Topic: Houdaille Shock Oil


len47merc    -- 05-30-2014 @ 4:34 PM
  Just finished restoring the primary mechanicals of a '47 Merc only to find leaving the Houdailles for 'possibly' last, assuming them to be functional, a potentially large oversight and false assumption. When opening the fill 'tube' found the original glycerin to have gelled apparently due to the 30+ years of inactivity. In calling rebuilders have been advised to fill the shocks with 30 wt hydraulic oil. This seems concerning on the surface - 'this' being mixing a petroleum based product with a now gelled water-based product. Sounds like a recipe for disaster. Four questions:

1) Recommendations for rebuilders if ultimately needed
2) Which 'modern' material (& weight) is best for replacing the original glycern?
3) Success &/or failure stories with simply moving forward with 30 wt hydraulic oil (or other) on top of the original glycerin
4) Best practice if applicable (secondary to complete rebuild) for ensuring and preserving the integrity of the original shocks (e.g., flushing with isopropyl to remove the glycerin, then changing to hydraulic, etc.)

Steve

This message was edited by len47merc on 6-1-14 @ 5:27 AM


supereal    -- 06-01-2014 @ 3:11 PM
  If the fluid is hardened, you would have to disassemble the shock to clean it out. That is a job for a shop that does rebuilding with specialized tools and equipment. The 47's did switch to tubular shocks. Mine has them. By the time you rebuild or replace the lever shocks, you will usually have more cost than the conversion, and a better ride. C&G sells kits for front and back at $212.95 each. (800-266-0470). Full rebuilds for lever shocks are in the range of $100 per.


len47merc    -- 06-01-2014 @ 3:37 PM
  Thanks supereal - the 'fluid' in all 4 shocks has gelled to a mildly viscous greenish-black paste but is still fluid and not hardened. Wondering if I can just go ahead with 30 wt hydraulic fluid (again, petroleum base on top of original water-based glycerin) and give it a go. Looking inside the small fill hole the internals look good, just no fluid to allow for performance.

Note I have no idea what may have been put in these shocks beyond the original glycerin in the 67 years prior to my obtaining it. The car sat idled & covered for ~30-35 years after being used for parades only in the late 60's thru mid-70s and the shocks were represented to be functioning properly and never touched by the then owner. Given the arms move freely do I have anything to lose in trying or should I just bite the bullet and move forward with complete cleanings and rebuilds?

Steve

This message was edited by len47merc on 6-19-14 @ 8:25 AM


supereal    -- 06-01-2014 @ 4:08 PM
  Try each shock by moving the arm briskly to see if there is any resistance in either direction after filling with hydraulic jack oil. If there is none, or very little, you will have your answer. The only reason I can find for retaining the lever type is to present an original appearance for judging. Effective shocks are necessary for safe driving, in any case.


len47merc    -- 06-19-2014 @ 8:58 AM
  UPDATE - After filling the original rear shocks multiple times using a pipette with 30W hydraulic fluid, each fill adequate to force out decreasing amounts of the greenish 'muck' (for lack of a better word), pumping the arm up and down 10 times manually after each fill (10 total 'fills' for 100 pumps total), then driving the car on 5 trips of 20-40 miles/trip, the original Houdailles surprisingly and fortunately have begun functioning again and are improving with each drive - am able to drive comfortably now at 60-65 mph (previously impossible due to rear axle/wheel hop). This morning I opened both shocks again for the first time since these first efforts and found them to be under minor internal pressure which forced a fairly sizable plug of the remaining green muck out when removing the fill plug.

Not an expert or seasoned veteran here, so take this for what it is worth. My assumption is it took a while for the hydraulic fluid to work through to the bottom cavity and, as this new fluid is more dense than the greenish sludge, the original material is now in the top of the chamber and the new fluid has now freed-up the check valves, etc., and also filled the bottom/working end/cavity. When filling the shocks this morning it took quite a bit - ~3-4 pipettes - to top them off (they are also surprisingly and fortunately not leaking - knock on wood) and more significant amounts (this time) of the greenish sludge were expelled with the first 2 pipettes. Kept filling as before until no further sludge was expelled with the excess 30W fluid.

A lot of work but for us Rouge class guys it is hoped this info and results are of benefit to others considering wholesale change-out or rebuild of shocks. Regardless of whether this ends up being only a short-term band aid fix or produces long-term results I will update again. Currently have a couple hundred miles now with the shocks functioning and am moving on to the front with the same process.

Steve

This message was edited by len47merc on 6-19-14 @ 9:01 AM


len47merc    -- 06-23-2014 @ 6:57 PM
  UPDATE 2 - Front shocks unfortunately failing to respond at all to this process. Rears continuing to improve but will be surprised if they'll ever make it to full performance. Believe the fronts are absolute no gos. Moving on to rebuilds/replacements. Worth the trial for the learning value. End of discussion thread.

Steve


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