04-09 FZ6 FORK OIL and seal replacement!

FinalImpact

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I've had about 4 of them apart. So far, tighties go up top, loose at the bottom. Brand new or not, your's seem backwards.

Per our PM's; although you compressed it and saw the tighter coils collapse first, I'm pretty sure thats the result of them being in upside down and they are weakening.

If you check the bikes static SAG it will give us an idea as to the springs health. All you need to do is throw a zip tie on a stanchion tube and let the bike stand on its own. Measure the difference from FULLY EXTENDED to ACTUAL ride height (how far did the Zip tie move). That's the ball park bike SAG.

Repeat with you on board and you have rider sag which when you RECORD IT and measure again at the end of the season, then you see the springs sank another 1/2" (OR MORE) and you know they are getting weaker!

Anyway - As stated in PM; on a dual rate spring installed correctly, the action of the forks compressing acts first on the spring nearer the bottom. The coils near the bottom are constantly flexing. As you encounter bumps, more of the spring compresses.

When installed with the heavier rated towards the bottom, you've increased the unsprung mass. In the ideal world with newer springs the lower rated section should compress first. And when upside down, that means the WHOLE SPRING HAS TO MOVE AND ACT AGAINST THE SPRING CAP so the lower rated section (at the top) can compress. But its not that simple. The initial shock of being moved can win and force the bottom (higher rated coil section) to collapse just due to the action of trying to move the mass of spring.

Measure the bikes static sag and tell us how much those spring settle just from the bikes weight.
 

FIZZER6

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If you check the bikes static SAG it will give us an idea as to the springs health. All you need to do is throw a zip tie on a stanchion tube and let the bike stand on its own. Measure the difference from FULLY EXTENDED to ACTUAL ride height (how far did the Zip tie move). That's the ball park bike SAG.

Measure the bikes static sag and tell us how much those spring settle just from the bikes weight.

I am assuming when you say "let the bike stand on it's own". Just stand it upright and support it lightly by holding the bar without applying weight to the bar? Can you give me the NORMAL sag on healthy forks? What about normal main spring length when removed from the forks? If I'm removing the springs anyway to install them the other way I may as well measure them while out.

Thanks for the help. Sounds like my forks were assembled at the factory at 4:50pm on a Friday!
 

FinalImpact

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Springs are supposed to be 350 mm free. Its in the FSM. But off hand it doesn't mean much. Well, unless they're 320mm! Just set the bars aside and drag them out slowly so the oil can run off. Its easier to put the caps back if the nose is unloaded.

It really varies, but ideal is 10-13mm bike only, just holding a bar end as you indicated.

I recall my OEM forks/springs had 45mm of rider sag at 8,000 miles, I'm at 180lbs in rider position. Hint previous owner was likely pushing 260lbs. They were toast. Any weight transfer from braking and I was on my nose.

You can use a wall to do rider sag solo. Just use a zip tie, then PULL UP as you dismount and continue pulling up until you can raise the nose. i.e. pushing DOWN on the seat and kick a block of wood under the headers and measure how far zippy moves. Do it 3x and take the average.
 

FIZZER6

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Great info! I still have the forks off the bike as I am still working on swapping head bearings so I'll remove the springs, measure them and reinstall tonight. Won't have a change to measure sag for a few days or weeks when I get around to putting it all back together, no big hurry as this month is pretty much a bust for riding in VA.

I'm about 150 lbs with gear and have been the only owner so my bike has never been overloaded.
 

FinalImpact

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If my static Bike SAG is greater than 15-25mm, can I increase the preload to bring it into spec?

Maybe, however its not that easy and we need to look at the whole picture. A springs rate if proper for its intended use cruise, highway, or track use, neither tops out or bottoms out and it keeps the bike at the proper ride height so the suspensions geometry is maintained throughout most of the terrain we ride in.

You need to know what the rider SAG value is too. With the two numbers you can ballpark if the springs rate and preload is proper for your intended use. This will vary based upon what you expect from the bike in your environment.

Lets say your bike is using 25mm of static SAG to support itself and with the rider it compresses another 40 to 50mm. Unless adjustments are made to the rear, the steering angles will be less than ideal. Not to mention most of your travel has already been consumed leaving little for surface irregularities. Stock has 130mm (5.12") of travel.

Point: you have to take rider SAG into the equation before increasing the preload.

Spring Rate:
- Too low and we risk bottoming from a bump and poor handling.
- Too high and the bike handles poorly as its topping out.
 

cmantis

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Re: 04-09 FZ6 FORK OIL and seal replacement - With Steering Head Bearing Swap!

Hmm now im wondering if I ordered one kit or two. Im thinking just one thinking it was enough for both.

