Fitting Race Tech Springs and Valves to Showa Forks

[Uncle Flash]

As with a lot of motorcycle projects, this one started small and grew as it progressed. What started as an attempt to repair cosmetic damage to the finish rapidly became an overhaul and upgrade. In this case, once the forks were disassembled, it seemed senseless not to replace the too soft springs and modify the compression valving at the same time.

Whilst researching this procedure, I felt that it may help others if I recorded each step and took as many photos as possible as the instructions that came with the new parts were generic and a little unclear.

Sorry about the big pics.

I can email a 2.05mb .PDF of this that is set up to print on A4 if anyone wants it.

[Uncle Flash]

The forks being worked on here are the Showa GD011 from an early 1994 Ducati 900SS. While these forks are not seen on other motorcycles the design is common to many Showa models. The Race Tech parts used come highly recommended by many people and it is a common modification to these forks.

A good tip is to try and have all the parts on hand before commencing the job as it can be frustrating to wait after the forks have been disassembled. All the parts used here had to be sourced from out of state. All seals should be replaced as a matter of course and older bushings inside should be presumed unserviceable as they are easily damaged when removed.

A minimum of tools are required for this job and the following were used:

• A 1/2 “ drive metric socket set
• A set of metric Allen keys
• A set of metric combination spanners
• A small flat head screwdriver
• A rubber mallet
• A vernier caliper
• A large syringe

There is a requirement for a few specialised tools: A spring compressor was easily constructed from odd items in the scrap bin. The one used here was made from a large nut and two M10 bolts. A seal driver and damping rod holder are also needed but as seen later, a little ingenuity can make this unnecessary.




The forks required just less than one litre of oil for this job. Other Showa forks with larger diameter stanchions will require more oil. Annoyingly, this normally means the best part of a second litre will not be used.

Finally, this can be a messy job. Wear old clothes and gloves. Have plenty of rags on hand and a large container to catch any oil being drained.

• Before anything else, unscrew the cap of each fork one whole turn whilst the forks are still fitted to the bike. This makes it easier to remove them later.

• Spray penetrating oil around the top and bottom fork clamps and the handlebar clamps located between. There is nearly always some corrosion in this area on older bikes which can be annoying when removing the forks later.
  
• Remove the fairings and front guard.
  
• Remove the brake callipers from the forks and attach them to the frame with zip-ties.
  
• Remove the front wheel. The speedo drive will hang from its cable but be careful not to lose the drive washer in the wheel.
  
• Working on one side at a time, loosen the fork clamps and handlebar clamp before carefully dropping each fork down and out of the frame.
  
• Unscrew the fork cap all the way and allow the top tube to drop down the stanchion.

• Fit the spring compressor and push down until you can place something below the 14mm locknut. A 12mm spanner is shown here for display purposes but an offcut of steel plate with a 10mm slot did the job better. This is one step that can benefit from an extra pair of hands.

• And this is the home-made tool that should have been in the photo but was left on a distant bench. It is not easy to hold the compressed spring with one hand whilst trying to find a missing tool and take photographs. The moral here; be prepared.

• Holding the locknut, unscrew the nut immediately above it using a 17mm spanner and remove the complete cap. Compress the spring again and remove the tool below the locknut. This will allow removal of the spacer and other parts above the spring and the spring itself.

• Drain the oil and dispose of sensibly. It is near impossible to remove all the oil without removing the damping cartridge but as this is done later, it is no problem.
• Using an 8mm Allen key, unscrew the bolt at the bottom holding the cartridge inside the stanchion.

• Once this bolt is ‘cracked’, the cartridge can spin inside while unscrewing but pushing down or sideways on the damper rod should stop it. Remove the cartridge.

• Lay the parts out on a clean surface in the order of assembly. This will ensure that no parts are missed during reassembly. The cupped bottom spring seat will usually fall out when removing the cartridge. When assembling the forks later, the cartridge sits inside the cup.
• Using a small screwdriver, prise the dust seal free and release the spring ring below. This ring secures the oil seal but the seal itself can be difficult to extract even with the clip removed.

• Clamp the bottom of the fork in a vice and using the top part like a slide hammer, remove the upper part of the fork leaving the seal behind. During this part of the operation, the bushings inside can overlap causing the two tubes to stick together at the top of the stroke. Use a rubber mallet to free them but be careful not to damage the top tube.

• If the forks have had much use, the bushings will invariably need replacing. The Teflon (PTFE) coating may also be damaged by overlapping during the fork disassembly. The local Ducati dealer will not have these on their parts list but they are available from Race Tech. The inner is part number FMBI 41201 P and the outer is FMBO 41202 P.

