front shocks

[1934clint]

I got a pair of original 1934 Ford shocks that still works. I want to put new fluid in them. Do I need to wash them out first, if so what do I need to use?

[Frank Miller]

you can top them off but I believe changing the oil is done by disassembly. Changing the oil was not a maintenance item.

[HD Rider]

I'm going through the same thing. My plan is to flush them out with Methanol. I use Heat in the yellow bottle or air brake antifreeze. Fill with alcohol and work it drain it and work it until fluid comes clear then work it until you get no fluid. Then refill with your choice of fluid. I will be filling mine with 20w-50.

[tubman]

I would have to believe that if they are off the car, you should not miss the chance to clean them out. The above approach for cleaning seems fine with me. I don't know enough to comment on the choice of fluid to refill them, but "motor oil" makes me wonder.

[FortyNiner]

Ford used castor oil and hydraulic fluid at different points., I understand.

[1934clint]

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Thanks to all information. Any more information will help.

[TJ]

I'm no expert, but if there are seals around the shaft I would be careful not to use any type of cleaner that could damage the seals.

[fordor41]

I used hydraulic jack oil in my '41 shocks. If the shock leaks somewhat, they can be filled on the car with a pump oil can with spout

[HD Rider]

Originally Posted by tubman

I would have to believe that if they are off the car, you should not miss the chance to clean them out. The above approach for cleaning seems fine with me. I don't know enough to comment on the choice of fluid to refill them, but "motor oil" makes me wonder.

Houdaille originally used a mix for alcohol and glycerin. 20W-50 motor oil is about as close a match as I could find to the original viscosity and is what many on the Model A side are using. My reasoning behind the use of methanol to flush and clean them out is because it is a good solvent and compatible with the original fill.

[Terry,OH]

IMO: Empty the old fluid (if there is any) and refill with Marvel Mystery Oil and then empty and refill with Jack fluid. Work the shock back and forth to the extremes in each step.

[HD Rider]

tubman got me thinking about this. He wondered about my choice of fluid. That made me wonder.Why not use a fluid meant for shock absorbers in our shock absorbers? When I worked in the motorcycle shop we had "Fork Oil". It wasn't just for forks but also for the rebuildable shocks on the rear suspension of the race bikes. We stocked 5w, 7w, and 10w oil. I had also heard of 15w oil. So I did some looking and found this.
https://www.belray.com/product/high-...ance-fork-oil/
It looks to me like 20w or 30w might be a better choice. Just some food for thought.

[51woodie]

I need to do the oil in the shocks on my ‘46 Deluxe this spring, and have been thinking about what oil to use. It seems there are a number of opinions as to what is the best oil. I believe the oil needs to be one that resists aeration, such as a oil designed for use in hydraulic systems. If the internal action in the shock develops air bubbles in the oil, the shock becomes ineffective. Shock oil for motorcycles would work, as long as the viscosity was heavy enough to compensate for the design and clearances that are in the Ford shock. I have had several motorcycle shocks apart, and the tolerances of fabrication are much tighter than in the Houdaile units, and the valving is quite different as well.

[Lawrie]

I would not use jack oil, that is meant for a static type hydraulic system and is usually just cheap oil.
I would use either engine oil or as HD rider said a good quality motor cycle fork oil.
Just think of what's going on in the shock over a rough roads.
Lawrie