Article [13] ST1300 Front Fork Overhaul: An Illustrated Bibliography

[970mike]

MIne didnt work well and now I see why, I didnt ziptie the bottom. (just middle) Does your sleeve atleast expose some of the fork for travel at the top??

I moved it to the top and it works great.

 

[St1300biker]

What's the consensus on the forum for the service interval for changing the fork oil.

In his video, Dave Moss Tuning suggests 6000 miles because he considers it such a vital task

Paul

 

[CYYJ]

Dave Moss Tuning suggests 6000 miles because he considers it such a vital task...

That sounds a bit overly-ambitious to me. Certainly, if you want to achieve perfection and are not willing to put up with any degradation from perfection, changing fork oil every 6,000 miles might be necessary. But that's a bit like washing the bike every single day because you're not willing to tolerate any dust on it.

I think that for the average rider, considering that we use the ST mostly for long-distance travel, changing the fork oil once every couple of year (once every 20,000 miles) would probably be about right. After all, there's no safety risk or risk of damage to components if the fork oil has degraded - it's not like the rear differential splines, where damage will occur if we don't lubricate it correctly using the exact correct lubricant.

My bike had about 60,000 miles on it and was 8 years old when I did the first fork oil change. I did notice an immediate and significant improvement in front end performance after I did the overhaul. I certainly won't leave things that long again - but then again, I won't be changing fork oil every 6,000 miles either.

Michael

 

[STimpa]

Replaced the seals on my ST13 today. I had read your article ahead of time, but wasn't able to have it available when I proceeded. While I wasn't as meticulous as you explained, it was rather straightforward process. Upon reassembling the forks and adding fork oil, I failed to pump the rods as completely as you detailed, probably 5 or 6 times. After adding the oil and measuring the 62 mm from the top, I replaced the springs, etc and closed up. After getting home (I did this at a friend's garage) I measured the remaining oil into a paint mixing container and found each fork even in volume, but with 3 oz too much left over. Is it more important to have the correct amount by liquid volume, or measurement to the top? ie, would I be wise to add the 3 oz, assuming I didn't pump all the air out of the pushrod, or leave it be? Or take the caps off, pump the rods and check again? Not sure how critical all of this is...

 

[Macedo]

A very good post, thanks.

 

[MaxPete]

Hey Michael: I just ran across this article and want to thank you very much for the really great job you did on it.

Very well done indeed!

Pete

 

[CYYJ]

...Is it more important to have the correct amount by liquid volume, or measurement to the top? ie, would I be wise to add the 3 oz, assuming I didn't pump all the air out of the pushrod, or leave it be? Or take the caps off, pump the rods and check again? Not sure how critical all of this is...

Hello:

Sorry for the very late reply, I just saw your post today.

I honestly don't know how critical the measurement of the oil level within the forks (either by volume or by distance from the top) is. I'm going to guess that the governing measurement is "distance from the top of the fork tube", rather than total volume, because that is how Honda specifies the quantity in the repair manual.

I think that if you are satisfied with the performance of the front end suspension as it is now, and you are not encountering any problems such as bottoming out, you can probably leave things as they are, and just correct the problem next time you service the front forks. But, if you have concerns about front suspension operation, it should not be too difficult to take the caps off the top of the forks and bring the oil quantity up to the specified 62 mm distance. Without re-reading my original article again, I don't know if all you have to do is take the caps off and add fluid to achieve the 62 mm distance, or if you have to establish other conditions (e.g. forks fully extended, etc.) before doing the measurement.

Michael

 

[TerryS]

Michael is quite correct; the air gap over the oil is the critical measurement, not the oil volume. The air gap acts as a spring in its own right; as the fork compresses and the oil level rises in the tube, the air volume reduces and that generates some pressure. The air provides a rising rate spring (resistance increases with travel) so it has the most effect near bottoming, and little effect when the fork is extended.

Crude maths on my part (I ignored the volume of the springs) would suggest that compressing air from170mm (62mm gap plus 108mm travel) to 62mm would increase pressure by 176kPa/25psi and generate something like 24kg of force. That would be added to the mechanical springs (e.g. 1.0kg/mm spring rate and 108mm compressed is 108kg of force, so you'd have something like 132kg of force required per leg to bottom out. Purists will also point out that the initial spring preload also adds to the force required to bottom the fork.

If the oil level was say 72mm instead of 62, then the bottoming force would drop to 129kg ( a reduction of 3kg). So a reduction in the oil level has some effect, but nothing major/dangerous. If the oil level was really low then you could possibly have insufficient to fill the damper but that would have to be REALLY low.

Getting the oil level reset with the forks in the bike will be a challenge (I have done it on my VFR800) unless the bars were also removed, as you need to remove the caps and the springs (watch the mess), then compress the forks fully to get the level right. No need to do more fork pumping because you will definitely have bled all the air out of the cartridge just by riding.