* I just checked got two :)
 
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tejkowskit

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Part #47 is a Yamaha OEM seal kit with all the seals included. If you check each seal needed, its states its included in the seal kit. Might be something new as I haven't seen this kit either..

Yamaha Motorcycle Parts 2006 FZ-6 - FZS6V FRONT FORK Diagram

Awesome! I didn't even think to check it like this. Does appear to have seals for both forks in this kit. I'll order 1 and confirm that part #5VX-W003B-00-00 has seals for both when it comes in. Thanks.
 

FinalImpact

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Fwiw boats.net same part, same item, same price but no picture of what you get. However, at the bottom of the fiche diagram it states item 47 has the 4 seals needed (points to them via item #). Cheaper than buying non-kit item. Good find...
2005 FZ6 - FZS6T Yamaha Motorcycle FRONT FORK Diagram and Parts

Now the big question; which way are your springs installed?
 

FinalImpact

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Boats net and Partzilla are sister companies.

Look on the very bottom of this page, boats net is Partzilla "sister" site

Yamaha Motorcycle Parts 2006 FZ-6 - FZS6V FRONT FORK Diagram


Well I'lbe Damned.... lol ^^ :thumbup:

Been using b net parts fiche as it lists the "where used" pretty easily and not all sites do that. Although b net is not entirely friendly from the inside to find bike parts. lol
- Ronayers.com was my fav goto site, but they made it such a PITA to use I quit. It has since been revamped!

It's a small world! :D
 

tejkowskit

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Got this out of the way recently. Add me to the list of fork springs were installed by factory with tight coils DOWN. I reinstalled with them up as says in the manual.
To verify, part #5VX-W003B-00-00 comes with 2 dust seals and inner seals. Here's the packaging, and a slip that was in the box showing its contents.

Did this job pretty much as shown in the demo. Made a fork seal driver from 2" PVC.
My damper holder was a wooden broom stick handle with duct tape around it.
Here's how I measured the fork oil in the forks. Used this pocket ruler like a dip stick. Set the end to 135mm, and looked for oil to be at the 1mm mark.
See the oil on the end in the below pic? Got each fork within 1mm of each other this way.


Measured fork springs. Both at max 13.94"

This wasn't a bad job at all to do. As with all projects, have patience and take lots of pics to reference during reassembly so everything goes back together later the way it was disassembled. I replaced with the same maxima 5wt as OP used. Forks are muuuuch better. The oil that came out was brown and dirty. This has never been done before on my bike which now has 32500 miles.
 
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TownsendsFJR1300

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Thanks for the update, nice to have that verified..

I changed just the oil at 18,000 miles +. No leaks..

the fork oil smelled funky, very dark colored. Flushed some thin sludge(if you would) out with another quart of fork oil before putting in the final "good oil" (Maxima non-stiction, 7.5 weight).

The OEM designation of "00" is supposed to be equivilent to 5 weight. Maybe because the oil was old, it certainly seemed much thicker when it came out than the 7.5 weight I put in. Closer to 10 weight..

As for measuring height, I simply trasferred the height to a thin screwdriver and marked the shaft off with masking tape. Simply slip the screw driver down until you see the oil wick up and check you tape mark. When they both equal up, its done. Like yours, within 1 mm easily..
 
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1. Does anyone know what size is the seal driver if I were to get one for pounding the fork seals in place rather than improvise from a pvc pipe? I see that there are sizes between 37mm to 44mm on websites selling them.

2. Also, would appreciate if anyone could share which hex drive opens the end bolt. Is it size 10, 12 or 14? I am only getting 1 rather than all 3, as I have allen keys for the others.

3. Lastly, I am looking for a metal rod or rebar rather than the wooden stake used here. Would the shape of the tip of the rebar matter for holding the end bolt in place for tightening/loosening?

Gathering our necessary tools before we begin this operation. Newbies here
 

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#18: Slide the damper rod with small spring down the inner tube in the same way it came out of the tube originally.
Use your stake you used previously or a piece of rebar with a cotton rag wrapped over the tip like this and duct taped in place to push down the inner tube and hold the damper rod in place while you install the end bolt with new copper washer.



Instead of using a rebar to hold the damper in place to tighten the end bolt nut, does it work if I reassemble the fork springs and fork cap (without putting in the fork oil) and tighten the end bolt?

Likewise, when I loosen the fork cap and remove the fork from the motorcycle, could I loosen the end bolt at the bottom before opening the fork caps fully and removing the fork oil and springs? This would eliminate the need for a wooden stake or rebar to hold the damper in place to loosen the end bolt. Does this work?
 
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