Technical: Shock Absorber
Stan Diener, Jerry Raino, Dave Hennessey

1952 - 1955

These are the “Old Style” shock absorbers shown in the Spare Parts Catalogs up until 1959. The shocks used on 1952-1953 and 1954-1955 are very similar, and at first, are quite difficult to tell apart. Look closely at the adjustable cams - the 1952-1953 shocks have two positions, while the 1954-1955 shocks have three positions.

The only other externally visible difference is in the 54595-xx Upper Eye. Look at the comparison photos. The -52 version is straight at the bottom where the -52A has a decided flare. Of course, if the bike has the stainless steel shock covers, you won't be able to see this area. Once you get inside the shock, you'll find many differences in the internal parts.


The standard spring for all 1952-1955 models was 54550-52 Rear Shock Absorber Spring. In addition, there was a 54550-53 Rear Shock Absorber Spring (For Heavy Riders). This first appeared in the 1954 Spare Parts Catalog, and was continued until 1963, when “extra strong” replaced “heavy riders”. For some unknown reason, all the Catalogs list it as fitting 1953 and 1954 only. There's no known reason why it would not fit 1952 and 1955 also. Apparently, the standard 1952-1955 spring was a little weak for the job. No “heavy riders” spring was offered for the 1956-1964, 1965-1966, or 1967-1969 types of shocks.


You will need a spring compressor to disassemble and reassemble the shock. Below is a nice one Stan Diener fabricated. The rods are 3/8" All-Thread. The wrenches are “flat ratchets”. Instead of metal plates, you can use 2x6s.

Apply penetrating oil to the bottom of the Upper Eye. Clamp the 54557-xx Spring Plate in a soft-jawed vise, and use a large screwdriver or bar to break the eye loose from the shock's piston rod. The Spring Plate will hold the Piston Rod, so the Eye should break loose easily. Now compress the shock slightly with the compressor, and unscrew the Upper Eye. Loosen the compressor, and remove the shock. It can be disassembled except for the lower cam. That's the next step.

The Lower Cam has a 604 roll pin which limits the travel when you turn the cam. It also prevents the cam from being removed. There is a secret to removing the pin, so read on before doing anything. You will be driving the pin inward, and once clear of the Lower Cam, it will fall out. But the secret is that the groove the pin rides in has a slightly variable depth. This may be due to dried-up grease and crud in there, so clean it out thoroughly. Turn the cam through its travel, and use a caliper or other measuring tool inserted through the larger hole for the adjuster tool to find the position of the cam where the groove is the deepest. It's only about .010" deeper at that point, but it makes the difference between the pin falling out, or bottoming out in the groove. The photo below shows the pin already removed, and the cam slid up so that you can see the groove beneath.

Lay the shock down so the back of the cam is resting on a table, and carefully drive the pin inward. Once the pin falls out, you can remove the Lower Cam.

A couple of notes on the diagram in the parts books. I wondered and wondered about part 54585-52 - until I figured out that it is welded to the top of the shock. The drawings at the bottom, which are supposed to be the 54501-52A shock absorber only, are actually partially assembled units, with the spring plate and upper eye on them.

Here are the markings on the shock absorber units.


Paint the shock itself a glossly black, similar to the motorcycle's frame. Parkerize the rest of the parts. The springs were probably parkerized, but you can paint them black instead - it really doesn't matter, since you will never see them once the covers are on. Note that the cams are somewhat hardened where they meet each other, and the parkerizing color will vary there.


Apply a light coat of grease to the inside of the cams. Reinstall the lower cams with the 604 roll pin. The upper cams are keyed, so they can only go on one way. Install all the other parts, as shown in the illustration in Spare Parts Catalog. Put the unit in the spring compressor and then screw on the Upper Eye, and moderately tighten. Then de-compress.


The shocks can be installed on the motorcycle so that both of the 604 roll pins face toward the rear of the bike, or both face toward the front, or are opposed. It's unclear how the factory did it, or even if they did it one way consistently. Functionally, it doesn't make any difference. Appearance-wise, it doesn't make much difference either.


The 1952-1953 shocks have a two-step cam, putatively for solo and buddy use, although the 1952 Rider's Handbook does not mention adjustment. The 1954-1955 shocks have a three-step cam, for solo, heavy riders, and buddy. Using the 94700-52B Rear Shock Spanner Wrench, turn the rotating (lower) cam counter-clockwise (as viewed from the top) for heavier loads. Turn the cam clockwise for lighter loads.

The 1954 Spare Parts Catalog lists the 54550-53 Rear shock absorber spring (for heavy riders), as fitting 1953 and 1954. The last mention is in the 1963 Parts Catalog, which euphemistically calls them (extra strong). These springs have 19 coils, where the standard 54550-52 Rear shock absorber spring has 21 coils.

1952-1953 Hard Plastic Covers

The 1952 and 1953 shocks have hard plastic covers, secured by a clamp at the top. The material is a hard plastic, like Royalite. It has a pebble finish similar to vinyl seat covers, but is about .056" thick (just under 1/16"), and unlike vinyl, is fairly rigid.

The 1952 and 1953 models use the 9955 clamps at the top of the shock. These are extremely difficult to find.

Stan writes about them: “I was lucky enough way back in the day to have gotten a pair of NOS clamps through Roger that came from Charley Stahl? when he had his dealership in Toledo Ohio. Not much is really known to us about these clamps since we ( Roger and Myself ) have never seen any others, other then the two that he got from Charley and one that I found somewhere that is silver. The interesting thing is when I got the two new ones they had an unusual green finish on them. You can see part of that in the silver clamp picture I provided. Most pictures that I have seen where the clamp is visible enough to tell the color are quite dark as in black as indicated by the picture of the '52 K Service School picture. Oddly enough though, the other picture of an original paint '52 K was Al Doerman's who owned A. D. Farrow Harley Davidson in Columbus, Ohio. Those clamps seem to retain that weird greenish finish. That kind of makes me wonder just how they actually came from the factory. Al Doerman's 52 is the only bike that I have ever seen with the green finish. When I was putting my bike together I decided to paint them black. So what is correct, I don't know for sure. Then I have the one in the pictures that was painted silver? I do believe that all of them did have the ( CENTRAL EQUIPMENT CO. CHICAGO PATENT-195607 ) stamping on them. The width of the clamp band is 1/2 inch.

1954-1955 Stainless Steel Covers

The stainless steel shock covers became available in 1954, however, they do not appear in the Spare Parts Catalogs until 1956. The drawing shows the covers upside-down - the closed ends should be at the bottom, and the clamps go over the caps. The 54510-52 hard plastic covers are used underneath to prevent rattling. The 9955 clamps are not used. Since you can't see the plastic covers under the stainless steel ones, you can fabricate them out of some material of a similar thickness. Clear vinyl from a convertible car's rear window is one such material.

Here are some photos of an original set of 1954-1955 SS Covers with the Royalite Inners. Note that they are assembled incorrectly - the closed ends should go towards the bottom.