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356 Posts
Discussion Starter #1
*Disclaimer: I am not a professional mechanic. All torque settings are from the Haynes Service & Repair Manual.

This tutorial is for installing the Progressive Suspension progressive fork springs on a 2003 T100. The springs for this application can be found here: part #: 11-1126.

Progressive Suspension fork spring kit #11-1126
Fork oil of your choice. I used 15wt.
1" Sch 40 PVC pipe

10mm socket
12mm socket
22mm socket
24mm socket
6mm allen socket
8mm allen socket
breaker bar
ratchet wrench
torque wrench
Phillips or JIS screwdriver
adjustable wrench
miter saw
sand paper
graduated cylinder or beaker
large syringe
floor jack
center stand/track stand
3 bricks
1 2x4

Step 1: Secure the Motorcycle

Start by placing the motorcycle on the center-stand or track stand. Then jack up the front wheel, and place the three bricks underneath the frame rails with the 2x4 going on last against the frame so as not to mar the paint.

Give it a shake to make sure everything is secure.

Step 2: Remove the Front Wheel and Fender

Use the 24mm wrench to loosen the front axle nut. Then use the 6mm allen socket to loosen the pinch nut. Finally, use the JIS or phillips screwdriver to remove the retainer screw for the speedometer drive. Slide the axle out of the wheel taking care not to misplace the washer underneath the axle nut.

Set wheel and speedometer drive assembly aside.

Remove the four 10mm dome-shaped bolts that fasten the fender stays. Then, remove the four 12mm bolts that fasten the fender brace. Don't lose the bolts.

Step 3: Remove the Fork Leg

Step 3 will be repeated for each leg, but it is strongly recommended to only do one leg at a time so that the headlight ears and gauges are secured and do not fall loose.

Start by cutting away any zip-ties that may be securing the fork gaiters.
Use the 8mm allen socket to loosen the top fork clamp. Next, use the 22mm wrench to loosen the fork cap. Do not remove the cap completely at this time.

Next, loosen the lower fork clamp. Using a twisting motion, guide the fork leg out of the fork clamps being careful to not drop the leg on the ground.

Finally, remove the gaiter from the fork. I found that rolling the gaiter up helped to free it from the lower. Pulling it straight off proved difficult.

Step 4: Drain and Clean the Forks

*Before commencing this next step, you will want to have something in place to hang the forks upside-down from. I used a piece of 3/4" dowel clamped in my bench vise with a zip-tie through the axle hole of the fork.

Start by carefully removing the top nut. I used a ratchet wrench with a 22mm socket, and while holding downward pressure, turned until I could do it by hand. Coincidentally, as soon as the o-ring is free from the fork leg, you should be able to turn it by hand. Continuing with the downward pressure on the top-nut, remove it completely.

Remove the o-rings and replace if necessary.

Next, gently, and slowly, compress the fork leg to the bottom of its stroke. Remove the spacer first, then using a pick (I used a 90* allen wrench) remove the fork spring and washer. Set aside on something to catch the fork oil.

Then, drain the fork leg of the old oil. Give it several slow cycles of its stroke to remove the oil from the damper.

**Now, because I wasn't going to be replacing the fork seals, it was not necessary for me to remove the damper assembly. To do that, use a long 8mm allen head and, preferably, an impact gun. Be prepared to replace the copper washer when reassembled.**

It is necessary to flush the forks of debris, old oil, etc. To do this, I used automatic transmission fluid (ATF), followed by some extra 10wt fork oil I had laying around. I gave the fork two flushes with the ATF, and one final flush with the spare fork oil.

Step 5: Reassemble the Forks

Now that the fork leg has been cleaned, it's time to hang it upside down to let the oil drain out.

While the fork is draining, an opportune time presents to cut the new spacer, wipe off the washer, and measure out the fork oil.

When initially setting up the forks, I opted to make the new assembly the same length as the old assembly. I laid the two springs side by side, and measured just shy of 3" difference.


356 Posts
Discussion Starter #2
I opted for a 3" spacer for several reasons, which if you're curious about, you can ask about later. Regardless, I used my miter saw to cut a 3" section of the 1" sch 40 PVC pipe. I then used sand paper to clean up the ends.

Next, I measured out the 484mL of fork oil that is called for.

And took the fork down from the draining apparatus. The service manual call for 484mL of fork oil to be used, and for the fork to be at the bottom of its stroke, or said differently, fully compressed. Neither the spring, nor the spacer should be in the fork leg at this time.

Pour the oil in, give it a few pumps to settle the oil and remove any air.

Then, from the top of the leg, measure to ensure that a difference of 120mm between the top of the leg, and the level of the oil exists. If there is too little oil, add some more. If there is too much oil, use the syringe to remove some oil.

Next, we can put the new spring inside the fork, with the tightly wound coils at the top. Followed by the metal washer, and finally with the 3" spacer.

You'll note that the spacer protrudes slightly from the top of the fork leg. No matter, the spring will easily compress to allow the fork cap to be replaced.

Step 6: Reassemble the Front End

Reassembly is the opposite of dis-assembly. At this time, the fork gaiter should be replaced. Remember to roll the bottom of the fork gaiter up, and it goes back with little fuss.

Using the same twisting motion as before, guide the fork legs back up through the headlight ears, taking care not to displace the rubber seals at the top and bottom of the ears. The forks are in proper orientation when the top nut of the fork protrudes, and just the very top of the leg is visible.

Torque the top and bottom fork clamp (yokes) to 27Nm. I didn't bother torquing the top nut, but the spec is listed as 23Nm.

Replace the fender, and front wheel.

53 Posts
Thanks, cb200t. I just found this thread...very timely, as earlier today I ordered the exact same springs for my mag wheel Bonnie. Looks like a pretty straightforward job. I'm curious how much of a difference these new springs made on your Bonnie. I've replaced springs on several bikes, and every time the improvement has exceeded my expectations. I hope that trend continues. The difference is that the other bikes had quite a few miles on them, but this bike only has about 3K miles.

Premium Member
34 Posts

I just want to underline that instructions from Progressive Suspension warns not to go higher (ie less than) than 140mm from top of compressed fork to top of oil, although specs for a Bonnie T100 is 120 mm.

The reason is that this is measured before the spring goes in and the new spring as a bigger volume than the stock spring + damper.

You don't want to bust those seals, which will happen if you have too much oil...

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