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Fork Seal R&R Tips ( ST1100 ) *

Started by KoTAOW, December 09, 2007, 02:31:18 PM

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First off:
1 - replace them both as long as you're at it.  The other one will start leaking 2 weeks later if you do just the leaking one now (Murphy's Law, 3rd corollary).
2 - use this opportunity to upgrade to Progessive Suspension fork springs.
3 - buy and use the Honda ST1100 Service Manual for your fork seals R&R.

Doing the deed:
1 - use a mechanical sissors type jack under the engine for precise control up and DOWN!
2 - loosen the hex socket bolts at the bottom of the sliders after the wheel is off/axle out, but BEFORE the fender is removed. You'll need to buy (or make, BTDT) a longer 6mm hex-bit socket to get to the bolts.  If a bolt and innards just spin like some LiSTers have reported, use an impact/air wrench.  If all else fails, you may have to drill out/off the bolt heads and replace with new bolts and washers.  Putting those bolts and washers on your parts order is cheap insurance against a possibly lengthy work stoppage during the R&R. *
3 - loosen the fork caps (17mm hex-bit or 24mm socket depending on yr/model) after loosening the upper fork pinch bolt, but with the lower pinch bolts still tight. Trying to loosen a (dealer over-) torqued fork cap after the fork is pulled is a bear...
4 - the left fork cap (all standard models, right cap on later model ABS) is under spring pressure of course and can become a projectile when the last thread clears so remove carefully with counterpressure.
5 - the right fork cap (all standard models, left cap on later model ABS) is attached to the top of the damper rod.
6 - use the longest 10mm x 1.0 bolt you can find with a coupla nuts and a length of stiff wire to hold the fork damper rod extended while removing/reinserting the spring seat stopper.  Or borrow one of my friend Andy Hand's super cool hand-made damper rod holders. See pictures in reply #2 below.
[I'm quite happy to loan mine out for the price of my postage, along with my hand-made 3/8" dr 17mm hex socket for the fork caps]
7 - before you begin whacking/slamming/thunking/pumping the fork tube and slider apart, be sure the stopper ring (spring clip) above the oil seal is removed!  To get the fork tube separated from its fork slider (after the lower bolt and all the innards are removed of course) you set and hold the fork slider on the floor, grab the fork tube and jerk upwards to bang the bushing against the back-up ring, thereby driving the fork seal out.
8 - the Common Service Manual sez to replace the fork tube and slider bushings if their gray teflon surfaces are more than 50% worn. IMO if they show any wear (you can see the underlying copper), replace them.
9 - inspect the fork tubes carefully for burrs that might have caused a leak (use your fingernail). If you find any, dress them circumferentially with crocus cloth or fine carborundum paper, or you'll be repeating the seal R&R again soon.
10 - you'll need to make a seal driver - use schd 40 PVC pipe.  Cut longitudinal cuts in the end and use a hose clamp to get the ID down to the 41mm (or 43mm if you have a 96-02 ABS).  If you replace the upper bushings you'll have to make another driver (or use the other end of the seal driver with a pipe cap) with a beveled edge on the ID to compress and hold these bushings to get them started. Then drive them as far as you can with the seal driver.  I used a small hand-made brass drift with a specially ground tip to finish driving my bushings all the way 'home'.
11 - before you reinstall the springs, screw the fork cap in and mark the cap and the fork tube at the point where the last threads release/engage (great tip, Alan Hunt). Then when you reinstall the caps against the spring pressure you'll have a point of reference. Be very careful not to cross thread these very fine threads...!
12 - be careful not to pinch/cut the fork caps' O-rings as you fully seat the caps.
13 - final torque the fork caps with the upper pinch bolts loose and the lowers tight, of course.
14 - don't forget the bottom hex head bolts after the fender's back on...
15 - use the manual... and read the NOTEs... there are reasons Honda has separate pages for both disassembly and reassembly.
16 - pushing the brake pads in a bit will make reinstalling the wheel easier with more clearance for the rotors.

