Value of changing fork oil/rebuilding forks. 2015. 17k miles

Tech section strictly for the FJR. Everything from oil changes & suspension setup's to removing sheep hair from hard to reach places on the bike so that your wife never finds out.
BruinFJRguy
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Re: Value of changing fork oil/rebuilding forks. 2015. 17k miles

Post by BruinFJRguy » Sun Mar 31, 2019 7:48 pm

Thanks, guys. I'm reassembled and ready for a test run. Home with the daughter now, so it will have to wait. But it feels better even going up and down the driveway.

I shall report back.
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BruinFJRguy
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Re: Value of changing fork oil/rebuilding forks. 2015. 17k miles

Post by BruinFJRguy » Mon Apr 01, 2019 5:09 pm

UPDATE:

The upshot: The new fork oil has improved the situation CONSIDERABLY! I'm very happy.

Having realized just how easy it is to remove the forks and change the oil, I wish I did it sooner!

I had become so frustrated with my inability to set the suspension in a way that allowed me to use this bike to its potential that I was ready to get rid of it and opt for a smaller, more "race-like" performance-oriented machine. I still may add to the fleet, but I have fallen in love with this bike all over again.

Recently, going uphill and hitting the curves hard has not been an issue, but going DOWN hill has been a totally frustrating and confidence-UNinspiring experience. I could not get the forks adjusted in a way that didn't either bang the hell out of my wrists, or, alternatively, pogo all over the place causing me to drive at un-fun speeds.

Today I did a several mile stretch on Angeles Crest Highway between Angeles Forest Highway and the turn off for Mt. Wilson that has been closed for several weeks. Due to the closure, the road was sparsely populated, which allowed for much experimentation. I leathered-up and and went out to tweek my dials after the fork oil change.

I am happy to say I was able to ride this bike much more spiritedly than I have in a long time, maybe ever! I ground much more metal off my peg feelers and was even stable on the downhill potions.

I chop up the earlier problems with stability to relying way too much on spring compression on these progressive forks, due to the lack of dampening. In addition, because there was no dampening, I believe the bounces were especially jarring. I can't say much about the poor performance of rebound dampening, other than that it was basically "on" or "off," neither of which helped the ride.

What changed and what I've got now for settings:

As mentioned earlier, I added the correct amount of Motul Expert 5w. This oil looked to be a decent increase in viscosity over stock without going over board for my average size frame at 175lbs out of the shower.

I realized after some experimentation that I needed to crank the preload in significantly to allow to achieve an adequate spring rate and suspension travel. I think I was bottoming out, and simply cranking in compression dampening didn't firm things up enough or in the right ways.

Right now I'm showing only about 3mm from the top of the first rung on the dials, or 3mm below the bottom of the hex-portion. So, it is basically all the way in. But I'm happy with the firmness.

As for compression, I'm currently at 10 clicks out. Much less dampening than I was running before, but the oil is of course thicker. I imagine as the miles roll over I will again have to tighten a click her and there, until eventually I have to change again.

I have not tweaked the rebound dampening much. I'm still around 8 clicks out on rebound. I did adjust a click here and there on the fly, so I'd have to double check. But around 8 clicks out from firmly seated I think is where I'm at.

So, I'm firm enough on the springs that I'm not diving into bumps going downhill, I'm dampened enough on compression and rebound that my "bounce" into and out of bumps is much more under control. I'm happy and am loving the bike again!

I only had about an hour and a half up there today, but I'm looking forward to my next ride in a way I haven't in a long time! The cost was only about $30 bucks for the oil and some cleaner, and another $40 or so for a cheap 3/8 torque wrench (I only had 1/2", which doesn't fit inside the fairing) and a cheap socket set with a 24mm socket to remove the caps.

This was an easy fix with minimal effort. I don't know if it is better than it was new or not (I think it is), but it is definitely better than it was with 22k miles worth of spirited riding on the original oil!

Thanks again to everyone for all the suggestions and advice!
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fontanaman
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Re: Value of changing fork oil/rebuilding forks. 2015. 17k miles

Post by fontanaman » Mon Apr 01, 2019 8:55 pm

I change my fork oil annually to prevent dirty oil from abrading the fork bushings.

BruinFJRguy
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Re: Value of changing fork oil/rebuilding forks. 2015. 17k miles

Post by BruinFJRguy » Tue Apr 02, 2019 10:14 am

fontanaman wrote:
Mon Apr 01, 2019 8:55 pm
I change my fork oil annually to prevent dirty oil from abrading the fork bushings.
Nice! Fork maintenance will now be part of my routine, also. Until now, I've not really paid attention. But what I expect out of bikes is changing, so it is a good time to start!

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