richard hulme Posted July 20, 2009 Share Posted July 20, 2009 When removed, should the lever arm on the shock absorber resist movement in both ways or just one? All 4 of my shock absorbers only seem to resist in 1 way (down and not up) and so the ride seems a little, well, bouncy! Any help appreciated! Regards Richard Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted July 20, 2009 Share Posted July 20, 2009 Both ways, but in one direction much more than the other. If you have them off the truck, look for the filling screw in the side, then fill them right up with shock oil (or jack oil if that is all your supplier has) and work them forward and back a few times. I've looked at a lot of these, and I've only ever found one of the knee-action shocks that didn't respond well to a fill up and a little gentle exercise. I suppose it is possible you re-fitted them the wrong way round and the basic shock action is in the wrong direction? Quote Link to comment Share on other sites More sharing options...
Tony B Posted July 20, 2009 Share Posted July 20, 2009 Gordon, for future reference. Is there an easy way to tell which way up the shock should go? Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted July 20, 2009 Share Posted July 20, 2009 I don't think so Tony, but if you took the arm off the shock you could put it back on wrongly on the other side. SHould be no way to get them wrong if you don't dismantle, but remember there are front and back shocks. Quote Link to comment Share on other sites More sharing options...
Tony B Posted July 20, 2009 Share Posted July 20, 2009 Thanks. Quote Link to comment Share on other sites More sharing options...
Stormin Posted July 21, 2009 Share Posted July 21, 2009 For leaf sprung vehicles the major damping action should be on spring rebound and not bump. If it's the wrong way round that'll lead to a very harsh ride. Quote Link to comment Share on other sites More sharing options...
richard hulme Posted July 21, 2009 Author Share Posted July 21, 2009 There is major damping effort on the rebound but very little on the bump. So I guess that my shocks absorbers are working correctly. I have tried "motorcycle fork oil (5w)" as recommended somewhere, this allows me to move the arm with light to moderate pressure, is this oil thick enough? As a test I cleaned the unit out and filled it with some SAE90, this required heavy pressure to move the arm, increasing its dampening effect considerably. Can anyone recommend a specific oil viscosity? Thanks for all the help though, saved me hundreds as I had planned to replace them all as I thought they were all faulty!! Regards Richard. Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted July 21, 2009 Share Posted July 21, 2009 I don't have a specific viscosity to suggest, but all the work I've done on them was with hydraulic jack oil which was fairly light / low - basically I just poured out some of the oil that was in them and matched the viscosity of that. Power Wagons and civilian Dodges normally have tube shocks on them which are quite dreadful (ask me how I know...) Some of them had no shocks at all on the back axle. Dodges 1.5 ton and up used knee-action shocks as standard. I'm pulling tube shocks off one of my one tons and fitting a set of knee action shocks. Keep them clean and filled, replace bushes when they need it, and you shouldn't have to spend anything else on them. If you find a spare or two for the shelf all the better, as when they do fail I don't know of anyone who rebuilds them, though there are so many about no real reason to. Quote Link to comment Share on other sites More sharing options...
richard hulme Posted July 21, 2009 Author Share Posted July 21, 2009 I have to ask, how do you know tube shocks are dreadful.... Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted July 21, 2009 Share Posted July 21, 2009 I've had no less than four Dodge trucks here that had tube shocks on, two half ton militarised civilian WC36 Carryalls, a 1939 133" one ton TD20 pickup, and a 1941 one ton WD21 panel van; http://www.gwim2.pwp.blueyonder.co.uk/wc36.htm http://www.gwim2.pwp.blueyonder.co.uk/td20.htm http://www.gwim2.pwp.blueyonder.co.uk/wd21.htm I've had several military Dodges and never had to do much more than clean and fill the shocks, I've only ever had one knee-action shock that didn't respond to cleaning and filling. In contrast ALL the tube shocks which were on contemporary trucks have ended up in the bin. Replacement tube shocks for the Carryalls were found easily enough (£££) as they were standard half ton length and rating, but the one ton trucks both had non-standard shock lengths and ratings (££££) I hunted down replacement shocks for the one ton pickup as it is entirely original, with only about three square feet of sheetmetal grafted from a 1941 cab roof, but when I came to the one ton panel I decided just to bin the tube shocks and go with military knee-action shocks - not worth the grief. Most of the running gear on 1/2 and 3/4 ton WCs is borrowed from the contemporary 1.5 ton civilian truck as the half ton civilian stuff is way too feeble. My 1940 VC3 pickup; http://www.gwim2.pwp.blueyonder.co.uk/vc3.htm ... shows signs of it's civilian heritage, as it has open 'C' shackles on the front spring (actually just the same as jeep shackles but about 3/8" taller) weak front axle housing, and thin flexible chassis - at least it was flexible before Uncle Sam did a depot-level rebuild on it and welded up and / or plated every single chassis joint. I know just about enough about the 1939 / 41 civilian and military Dodges to get by, especially the lighter ones, so ask away if you need to, but take my word on the tube shocks. Quote Link to comment Share on other sites More sharing options...
richard hulme Posted July 22, 2009 Author Share Posted July 22, 2009 Having used light shocker oil (5w) and having taken onboard what has been said here, I went and purchased some thicker shocker oil (15w) and the difference is noticeable. To conclude, I used too light an oil last time resulting in poor rebound resistance. It would seem a 10w or 15w shock absorber oil (or hydraulic jack oil) is the way to go as it gives much better resistance on the compression and even better resistance on the rebound. If you need shock absorber oil go to your local motorcycle spares shop, they will have it as "Fork Oil", Hellfords sell Jack oil. Thanks again to eveyone. Regards Richard. Quote Link to comment Share on other sites More sharing options...
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