Author Topic: C5 Fork Tutorial  (Read 32157 times)

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Ducati Scotty

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on: June 04, 2011, 03:22:25 am
The full slideshow of all pics is here:

I'm making this tutorial because the C5 fork is a little different than previous Enfield forks and I haven't seen it's disassembly well documented.  Even the factory manual glosses over things and leaves out some critical details, like which parts are reverse threaded.

A few notes first:
  • I don't advocate the use of an impact wrench to remove the bolt from the bottom of the fork though the manual and many people do.  Sometimes it works, sometimes it doesn't, sometimes it loosens but won't tighten again.  And impact wrenches are expensive and I don't have one.  Using the ratchets and extensions I detail should work no matter what.
  • This isn't rocket science but there is something to it.  If you doubt your abilities find a more experienced buddy to help you through it.
  • Your bike will be on a jack stand or something similar as you're wrenching away, potentially with a lot of force.  It can fall off.  That can mean damage, injury, and fire hazard if gas starts spilling.  Use caution and get some extra hands if you need help.
  • There are lots of things that are either reverse threaded or might get turned in an odd way.  Pay attention to the directions.
  • If you notice inconsistencies in the text and the pictures, do as I say not as I do.  When you can write your own tutorial instead of reading mine you can tell me what to do ;)

Special tools:
  • You'll need the usual smattering of metric wrenches, ratchets, allen keys, and pliers.  In addition you'll need a torque wrench to re-tighten some things and large sockets/wrenches to remove the front wheel.  You'll also need a jack stand or something to prop the front of the bike up with.
  • To remove the fork legs from the nacelle and the top caps from the upper fork sliders you'll need either the Enfield special tool:

    a long 12mm allen key welded to a water main wrench to replicate same, or a 12mm allen key.  If you go the cheap route like I did with the 12mm allen you've got one of two choices, you can get a steel pipe to put on the short end of the allen key for leverage or just cut the short end off and use a 12mm socket on the long straight part that's left.  I recommend the second option as it gives you the convenience to use a ratchet.

    Don't bother getting a 12mm allen socket, they're expensive and probably not long enough.
  • To separate the upper and lower fork legs you'll need a 6mm allen wrench for the outside.  For the damper rod inside you'll need a ratchet, 18" extension, 4" extension, and either 10mm or 14mm allen socket.  Either works and the 10mm is usually cheaper.  If you want to use several shorter ratchet extensions together that's probably fine but it really is about 20" deep in there.
  • If you plan to replace the seals you can improvise the removal and installation tools but I really recommend getting this:

    It's a ring designed just to keep you from cracking the fork tops when you pry/wedge the seals out.  I've seen posts on people cracking these.  Don't crack yours and then have to wait for a replacement part.
  • Get a 5 gallon bucket.  They're nice for keeping the fork legs and long bits from rolling around in the dirt.

Getting the bike prepped:
  • Get the bike on the center stand and then get a jack stand or some other suitable support under the front engine mounts to hold the wheel off the ground.  Make sure this is sturdy, the bike may move around a bit while you're wrenching.  Make sure your stand won't just collapse if it gets nudged.
  • Before starting anything cover the tank, nacelle, and fender with towels.  Protect your paint!
  • Remove the speedo cable at the wheel and tuck or tie it back out of the way.
  • Remove the turn signals and the nuts holding them, tie them back out of the way.
  • Break the pinch bolt on the left fork leg loose.
  • Loosen the front axle and remove the front wheel.  You should be able to tilt the bike up just far enough to get it out.  Set it out of the way.  Keep track of your spacers and speedo drive unit.
  • Remove the front brake, take the line out of its guide on the fender, and tie the caliper back out of the way.  Don't let it hang by the hose.
  • Remove all the remaining fender bolts and remove the fender.  It will take some careful wiggling.  Cover it with a towel and set it aside out of the way.
  • With a large screwdriver remove the two large chrome top screws from the top of the fork legs in the nacelle.  These don't hold anything together, they're just to seal the top.  You should be able to see the 12mm allen top cap on the fork.

Fork leg removal:
  • Loosen the pinch bolt on one fork leg on the lower triple tree.
  • Using whatever 12mm tool you have insert it into the 12mm top cap on the leg you just loosened the pinch bolt on.
  • Protect the wires and cables the 12mm may rub against.
  • Cover up the shiny bits with towels.
  • Now turn the tool CLOCKWISE to turn the leg down and out of the nacelle.  It may take some force to break it loose.
  • Once it's moving well hold the lower slider so it doesn't fall out.
  • Once it stops moving downward as you turn it's free of the nacelle threads.
  • Re-tighten the pinch bolt.
  • The 12mm top cap is a REVERSE THREAD into the fork upper.  Using the 12mm tool turn the top cap CLOCKWISE to break it loose and turn it out of the upper fork tube.  This may take some force at the start.  The cap should have enough room in the nacelle to completely turn out of its threads from the fork leg but probably won't pop out because it's held in by an o-ring.
  • When the top cap stops moving up when you turn it's free of the internal threads.  Loosen the pinch bolt and spread the clamp a bit with a screwdriver to loosen it.
  • Turn the bars to the side, you should have just enough room to slide the leg out from the fork cover.
  • Put the leg aside or in the bucket.  Take care not to damage the threads at the top of the fork.
  • Repeat the fork removal steps with the other fork leg.

