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What do you use for shock oil?

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Sarastro

Sarastro

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Just wondering what everyone uses for shock oil. I did a little skulking through the archives and 20W motorcycle fork oil seemed to pop up most often. Is that still the best thing available, or is there something else that might be better?

I know that Moss sells a shock oil, but I'd rather use something I can get locally.

The application is both Girling (front) and Armstrong (rear) shocks on my TD.
 
One of the "old school" ideas was to use castor oil. Maybe it was the placebo effect but that seemed to be a bit stiffer and autocross handling felt better. Mineral oil would work in a pinch, too.

Today I'd go with the fork oil, methinks.
 
Fork oil, or from a tractor farm supply kind of store get their hydraulic oil rated at AW68 (about 20W engine oil) or for a softer ride, AW46. It has all of the anti-foaming stuff, etc, and isn't nearly as expensive.

Peter C
 
Thanks. I'll probably go with the fork oil. Tractor supply places are kinda thin on the ground here in LA, so that's probably not an option for me. On the other hand, there's no shortage of motorcycle places.
 
One bottle of shock oil should last you a couple of decades. The motorcycle fork oil is perfect.
 
I use Harley Davidson fork oil.

Castrol used to make a fork oil....don't know if they still do or not...
 
Well, I visited my local motorcycle store yesterday and came home with a quart of 20W fork oil. I hope that's the best viscosity for this car, as it might be some time before I use up that much. I don't inhabit motorcycle circles, but I enjoyed walking around the showroom and looking at the hardware.

My car's PO never topped up the shock oil. The rear shocks still have a little oil in them, but the front ones are empty. I don't think that's because of a bad leak, because there were no obvious signs of one. I'm hoping that fresh oil and a little work is all they need.

Thanks again for the replies.
 
Sarastro said:
Well, I visited my local motorcycle store yesterday and came home with a quart of 20W fork oil. I hope that's the best viscosity for this car, as it might be some time before I use up that much. I don't inhabit motorcycle circles, but I enjoyed walking around the showroom and looking at the hardware.

My car's PO never topped up the shock oil. The rear shocks still have a little oil in them, but the front ones are empty. I don't think that's because of a bad leak, because there were no obvious signs of one. I'm hoping that fresh oil and a little work is all they need.

Thanks again for the replies.
Click to expand...

I have to ask this.... forgive me, but if the shocks are empty, where do you think the oil went? It doesn't burn, or evaporate. It can only leak, and if it did, it will again.

Just sayin'

Peter C
 
Peter, my understanding is that the shocks are expected to seep slightly; I've been told that this is intentional, to lubricate things. After all, topping them up occasionally is a listed maintenance operation, so some slow leakage, for whatever reasons, is expected.

In this case, the tops were so tight that I had to use quite a lot of torque to get them off, and probably never could have removed them if the fenders were in place. I suspect that they haven't been topped up for quite some time, maybe decades, and had ample time to leak out even at a very slow rate. So, it's quite possible that they are basically OK, as I see it. We'll know when I can fill them and see what the story really is.
 
My words come back to haunt me. Yes, the original design permitted oil to reach the bushings, and it would weep beyond the packings. But, it needn't be that way. Whatever you do, don't over fill.

Peter C
 
I thought your site might have been where I learned that, but wasn't sure.

If they aren't working right, I'll definitely be in touch with you.
 
Well, I added some oil and they didn't leak, but instead they locked up hard! I drained out some of the oil, and it was full of black crud. So, looks like I'll need to have them restored. Probably I'll get the rear ones done, too, while I'm at it.

No shortage of surprises in a 60-year-old car! Not that this should be a surprise, I guess.

Just fired off an email to Peter...
 
Steve, They'll be better than new when you get them back! They will also be, "tuned", so right and left shocks have the same resistance. PJ
 
Yes, that's why I'm going to have Peter do all four. This kind of thing makes a noticeable difference in the feel and enjoyment of the car, so it's worth doing it right. I can't imagine driving the car without working front shocks, as was the case for some time. 'Course, I can't imagine being clueless enough to run the car without oil pressure, but the PO did that too. But we'll sort it all out.
 
I use this stuff, found unopened at a semi-operational foreign car junkyard just a few years ago:
shockol.jpg
 
Peter,
What is the proper fill level. I've always filled to the top and put the bolt back in! Assume that's too much.
 
ralph_s said:
Peter,
What is the proper fill level. I've always filled to the top and put the bolt back in! Assume that's too much.
Click to expand...
I assume on an MGB? On the front, the fill bolt is the right height. I'll try to attach a picture of what is inside that "turret". That reservoir is really for expansion, and when you add oil it will slowly work into the body of the shock. Don't try to force oil in. We sometimes get cores that have a zerk screwed in there so that the DPO can force even more oil in! (which is why we get the unit to rebuild)
A bit of history: The body of Armstrong shocks that fit the front of big Healeys, MGAs, and MGBs were identical through the first 600 cars of MGBs. After that, Armstrong added the turret bit to the top for the Bs. Sheet metal on the Healeys and A would not permit the turret structure. It is a good design feature, as it gave more room for oil (cooling) and allowed more room for expansion. To fill that area completely, negates the advantage and causes oil to weep more profusely from the shaft packings.... the only exit point. If you were to look inside at the oil level, enough to cover the piston bore of the upper piston is enough.
But again, there should be NO reason to add oil, UNLESS you notice it is leaking from the shaft. It doesn't burn or evaporate... it can only get low if it leaks. And... I have to say this... if it leaks, there is a solution.8177 oil level.JPG8177 air reservoir.JPG
 
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