 

[WeekendWarrior]

Thanks for posting this. Planning on this and other PM this winter.

 

[Ralf_CT]

Excellent step-by-step article!

I've just bought a 2009 ST1300, the selling dealer apparently changed a leaking fork seal. On an earlier ride I noticed the front suspension was very stiff, with all bumps transferred directly to the handlebars. I'm assuming they refilled with the incorrect oil weight and/or capacity?

 

[Lowndes]

Ralf_CT,

The PO may have installed stiffer springs or spacers, as well as new oil. Your condition sounds just like my '08 with Sonic Springs recommended 130 kg springs and 7.5 wt oil. It was like a solid front fork but the handling was SUPERB, razor sharp. THAT told me that the rest of the bike, frame and rear end, and the fork tubes, were NOT part of any handling problems, that it all had to be in the springs and dampening, compression and rebound. It turned it from a "TOURING sport" bike into a "SPORT touring" bike. GREAT handling and a blast to ride in the mountains of N GA and NC, but was brutal on a bumpy road.

It's relatively simple to pull a spring and look at it. Put it on the center stand, remove one side of the handlebar (leaving all the wiring and hydraulic lines in place), then the fork cap. EZPZ. The other side remains and holds up the front end. The OEM spring is a compound on one end and looked to be slightly tapered. All the aftermarket springs I've seen are straight wound.

The other thing to look at is the air gap between the top of the oil and the top of the tube. Not enough air will stiffen it up.

 

[Kevcules]

Excellent step-by-step article!

I've just bought a 2009 ST1300, the selling dealer apparently changed a leaking fork seal. On an earlier ride I noticed the front suspension was very stiff, with all bumps transferred directly to the handlebars. I'm assuming they refilled with the incorrect oil weight and/or capacity?

You should really take the front springs apart and see what's in there. Depending on your weight and the bikes front sag, it's probably not right. When I bought my 08, I complained of the same thing. Riding up the bumps instead of absorbing them. I had the OEM springs in there when I checked , but I needed to add another 15mm longer spacer to get the bike to sit up a little for my 170lb weight. (as per advice from Dave (dduelin)) Doing this, as well as cleaning, changing the bushings and changing to 5wt fluid, helped a lot.

 

[Ralf_CT]

You should really take the front springs apart and see what's in there. Depending on your weight and the bikes front sag, it's probably not right. When I bought my 08, I complained of the same thing. Riding up the bumps instead of absorbing them. I had the OEM springs in there when I checked , but I needed to add another 15mm longer spacer to get the bike to sit up a little for my 170lb weight. (as per advice from Dave (dduelin)) Doing this, as well as cleaning, checking the bushings and changing to 5wt fluid, helped a lot.

I'm average weight at around 83kgs/1.87m. Bouncing the bike with the front brake applied produces some fork movement, but it's very stiff. On my ''82 Gold Wing I recall looking at the forks through the fairing gap while riding, they moved up and down nicely, not so with this one.

The selling dealer suggested I return the bike for them to take a look, but I'm concerned, if they couldn't do a proper job the first time what hope do I have of them getting it right the second time. They're not Honda dealers and may lack the expertise/specs. Could they have done a 'cheapy', as in replaced the fork seal without stripping and refilling the forks? Dealers are inclined to spend as little as possible, thereby ensuring maximum profits.

 

[Lowndes]

I'm average weight at around 83kgs/1.87m. Bouncing the bike with the front brake applied produces some fork movement, but it's very stiff. On my ''82 Gold Wing I recall looking at the forks through the fairing gap while riding, they moved up and down nicely, not so with this one.

The selling dealer suggested I return the bike for them to take a look, but I'm concerned, if they couldn't do a proper job the first time what hope do I have of them getting it right the second time. They're not Honda dealers and may lack the expertise/specs. Could they have done a 'cheapy', as in replaced the fork seal without stripping and refilling the forks? Dealers are inclined to spend as little as possible, thereby ensuring maximum profits.

Ralf_CT,

Just open a fork tube cap as I suggested above. It's a simple, one-hour, driveway job and can be done with the bike's tool kit. That will show YOU what the issue is, either too much oil and/or aftermarket (too stiff) springs. Then you can decide to take it back to the dealer for corrections or not. You might want to see if their assessment is the same as yours. A "stuck" front end is not good and definitely not normal for an ST. If anything they suffer from a WAAAAY too soft front end, IMHO.

It seems to me that there is a very specific sequence of assembly and torquing of the front wheel axle and triple-head bolts that must be followed. Think I read that here somewhere. That shop may not have known about it. You DON'T have to do any of that when you open the fork cap and pull a spring, only when the forks are disassembled or front-wheel removed.