Fork leg disassembly:

Seal removal/replacement is not detailed here because I didn't do it.  Except for the special tool mentioned above to keep from cracking the fork legs it is a fairly universal process.  It's in the manuals and a million other places on the net.  The upper dust seal is easy to remove with a small pry, screwdriver, or manly fingernail.  Under that is a circlip and then the inner seal.  I did take a pic:

Fork reassembly:
  • Everything should be clean, clean, clean.  Especially the threads on the fork ends and top caps.
  • Have your seals and dust seals installed on the fork lowers.
  • Pass the damper rod through the rebound spring.
  • Insert the damper rod and spring into the upper leg held at a shallow angle and slide it to the bottom gently.
  • Poke and wiggle it a bit and get the damper rod end to drop out of the upper leg.
  • Insert the ratchet, extensions, and 10mm or 14mm allen socket in to hold the damper rod in place.
  • Turn the fork upper to face straight up with the ratchet on the bottom.
  • Put the internal end cap on the damper rod.
  • Slide the lower slider onto the upper leg until it seats on the damper rod internal cap.
  • Look into the bolt hole on the bottom of the slider.  It the threads are not lined up use a small screwdriver or probe to move the threads into alignment with the hole.
  • Insert the retaining bolt with the copper sealing washer and get it threaded a few turns.
  • Tighten up the retaining bolt using the 6mm allen on the bottom and the 10mm or 14mm that's already in the upper leg.  There was no torque spec so I went for 'good and tight'.
  • Turn the assembled fork leg right side up.
  • Fill it with 195ml of oil of your choosing.
  • Pump the fork leg in and out repeatedly until you clear all the air bubbles.  You'll hear and feel it when it's right.
  • Extend the fork completely.
  • Insert the spring, washer, and spacer.
  • Grease the sides of the 12mm allen top cap.
  • Using latex gloves for grip grab the top of the fork tube and presse the top cap in.  The pressure of the o-ring will keep it in once you get it past the end.
  • Remember the top cap it reverse thread.  Hold the top of the upper fork leg and using your 12mm tool of choice, turn the top cap COUNTERCLOCKWISE while pressing down.  This should start to get it threaded into the fork upper.  Get at least a few turns.  You'll complete the tightening once the fork leg is bolted into the lowe triple again.
  • Go back and disassemble and re-assemble the other fork leg.

Fork leg re-installation:
  • Remember, the fork leg with the pinch bolt goes on the right ;)
  • Put a little grease on the threads at the upper end of the fork.  This is steel going into aluminum, let's keep it from corroding in place.
  • Turn the bars and insert one fork leg into the triple tree.  Slide it up as far as you can.
  • Tighten the pinch bolt on the lower triple tree.
  • Cover all the shiny bits on top and insert your 12mm tool of choice into the fork top cap.  Protect the cables wires if needed.
  • Turn the 12mm tool COUNTERCLOCKWISE to tighten and fully seat the fork top cap in the upper fork leg.  There was not torque spec so I went with 'good and tight'.
  • Loosen the pinch bolt.
  • Now press up gently on the fork tube while turning the 12mm tool COUNTERCLOCKWISE to tighten the fork upper leg into the nacelle.  Once again, 'good and tight'.
  • Snug up the pinch bolt but not all the way.  Center the fork cover over the lower slider so the two won't scrape each other.
  • Torque the pinch bolt to 24 ft.lbs.
  • Install the large chrome top screw.
  • Repeat Installation with the other fork leg.

Final assembly:
I'm going to gloss over this a bit, it's covered lots of other places.
  • Put the fender back on, it takes a little wiggling.  VERY IMPORTANT: Make sure the divots in the sides of the fenders are centered with the fork covers.  If they're not they could rub off some paint.
  • Re-install the wheel, axle, spacers, and speedo drive.  
  • Make sure the speedo drive is at the right angle and re-attach the cable.
  • Torque the front axle to 37-51 ft.lbs.
  • Tighten the fork pinch bolt.
  • Spread the brake pads apart a bit with a clean screwdriver.
  • Re-install the front brake caliper.
  • The bike should be mostly back together and ready to come off the stand.  Take it down.
  • Fan the brake lever until the pads grab the disc again.
  • Hold the front brake and gently press down on the front end to see if it feels ok and that the fender is not scraping.
  • Re-align as needed and torque all the fender bolts and brake caliper bolts to spec.
  • Check all the bolts to make sure they are tight.
  • Re-install the turn signals.

