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PATIO

Installing WP Fork Springs on a 1995 K1100RS
by Ted Verrill,
with notes by Karl Rosenbaum
As always, this is my experience and yours may differ.
Please use common sense and if you feel this is beyond your capabilities please bring it to a shop.

I. INTRO

Installing fork springs on my 1995 K1100RS was much easier than I thought it would be. This was partially due to the fact that the WP springs require no spacer (they are full-length and progressively wound on both ends) so they simply drop in. It may seem quite intricate, but as long as you have time and patience (and 2 helpers) you will be fine. The only difficult parts are removing and replacing the dogs (this took several tries both removing and especially replacing) and should you have a non-full length brand of replacement springs, measuring and cutting the spacers.

There are basically two choices for replacement springs, full-length springs and shorter than full-length that require a custom spacer to be cut (the K11 comes stock with shorter than full-length springs and a spacer.) As you can see from this photo, the WP Springs are the longest and progressively wound at both ends, the stock springs are shorter and progressively wound on one end, and the Race Tech springs are shortest (though much beefier than stock.) The WP Springs are as rare as hen's teeth (you can order directly from WP, call Brian at 714-692-3404, ext. 224), but several other brands are readily available available such as Race-Tech and Progressive.

Because we installed two sets of Fork Springs, this write up will vary a bit. It was written with the WP Springs in mind, and Karl added notes where necessary to take into account the installation variations from the WP's.

Karl Notes: Race Tech Part #: FRSP S293890 (important – the LT uses the same springs as the RS, but the springs are only labeled for the RS – THEY WILL FIT the LT – make sure that the dealer that you are ordering from understands). The Race Tech Springs come with the following enclosed in the box: Two springs (shown above), 2 aluminum spacers that must be cut to the correct length, 6 washers (4 of which will actually be used), and some very generic instructions.

II. PREP

Parts:

• WP Fork Spring Kit, #: 93759 9932.192.A (1202B)
  Race Tech Part #: FRSP S293890
• 1 Quart of BMW Fork Oil
• 1 Set of Rubber Drain Plug O-rings

Tools

• Two (Patient) Friends handy with tools
• Complete BMW K-Bike Tool Roll
• 30mm Socket
• Dental Pick or Awl (not required but makes it go much easier)
• M5 size Machine Screw
• 6' strong dacron-type string
• 2 Philips Head Screwdrivers
• 1 Medium Flathead Screwdriver
• 1 Magnetic Pickup (not required but makes it go much easier)

III. OVERVIEW

The fork spring arrangement on a K11 is pretty simple. There are basically a few parts that matter in this procedure: the fork tube cap ("cap"), the spring retainer cap ("retainer"), the two split collets ("dogs"), the spring itself, the spring sleeve, the spring retainer circlip ("circlip"), and the spring spacer.

The rod arrangement slightly compresses the spring by connecting to a retainer at the bottom, and the cap on top with the spring sandwiched in the middle. When the cap is removed, there will often be an inch or two of "spring" so be careful when removing it. The dogs fit into a "slot" in the rod and against a recess in the retainer cap (so that when the dogs are removed the retainer cap will freely slide off the rod under the spring pressure.

IV. PROCEDURE

DISASSEMBLY

1. Remove cap
(Bike should be on the centerstand, towel over tank to prevent damage.)

You will need the 30mm socket for this. Go slow and put plenty of pressure on the socket to keep it from popping off of the cap and damaging the corners. It also helps to have a friend steadying the handlebar and one steadying the bike (this cap can be on quite tight!

2. Drain fork oil

Make sure to have a piece of cardboard or tin foil handy or the oil will drain all over your wheel and tire. Make sure to replace the rubber drain plug o-rings, and for heaven's sake remember to put the drain plugs back in :))

3. Insert machine screw

Using a pair of pliers (needlenose work best), get a good grip on the rod to keep it from spinning. Insert and screw the machine screw into the hollow recess at the top of the rod - really there is no proper size, just large enough to get a good purchase on the rod without marring it up too much or going too deep. The screw should be snug, but not too tight.

4. Tie Screw with dacron string

Tie a good slip knot around the screw and make sure that the knot is secure and that the screw will not pop out with tugs from different directions. You will want to make sure that the knot does not extend beyond the head of the screw or you will have trouble slipping the retainer cap past the knot/head of the screw.

5. Push down on retainer cap with 2 philips screwdrivers to allow the dogs to be removed
Take the bike off the centerstand and be sure to have someone holding it from the rear. Keep the sidestand down so if the bike-holder loses balance he can sway the bike to the left and keep it from going over.

There are four holes in the retainer cap. Insert the tips of two large, long-handled philips screwdrivers into two opposing holes and, standing on the pegs, push down. Simultaneously your two helpers must be busy, the first steadying the bike and the second pulling on the string. The aim is to push the retaining cap down on the rod so that the pressure on the dogs from the cap recess is removed and the dogs can be removed from the slot on the rod.