• The oil seal is apparently the same 41mm ID x 54mm OD x 11mm as used on some Suzuki RGV250 and Honda NSX650 but the seals used here were ordered from the local Ducati dealer. The oil seal part number is 93010021A and the dust seal is 34910581A. The Race Tech part numbers are FSOS 41 P and FSDS 41 P respectively.
• The bottom collar on the upper tube can be removed by pushing it back to remove the spring clip. There is an o’ring inside the top of the collar that will catch at the clip groove but should roll out with a little circular manipulation.

• The fork leg uppers were thoroughly degreased and sent for polishing prior to re-anodising. The stanchions were noted as having a few small pits in the chrome around the base. These were most likely caused by a poor cleaning regime leaving brake pad dust to settle on this area. The dust holds moisture next to the already porous surface allowing corrosion to follow. As the pits were not deep enough to compromise the integrity of the tube and would not come into contact with the seals, replacement of the stanchions was not considered necessary but something that should be watched for future reference.

Cleanliness is important with this part of the job as just a small piece of swarf can do damage to the inside of the fork and reduce the effectiveness of the rebuilt suspension.
Following the instructions supplied with the valve kit, go to the Race Tech website and retrieve the settings that apply to the rider. Print the results as the password can only be used for a limited period. Try not to misrepresent the rider’s weight or riding style as this will affect how many shims are fitted and subsequently, how the forks behave. The objective here is to improve the suspension performance and not shim it back to stock.

• Carefully drill out the indentations at the bottom of the cartridge using a 4.5mm drill. Be careful not to drill too far into the aluminium valve body inside but enough of the outer tube will have to be removed to allow the compression assembly to slide out later.

• Push the compression assembly down into the tube far enough to reveal the retaining circlip. It is easier to remove this circlip by pushing one end down first rather than trying to pick it out upwards. Cover this procedure with a hand or a rag to prevent the circlip joining the many other springs hiding in the dark recesses of the workshop. Remove the valving assembly by threading in an M8 bolt and pulling gently. The inside of the drilled holes will scar the aluminium body but this will not impair its function when refitted.

• Using a very small round file, clear the drilled holes of roughness and follow by smoothing with a fine sanding cloth. This is important as during reassembly the new o’ring will have to pass this hole without suffering damage. Follow this up by carefully cleaning the inside and outside of the cartridge.
• Clamping the aluminium body in soft vice jaws, carefully remove the screw holding down the shims. Bag all of the items except the body in case they are needed in the future.

• For reference, here is a photo of the order in which the stock shims are fitted.

• The Race Tech shims supplied for these forks came in three separate bags marked with labels that don’t appear to be referenced in the instructions. However, a process of elimination and a vernier caliper made it easy to determine which shims to use.
• Assemble by stacking the parts onto the screw supplied. The order is in the photo but for clarity;
  
  
  A. Spring.
  B. The check plate (the only shim with a large hole)
  C. The gold valve (see photo for orientation)
  D. The quantity of small restrictor shims determined by the settings.
  E. The quantity of the large compression shims determined by the settings.
  F. One of each supporting shims, stepping down in size to the smallest.
  G. The thick steel washer.

• Using a small amount of Locktite 271, fit the screw and shims onto the aluminium body and use a torque wrench to tighten. It is easy here to strip the thread so the utmost care must be taken not to exceed the recommended torque setting.

• Confirm that the check plate below the spring is free to move as in the photo. If it does not, unscrew a couple of turns and centre the shim before retightening. Locktite 271 is a heavy duty thread locking compound which starts curing after 15-30 minutes but if left overnight, it will require heat to loosen.

• Admire your work and wonder how something so small can make such a difference to the suspension.
• Refit the valving into the cartridge and make sure to feed the o’ring past the lip and drilled holes if necessary. Replace the clip and using a bolt, pull the assembly back into position. If this isn’t done, the bolt that screws into the aluminium body may not reach it during reassembly.

Next, the refinished upper tubes were collected. In order to re-anodise, the old finish needed to be removed and the surface polished. This unfortunately also removes the crisp edges at the changes of diameters and the fine machining marks that can be felt when dragging a thumbnail along the length of the tube. If this is unacceptable, the forks can be re-machined but this will remove even more material and may necessitate shimming of the fork clamps when refitting.

The upper tubes were sent to the anodisers whereupon they were found to be made from 7000 series aluminium which does not take anodising anywhere as well as 6000 series. The original finish may have been a plating of some kind or a microns thin layer of 6000 series over the base material and then anodised. Polishing removed all traces of any plating.

