MG T-ABC

Evening Gents,

While the car is inoperable due to me working on the fuel tank, I took a peek at the fluid levels in the Girling Dampers. Noticed that I can't see any fluid in there. I pulled on of them and It seems like it's okay, travels well with a fair amount of resistance, more resistance in one direction than the other, doesn't bind. So I'm thinking they are okay.

What level should they be filled to? Planning on using jack oil, non foaming, as I've seen that mentioned else where.

TIA

Jeff

Jeff, use motor bike fork oil. Any bike shop will have it.

Top up to the very top.

Check if they're leaking by feeling under the shock absorber before topping up with new oil.

I'd leave a bit of air at the top to allow for heat expansion of the fluid. If you don't, any expanded fluid will be forced out of the seals and eventually find its own level anyway.

The top filler bolt is also the shock "dipstick". Fill to the bottom of the threads - or at least halfway up the unthreaded portion ...

I filled mine, when in the vice, to te top. Left them an hour and the level had gone down to the bottom of the thread as the air rose to the top.

The bleeding process is normally done by working the shock arm up and down until you can no longer feel your own arms, then take a break and do it a bit more.

Steve, after I did that, I topped up and this introduces some micro bubbles of air. It reduces the level down a bit, which is why I said top up to the top. It will go down enough to allow for heat expansion.

C'mon Norm!....... Steve and Peter are correct as was the direction of your earlier post headed in the normal leveling due to the oil self bleeding or being force bled as Steven said.

Simply pouring today's refined oils into a container or system reservoir in the process of "topping up" does not and will not create "micro-bubbles" of entrained air into the oil. Micro-bubbles in oil are created by the forced intrusion of a gas into the oil under a set of very specific conditions. Our garages and driveways at atmospheric conditions do not come remotely close to matching those necessary for creation of said micro-bubbles.

Marv.....

Here Here Marv !!!!!

Well, all I can do is report what happened. I topped the s/absorbers up to the very top and an hour later the level had settled so a small empty space was at teh top. I assumed thsi was air in the oil created when it was poured in.

Try it. Get a coffee jar and pour some brake fluid in the jar from a tin. Hold the jar up to the light and you'll see air in the fluid.

Brake fluid is different than shock oil. But your settling was probably due to trapped air pockets rising to the top.

Or..... Micro-bubbles!

Whatever it was, if you fill to the top it will settle leaving some air for heat expansion.

there is a marked difference between a solid opinion and a mere fact!

No, Dirk, fluid isn't solid. Not sure it's meer either

The fluid doesn't "settle", so to speak. When you pour it in, there may be large air pockets trapped below, like when a ship sinks and there is still air in it. When the shock moves, even a tiny bit, that air is usually released from its hiding spot. It then moves to the top and the fluid takes its place. Displacement might be a more accurate term. I wouldn't rely on this happening on its own. Fill it near the top, work the shock up and down, then check the level again and put it at the proper mark!

We're not going to win this one Steve. Logic and reality are bested by the "Bubbles"!

There may actually be furious agreement going on here. IMHO there is a big difference between a small top-up and a complete refill.

In a refill of an empty shock, because of the geometry of the compression chambers, it is inevitable that there will be some air pockets trapped. This air has to be eliminated by extended working of the lever arm. Simply standing may lose some of it if the repose angle is slightly different to the one used during the fill or if the unit is moved but working is the only sure way.

For a simple top up, entrainment of air should be minimal and will be in non-micro bubbles as Marv states. The fluid used should contain anti-foam and this will make any such air escape very quickly.

I think the article in this link is interesting and relevant. http://www.mg-cars.org.uk/imgytr/hints&tips/luvax.shtml

No Richard, I don't agree that apples and oranges are being discussed as in a total refill vs. a top-up! The total refill was never contested on the entrained air and the reason for it. The "top-up" is the base discussion. The rest of your statement is spot on except I don't think it necessary to add an anti-foaming agent to 20W, 30W fork oil or whatever you choose to use for your preferred ride stiffness. I have a friend who would put STP in the shocks of the MGA that he raced. Who knows, maybe there is an anti-foaming additive already in the oils most commonly available. I use the stuff from the Harley dealership and have never has any issues with "settling" on just a top-up. Giving Norman his due, the stuff in France may be different!!!!

Marv, again I may still see underlying agreement. From his first post in this thread - and from his rebuild log (3 June) - I interpreted Norm's comment on the level dropping as his experience after a refill, not a top up. I do acknowledge that this thread is on top up and that his comment was directed at that topic - hence, to me, the potential confusion.

Re antifoam, I am not suggesting a need to add it. I am ex the lube oil industry and fork oils, engine oils, essentially all oils sold for automotive use have antifoam already added by the manufacturer. Sometimes they promote that fact but often not.

Some trivia - there are two aspects to antifoam additive performance. One is what is called air release - the ability of air bubbles in the bulk of the oil to combine and rise. The other is the ability of the bubbles to break up ("pop") once they reach the surface - what we call foam.