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Lever shock fluid

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John_Mc

John_Mc

Jedi Knight
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I can't seem to find any guidance in Hayne's or Bentley as to the proper fluid to use to fill the lever shocks. And if motorcyle shock oil is used, what do I look for? TIA

Also, if the shock is shot, any recommendations as to rebuilders in my neck o' the woods?
 
I used to use a straight 30w oil, nondetergent. The big three carry a recommended oil.
 
Mineral oil is acceptable. Petro-chem lubes may affect the seals if they're original.
 
My copy of TR5-TR250-TR6 Owner's Workshop Manual specifies "Armstrong Shock Absorber Fluid" (page 75) and warns against overfilling. TR3 Bentley says "Armstrong Shock Absorber Oil No. 624" and warns that any other fluid will void the warranty ... not that that is any real concern today of course
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If you use motorcycle fork oil, you'll want a fairly heavy grade (as it definitely affects the damping). Unfortunately, most motorcycles use a lighter oil than the Armstrong (which is about SAE 20). However, I managed to find some SAE 30 fork oil at a independent Harley shop.

Proper shock/fork oils are optimized for shock absorber service; lots of other things will do but why settle for second best?
 
Thank you, gents! A treasure trove of wisdom and experience, as always! Should I just add it straight, or drain out what's in there first?
 
If you are sticking with the same oil that is in there, then just top it up.

Something different probably merits draining and cleaning/flushing as they may not be compatible.
 
Castrol Hyspin AWH68 Hydraulic Fluid is correct for the lever shockers.

Moss sells it, or an equivalent, as Shock Fluid in a convenient sized plastic bottle.

Viv.
 
Not yet, Tom. Gotta get some time to get over to the Harley shop. If I discover the shock is still non-functioning, did I recall you mentioning a rebuild shop in San Jose that you had had some experience with?
 
Hi John - I've always used Peter at NOS Import. In fact, whenever I start digging into a new car I just order replacement shock from him as a matter of regular process. Bugeye, MGBs, MGC, TR4a and TR6, all of them... It's cheap, he does great work, worth knowing I don't have to worry about it.
 
Tom, do you send your shocks to be reworked, or do you just order new/rebuilt ones from him?
 
They do a swap John. All you do is call them up, they'll send the rebuilt ones, you pull yours, send those back in the same box. Postage paid, pre-addressed and everything.

So easy even I can do it!
 
I'm back again. That hole sure is small to see into. How do you tell when you are at the right fill level, since overfilling is not recommended? Do I just need to squint better?
BTW, I got some Harley heavy fork oil, and assuming that it works as well as what Moss offers, it's only about 1/3 the price.
 
I just used plain old fork oil, disconnected the shock, I got a syringe from the drug store, put a piece of clear hose on it and used that to squirt the oil in. I filled till it ran back out, worked the shock and did it again till it flowed out - put a last little bit in and put the plug back in. works fine now
 
No, I haven't had a problem at all. I did mine on the car so I suppose there is a little bubble over the hole. That being said, you would think that as long as the fluid can move, you would want it full. I couldn't find the reference to "fullness" in the article you mentioned.

Not sure whether your shocks are on the car or the bench, but, either way, this is a very easy job, so, you fill it, you try it, if it doesn't work because it is too full you siphon or pour some out. There is nothing permanent about adding oil.
 
The danger in overfilling shocks is that the oil expands much faster with heat than the aluminum does; and shocks get quite hot in service (the energy they absorb gets converted to heat). The resulting pressure can actually break the shock body, ruining it.

If you have the ones with the fill plug on the side, they should be filled only to the bottom of the plug. If the fill plug is on the top, you need to leave some air space under the plug.
 
Any idea what the capacity of the shock is? I just drained the oil, and I'm guessing there's maybe 2 oz. of fluid that came out. And it was black. It seems like there should be more that goes back in, but how much?
 
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