While doing some suspension work on my 47 Pontiac I noticed the manual mentioned adding fluid to the front shocks. I’m sure it hasn’t been done in 70 years, anybody have an idea of what to use?
A friend did some research for his motorcycle and found that the right viscosity for his was found in good old Dexron II. Way way cheaper than the special stuff.
90% glycerin and 10% denatured alcohol for the lever type shocks...though I bet the alcohol is evaporated leaving the glycerin....I sure wouldn't mix any hydraulic fluid in it
There is a whole family of water-based hydraulic fluids: ethylene glycol + water, propylene glycol + water, glycerol + water, in different proportions depending on the application. In fact air spring manufacturers specifically mention glycol/water if you wish to use an incompressible medium in the bags. They cease to be springs, of course, but it's one way to do hydraulics without having to deal with sliding seals — albeit a bulky one.
@skooch , even this early, it sounds like you might want to take a sample and try to find out what it has now. Seems like there are a lot of incompatible choices! I didn't find a quick easy DIY for this, but color and texture would be the first step. You can move up to taking a small sample and pour it in a glass with (individually) water, hyd fluid and ATF to see the specific gravity or move up to a tester. https://www.walmart.com/ip/Specific...th-Borosilicate-Glass-Test-Tube-Jar/662270548
Considering they have computer-controlled fluid-filled engine mounts now, the poor counter person could be forgiven for not knowing every possible application on every car made. Don't be the guy that sprays silicone on his rubber seals in the body shop!
I can remember with my Roadmaster ignorantly shooting something like 160wt gear oil in there. Many years ago, haven't touched that since---front end rides good.
Heavy oil does wonders for Armstrong lever-arm dampers. There is an ongoing debate in Morris Minor circles about whether telescopic conversions are worth the effort. All things considered I reckon telescopics still have the advantage.
You might call Apple Hydraulics, they rebuild all sorts of lever shocks, they will know what fluid you should use. https://www.applehydraulicsonline.com/?srsltid=AfmBOopmcMioJYjM55rDeNqH3XxCeOBYIPSUwVZw3GVrTFZRJFZa1lXA I’m guessing that your shocks use hydraulic fluid as mentioned above, viscosity does effect dampening rates, Moss Motors sells a shock fluid. https://mossmotors.com/220-306-shock-absorber-oil-by-dynolite-1-liter Dan
http://www.nosimport.com/ These guys also service lever shocks, I believe that they can make Lucas shocks adjustable, maybe Armstrong shocks also, they will be rebuilding my OT Sprite shocks Dan
If it's a GM car it needs Knee Action Fluid which hasn't been available in parts stores in years. Hydraulic jack oil is a good substitute.
Thanks again for all the replies. Between the hamb and other sites I have seen many different products used for this, including brake fluid, power steering fluid, fork oil, transmission fluid, gear oil, hydraulic jack fluid, regular hydraulic fluid and glycol. The one consensus seems to be that if it was originally filled with glycol you don’t want to mix an oil based fluid with it and visa versa. Since I’m pretty sure that gm didn’t use glycol in 1947 I ended up using hydraulic jack fluid and feel pretty comfortable with that.
Good to know as a few of us have these type shocks. Again, Apple Hydraulics would be a good place to confirm your choice!
If they haven't been filled in 70 years it probably won't matter what you put in. It's going to leak out anyway. I put STP in mine one time. It rode really great... until the next day when I had to clean it all up off the shop floor. .bjb
Judging by the rounded off filler heads that I had to file down I guess somebody did fill them at one time. If they leak out I’ll just stuff some cornhole grease in them. Note to add stp to the product list that people have used to fill these.
Considering what was used to clean gun barrels when shooting corrosive powder, anything could have been in there! Let us know how it rides and if it leaks.
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