Really tired forks

[ChrisK]

When I push down on the front end of my bike, it travels down about 2-3 inches and then it doesn't push back up. I can easily lift it back up, and then it stays put. 1998 M900.

I crashed the bike in June, and am in the process of rebuilding it, expect to be back on the road in two weeks. I just noticed this problem while working on the wiring on the front end. What would this mean? Just really old, tired fork oil? I've owned the bike for almost exactly a year now (right around 5000 miles of ownership), and I've never serviced the oil, and don't know if the PO did or not.

I plan on changing the oil, but should I be worried about another potential problem? I'm starting to think this issue was a contributing factor to my crash (anything that pulls more blame off of me, right?). I plan on doing either race tech springs or a full-blown conversion to newer GSXR forks when I have the cash. I weigh 210 so I'm sure I'm vastly overweight for what my forks were designed for.

Anywho, any advice?

[ducpainter]

Either something is bent/misaligned, or the springs are worn out. I suspect something got tweaked in the crash.

Try loosening all the lower triple clamp bolts and the axle clamp bolts and push up/down to see if things will align.

[ChrisK]

So you're basically saying any lines (forks and axle) that aren't parallel or perpendicular to each other will cause this sort of problem?

Great news, DP, great news...

I'll try that out tonight though.

[ChrisK]

I'm remaining hopeful that the forks aren't bent, because as a result of the crash nothing on them was even dinged. There wasn't a single mark on the forks, triples, or wheel. That said, the handlebar took a hard hit, along with the headlight.

I'm hoping this is installer error, plus some old oil.

[Speeddog]

Try dp's suggestion, forks twisting in the clamps is common when the bike is crashed.

[ChrisK]

Try dp's suggestion, forks twisting in the clamps is common when the bike is crashed.

Will do, thanks guys.

[ChrisK]

I was able to mess with it a bit at lunch, and got some results, still not perfect though. The forks aren't at the same height in the top triple, only off by 1-2 mm, but still I don't know how I missed that. So I'll suspend the front end tonight and make it perfect, then see what happens.

[Ddan]

It's not uncommon that the top of the two forks protrude a little differently over the top triple.  You want to check from the axle to the bottom clamp and then to the top triple on both sides. Those two measurements should be the same side to side.  Do what DP said first.

[ChrisK]

It's not uncommon that the top of the two forks protrude a little differently over the top triple.  You want to check from the axle to the bottom clamp and then to the top triple on both sides. Those two measurements should be the same side to side.  Do what DP said first.

Ahhh that makes sense, don't know why I didn't know/think of that, I'll be doing this tonight and reporting back either tonight or tomorrow morning. Thanks fellas.

[ducpainter]

What I do is remove the wheel and adjust the forks in the triples until the axle slides all the way in and starts threading. Once you get that you shouldn't have to mess with them unless you disassemble.

[ducatiz]

A very unscientific but useful method is to remove the wheel and reinstall the axle, then put a spirit level on the top triple and one on the axle.  they should be the same.

[ChrisK]

I did everything that was suggested above my last post and it helped quite a bit, you guys did good there. It springs back up now. However, it still feels tired. Like its far too easy for me to compress the forks. Does this point to an oil change, worn out springs, or possibly both? Also, I'm lazy, do these things take 10W fork oil?

[ducpainter]

Stock springs are too light when new. Stiffer springs will actually smooth out the ride. Monster forks are under sprung and over damped from the factory.

I think they use 7.5 W. I would stick with that weight oil if you upgrade springs for your weight.

[Ddan]

Before you start throwing parts at it:

http://www.ducatiwiki.net/index.php?title=Suspension_Setup

[brad black]

if they're showa i'd go 5 weight or even try 2.5.  this reduces the excessive high speed compression damping.  but respringing with a linear spring and lowering the oil level is a great start.

but if they don't rebound when you push them down the oil has suddenly got a whole load thicker, the springs have suddenly collapsed, things are out of line causing stiction to hold them where they stop, or they're bent.  the first two suggestions are most certainly rubbish.  the third you've dealt with, the fourth you need to investigate i'd think.  lift the front, unscrew the fork caps and see if the forks will move through their travel.