front fork problem

[Nevstah]

hi all

whats the chances of the damper rods simply wearing out? my bike has done 28000 miles

symptoms are pogo-like forks! bounce all over the place like theres no damping.

I've changed the oil, even put heavier weight in (currently 15w) the springs are the correct length, there is no play in the bushings and everything is assembled properly with no obvious signs of internal damage

cheers guys, i'm a bit stuck!

 

[Cloggy]

Sorry I'm not very mechanical but I seem to be having the same problem. It wasn't like this when I bought the bike, still using the stock springs (done 80,000Km's) so I'm going to get some progressive springs and new oil put in at the dealer, hope this solves my problems.

 

[outasight20]

Check your fork oil level. It sounds like they may be overfilled. This would cause the ride to be extremely bouncy and limit fork travel. The damper rod is made out of steel. It doesn't really wear out.

 

[Nevstah]

Hi

I've triple checked the level already and it seems right

Travel isn't limited at all, you don't have to brake very hard for the forks to fully compress. I can get 3/4 travel just by bouncing the front end

You're right, they are steel. But they have a plastic collar on them, wondered if that may be a weak point? And letting oil past instead of going through the damping mechanism??

 

[outasight20]

Hi

I've triple checked the level already and it seems right

Travel isn't limited at all, you don't have to brake very hard for the forks to fully compress. I can get 3/4 travel just by bouncing the front end

You're right, they are steel. But they have a plastic collar on them, wondered if that may be a weak point? And letting oil past instead of going through the damping mechanism??

It's possible that the plastic collar is worn out, although I just recently changed the fork seals, brass bushings, and oil on my '05 with 30K miles on it and the front suspension feels better than new. So I find it hard to imagine that the collar on yours is letting oil past. I think we need someone more experienced to chime in here...

 

[greg]

and you put the spacers back in?

even if one fork was damaged the other would still compensate for it a bit

how are you measuring the oil level?

 

[Nevstah]

OK

When you did yours, did you notice if the collar was a loose fit on the damper, as mine is. Also it's split, but it looks like it was made that way

I did the same but it made no appreciable difference

Thanks a lot

 

[greg]

tbh I have no memory of the plastic collar on mine, it was a few years ago now

 

[Nevstah]

and you put the spacers back in?

even if one fork was damaged the other would still compensate for it a bit

how are you measuring the oil level?

the bike was ok when i got it 14k miles ago, but deteriorated in the last few 1000. i but everything back together the same way it came apart and also found a diagram to double check things

i wasnt sure on oil levels, but i found a volume online and i measured out the oil with a syringe so it should have been fairly accurate. i changed the oil again for a heavier weight and used the air gap method and made a tool of the right length to get the level right that way - both times the resulting symptoms were the same, though with the heavier oil it did change things a bit.

yesterday when it was quite warm, the ride home from work was diabolical!!

 

[iSteve]

Are the forks just bouncing up and down while you're riding? Could it be a out of balance front wheel.

 

[darius]

Have you been gaining weight recently? :spank:
The stock springs are for a 150lb rider.

 

[Nevstah]

Have you been gaining weight recently? :spank:
The stock springs are for a 150lb rider.

haha no, i'm the same weight, nothing has changed weight-wise, not added anything to the bike!

the forks just feel like they are compressing and rebounding with very little damping effect. if when i'm standing by the bike i push down with my hands on the grips, its not difficult to achieve atlest half the travel. when i'm riding, anything less than a perfectly flat road surface and the bike tries to buck upright and under braking it gets decidedly boat-like. - dont get me wrong, i know fazer forks arent the best in the world, but they just dont do anything anymore!

 

[FinalImpact]

haha no, i'm the same weight, nothing has changed weight-wise, not added anything to the bike!

the forks just feel like they are compressing and rebounding with very little damping effect. if when i'm standing by the bike i push down with my hands on the grips, its not difficult to achieve atlest half the travel. when i'm riding, anything less than a perfectly flat road surface and the bike tries to buck upright and under braking it gets decidedly boat-like. - dont get me wrong, i know fazer forks arent the best in the world, but they just dont do anything anymore!

As many times as you've fiddled with them, you might cut your losses and throw some emulators in them and get some control. I pulled mine after the first riding season just for that reason (pogo stick action). It came to me with 4000 miles and at 8000 I couldn't take it anymore.

Question; how silver looking is the oil each time its been dumped? It really sounds like you need to dig deeper and find the root cause and IMO, if you open them, FIX them! You will be rewarded by gaining control of the bike!

Or replace w/R6! Very happy w/mine.

 

[Nevstah]

As many times as you've fiddled with them, you might cut your losses and throw some emulators in them and get some control. I pulled mine after the first riding season just for that reason (pogo stick action). It came to me with 4000 miles and at 8000 I couldn't take it anymore.

Question; how silver looking is the oil each time its been dumped? It really sounds like you need to dig deeper and find the root cause and IMO, if you open them, FIX them! You will be rewarded by gaining control of the bike!

Or replace w/R6! Very happy w/mine.

Answer: the oil was rank after only a few 1000 miles, very dark coloured and totally opaque. i would love to open and FIX but as yet not found anything to fix!!

what are emulators? i thought that just let me play manic miner on the pc!! lol

from what i understand, replacing with R6 forks means parting with plenty of cash, which isnt really justified to me

the oil was new, the bushings (inner and outer) both fine, inner fork in good order, seals not leaking and damper rod 'looked' (to someone who doesnt know what a new one looks like) perfectly ok and the spring was the correct length. i dont know what else can be a problem! how much deeper can you go?

