K. R. Wilson Testing & Adjusting Rebuilt Shocks

[H. L. Chauvin]

1. This shock adjusting subject is often discussed on Model A Forums, & shock adjustment recommendations are offered in modern repair books as well as that of a few individuals formerly relating how they attempted to adjust their own shocks.

2. If anyone has faith in the Ford Service Bulletins & in the K.R. Wilson tool indicated in Figures 1097, 1099 & 1100, in the February 1931 Model A Ford Service Bulletins, I seriously doubt if all shock rebuilders actually test their shocks with a tool that closely resembles this tool & doubt if their rebuilt shocks can pass this Ford recommended test.

3. FWIW, I contacted Mr. Tim Wilson with the website www.krwilsontools.com who was very cooperative in furnishing details for this K. R. Wilson tool.

4. He sent a drawing & confirmed by email that the weight on the end of this 1931 K. R. Wilson tool is exactly three (3) pound & 5.80 ounces, or 53.80 ounces.

5. The distance from the center of the square shock lug to the center of the weight is exactly 26-1/2" which determines the foot-pounds of torque provided with the weight on this K.R. Wilson tool.

6. I made a tool like the one shown in the Ford Bulletin with 1/4" x 1" flat bar bolted to an actual Model A shock arm, & with a gram scale, used a steel pipe nipple & (2) pipe flanges to obtain exactly 53.8 ounces for the weight 26-1/2" from the square shock lug.

7. The weight is suppose to travel 23 degrees downward in 15.5 seconds in summer temperatures & travel 23 degrees downwards in 58 seconds in winter temperatures.

8. Unless I can find a shock rebuilder who claims that he actually tests his rebuilt shocks with this K.R. Wilson tool, or one that is similar, I am in no mood to try to have shocks rebuilt again.

9. Out of the (4) I tested, one (1) passed & three (3) failed miserably after dropping 23 degrees in about from (2) - (4) seconds with the shock adjustment bolt turned as tightly as it can be tightened. All were filled with thick recommended shock oil sold by vendors.

10. On all four (4) shocks I noticed a good bit of resistance traveling upwards, but they dropped very rapidly with very little resistance.

11. The one that passed the test was very sensitive in that one-thirty-second of a turn made a tremendous difference in the amount of seconds that it dropped.

12. Just sharing an experience. Glad I called Mr. Stipe earlier this week who is still taking orders for his new shocks which should arrive January/February 2015.

[Rowdy]

That has been my experience also, inconsistent rebuilds to the point you can feel the difference with a 12" cresent wrench. Right now I have 58 shock cores. I may start to dis-assemble them this winter. Hoping to get enough good parts for 2 sets. I do not have the test equipment yet, so could use the details if you wish to share them. Rod

[Kurt in NJ]

it could be that some of the shocks were put together wrong---a "CW" shock put together as a "AC" making the compression resistance greater than the rebound resistance ---what results do you get if you flip the test arm the other way

Thanks for giving the actual values for the tool, I had guessed at about 24", and 4=5 lbs just by scaling the picture

Having taken a lot of shocks apart to make ones for my car I have wondered how 75$ can make a properly working shock out of a better than average core ---that a true total rebuild to original specs should cost more than a new Stipe shock


having driven my car without shocks (scarey at 35), properly working shocke with limber well lubed springs make the car a joy to drive at 60+

[Kevin in NJ]

It is great to have those numbers. At some point I would love to have the prints.

From my minimal shock experiments. I found shocks with zero play, that is when the inside cover is off there was basically almost no rocking movement were much stiffer then shocks with some slight movement. Using the same fluid. Yes, have a couple of super tight shocks and a few that are pretty darn good. The super tight were very noticably better then the pretty darn good.

With the above, if you reference the attached article from MAN Vol XIII No.2 you will find some reference on the fluids used. From this article I know I was using fluids that were way too thin. I was using jack oil and thinner motorcycle shock oil.

Lots of variables in getting shocks right. The key understanding is just how stiff the original shocks should be. Most do not realize theirs are most likely way too loose even though you might think they have enough resistance, it is likely way less resistance then a factory unit would have had.

I believe a big mistake is putting the same fluid in every shock. You may have very tight to pretty darn good shocks. The very tight shock may need a little thinner oil or a bit wider open valve to equal your pretty darn good shock.

Hope that all makes sense. I hope to be revisiting the shocks within the year, we will see how time allows me to get to it.

[H. L. Chauvin]

FWIW:

If one looks at the Ford Bulletin's photo & scales the drum diameter measurement in relation to the lengths of each member of this "Z" shaped tool, one finds that, (after taking into consideration the foreshortening of the perspective of the photo), that there are three (3) different measured lengths on this tool as follows: (Drew mine in a reverse or reflected image from that of the 1931 photo):

1. Point A to Point B at 180 degrees horizontal = 8"; i.e., in the center of the tool's arm, (moving towards the left), from center of shock lug to tool center of the first joint.

2. Point B to Point C, (dropping down & again towards the left), at 120 degrees from the 180 degree horizontal = 11": i.e., measured in the center of the tool's arm, from Point B to the tool's center of the second joint's Point C.

3. Point C to Point D traveling 4 degrees downward & towards the left from the horizontal of 180 degrees, i.e., traveling downwards & left at 184 degrees, measuring from the center of the tool's turning point C to Point D located on the far "end" of the arm of the tool.

