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MG Midget and Sprite Technical - Lever Damper Oil

There's many comments about using Motor Cycle Fully Synthetic Fork oil in lever dampers.
Has any one any experience using this oil with up-rated dampers. There's two grades 5 & 10, 5 gives a smoother ride the 10 gives a harsher ride so I'm told by my motorcycle mad neighbour.
Peter King

I can't remember the details but IIRC the bike numbers relate differently than to LA type damper oil numbers. 5 and 10 bike may relate to a street bike of certain weight, build and design use.

If you already have uprated valves then it might be even more experimenting.

The type of car and type of racing may make a difference too, probably why the stability of "fully synthetic" oils is asked for too.

Malc the french knight (1500), on here, done some work on LA dampers, but not for racing purposes, but might have use useful comment (much more so than my general ramblings at least - save you typing it). :)
Nigel Atkins

Peter

I used Silolene 20 weight fork oil on my dampers: https://www.opieoils.co.uk/p-89690-silkolene-sf-20-fork-suspension-fluid.aspx

Thanks
Mike
M Wood

^^ What Mike says.
BTW Malcolm Chevalier sells damper refurbishment kits - oil, O ring seals, gaskets, crush washers and screws.
Jeremy MkIII

Motorcycle fork oil comes in several grades going up in 2.5W steps--2, 2.5, 3, 5, 7.5, 10, 15 20 etc
5 and 10 weight oils will be too thin
Std .spec oil is 20w
It's not uncommon to blend oils for the right feel on a bike--eg. mix 15 and 20 50/50 mix to get 17.5
In a car you probably wouldn't feel the difference but on a bike it's quite noticeable

I'd just stick to 20W and play with the valves instead

willy
William Revit

Yes I do, if you ask me nicely! ;-)

The general consensus is to use a 20w fork/hydraulic oil.
Malcolm Le Chevalier

I used 15W fork oil in mine and the arms are really quite hard to move by hand.


I recently swapped out one of the rear dampers for a reconditioned unit from Moss. The arm is noticeably easier to move by hand.

Is this down to a different spec oil or some thing in the damper is different?
C MADGE

Peter Caldwell recommended 20w fork oil in combination with uprated valves, so that's what I use, Wilbers, I think......
Jan Kruber

The reconditioned dampers from Moss are generally sh*te! I am not convinced they change the oil and it could have any kind of valving in it. They really are a lucky (or unlucky) dip!

Malc.
Malcolm Le Chevalier

Chris, I'd say probably both but unlike Malc I've never taken them apart.

There's no way of knowing the history of the dampers they could have had a hard life, easy life, been looked after or not, been reconditioned well(?) or not, been reconditioned few or many times - or a combination or permutation of many of the factors.

If they function well and continue to do so for a reasonable time then the above doesn't matter but what do you have to measure against.
Nigel Atkins

The Moss one works, it doesnt leak oil like the one I replaced. But its not matched to the other side.

I may try filling it with my fork oil and see if that makes a difference.
C MADGE

The difference might be in the amount of wear one has to the other but also yes in oil, type, weight, quality, I can't see Moss suppliers using the finest oils known to man or woman at the damper retail selling price.

Matching is of course relative and relative to the likes of a vehicle like a midget overall.
Nigel Atkins

Chris,
I couldn't remember the ISO figures and knew the info was somewhere and I found the following for you.

Opie Oils - "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."

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).
Nigel Atkins

Thanks Nigel, useful info.
C MADGE

No problem, I knew there was something about figures but could remember what, ISO numbers.

Peter Cadwell's "better than new exchange service" always seems to get good reports on here from the few who have got them from USA thought apparently it's not worth the cost to return the previous dampers to USA.
Nigel Atkins

I have used STP in my front shocks for many years. It goes against the usual advice but they haven't burst or blown the seals out and they don't leak. Coupled with a heavy anti-roll bar (with reinforced mountings) it corners very 'flat' with very little body roll.
GuyW

Interesting, the stuff in the (now?) blue bottles the additive?

What SAE number do you think it might be, calm down, it might be on the bottle label but I doubt it but I bet you've still got the bottle in your garage or shed(s) or workshop(s).

I think I remember that sort of stuff being quite thick, thicker perhaps than 20w/50, in cans with a pull off strip to two holes, but that was decades ago so perhaps I'm wrong and of course it might have changed over the years.
Nigel Atkins

The rears are a bit of a pain to remove the valves from, as you have to remove the wheel and damper. But if do want a matched pair of valves, I have loads and will swap you whatever you have for something matched and about the right strength.

In about two years off offering, nobody has ever taken me up on this! :-D

Malc.
Malcolm Le Chevalier

Nigel, all I can remember is that it was an STP oil additive. I don't know if it was their only product at the time - about 20 years ago. And no, I don't still have the empty bottle!

But one thing, it could be time for a flush out and refill.
GuyW

Peter

Don't forget to take the dampers off so you that can turn them upside down to drain all the old oil out and the dirt.

I found a couple large plastic syringes (from a chandlers used for glues and resins) handy for cleaning out and refilling lever arm dampers. You can then also cycle the dampers on the bench by partly filling with some new oil to further clean them by circulating the oil by pushing the lever arm and drain that oil off and then put the dampers back on and refill completely with new oil.

I got my Silkolene 20W fork oil from a local independent motorcycle shop. They kept trying to ask what bike it was for!

Malc - thanks for the kind offer, must take you up on it

Cheers
Mike
M Wood

Malcolm, thanks for the offer. Having just got the car on the road I want to drive it a bit first and see how the dampers perform.

But if you offer is still there later on I'll take you up on it.
C MADGE

Personally I would refurb them. Clean them out thoroughly, take note of all advice from Malcolm and purchase two of his kits c/w balanced vvs. Use Silkolene 20W fork oil.
Oggers

This thread was discussed between 29/04/2019 and 04/05/2019

MG Midget and Sprite Technical index

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