 

[FinalImpact]

Answer: the oil was rank after only a few 1000 miles, very dark coloured and totally opaque. i would love to open and FIX but as yet not found anything to fix!!

what are emulators? i thought that just let me play manic miner on the pc!! lol

from what i understand, replacing with R6 forks means parting with plenty of cash, which isnt really justified to me

the oil was new, the bushings (inner and outer) both fine, inner fork in good order, seals not leaking and damper rod 'looked' (to someone who doesnt know what a new one looks like) perfectly ok and the spring was the correct length. i dont know what else can be a problem! how much deeper can you go?

That seems to have happened VERY FAST. At glance the wiper seal on the damping rod must have too much clearance and oil is blowing past it. You mentioned it has the split ring, how did the actual wear on the sealing ring look? And what of the inner tube? Did you see gouges or anything in there where the seal rides? IMO the springs rubbing on the body during compression likely make a good deal of the metal we see as they are uncoated and abrasive to the upper tube thus making lots of fine particles.

Did you individually test their compression rate/rebound rate? I know this would be very subject but with the spring out it may become very obvious...

 

[darius]

So the front end feels like it's rocking like a boat and harsh? When traveling at speed, the fork needs to be able to move fast enough to react to bumps.

I think what's going on here is you've put in 15W oil which is much too heavy and slowing the forks down so much that they can't react to bumps in the road. The forks still move, just too slow and the bumps are getting transmitted to you. Then you're interpreting that as lack of compression damping.

The forks are cheap and they don't have much compression damping, however they will work effectively with the correct viscosity fork oil that Yamaha design them for.

I've been through all of this recently. It's all in this thread and will help you select the correct viscosity fork oil that Yamaha recommends:

http://www.600riders.com/forum/gara...-setting-up-hyperpro-progressive-springs.html

 

[FinalImpact]

Here are some links on fork mods and emulators. Both Race Tech and Ricor make them for our application. If you can take your fork apart the level you have, you can install these. Price from $100 to 200 depending on when and where you find them.

Found this along the way:
--------------------------
Level: 134.0 mm (5.28 in)
Quantity: 467.0 cm³ (15.79 US oz) (16.47 Imp.oz)
Recommended oil: Suspension oil 01 or equivalent
--------------------------

http://www.600riders.com/forum/fz6-mods/33288-everything-about-fork-mods.html

http://www.600riders.com/forum/fz6-...ings-cartridge-emulators-installed-w-how.html

http://www.600riders.com/forum/fz6-...rtridge-emulator-hows-service-their-shop.html

fork emulators, FZ6 - Google Search


Race Tech Gold Valve Cartridge Fork Emulators for FZ6 04-09
Product Information

From The Manufacturer, Race Tech
*Make damping rod forks perform like well-turned cartridge forks
*Tunable calves sit on top of damping rods; held in place by the main spring
*Typical road race track tests show an improvement of 2 sec. per lap
*Simple to install and tunable for all conditions and rider preferences
Product ID: 1029556
Manufacturer: Race Tech (learn more)
Manufacturer Part#: FEGV
Sold As: KT
Fits (click your bike to view all items for it):
– Yamaha FZ6 2004
– Yamaha FZ6 2005
– Yamaha FZ6 2006
More
Condition: New, unless otherwise noted.
SoloMotoParts.com is an authorized Race Tech dealer

 

[Nevstah]

That seems to have happened VERY FAST. At glance the wiper seal on the damping rod must have too much clearance and oil is blowing past it. You mentioned it has the split ring, how did the actual wear on the sealing ring look? And what of the inner tube? Did you see gouges or anything in there where the seal rides? IMO the springs rubbing on the body during compression likely make a good deal of the metal we see as they are uncoated and abrasive to the upper tube thus making lots of fine particles.

Did you individually test their compression rate/rebound rate? I know this would be very subject but with the spring out it may become very obvious...

i didnt see any kind of seal (apart from the main oil seal) just the split ring which is a hard white plastic. i never though to test the damping without the spring in, might try that over the weekend!! the tubes looked ok

So the front end feels like it's rocking like a boat and harsh? When traveling at speed, the fork needs to be able to move fast enough to react to bumps.

I think what's going on here is you've put in 15W oil which is much too heavy and slowing the forks down so much that they can't react to bumps in the road. The forks still move, just too slow and the bumps are getting transmitted to you. Then you're interpreting that as lack of compression damping.

The forks are cheap and they don't have much compression damping, however they will work effectively with the correct viscosity fork oil that Yamaha design them for.

I've been through all of this recently. It's all in this thread and will help you select the correct viscosity fork oil that Yamaha recommends:

http://www.600riders.com/forum/gara...-setting-up-hyperpro-progressive-springs.html

its over-reacting to bumps, not under-reacting. and the problem presented itself with the recommended oil weight

 

[darius]

its over-reacting to bumps, not under-reacting. and the problem presented itself with the recommended oil weight

I can understand why you think that. However, our forks are designed to use a light oil. In our manual it states to use Yamalube 01 Suspension oil or an oil of equivalent viscosity. It has a weight of around 0 to 5W.

You cannot just pour really heavy 15W oil into the fork and get free damping. The compression damping holes are sized for a much lighter oil. Heavy oils will slow the action of the fork and it won't work as designed.

I had 15W in my fork and it was harsh. I put Silkolene 2.5W (very close in viscosity to Yamalube 01 Suspension oil) and now the forks work like new. It's all in the thread I linked to above.

 

[Nevstah]

i think understand what you are saying, but i also know if i put the correct oil in (as i did 1st time round) i still have the problem, so it cant be simply the oil grade thats causing me to have little or no damping

but surely heavier oil will move through the holes in the damper at a slower rate that lighter oil?

i'm confused