6. Remove dogs with pickup magnet or loosen with dental tool/awl then remove by hand

When the retainer cap is pushed down on the rod, the pressure from the retainer cap on the dogs will be released and they can be removed from the slot in the rod. If the stringholder is careful, once the retainer cap is pushed down enough he can place the string in his mouth and at the same time use either a magnetic picker-upper to pick out the dogs, or carefully try to pick them out with his fingers. Really, a third helper helps here.

From the photo you can see how the two half moon dogs rest in the circular impression of the retainer cap (see the picture in the overview for what the complete assembly looks like.)

7. Slowly release pressure on the retainer cap being careful not to pinch string
Be Careful here as there may be  pressure on the cap from the spring - go slow.

When the dogs are removed, the person who has patiently been pushing down the retainer cap with the screwdrivers can slowly begin to ease off the pressure. While he is doing this the stringholder must make sure that as retainer cap slides off the rod the head of the machine screw passes easily through the hole in the retainer cap. Some jimmying may be required.  A secure screw/rod connection pays off here as it is an easy fix if the string breaks (it did several times for us) but would be a major pain if the screw were to come out of the rod. We simply fed a new slipknot down into the fork tube and over the head of the screw. After the retainer cap has been removed, put the bike back on the centerstand.

8. Pull out circlip

On my right fork this circlip was already loose in the fork tube, the left tube's circlip took about 30 seconds with a flathead screwdriver to pop it out.

9. Remove spacer, sleeve & spring

The spring assembly should be removed, including the spacer, the sleeve and the spring itself. They will slide right out, though you may have to use something like the curved tip of a dental tool to get down into the tube and hook them. In a pinch a coat hanger with hook bent in will work fine.

NOTE: If you have springs that require a spacer, you will need to carefully follow the directions that came with the springs to  measure and then cut the new spacer sizes. You will then need to follow the directions on the order of reassembly.

REASSEMBLY

10. Add the fork oil, then feed string through new spring, sleeve, and retainer cap.
If your springs require a spacer and washer, remember to include them in the proper order.

Add the new fork oil - at this stage you can simply pour it in (later you will need a syringe or a small funnel and lots of time :) One of the forks takes 400cc's and the other takes 350cc's (you'll need to check the manual that came with the bike for which side takes which...)

We tied a washer at the end of the string to help ease the it through the spring. Make sure that you start feeding the string through the bottom of the spring so that the spring ends up correctly positioned in the fork tube. For the WP springs, the spring goes first, then the sleeve, then the retainer cap. Make sure to be careful when passing the retainer cap over the head of the machine screw and onto the rod.

11. Using same two philips heads, push down on cap (while keeping it centered) and pull on string so that rod feeds through retainer cap hole.

Take the bike off of the centerstand and like before have a helper holding onto the back to keep it centered. As you can see from the photo, there will probably be one eighth of an inch to an inch of spring coming over the rod-end. You will need to force the retainer cap with the two screwdrivers over the machine screw and rod end so that the slot in the rod that accepts the dogs is fully visible. It may take some jockeying around and a third set of hands centering the retainer cap over the spring assembly. When you get to that point, hold it :)

12. Seat dogs in slot on rod
NOTE: It may be prudent to wear eye protection when reinserting the dogs as they have been known to pop out when the spring pressure is applied if they are not seated properly.

This sounds much easier than it is. As a matter of fact, if you go slowly and accept that it will take a few tries to fit them in you may very well get them in on the first or second try. Be very careful here as the dogs have a very bad habit of popping out and falling down into the fairing when slightly misaligned - have the magnetic pickup tool ready at hand and don't get frustrated.

This will take a lot of patience from the screwdriver-pusher as the biggest problem we had (aside from the string breaking once or twice :) was the pusher inadvertently moving the retainer cap around while trying to keep pressure on it to keep the dog slots in the rod visible and accessible. Once you've put them in on one side the other will go much quicker as you will know precisely what is needed to get them in and seated (patience & dexterity ;-)

13. Slowly release tension - eyeball to ensure proper fit.

Once the dogs are seated, simply slowly release pressure on the retainer cap and the dogs will fully seat, holding the cap and compressing the spring. Remove the machine screw and string, and it should look like the pic to the right.

14. Replace Cap

Replace the cap, tighten (but not too tight!) then either do the other fork or if you are done take the bike for a *very careful* test ride to make sure everything is seated correctly and that you didn't forget anything (you made sure you didn't have (m)any parts left over, right?)

CONCLUSION

I love the WP springs - I noticed the change gradually as I hit road varying surfaces where the bike before performed one way and now performed differently. On the whole, the difference is most noticeable over rough or rippled pavement where it is much smoother and seems to float over the imperfections, and in cornering where the front end stays completely planted with none of the previous "twichiness."  I would highly recommend these springs.

NOTE: Thanks to Bill Shaw, Karl Rosenbaum and Brian Horais - Bill was the man with the screwdrivers and a warm garage, Brian had the spring swap experience and a band saw for Karl's spacers, and Karl was the man for the fork oil and, yes, the digital camera!