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Old 09-10-2020, 07:28 PM   #1
Bob Johnson
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Default Shock fluid test results

I did some tests using a shock that has wear. I do not have a spare shock that has no wear. I used 4 different fluids, Water, 10-40W, 140W and "600W" oils. I tested with the needle valve closed and with it open 2 turns. I found that I could not get enough resistance because the shock was too worn. So I repeated the tests this time after plugging the lower bypass hole in the rotor. The values in the table are foot-pounds. I estimate that the weighed arm in Ford tests exerted about 9 foot-pounds on the shock. My tests are torque values not timed drops as Ford did. You can draw your own opinions on the results.
Bob





Last edited by Bob Johnson; 09-10-2020 at 08:49 PM. Reason: correction
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Old 09-10-2020, 08:05 PM   #2
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Default Re: Shock fluid test results

I'm running 80W-140 in mine on the speedster and they seem to be working OK. I haven't taken mine apart but they look really good on the outside and all have consistent resistance.

Per your test I think you either need time to sweep or torque amount during the sweep.
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Old 09-10-2020, 08:15 PM   #3
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Default Re: Shock fluid test results

While researching the rebuilding of my shocks which I am still in the process of and documenting it on the HAMB I came across this list. It would be applicable for rebuilt good condition shocks. Are your results for worn shocks or rebuilt?


Modern oil.JPG
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Old 09-10-2020, 08:46 PM   #4
Bob Johnson
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Default Re: Shock fluid test results

worn shock
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Old 09-10-2020, 08:46 PM   #5
Herb Concord Ca
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Default Re: Shock fluid test results

Hi Bob, I too have some worn shocks, in my case pitted. Can you post your reason for plugging the lower bypass hole in the rotor? I, and I think others would be interested in you logic on this!
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Old 09-10-2020, 08:51 PM   #6
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Default Re: Shock fluid test results

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Ranchero50,


The torque reading was done while moving the torque wrench. I should not have said static (I changed static in the original post to torque). So as I operated the shock with the torque wrench I recorded the torque reading. Thanks for picking up my poor description.



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Old 09-10-2020, 09:27 PM   #7
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Default Re: Shock fluid test results

The reason for plugging the lower bypass is to make up for all of the extra fluid due to wear that is moving from one chamber to the other. A shock that is not worn will move most if not all of the fluid through the bypass holes. A worn shock will move some fluid between the rotor (wing) and the shock body. It can move under the rotor, above the rotor or even the ends of the rotor. Depending on where it is worn.

Let's do some math. The bypass holes vary but are around 0.12" in diameter. That means the cross section is 0.013 square inches. The rotor (wing) sides are 1" tall and it is 2.5" wide. There are 7" where there can be a gap for the fluid to pass through. Actually only 6" because the fluid can not pass through the shaft at the top of the rotor. Are you still with me? Now 0.013 square inches divided by 6" gives about 0.002". I am not sure what the original clearance was for the shock. I seem to remember 0.0005". Anyway wear of 0.002" around the rotor will move as much fluid as the bottom bypass hole.

I conclusion you can make up for 0.002" of wear by blocking the lower bypass hole.


If you got this far you have too much time on your hands.


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Old 09-10-2020, 10:59 PM   #8
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Default Re: Shock fluid test results

Bob, very interesting and thank you for doing the work and sharing results. Since the torque value from your test is highly dependent on the speed that you stroked the shock absorber, can you give some estimate of how fast you stroked the shock?

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Old 09-11-2020, 08:07 AM   #9
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Default Re: Shock fluid test results

Don't know if they are still available, but there was a shock restoration kit that had a bunch of lead shot to block off the holes.
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Old 09-11-2020, 09:50 AM   #10
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Default Re: Shock fluid test results

Joe B.


My reason for the testing was to see if there is a difference with different fluids. I think I accomplished that. I was not trying to compare with the Ford tests. But to answer your question. The sweep times were about 5 10 sec for about 1/2 the max travel of the shock arm. I may try to set up the Ford test system just to see what I get. I would not tests all of the same scenarios. I may also see if I can find some glycerine and test it in the shock.


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Old 09-11-2020, 01:03 PM   #11
Herb Concord Ca
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Default Re: Shock fluid test results

Hi Bob, thanks for your detailed explanation. Looking forward for more of your experiments.
Thanks for your work!
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Old 09-11-2020, 03:52 PM   #12
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Default Re: Shock fluid test results

I have attached the fluid type documents from Ford.
Attached Files
File Type: pdf 2014-05-16 06-23 page #0.pdf (1.33 MB, 17 views)
File Type: pdf 2014-06-21 18-26.pdf (1.65 MB, 11 views)
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Old 09-11-2020, 04:13 PM   #13
Kevin in NJ
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Default Re: Shock fluid test results

Here are some pictures from the last I was working on shocks.

The first one is an example of one that is might not work so good.

Next is a picture of all the parts from one shock laid out.

Then you can see a shock that will have a tough time working well. Too much area for the fluid to bypass the vane.

Then a close up of a slightly worn body.

Here are 3 shocks that are slightly to a bit more worn. This is just to illustrate the 2 different directions and how the parts go. The black line shows the path of upper cross hole which is part of the valve.

Mentioned earlier was the lead balls. They are for sealing the corners of the static vane in the lower corners.

While all these shocks look really good, they will not give factory performance with the original viscosity oil. I am guessing that there might be a couple of thou wear at most on these. You can visually see the 'looser' ones and they have much less resistance then the ones that look tighter.

Of course you can not swap parts around. First off there are more manufacturing variations then you might first think. They did little changes internally through production. The parts also may be hand fit to some extent.

When selecting oil there needs to be some concern for the oil foaming as it move through the passageways. Plus the oil has to be able to flow through some small holes. If one is experimenting with oil it might be wise to freeze a shock and see how it preforms with each oil as well as get it up around 100 degrees.

One of these days I will pull out the box of shocks and continue my testing. I had a lot of questions and no answers so I put them aside. Now I have some more answers and need to try the ideas.
Attached Images
File Type: jpg P2171257.jpg (71.1 KB, 22 views)
File Type: jpg P3081259.jpg (53.6 KB, 24 views)
File Type: jpg P3121286.jpg (86.1 KB, 23 views)
File Type: jpg P3121288.jpg (77.3 KB, 23 views)
File Type: jpg P3131290.jpg (82.6 KB, 25 views)
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