* [edit Aug '11, added this collected tip] "Removing the Allen bolts to separate the forks can be a frustrating problem. I have just finished the fork rebuild on my 1100 and a trick I've used for years is to stand each fork leg in a large saucepan of hot water [almost boiling] for the bottom 4" or so untill the bottom of the leg is hot to touch, they usually loosen easily after that." - Brian Robinson, STOC 5348

Good luck and HTH.  If you want to borrow my fork tools, you must read this post:

ST1100 Fork Seals R&R Tool Kit:

and agree to the loan terms.  To read it you must be registered, but if you own an ST you owe it to yourself, and your ST, to join us.

by John OoSTerhuis STOC 1058


Comments by Tom Wacker:

Impact tool for the bottom bolt.  I drained mine completely and turned the whole tube upside down in the vice to get to the thing.  Then promptly broke my "long" (you do need long) allen socket.  Twice.  An electric impact wrench (1/2") turned the trick for me, but I"m sure air would do, as would an impact driver....Otherwise, it is pretty straight forward and per the manual.


Comments by Jon Ransom:

Two tips...
Break the end of the forks loose while still mounted in the bike.  Both the fork caps and the drain bolts may be overtightened.  Get them started before removing the forks from the bike.

I guess I was lucky, as the drain bolts presented no real problem.

Disassembly wasn't so bad.  Just kept the parts in order as I went.  Reassembly is a bit more challenging.  In the mechanical classic, I have a part left over.  Fortunately, I know where it goes and need to open up the right fork (or is it the left?).  It's the part the caps the spring on the side with the damper rod.


Comments by John Oosterhuis:

Guess it's worth mentioning if one's never done this before, that to get the fork tube separated from its fork slider (after the lower bolt and all the innards are removed of course) you set and hold the fork slider on the floor, grab the fork tube and jerk upwards to bang the bushing against the back-up ring, driving the fork seal out.   Be sure you've removed the stopper ring and then 'whack' away.


Comments by John Parker:

The following procedure has worked very well for many of us over the years:

Procedure written by Bruce Triplett:

"This next step is VERY IMPORTANT.  This is the PROPER WAY to install forks.  ATTENTION â€" if improperly installed, the forks can’t work to their full potential.  First install the left fork (left is determined as if you were sitting on the bike) into the triple clamps.   (A little WD 40 sprayed on the fork tubes will make them slide in easier.)  The measurement you took before you removed the forks will allow you to reinstall the left fork at the proper height.  VERY IMPORTANT â€" Torque the pinch bolts to factory specs.  Next, install the right fork in the triple clamp at approximately the same height as the left fork and LIGHTLY tighten ONLY ONE of the pinch bolts.

This next step is CRITICAL â€"install the axle into the forks, grab the axle between the left and right fork, and begin rotating the axle.  As you rotate the axle, loosen the pinch bolt on the right fork and move the right fork up and down until you locate the place where the axle turns most freely.   Now, at this position, torque the pinch bolts to factory specs.  Install the wheel and brakes, and tighten the axle and/or axle nut.  Torque the axle pinch bolts on the LEFT FORK ONLY.

Now, you need to work the forks up and down.  The best way is to tie the cycle down in/on your trailer, or ride the cycle SLOWLY up and down the driveway, and pump the front brake level several times, making the forks move deep into the travel.  Now you can TORQUE the RIGHT axle pinch bolts."

edit 28 Mar '14: By John OoSTerhuis.  Here's a nice British video on fork seals removal and installation with a different, home-made version of bushing and seals driver:
Delboy's Garage, How-To Replace Regular Type Fork Seals

John OoSTerhuis

Damper rod holding tools.
John OoSTerhuis STOC 1058
1991 Honda ST1100 in Sparkling Silver Metallic, "The Grey GhOOST" (the ST, not me!)
Bettendorf, Iowa
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