That still leaves a little space for oil expansion and they have never leaked. I also do change the oil occasionally. I am not convinced by the comment that the oil doesn't deteriorate. It works hard and must suffer a physical pounding plus temperature changes as it is worked by the pistons and valve.
GuyW

Thank you for the feedback Jeremy. Good luck with the rebuild.
Malcolm

This thread was discussed between 12/10/2020 and 13/10/2020

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