Fork bottoming out at half travel

[Will3554]

Hello everyone, brand new here. I just picked up an 04 fz6 and riding it home it was bottoming out the fork badly. The seals were junk so I had a local shop change out the seals and refill with 10w oil. After getting the forks back and reinstalling them it's still doing it. I put a ziptie on the stanchion to see what was going on and I'm barely getting 2.5 inches of the 5.1 it has. It's a very sharp, solid, metallic bottoming. Any ideas??

 

[trepetti]

Not sure about the metallic part, but if a fork is overfilled with oil it will hydro-lock and abruptly stop collapsing. I am giving the repair shop the benefit of the doubt, during the seal change they should have been able to detect an internal mechanical defect that would prevent full movement.

 

[Gary in NJ]

Too much preload? Wrong springs? If the springs are short they might be hitting their mechanical stop (fully compressed) before the full 5.1” of travel. I would measure their free length as well as the compressed length. Don’t forget to account for preload of the spring when measuring.

 

[TownsendsFJR1300]

I'd put the bike on the CC, raise the nose (scissor jack under header) and let the forks fully extend.

Take a measurement, then put it back on the ground and re-measure. Stock forks/springs have a bunch of droop from the factory. It sounds like your springs are possibly worn and while seating(not moving half your travel is already gone).

Use your zip tie again and push up and down on the forks.. Now measure your total travel.

What we/I'm trying to see is of your simply bottoming out...


Note, I have stock forks and springs which had a bunch of factory droop. A simple mod, which I did and works wonderful, was to add Schrader valves to each fork cap. Adding about 15PSI to each leg, brought the nose up nicely and the forks are infinitely adjustable... (I might loose 2 lbs in a year so "topping off" is not often)




This mod has been in place since March 2015 and no, the forks don't leak oil and at 28,000 miles, seals are original..

 

[Will3554]

Thanks for the ideas guys, I really like the air assist idea, my center stand is removed but I did put it on the side stand and rock it over and lift up on the bars so I think the fork was fully extended when i took my measurement.

 

[TownsendsFJR1300]

So the fork is locking up approx. half-ways thru the travel?

If it is, I'd pull the front wheel, fork caps and cycle each leg by hand. That will definitely let you know if you have full travel...

 

[Will3554]

Great idea, maybe I'll do that tomorrow

 

[Gary in NJ]

When you get the cap off of the fork, remove the spring and check its free length. It should be 354mm (13.94 in). It's service limit is 347mm (13.66 in). Also note how long the spacer is. From the factory its 131.5mm (5.18 in). This length will provide 7mm of preload. The prior owner should have adjusted the preload for his riding weight...but we are talking about 5-15mm additional spacer (maybe washers or PVC). If the spring and spacer are not OEM, their total combined length should be 485-500 mm.

The OEM spring only allows for about 5.12 inch of travel, so if the prior owner put an additional 2.50 inch of preload on the spring, that would account for it reaching its mechanical limits too soon in the stroke.

Let us know what you find.

 

[Will3554]

That's great info to have for when I tear into it, thanks alot

 

[Will3554]

So when I pull the cap off I should find a spacer, then a washer, then the spring in that order correct?? Is there anything else under the spring?? Anything else I should be looking out for that could be the problem besides the lengths of the spacers and springs??

 

[Gary in NJ]

My guess is that it’s not an OEM arrangement in there, but yes you have the order correct. You may find a washer or stack of washers (or a length of pvc) on top if the prior owner made preload adjustments.

 

[TownsendsFJR1300]

You could flip the fork up side down at that point (spring, spacer, washer removed) and nothing else but oil would come out...

That's how you replace the fork oil...

 

[Will3554]

Ok fork is apart, all lengths match up. I did notice that the springs wer upside down, tight wound part was at the bottom, I wouldn't thank that would be the problem though. I'm getting ready to cycle the fork with everything out and see what kind of travel I get

 

[Will3554]

Still bottoming at just under 2.5 inches even with the internals removed from the fork. I'm gonna pull the wheel and front fender and do each leg individually, I'll report back

 

[Will3554]

Left (clutch side) fork leg is the one bottoming out. Other side slides almost to the lower triple clamp. Its stops with a solid, metal on metal sound. Any ideas were to go from here??

 

[Gary in NJ]

It’s the bushing. I’m shocked (pun) that the mechanic that replaced the seals didn’t pick up on that.

 

[Will3554]

Not installed correctly or bad?? Is it the one that comes out with the seal or is there another one??

 

[Will3554]

Sorry I'm being a pain, I've rebuilt a few mtb forks but never had a motorcycle fork apart

 

[Will3554]

And I'm not overly shocked, they are a good ole boy vtwin type shop but they are local and reasonable rates. They redid the seals on my old 07 fz1 a little bit back and I was telling my wife I was a little worried because fz1 forks are a little more complex then harley forks haha but they turned out fine

 

[TownsendsFJR1300]

Well, glad you found the answer...

Bring both forks, (still off the bike, no springs) back to the shop and demonstrate
the shorter travel on the bad one and have them fix it properly..

Agreed with Gary, that should have been caught before leaving the shop...