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TR2/3/3A Testing a TR3 lever shock?

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K

karls59tr

Yoda
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If the shock is off the vehicle and in a vice how much resistance should there be when pressing down on the lever? I assume that if it goes down easily it's shot but is it possible to encounter a certain amount of resistance and the shock is still bad? Any way to tell if it's definitely kaput or will it be obvious?
 
IMO yes, it is possible for the shock to be worn until it only presents some fraction of the resistance that it should, without doing anything obviously "bad".

The real way to test it is to apply a constant force and time how long it takes to move. Unfortunately, I don't know any numbers offhand. One of my background/retirement projects is to build a shock dyno, but I haven't started on it yet.

BTW, the shock body is fairly thin and fragile. You really don't want to be clamping it in a vice by anything but the mounting ears.
 
I don't have any empirical numbers, but if you apply force to the lever arm it should have a steady and consistent resistance, if you try to move it fast it should really slow you down if pushing by hand.

If it were in fact worn to the point of losing resistance but still functioning correctly otherwise you might be able to revive it by filling with a thicker hydraulic fluid, isn't the stock shock oil about a 20 weight? I know a did that with my 4A many years ago and it seemed to work fine for many years after.

Personally I think most TRs have such stiff suspensions and limited travel that they aren't that sensitive to the condition of the shocks, so if you are getting a strong steady resistance both directions probably OK.
 
A quick change of direction is your best indicator, if it stops your hand from moving, it's a good one.

Wayne
 
Good point Wayne, that is what I meant by strong steady resistance, no free spots or hiccups, you stated it more clearly.
 
I've dissected a couple for curiosity. The teeter-totter plungers have a load and a return chamber. The wear point is where the metal plunger's ring sits in the bore of the main chamber most of the time (normal flat driving?). The other side has a rubber seal like a brake cylinder and shows no wear to the wall. As pointed out already, wear shows up as a loose feel in the mid travel area. Resistance amount in a long stroke is probably due to oil viscosity and/or dirt in the pressure valve between the chambers. Sorry to say, I didn't see much chance for amateur repairs to the walls of the main chamber. You can clean it all up and replace the oil is about all. Spring tensions in the valve are not mentioned any where I found. So messing with that is a gamble (the two valves, pressure and return, are actually connected). Again as previously said, the cars are pretty industrial on the spring loads and the shocks may work just fine in a worn state. I have pictures if anyone cares.
 
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