Shock fluid leakage ... How much is OK?

C

Commander Toasty

Member
Original shocks, and they work, but they all leak. Just enough to keep them messy, not like it's pouring out and going dry quickly. Is some leakage OK, as I have understood it to be? What is the line between 'some' leakage and needing attention? Should I just rebuild the darn things and see what happens?
 
Commander Toasty,

Robert Paul, from Yoder, Colorado, rebuilds shocks and does a great job at a very reasonable price. I'm not related and have no business interest, just that he's done nice work for me. I've got a set of shocks he rebuilt in 1989, and one just started seeping a tiny bit this year. That's great service!

Anyway, I had some shocks on my unrestored Fordor that were leaking and called Robert. First question he asked was how much did I fill them. I told him just a little below the opening. He laughed a bit, and said to drain about a third out. He recommends running the shocks about 2/3 full.

But, to quote Ford Service Bulletin, January 1928, page 205; "The filler plug in the reservoir should be removed at intevals of 5,000 to 10,000 miles, and the reservoir filled with glycerine (Commercial). NEVER REPLENISH WITH OIL. Oil will solidify in the winter or reduce resistance and will not mix with the glycerine in the instruments."

The rebuilding of the shock is covered in the Service Bulletin begining on page 536, February 1931. Figure 1115, and the caption below the figure, inddicates, "...fill the instrument with fluid up to the level of the filler plug opening, then replace filler plug."

I didn't see any other references to the level we should fill the shocks. I know that when I took Robert Paul's advice and removed a bit of the fluid form my leaking shocks, the leaks stopped. I don't drive that car enough to determine if there's any ride difference.

Dave Lopes
 
"But, to quote Ford Service Bulletin, January 1928, page 205; "The filler plug in the reservoir should be removed at intevals of 5,000 to 10,000 miles, and the reservoir filled with glycerine (Commercial). NEVER REPLENISH WITH OIL. Oil will solidify in the winter or reduce resistance and will not mix with the glycerine in the instruments."

Dave, does Robert Paul use glycerin or shock oil? Glycerin attracts water, the reason so many shocks are rusted.
 
Something to think about: multi-weight oils did not exist in the Model A era. Perhaps if they were available, they would have been used instead of glycerin.

Doug
 
Pat,
I can't recall asking Robert about that. I know that I added shock oil purchased from Bratton's to the Fordor shocks.

Dave Lopes
 
quoting the service bulletins June 1930 page 467
"New shock absorber fluid
We are purchasing a quanity of shock absorber fluid which will be known as M-564 Ford hydraulic shock absorber fluid.This will be availible for dealers in the near future.
As soon as this fluid is availible ,it should be used in all Ford shock absorbers instead of the glycerine and alcohol mixture.
Under no circumstances should any other materials be used in Ford shock absorbers. "

now for the $64 question. Just what is M-564 shock absorber fluid?

it sure seems that Ford did not use glycerine in the shocks after maybe July 1930

That said ,I just opened over 50 shocks and did not find any that appeared to have oil in them ,either they were dry and rusty or had glycerine in them.
Tom
 
I also have shock fluid from Bratton's but what is it? Might it be oil? I doubt it because that would mean they are making a decision on what is best to use.

What type of oil are you folks adding if you aren't using glycerin?
 
I have used motorcycle shock oil for years, for me it was always a mixture of several weights, I used the leftovers all combined from when I worked at a motorcycle dealer.

My shocks have been on the car for more than 25 years, about every 2 years I check and fill them, the past 5 years there has been some seepage.

As for how often is too often that is for you to decide, if you have nothing better to do you could fill them every week.

the shaft seals can be changed without totally taking the shocks apart, just the covers need to come off to change the seal. --even if the shaft is worn where the seal rides if that surface is very smooth the seals can work.
 
My guess is that Ford used glycerine because oil because he used a natural rubber band to seal the large ring. Oil would damage that ring. Worn shocks need heavier (higher viscosity oil) to provide the proper resistance to movement. Ordinary hydraulic fluid is too thin for any Model A shock. It is thinner than glycerine.
 
Do I recall correctly a post sometime back about using Hydraulic Jack Oil??

I suppose you would need to remove all of the current shock fluid before changing over.
 
Re: Do I recall correctly a post sometime back about using Hydraulic Jack Oil??

roccaas said:
I suppose you would need to remove all of the current shock fluid before changing over.
Click to expand...
If it were my car, and I wasn't certain of the fluid that was in the shock, I would absolutely remove as much of the current shock fluid before adding anything.
 
I don't think that the shocks need to be filled up to the filler screw/bolt. I remember reading somewhere that the fluid should be no higher than 1/4" below the filler opening. I think that as long as there is some fluid in the reservoir, that will be enough.

Also I use rear end oil (85W140) in my shocks. Seems to work and no leaks - so far.

Dick
 
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