The upside however, is that the 7000 series aluminium will accept Type II anodising which is also known as hard anodising. The colour is uninspiring but the finish is far more durable. Usually, hard anodising is only available in shades of grey or brown and in this case, a difficult to do, dull gold. Be warned, the colours of this finish is can be unpredictable and the results may disappoint.

Reassemble the forks by starting with the stanchions. Tape over the bushing seat in the stanchions with electrical tape as this is very sharp and could damage the forks seals when fitted.

• The cartridge is installed into the stanchion before anything else but not forgetting to place the cupped spring seat onto the cartridge first. This part of the reassembly can be troublesome as the cartridge will spin whilst the screw is being tightened. There are many remedies for this but commonly, sideways pressure to the damping rod will allow the screw to tighten to the point where it can be torqued normally. This can be made easier if all the parts have been cleaned of any oil.
• Paying careful attention to orientation, the dust seal goes on first followed by the oil seal retainer and the oil seal itself. The oil seal orientation should be so that the identifying markings are closest to the wheel axle.

• The steel washer is next and then the bushing with the Teflon coating on the inside before removing the tape and fitting the other bushing with the coating on the outside into its seat. Rub a little fork oil over all the parts to assist in fitting and to prevent dry start up. Not much is needed, just enough to leave a film on the surface. Excess can be cleaned off after the forks are assembled.

• Introduce the inner to the outer tube carefully feeding the bushings into place and sliding the two tubes together. The second bushing may need a little persuasion. Use the steel washer and the seal driver tool to drive it home.

• Ensure that the collar is then extended over the connection far enough to allow the fitting of the seals and clip.

• The oil seal can be fitted with a seal driver tool although in this case a makeshift tool was constructed from a PVC pipe fitting. Sometimes the seal is able to be eased into place using thumb pressure. Push far enough down to enable the spring seal retainer to fit in the groove.

• The dust seals can be pushed into place easily. Wipe down with a clean rag.

Clamp the bottom of the fork leg but be sure to allow the upper tube to fall to the bottom of the stanchion. You should see no chrome tube.

• The Race Tech instructions specify filling with oil to a recommended distance from the top of the upper tube. There are many ways to do this but most rely on a thin tube being inserted to the depth required and drawing out any excess. The same was done here but with a cheap syringe and an elastic band around the tube for a depth indicator.
• Insert the new spring and one of the steel washers supplied. While it is still possible to reach, raise the damping rod and tie a length of wire to the threads above the lock nut. Insert the standard spring seat and spacer feeding the wire through the centre. Take care not to eject fluid when compressing the spring and raising the damping rod.

• Further reassembly is the reverse of the disassembly procedure.
  

The Race Tech recommended suspension settings for this installation were used as a base to work from but ended up being very close to the end result. The ride is noticeably more comfortable over bumpy surfaces and the fork behaviour in the corners is much improved. The extreme fork dive has disappeared completely. Overall, the bike now feels as if there is more front end grip and yet it is easier to steer. Further experimentation will be made with this bike to see if more improvements can be made but the results so far are extremely pleasing.

A final word: This account was written to assist others who may be considering modifying their suspension at home with limited resources. It is by no means the only way to do the job and as sure as dogs eat homework, there are professionals out there that can do it faster and more efficiently. Most even have correct tools for the job but nearly all will charge you money for the privilege of keeping your hands clean. Doing the job yourself will also teach you a lot about how your suspension works and dispel some of the myths surrounding this subject. The added satisfaction you will get from repairing, maintaining, or modifying your own motorcycle is something that should be experienced by every rider.

However, if you are in any way concerned that this job is beyond your capabilities you should contact one of the aforementioned professionals. Refining your suspension is worth doing regardless of who gets their hands dirty.

Good luck and ride safe.

Flash

[Max Power]

Thats pretty badass man, good work!

[Loud]

Looking to do almost exactly the same to my RS250's Showa Forks, but won't be needing to reannodize. Thanks for the instructions, great effort!!

[Neil-51]

Impressive work with fabrication of the special tools.

[jules_1972]

Very Neat write up, great pics!!

Way to go!!

[BERT]

I thought you were dead Flash,
Nice work

[Uncle Flash]

Impressive work with fabrication of the special tools.

I can't claim the credit for the spring compressor. It was put together by our workshop manager.

Sadly, I think the boss threw it out during clean up.

[Roger Explosion]

Hey Hey!
You've been quiet lately. Good to have you back
(nice write up btw)

[Uncle Flash]

I've just added a hot tip from our resident suspension expert on how to get that second bushing in easier.

Thanks Marty. How did I not see that?