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Old 09-08-2020, 04:12 PM   #1
Bob Johnson
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Default Shock tester

Does anyone know how many foot-pounds the KRW shock tester applies the the shock? I think I can estimate the length of the arm but not the effective weight at the end of the arm.


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Old 09-08-2020, 05:36 PM   #2
BRENT in 10-uh-C
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Default Re: Shock tester

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Originally Posted by Bob Johnson View Post
Does anyone know how many foot-pounds the KRW shock tester applies the the shock? I think I can estimate the length of the arm but not the effective weight at the end of the arm.

Bob, I'm not really sure it matters. Notice the notches on the fulcrum arm that allows the weight to be moved. As you know, in all likelihood the amount of weight is there mainly to move the fulcrum arm to test compression and rebound of the shock by timing the range of motion. The two pins on each side allow the arm to be set multiple times to compare shock travel timing. I'd say the tester only gave a baseline for the mechanic to set the needle to his desired firmness, and then he test drove it to make sure he liked the ride. He likely just adjusted each shock until he was happy, and until he felt opposite sides were dampening equally.

If you still want to pursue the weight, scale it out and give me the dimensions including the extruded portion in the middle, and we will draw it up in CAD to figure the weight it would be when made of different type metals.
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Old 09-09-2020, 08:00 AM   #3
Kevin in NJ
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Default Re: Shock tester

I think you want to look at this previous thread:

https://www.fordbarn.com/forum/showt...rebuilt+shocks

I always like exact information.

My experience has been that shocks with slight wear do not come close to the Ford standards. That is I have shocks with minimal wear and I used something close to the KRW testing tool. With the valve closed the shocks were very hard to move by hand. Using the test arm the shock went stop to stop in like 5 seconds. No where near the required 15 seconds.

I need to add that in the past I rebuilt shocks where they were just really hard to move by hand with an original arm. This allowed me to drive a car that was unstable above 20 MPH at 60+ MPH quite comfortably.

I have not revisited shocks as I need to get some thicker oil to find out what happens. Some day in the future.
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Old 09-09-2020, 11:35 AM   #4
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Default Re: Shock tester

Thanks Kevin. Using data from that post I estimate just under 9 foot-pounds of force applied to the shock. That includes about 7.4 foot pounds for the weight and about 1.4 foot pounds for the arm. I am guessing that the arm has the two bends so it can be used with the shock on the car and be able to swing the required arc.

Last edited by Bob Johnson; 09-09-2020 at 11:37 AM. Reason: add info
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Old 09-09-2020, 11:55 AM   #5
Kevin in NJ
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Default Re: Shock tester

The bends are for on the car testing as it seems to get around everything with those bends.

Of course, you will want to read the service bulletins as they specify the distance traveled by degrees of rotation. I am not sure that is lock to lock distance.
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Old 09-09-2020, 02:52 PM   #6
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Seems pretty technical And unnecessary for a Model A Ford. After you get your guesstimate what will you do with it ?
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Old 09-09-2020, 06:32 PM   #7
Kevin in NJ
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Default Re: Shock tester

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Seems pretty technical And unnecessary for a Model A Ford. After you get your guesstimate what will you do with it ?
No guesstimates. We have the information to properly test the shocks for factory correct function. You can read about this in the Service Bulletins where they tell you how to rebuild and test the shock. This allows one to build a car that drives like factory.
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Old 09-09-2020, 09:57 PM   #8
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Default Re: Shock tester

My'39 shocks have a chisel marking where the factory thought the shock should be set. I haven't checked my model A
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Old 09-10-2020, 04:14 PM   #9
Kurt in NJ
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Default Re: Shock tester

I found that a unworn shock will near lock up in the rebound direction, but still moves in the compression direction with a closed needle valve with light oil, using the weight and timing different settings you can mark a couple settings and match operating times so they all match, some may take a 1/8 turn, other 1/4 turn to have same action
I found that lubricating the spring enabled tighter shock setting and better ride
It took taking apart at least 20 shocks to get 4 that could meet the service bulletins times without totally closing the needle valve
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Old 09-14-2020, 11:20 AM   #10
Clem Clement
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Default Re: Shock tester

I see no chisel marks on my A shocks. I guess this feature came around in the eV-8era
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