Cartridge of damper rod forks ST1300

[waltr]

I want to change up my fork springs and looking for some help. I pulled up the parts fiche on the Babbits website and it looks as if it is a damper rod fork.
I am confused.
I have a 17 mm Allen bit to remove cap but unsure what to find under the cap. I looked at a number of online video's on how to remove springs from cartridge forks. I have done damper rod forks, no problem. Just unsure of what to find under the cap and the procedure to swap out to sonic or race tech.

 

[waltr]

Sorry that should read Cartridge OR Damper rod forks ST1300

 

[dduelin]

There will be a damping rod screwed into the fork cap with a lock nut (14 mm IIRC). The cartridge is fastened into the bottom of the slider with the oil bolt. Unless you are changing the cartridge out you will not mess around with it.

To just change springs and/or spacers you will screw the fork cap out of the top of the tube and then screw the cap off the damping rod then the spring, spacer, and washer are free to come out.

 

[dwalby]

post deleted, was originally referencing 1100 fork, not the same as the 1300 fork.

 

[MajorTom]

the basic difference is instead of a spring that just falls into the tube and you shove the spacer on top of it (damper fork) the cartridge design has a steel rod that runs inside the spring, and has threads at the end that attach to female threads on the bottom of the fork cap. So when you extract the fork cap, it won't spring out like the damper fork cap, because the spring tension is applied just below the fork cap with a U-shaped washer and nut. To get at the internals you push the top slider down into the lower tube. Once you do that, it will look something like this:

fork cap
|
nut
washer
spacer
spring

The threaded part of the inner rod has enough threads to hold the nut against the U-shaped washer to provide the spring compression, and still retain about 10mm of threads above the nut that go into the bottom of the fork cap.

The tricky part about working on it is as soon as you remove either the nut or the U-shaped washer, the inner rod will sink inside the spring. So re-assembly is a bit tricky to keep the rod from sinking while compressing the spring and putting the U-shaped washer back in place. It requires 3 hands ideally, it can be done with 2, but its very difficult to do it reliably with just 2.

Sorry, but I believe the correct part order is:
fork cap
|
nut
spacer
washer
spring
cartridge

with the washer between the spacer and the spring.

I changed out my fork springs recently and found this to be a useful post: https://www.st-owners.com/forums/showthread.php?160736-Fork-R-amp-R-Made-Easier-A-Jig
I used the 5 gal pail and bungee cord to hold the fork upright while adding fork oil and made up a metal plate with a slot in it to hold the spacer below the fork cap locking nut while I threaded the fork cap on. With the longer Race Tech spring it was a bear to compress the spring/spacer enough to slip the holder in and I wouldn't have been able to do it by myself without the holder.

 

[TerryS]

Here's the parts diagram for the fork; under the fork cap you will find a locknut, the locknut keeps the fork cap connected, and also holds the spring/spacer/washers under compression on the damper rod, and you will need to compress the spring before you can remove the locknut.

I've attached some generic info from RaceTech, for reference you have cartridge forks with external top-out springs and a Type D cap arrangement.

 

[dwalby]

@MajorTom

I just realized the ST1100 cartridge fork is different than the ST1300 fork, and I was describing the 1100 fork. My bad, I thought they were the same. OP, please ignore my post.

 

[SMSW]

I replaced my front valves last fall with gold valves (Race Tech) and immediately noticed a world of difference. Do a search for Gold Valves and see what I and others (esp Miheck) had to say. Short story is the front end was much much more compliant. It spread out the bump so that it seemed to have a ramp on both sides of the high point - and yes, I rode over the same bumps after installing the GV. I'm not pushing these, because they are not cheap, but it was very easy to swap out the old valves/shim stack for the new ones. I also added preload in the form of a spacer 1/2" longer than stock. I had measured the sag on my bike (I weigh 170 all geared up) before beginning work.

 

[dduelin]

Here's the parts diagram for the fork; under the fork cap you will find a locknut, the locknut keeps the fork cap connected, and also holds the spring/spacer/washers under compression on the damper rod, and you will need to compress the spring before you can remove the locknut.

In the interest of accuracy, this description really isn't accurate. The lock nut serves to lock the fork cap to the threaded damping rod and no more. The fork cap keeps the stack under compression and when the fork cap is unscrewed it's a doddle to insert the wrench between the top of the spacer and the underside of the fork cap so you can hold the lock nut still and back the cap off with a hex drive. My spacer is 5/8" longer than stock and it's still easy to do this with my two hands.

 

[SMSW]

If you are going to work on your forks while they are off your bike, a good way to hold them is to take a 2x4, and drill a large hole in the 3 1/2" face. I had to sand the hole a bit bigger so the fork slider would just fit. Then I made a saw kerf through the hole and drilled a 3/8" hole through the kerf. This completes your clamp that holds the fork leg. I put the 2 x 4 in a bench vise and used a piece of wire wrapped around the rod to hold it up. This jig also makes filling the fork with oil easy since it is held vertically.

If you really want to go first class, do an Igofar routine. Larry picked up an old triple tree from another bike that accepts the same size fork tube as our ST's, and clamps that in a vise. It holds both legs simultaneously.

 

[waltr]

Thanks to all here. I ordered Sonic Springs. Should they indicate the correct oil level to use with their spring swap or just use stock specs?

 

[T_C]

Should they indicate the correct oil level to use with their spring swap or just use stock specs?

Email Sonic and ask for recomendations. Give them all the data, weight, spring size, 1-up or 2-up, preferred riding mode (touring/sport). They sent me a set of suggestions for spacer, weight and fill level.