Glycerin? No I Don't Need a Laxative Thank You!

[leo]

My coupe has a set of shocks rebuilt by Robert Paul several years ago and the past threads say that he fills his shocks with glycerin. OK, what type, I went on line and found several kinds each with different additives for different purposes. What type or brand would be compatible with what he has used?

[Oldbluoval]

All I hear he is still kicking around, I hope. Why don't you go to the source? And BTW, post the answer here for all??

Robert Paul in Yoder, Colorado (719-478-5102)

[Dennis Pereira]

If Glycerin absorbs water how long before you have rusty stuck shocks again? will they last for years?

[leo]

Will report back when I have spoken to Mr. Paul.

[richsfords]

try the nitro brand but stay off bumpy roads
just a thought?
best of luck.

[Oldbluoval]

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I used to build shocks back when 1 out of 4 could be rebuilt.
Now I think it is 1 out of 20 if lucky.
Back then I used hydraulic oil. If the shock would not completely lock Down (i.e. Still some wear), I would up the weight of oil accordingly. That would improve the resistance to make it a viable shock.
I would use hydraulic oil. But you likely should use neoprene o-rings and not cork.

[Kevin in NJ]

Ya, no.

Ford changed over to oil for the shocks. Do search I have posted the reprint of the article that appeared in a model a magazine.

If there is even slight wear you will need a thicker oil. See the service bulletins for the testing procedure for proper operation. That is a 6 lb weight in the tool.

[Mike V. Florida]

Originally Posted by Dennis Pereira

If Glycerin absorbs water how long before you have rusty stuck shocks again? will they last for years?

That's why they changed.

Originally Posted by Kevin in NJ

Ya, no.

Ford changed over to oil for the shocks. Do search I have posted the reprint of the article that appeared in a model a magazine.

If there is even slight wear you will need a thicker oil. See the service bulletins for the testing procedure for proper operation. That is a 6 lb weight in the tool.

[Kevin in NJ]

Here is the article about shock fluid.

[leo]

Mr. Paul (a very nice fellow) said Glycerin 100% should be used in my shocks if I need to add some fluid. He also said not to over fill them because gas is created from the glycerin and if it has no where to expand to it will blow the seal on the adjustment valve. Regarding the adjustment on the shock he said that experimentation of 1/8th of a turn in either direction should result in a change in the tension of the shock. This will probably vary from shock to shock depending on the amount of internal wear. Again, a tip of the fedora to Mr. Paul.

[Bob Bidonde]

Shock absorption occurs by forcing (pumping) volumes of an incompressible viscous fluid through orifices inside of the shock absorber. Houdaille shocks used pure glycerin as the fluid.

I concur that glycerin absorbs moisture and will lead to internal corrosion of the shocks. Corrosion is accelerated as the glycerin gets hot from absorbing energy.

A substitute fluid product for use in 1930s vintage Houdaille shocks should have a minimum viscosity of SAE 60 which is equivalent to pure glycerin.

I have successfully used SAE 90 hypoid gear oil in the Houdaille shocks on my Coupe which have about 50,000 miles of use since new.

[FRANK PKNY]

I always used mineral oil! What has changed?

[leo]

OK so if the shocks contain glycerin or ? then the first step to replacing that liquid would be to dump it out and somehow rinse out the inside of the shock to remove all the remaining residue. Then the issue becomes how much wear is there to the shock internals because the amount of wear changes the clearances between the moving parts and I would think that more wear would require a fluid with more viscosity. How do we determine that part of the equation without taking the shock apart?

[leo]

None of you ever flushed out the old fluid from your shocks and experimented with a replacement? I find this hard to believe.

[jwilliams81]

How do you drain the shocks?

[Oldbluoval]

You have to remove them. Even then, they drain slowly because the inner chamber has very small weep holes. When I built them, I used to fill the inner chamber before putting the inner cover on. Otherwise, the transfer of fluid from the reservoir to the inner chamber where the pressure is maintained was very slow.
Took for ever for the shock to build pressure.
Just my experience.

[leo]

So it would appear that emptying and refilling your shocks with something regardless of what it is can be a daunting experience even for the well seasoned restorer. Having read many past threads on shock rebuilding and fluid replacement I find it odd that this little dilemma has not received any ink.