« Last Edit: June 07, 2011, 02:38:33 am by Ducati Scotty »


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Reply #1 on: June 04, 2011, 07:33:55 am
Nice wrtie up, thanks.
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Reply #2 on: June 04, 2011, 08:40:33 am
Thanks for all the hard work Scotty! Looks great. Not sure if thats something I'm ready to tackle just yet but will definitely need for the future. Kudos!  ;D


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Reply #3 on: June 04, 2011, 08:57:45 am
Ah, thank you.   This is most useful.
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Reply #4 on: June 04, 2011, 10:08:16 am
FANTASTIC WRITE UP! Thank you Scott. After all that work, did you change the spring or damping? Which fork oil did you use and can the oil be changed without complete disassembly?


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Reply #5 on: June 04, 2011, 10:22:11 am
Absolutely wonderful. Many thanks for all your hard work. I was going nuts trying to decipher the service manual!


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Reply #6 on: June 04, 2011, 10:49:15 am
Wow, that was amazing.  Thanks.

It is clear that I won't be attempting this by myself, and that is good for me know now.   ;)
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Reply #7 on: June 04, 2011, 08:59:10 pm
Nice work Scott.  Thanks for the detailed write up, pictures are great.   

This is something I plan to do later.
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Reply #8 on: June 04, 2011, 11:03:33 pm
Holy crap, I'm not doing that! You are brave, sir.

Why did you do anything past separating the upper legs and lower sliders? Did you just do this to replace the oil?

Wouldnt it be nice if they installed a fill and drain plug?! :)

Thanks  again for the writeup.

ps-  a few of the pic's links are off, mostly towards the middle.
pps- why not paste the pics inline with the post? :)

Ducati Scotty

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Reply #9 on: June 05, 2011, 01:32:50 am
Brave?  Nah.  Taking apart my Ducati engine to check the cam timing a month after I got it because stopped running when the adjustable cams came loose, that took guts!

I took apart more than I needed for just the oil change just to make sure it was all clean.  Lots of stuff seems to find its way into weird places on these bikes.  Yeah, I figure a few pics would be off.  I'll fix them soon.  You've got the link to everything.  I didn't paste them inline because there are only so many you can put in one post and then it would take even longer to put this together. 

Yes, why not a simple drain and fill plug?  Especially when you're supposed to check the oil every few thousand miles, at least according to the manual.  I've been chatting with SSR and Gorilla.  We think you could easily drill and tap the top cap to add a fill bolt.  Better yet, I bet you could just drill it out and let the big chrome screw and o-ring seal it like on the G5.  I'm not sure why they didn't do that in the first place.  For a drain, a bolt on the back of the fork leg between the lowest and middle fender bolts is in just the right spot to intersect the bottom of the chamber.  Usually drains are on the side but there's much more metal on the back to tap into.  If you want to do it, that's the place for it.  Gorilla's thinking about it.  I'm usually in there changing springs and setting preload so it doesn't help me much.

RE recommends 10w30 engine oil.  I used 10w Bel-Ray fork oil.  I also put in 195ml, the recommended amount.  I took out 150 and 165 from the two legs.  10w is definitely thicker and the fork moves a little slower, doesn't dive as fast.  With the right amount of oil the air space is smaller and the fork doesn't dive as far either.  Even without those attributes it just feels much better in general riding.  More solid, more planted.  Don't go adding oil to make it dive less.  I heard the reason it's now 195 is that at 200 they were blowing too many seals.

I put the stock springs and spacers back in but did find out that we have 0.7kg/mm springs.  The calculators I checked said I should be running 0.9-0.95 for my weight.  That seems a little stiff to me, it was on my Ducati when I put 0.95s in there.  And this is a lazier easy riding bike.  I think I may step up to 0.85 when money allows and probably drop to 7w oil then too.  I might go 0.9 or 0.95 when I add the side car.



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Reply #10 on: June 05, 2011, 10:15:40 am
That was a great write up...Keep this for prosperity...I'm using 15 wt. Spectro but having a iron, its pretty easy to change the fork oil as u are aware....That stated, you did all the c5/g5 fellows a service going through all that...That seal removal tool is a must if u gonna replace a leakey seal...Watched a Honda tech do a seal replacement on a sportbike and he had that job done in 20 minutes or so using a similar tool..So if the money situation improves, u were suggesting changing the springs. Knowing what u know, how long do u think it would take you now to complete that upgrade?
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Reply #11 on: June 05, 2011, 10:50:19 am
Probably a long afternoon or two evenings.  Longer if there's beer around :)



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Reply #12 on: June 05, 2011, 04:19:16 pm

Very nice write up and photos. You are pretty good with words  ;).
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Reply #13 on: June 05, 2011, 07:32:39 pm
Wowzer, good work!

I'm thinking this needs to be wikified. Anyone got webspace we can set up for this purpose?
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Reply #14 on: June 06, 2011, 02:03:04 pm
 Excellent write up Scotty. It was probably more work then taking the legs apart :D Great job man !
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