K and KH + 57 XL fork dampers

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K and KH + 57 XL fork dampers

Postby Ferrous_Head » Wed Aug 08, 2018 6:55 pm

OK. I have to admit I have no idea how other people are sorting this out.
In 1952 The K model started out with 19 inch wheels. Two years later (1954) it appears they offered the choice of either the 19's or 18 inchers. The 18's actually have a -53 part number.
In 1954 they made longer (or shorter ?) tubes and springs. I have always believed they were 1 inch longer. Damper assemblies also were made to suit with 3 different part numbers.
Fast forward to today and I see new springs being offered for K's and Sportsters. But all the same length – 20 inches.

Now if the tubes vary by 1 inch in length (and the dampers as well) shouldn't the springs ALSO vary in length ?

It might well be possible to compress a longer spring into a shorter tube. But that will effect static ride height. I have to wonder if coil bind might also be an issue.

And a shorter spring in a longer tube would introduce sag.

I believe that the damper rods are shorter or longer to accommodate the changes in spring length.
But I don't think (don't really know here) I've ever noticed damper rods with different lengths.

Why I am asking this is that I'm currently working on a set of forks for my 58 CH project.
It came with a set of assembled forks. But with chromes tubes I knew they weren't original.


Tube with installed damper and spring waiting for retainer.


Image



Length of spring that protrudes from the tube is about 2-1/4".




Image



Length of damper assembly is about 26 1/4 "




Image



Tubes are a little over 23"



Image



Springs are the 20 inch variety.



Image

So am I just getting to be too old to do these things ?
"I know only too well the evil that I propose, but my inclinations get the better of me."
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Re: K and KH + 57 XL fork dampers

Postby hennesse » Wed Aug 08, 2018 10:54 pm

Ferrous_Head wrote:OK. I have to admit I have no idea how other people are sorting this out.
In 1954 1955 they made longer (or shorter ?) tubes and springs. I have always believed they were 1 inch longer. Damper assemblies also were made to suit with 3 different part numbers.
Fast forward to today and I see new springs being offered for K's and Sportsters. But all the same length – 20 inches.

Now if the tubes vary by 1 inch in length (and the dampers as well) shouldn't the springs ALSO vary in length ?

I believe that the damper rods are shorter or longer to accommodate the changes in spring length.
But I don't think (don't really know here) I've ever noticed damper rods with different lengths.

Why I am asking this is that I'm currently working on a set of forks for my 58 CH project.
It came with a set of assembled forks. But with chromes tubes I knew they weren't original.


You are (mostly) correct. The fork tubes were made shorter in 1955 to compensate for the change in the the triple trees from "offset" (1952-1954) to "parallel" (1955 - 1967). Here's a snatch from the Enthusiast's 1955 new model introduction.

fork-1.jpg
September 1954 Enthusiast - 1955 New Model Introduction
fork-1.jpg (125.56 KiB) Viewed 9590 times


This drawing depicts the 1952-1954 situation where the triple trees are "offset". The red arrow kinda shows what happens when you change the trees to the "parallel" style, which they did in 1955 - as the bottom of the tubes move backwards, they also move downward about 1 inch. So they shortened the fork tubes by 1 inch to keep the bike level. The change from "offset" to "parallel" caused an increase in Trail by - sheer coincidence - 1 inch.
fork-2.jpg
Change in 1955 from offset to parallel
fork-2.jpg (18 KiB) Viewed 9590 times


Of course they couldn't just shorten the fork tubes by 1 inch, they had to also shorten the springs and the damper rod too. Here are what changed.

fork-3.jpg
1956 Spare Parts Catalog
fork-3.jpg (20.76 KiB) Viewed 9590 times


The long -52 parts were used on 1952-1954 K/KH, and on 1958-1967 XLCH. The short -55 parts were used on 1955-1956 KH and 1957-1967 XL and XLH.

During the wild and crazy 1960s, the parts books show that the long -52 parts could be used as "special 1 inch more ground clearance" on XLHs. To make matters more confusing, The Legend Begins shows a "low ground clearance" option for XLCH, and a "high ground clearance" option for XLH.

So back to your question. Yes, the -55 parts are 1 inch shorter than the -52 parts. Your 1958 XLCH should have the long -52 parts.

fork-4.jpg
1959 Spare Parts Catalog
fork-4.jpg (21.29 KiB) Viewed 9590 times


Unfortunately, I don't know what the length of the tubes and springs are for either configuration. Maybe someone with a big pile of parts can go measure them for us!

Oh yeah. Most everything changed in 1968...
fork-5.jpg
1968 Parts Catalog Supplement
fork-5.jpg (78.92 KiB) Viewed 9590 times
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Re: K and KH + 57 XL fork dampers

Postby Ferrous_Head » Wed Aug 08, 2018 11:29 pm

Thanks Mate, this has been driving me crazy for a couple months.
I knew about the early trees (I have a set of those and have considered using them on this bike). I think what has me going around in circles is that these forks were together when I got them. But they obviously hadn't been touched in many years and I figured I would replace the gaskets and oil as well as giving them a good clean (internally).
I can get the retainer on with the damper outside of the fork tube but once I put the damper and spring inside the fork tube I just can't manage to compress the spring enough to get the retainer started.
I see aftermarket springs but they are all exactly the same length as the ones I have now - 20 inches.
These may well be the correct forks for this bike and MAYBE i', just not able to compress the springs enough because I'm getting to be too old. I might have to make up a tool to do the job (or get someone younger to help).

Only problem with using the early reduced trail forks is this bike should have the later top tree designed to hold the small eyebrow headlight. But I think the "stance" on the XLRTT looks better. (Uses the reduced trail style trees).

OK - One more try.
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Re: K and KH + 57 XL fork dampers

Postby Ferrous_Head » Thu Aug 09, 2018 4:37 pm

OK. Finally worked out a way to do this.
I am getting old.
I used a set of vice grips on the end of the spring. Held the vice grips in a vice. Pushing on the end of the fork leg I was able to compress the spring enough to get the retainer on.
I still suspect the spring is a little bit long but that will improve static ride height. I'm good with that.
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Re: K and KH + 57 XL fork dampers

Postby Ferrous_Head » Sat Aug 11, 2018 8:39 pm

OK, so maybe not as old as I thought. But a littler dumber maybe.
Went to install the forks and discovered on leg was approximately 1 inch longer than the other. Now I knew exactly what that means. Internal dampers were mis-matched. Given that I bought these as a complete set and they certainly looked like matching legs and had about the same amount of gunk inside I can only presume that at some time a PO had done this. And then rode around on a bike like this. I shake my head in despair.
So now a question arises The fork tubes are obviously aftermarket (chromed). They measure pretty much exactly 23 inches. They probably should be 22-7/8's but there you go.
So these are the high road option (1 inch more ground clearance on XLH's) or the stock ones for xlch's.
What I have discovered is that if you put the long dampers into those tubes it's pretty easy to install the spring retainer. Trying to install the short dampers will make you feel old.
Back to my question.
Anyone have one long (26") damper they want to sell or to swap a long for a short ?
Oh. And I'm still curious about the spring lengths. Mine are 20 inches and work OK but there were obviously 2 lengths of springs as well as the dampers. (It's actually only the rods that are longer/shorter so just a rod would do me.

Abyone ?
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Re: K and KH + 57 XL fork dampers

Postby EKHKHK56 » Tue Aug 21, 2018 4:17 am

The standard springs are 19.5" 52-54 55 18.5" XLCH 19.5" Erik
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