Most dealers want to keep customers happy or they can't stay in business. Yes, they need to make a profit, "or they can't stay in business." Unfortunately, people sometimes make mistakes. I've always found that it's not IF a business makes a mistake (everyone does, we all have erasers on our pencils), but it's HOW THEY HANDLE THEIR MISTAKES that makes the difference. But you have to at least give them a chance to handle it.

EDIT:
Ralph, I'm no mechanic and an expert in nothing, please believe me. But I'm not afraid to get my hands dirty ...once in a while.

These are the pics I took while putting the air-boost on my '08 ST last year in my garage. There are two pics that show the OEM spring alongside the SONIC spring. The OEM is a progressive, or "DUAL RATE" - close coils and wider spaced coils. The SONIC spring is the same spacing throughout the length. The pics only show the "progressive' end (last 4-5 inches).

https://photos.app.goo.gl/kVCyRAZerss5Lgkj7

 

[Ralf_CT]

Ralf_CT,

Just open a fork tube cap as I suggested above. It's a simple, one-hour, driveway job and can be done with the bike's tool kit. That will show YOU what the issue is, either too much oil and/or aftermarket (too stiff) springs. Then you can decide to take it back to the dealer for corrections or not. You might want to see if their assessment is the same as yours. A "stuck" front end is not good and definitely not normal for an ST. If anything they suffer from a WAAAAY too soft front end, IMHO.

The front end isn't quite stuck, but it's damn stiff. They called on Friday to arrange collection on Monday so there won't be time for me to dismantle.

I'm not sure if I want to keep the bike, 30 years after owning an '82 Gold Wing GL1100 Interstate I'm no longer keen to wrestle a 325kg bike and constantly change gears in traffic. The past few years I've been spoiled by my PCX150's twist-and-go and think a late model TMAX 530 may be a more suitable choice. I also dropped the bike on Thursday: my stupid mistake by pulling away in 2nd, killing the engine and being forced to gently lay it down. Not exactly a confidence booster.

There seems to be some backlash in the driveline, I'm not sure if this is normal (it feels like a chain drive). The bike has done just under 48,000kms.

 

[Team2010]

+1 Great article ! Fairly easy job albeit time consuming.

To quote CYYJ :
"Evaluating and Correcting the Condition of the Fork Tube
The fork tube is subject to impact damage from rocks and hard-shelled insects. If it has suffered impact damage, there’s not much you can do about the impact crater, but what you can do is make sure that there are no ridges around the crater that stick up and will damage your new fork seal. "

I too had multiple craters clustered on the right fork tube just above the fork tube protector causing an oil leak. Unknown if it was from one of our off-road side trips/rocks/bugs or or a heavy handed mechanic (PO or possibly myself) with a wrench loosening/tightening the lower 3T. As suggested, I used a 2000 grit sanding disk kept rinsed and dripping wet to take off the high edges. Doesn't look perfect but so far seems to have done the job.
Just as an added precaution, I fashioned some fork tube protectors. They wont save the tubes from a mechanics wrench, but may help against direct hits from bugs, rocks or sand.

Stay safe everyone.
Jon

 

[Terminator2]

I am ashamed. When I serviced my forks Sept 2019, I never thanked ( CYYJ-Michael) the poster of this thread. Thank you. Now 15k miles later, I have no idea how often I should change fork fluid. Service manual evades my curiosity. I'm known to overlook things when reading. Enjoy all your riding.

 

[Kevcules]

I am ashamed. When I serviced my forks Sept 2019, I never thanked ( CYYJ-Michael) the poster of this thread. Thank you. Now 15k miles later, I have no idea how often I should change fork fluid. Service manual evades my curiosity. I'm known to overlook things when reading. Enjoy all your riding.

Don't be so hard on yourself! It's never too late to thank CYYJ, he's a very good asset to this forum.

If you read above about 8-10 posts, there's a sport rider (video) who recommended changing the shock fluid every 6000 miles. Then Michael commented about changing every 20,000 miles would make more sense.
You're at 15 thousand now, so if your suspension still works ok, maybe wait another 5 thousand miles , OR , if you have time, change the fluid. This will give you a good idea at how dirty the fluid got, or maybe it's still clean and in good shape? Then you can gauge your results to extend or decrease your next fluid change interval. Good luck....

 

[Andrew Shadow]

I have no idea how often I should change fork fluid.

I have never found any interval recommended by Honda. Internet searches seem to yield a consensus of up to 20,000 miles between changes for touring motorcycles and 10,000 miles for full sport bikes. ST's are sport-touring motorcycles, so 15 to 20,000 miles seems reasonable to me.

 

[Sidekick]

Aggregating all these threads together is making them much more usable.
On the top of that your step by step guide is so well documented and organized...
Thank you so much Michael! ++++