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Discussion Topic:
Shock Absorber Oil/Fluid
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Dolman |
08-03-2011 @ 5:59 PM
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New Member
Posts: 177
Joined: Dec 2010
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The shock absorbers on my '34 pickup appeared to be leaking. Took one off and it was covered with a thick substance that doesn't easily wipe off. Removed the fill plug and poured out some of what little was in there. The fluid has the color and viscosity of honey. No,I didn't taste it. Saw a reference to castor oil in a previous topic and wondered what color it is. I remember my grandmother used castor oil (sometimes Fels Naptha soap) on me to clean up my vocabulary but I don't remember what color it was then. There is resistance when I push/pull on the arm but I don't know how much resistance, measured in pounds at the ball, a good shock should have. At $195 each, I might just as well refill them with the correct fluid and let 'em leak. Everything else does.
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ford38v8 |
08-03-2011 @ 7:30 PM
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Senior
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Dolman, While your grandmother would have approved of your vocabulary turning into cottage cheese, I doubt that your Houdaille would appreciate it. As there were three very different "correct" fluids used in Ford shocks, your chances of producing cottage cheese are exactly two in three. Not good odds. As it sounds like your shock is otherwise in good condition, your wise option would be to flush it well with a compatible ???? solvent and use modern hydraulic fluid. The original fluids were: Castor oil, originally identified by a raised coin shape fill plug. Mineral Oil, originally identified by a raised nipple shape fill plug. Glycerin based fluid, originally identified by a flat top fill plug. (Modern hydraulic fluid is used by some rebuilders.) If you do a google search on those 4 fluids, you may well be able to report back to us with info on their characteristics and a compatible solvent. In any case, you don't know if the fluid you now have has been mixed with something else, so your grandmother needs to make an informed decision here!
Alan
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37RAGTOPMAN |
08-04-2011 @ 8:56 AM
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Posts: 1958
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Snyders Antique auto parts, sells SHOCK FLUID,part number M-1046 $6.00 for a pint. www.snydersantiqueauto.com hope this helps 37RAGTOPMAN
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Dolman |
08-04-2011 @ 10:56 AM
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Thanks for the comments. I can't consult with my grandmother because she passed away 25 years ago at age 103. My morning research found several recommendations for flushing with denatured alcohol which flies in the face of all the reports of ethanol's destructive properties in antique vehicle fuel systems. But then I don't know what materials are inside a Houdaille that might be soluble in ethanol. I sacrificed another small amount of the fluid from the shock and rubbed it between thumb and finger. It turned gummy and has no odor. My confidence level that the fluid is castor oil is such that notwithstanding the square flat top fill plug I will fill with castor oil. If I'm wrong, I'll confess and pay. Additional support for my decision is that glycerin is colorless as opposed to the light yellowish color of the existing fluid in the shock. Of course the coloration could be the the result of mixing different fluids. I think we all would be interested in the experience of someone who flushed a shock with denatured alchohol.
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supereal |
08-04-2011 @ 11:09 AM
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If the fluid of any type is leaking from the shock, it is more than likely that refilling it will not fix it, and replacement or overhaul by a specialist is next. If the shock doesn't hold pressure as it is operated, it is useless. An inexpensive fluid is hydraulic jack oil, sold by most parts places. I think we got ours at NAPA.
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Dolman |
08-04-2011 @ 11:27 AM
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Super: Now that the one that I have on the bench is cleaned up, I am not certain that it is in fact leaking. The crud that was on it could have been left over from previous re-fillings. Going to fill it up, put in a vise, and vigorously operate it to see if any of the juice appears. On Page 131 of the Yellow Book there is a statement, "Caution owner as to the necessity of occasionally replenishing the fluid in the shock absorbers." That implies that there is an expected loss of fluid. A slow seep perhaps?
This message was edited by Dolman on 8-4-11 @ 12:04 PM
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supereal |
08-04-2011 @ 1:31 PM
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If the shocks need to be refilled, it has to be getting out somehow. A byproduct of operation is heat in shocks, causing expansion of the fluid. I don't recall that there is any provision for release of the stuff. That is one reason that modern shocks are filled with gas, and to reduce aeration of the fluid from frequent operation on rough roads. I've replaced the lever shocks on all my cars to better control spring rebound. Model A's had problems staying between the fences with lever shocks.
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Dolman |
08-04-2011 @ 2:23 PM
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Not many fences here but there are a lot of ditches. I thought about gas shocks but decided the fabrications necessary would be beyond my ability. Maybe a member who has made the conversion on a '34 pickup can join in with what had to be done.
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ford38v8 |
08-04-2011 @ 2:46 PM
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Dolman, when you refill, do so with the shock in the as-mounted position to avoid overfilling. The fill hole is positioned to allow space above for heat expansion. Overfilling will cause rupture of the seals. On the later Houdailes, there is an adjuster which the 34's don't have. I put a matched pair in my bench vise to attain the same degree of resistance. If yours offer a full stroke of steady resistance in both directions, it's as good as it gets and a rebuild would only provide the additional assurance that seals were good. Tube shocks became instantly popular back in the day and continue that popularity due solely to economics. Lever shocks of the late 30's and newer are every bit as effective as tube shocks, but are expensive to manufacture and difficult to rebuild.
Alan
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carcrazy |
08-04-2011 @ 3:21 PM
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MAC'S Antique Auto Parts sells Shock Absorber Fluid claimed to be correct for Ford shock absorbers 1928-1948. It is part number A18099 and sells for $3.50 per pint.
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