4. Last measurement is from Point A, (center of lug on shock), to the center of last or third notch on the tool, which is also the center of the 53.80 weight. Note that this most important dimension is in a straight line measured from center of shock lug to center of tool's weight.

5. I then removed all four shocks, bolted them to a 2"x2" angle iron, & tested the drop while watching the second hand on a clock.

What got me curious was that I drove my 1930 coupe for years with no shocks & because of oiling spring every year, the ride was always smooth but "bouncy".

Then when I got my 1930 Town Sedan, the shock oil was leaking so I sent them off to be rebuilt.

Before & after rebuild, I noticed what this tool proved, i.e., that the shock's resistance was mainly in the upward direction only, so when I hit a bump, it felt like I was driving a an old time dump truck with extra heavy springs.

I then re-adjusted all of the shocks by turning the adjustment bolt all the way counter-clock-wise to obtain a much smoother ride like when crossing railroad tracks. If one travels on a smooth highway with no dips & bumps, shocks are not even needed.

In my opinion, what can be noticed is when one has one front shock operating properly with resistance on the rebound, & the other front one providing resistance in the opposite direction; hence, affecting engine weight distribution & even moreso effecting steering.

This is not to just complain about people's services, or to try to ruin the salaries of shock rebuilders; but only to point out that if anybody ever finds one who's rebuilt shocks can pass the K.R. Wilson tool test, that these shocks would meet Ford's February 1931's recommendation for Model A Ford shock resistance & in my opinion, produce a much smoother ride on back roads, especially at about 50 mph.

Hope this helps.

[Jim Mason]

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A better term is a rebound supressor. The spring controls the up stroke( little resistance from the shock) & the shock controls the spring rebound (high resistance).

[Kevin in NJ]

I do not think that some that rebuild shocks are even aware of how a good shock is supposed to behave. For that matter few know how the shocks are supposed to behave.

Thanks to your time and research I am sure there will be some that change how they deal with shocks.

[H. L. Chauvin]

Most sincere thanks Jim for the correct resistance term.

It also helps to note in scientific terms that one's Model A seat springs contribute more correct & proper rebound suppression than one's re-built shocks. LOL

[Jim Mason]

Didnt mean it as correction or anything. Its just the way i remember which direction is the high resistance. Prevents miss marked shocks being installed in the wrong place

[H. L. Chauvin]

Jim,

I really liked the way you described it -- makes it easy to understand how new or re-built shocks should function properly -- sincere thanks again.

[Mike V. Florida]

I would like to suggest the purchase of Les Pearsons book ""Model 'A' Ford Houdaille Hydraulic Suspension". Book. You will find a wealth of information in the book. did you know the metal to metal clearances of shock were .0005".

Les, if you're reading this, the information on the test fixture or how to build your own, pictures of the different covers for the different years as well as a picture of a properly shaped needle valve bottom to go along with the picture of the worn one are suggestions for the next revision.

[H. L. Chauvin]

I noticed that when "rebuilt" shocks react backwards, it feels like someone added several leaves to the springs causing a stiffer rough ride.

I think Kurt may be correct in his above reply #3 stating his many past experiences with the possibility that some shock rebuilders may be mixing the "AC" internals with the "CW" internals where some of their rebuilt shocks react backwards thus causing rougher rides with improper shock action.

Then with some of their rebuilt shocks offered, their rebuilt shocks were assembled correctly with worn internals; however, these appear to offer far too weak of a resistance in either direction.

Then after having different reactions from different rebuilt shocks on each wheel, one can only guess what will be experienced on a back road.

I just found it most interesting that with all of the "re-built" shocks sold over so many years "nobody" ever questioned if "all four" of their "rebuilt shocks" could be equally adjusted in order to pass Ford's shock test using his recommended K. R. Wilson Tool.

FWIW: After removing all (4) re-built shocks & conducting a road test on a back road yesterday, I noticed no shocks produce a smoother uniform ride than with improper rebuilt shocks that could not be uniformly & correctly adjusted with a K.R. Wilson tool.

[RHD]

Thanks for your well informed comments. I will make revisions in my next edition.

[RHD]

When using a homemade replica of a KR Wilson shock absorber resistance measuring tool, I have to following question.
What position is the shock absorber adjusting valve meant to be in? Fully wound in and seated???
I can find no reference in the Service Bulletins book.
I have a Houdaille shock here and although it has had some minor use, it is in brand new condition. When the adjusting valve is wound in and seated it feels almost solid and when first obtained, I thought it had seized. Only by backing the valve off one half turn did I manage to move the rotor sufficiently. I disassembled and found it had was filled with a brown glycerine was spotlessly clean and completely unworn. Strangely, when fitting the rotor back into the body in the correct position, it would not fit. The rotor appeared to be too big. The tolerance between the rotor and the body was only 0.0005” and could be less. I could not measure any further. The rotor I found had to be inserted into the body exactly vertically or it would not fit. I am using a heavy hydraulic fluid as near as the viscosity to glycerine which works extremely well. The best shock I have ever seen.

[Kurt in NJ]

Yes, a good shock will near lock up in rebound direction with closed needle valve using hydraulic jack oil, but still move in compression direction.
The needle valve is opened the amount it takes to get the timed movement with the test weight