Wildguzzi.com
General Category => General Discussion => Topic started by: chimchim on February 21, 2025, 03:53:40 PM
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Changing fork oil on my v85tt. 28k miles. Few miles late per maintenance but only doing per Guzzi maintenance advice. Doing left side now. I notice left fork yields 300 ml yet volume required is 386 ml. Do inverted forks slowly lose oil over time even if not leaking or maybe underfilled at factory? I dripped it dry to collect all oil and aside from slight residue in tube 300 ml is volume at 28k miles no leaks.Thoughts?
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Changing fork oil on my v85tt. 28k miles. Few miles late per maintenance but only doing per Guzzi maintenance advice. Doing left side now. I notice left fork yields 300 ml yet volume required is 386 ml. Do inverted forks slowly lose oil over time even if not leaking or maybe underfilled at factory? I dripped it dry to collect all oil and aside from slight residue in tube 300 ml is volume at 28k miles no leaks.Thoughts?
No, but I’m keen to hear from others.
Mine is due now.
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I can see how manual is confusing, putting air gap picture under rh side but stating volume only for left leg
Of course the volume measurement is only true for completely disassembled forks, oil clings and must be cleaned with solvent. Air gap (oil level) is the only way to do it. A wise man would measure air gap in both legs to verify before draining but I treat air gap as a tuning aid, cable tie on legs to measure travel, vary air gap for the last few mm, read up on it or get advice from suspension tuner, especially if you think forks could be better, now’s the time to look at spring and damping rates. All can be set up for individual use
(https://i.ibb.co/v65z2gN9/IMG-1974.png) (https://ibb.co/v65z2gN9)
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As the suspension is operating normally, and I only wanted to keep up with the oil change, I did not want to have to disassemble the forks, particularly the right one as it's kind of tricky to compress the spring and put the holding plate under the valve nut by yourself, so I was carefully measuring the oil I received out of each tube until no more was released, and planned to replace with that amount or the factory spec amount. I found the volume less than spec, so was wondering if some loss was normal. I have all the tools to disassemble and measure height, add, replace seals, etc., from doing it on another bike (Ducati, doing all that you advise) but seemed more than necessary for this job. Using Motul 7.5w synthetic. Appreciate the advice on the measurements.
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Personally if there is an oil height spec, I only use the volume spec to get close and then measure height - that's the number that matters.
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FWIW....
https://www.youtube.com/watch?v=k4BxjmIwVdY
I'm contemplating doing fork oil on my v85tt way earlier than recommended since I've changed oil on forks of new bikes having only a few thousand miles on them and the oil was filthy gray. The reason for changing oil early on those bike was because the forks were already off for replacement of stem bearings (balls to roller type).
Art
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Yes, oil height spec is most accurate, though Guzzi requires none for the left fork, just the right on a v85tt. Left is just volume. Anyone have an answer to my original question if inverted forks lose oil over time even if functioning normally?
Regards,
CC
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Yes, oil height spec is most accurate, though Guzzi requires none for the left fork, just the right on a v85tt. Left is just volume. Anyone have an answer to my original question if inverted forks lose oil over time even if functioning normally?
Regards,
CC
If the seals are not leaking the forks should not lose oil over time.
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When I did weights & measures work we had a regulation as to how long to let the test measure to drain when test fuel dispensers so that we got an accurate measurement. I doubt that you will get an accurate measurement draining oil from a fork. Although I doubt having exactly the volume specified is going to make much of a difference a cc more or less.
kk
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Did you pump the suspension to empty the cylinder?
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I held the fork upside down pumping the suspension full stroke (cleaning the tube all the way to the base before doing these compressions as the seal will travel further down than usual once the fork is opened and there will be crud down there) at multiple angles also rotating the fork when no further oil would come out in a given orientation to a new orientation. Once no more would come out at any angle, pump action, or position (I did this for 10 minutes per fork) I deemed it empty of all that could be removed short of complete disassembly once no further motions would yield any more oil.
I ended up replacing like with like. As there is no air gap for the left fork, and only complete disassembly would completely dry it of all residual oil, thus trashing a perfectly good seal, and my measuring vessel having its own inaccuracies, meaning adding 386 ml might not be 386 ml with my vessel, I replaced the exact volume with the exact volume with the exact vessel that measured it, adding 5-10ml for transfer losses. I ended up doing the same for the right one, though that one you can measure by air gap without having to disassemble and dry it so you know you have a give volume in there. The air gap will make up for any residuals.
On a 60 mile test ride today the bike rides more "plush" as if the forks are quicker to respond to road irregularities keeping the bike poised while still giving excellent control. Perhaps better stiction with this fresh oil? I don't know, but this method worked for me. I was not having a problem before the oil change, but the change did make a subtle improvement. Maybe at 48-50K when due again or if a seal leaks I'll do the disassembly, and replace seals and oil, and maybe bushings, and not just change the oil. Thank you all for your input. It is much appreciated.
Regards,
CC
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I held the fork upside down pumping the suspension full stroke (cleaning the tube all the way to the base before doing these compressions as the seal will travel further down than usual once the fork is opened and there will be crud down there) at multiple angles also rotating the fork when no further oil would come out in a given orientation to a new orientation. Once no more would come out at any angle, pump action, or position (I did this for 10 minutes per fork) I deemed it empty of all that could be removed short of complete disassembly once no further motions would yield any more oil.
I ended up replacing like with like. As there is no air gap for the left fork, and only complete disassembly would completely dry it of all residual oil, thus trashing a perfectly good seal, and my measuring vessel having its own inaccuracies, meaning adding 386 ml might not be 386 ml with my vessel, I replaced the exact volume with the exact volume with the exact vessel that measured it, adding 5-10ml for transfer losses. I ended up doing the same for the right one, though that one you can measure by air gap without having to disassemble and dry it so you know you have a give volume in there. The air gap will make up for any residuals.
On a 60 mile test ride today the bike rides more "plush" as if the forks are quicker to respond to road irregularities keeping the bike poised while still giving excellent control. Perhaps better stiction with this fresh oil? I don't know, but this method worked for me. I was not having a problem before the oil change, but the change did make a subtle improvement. Maybe at 48-50K when due again or if a seal leaks I'll do the disassembly, and replace seals and oil, and maybe bushings, and not just change the oil. Thank you all for your input. It is much appreciated.
Regards,
CC
Marvellous achievement, top points, shuts up all of us logical and methodical people in one go, makes following the manual just to retain factory std a bit absurd. Some of us spend huge to achieve the utopian “plush” , you got it in one go. Plenty of owners will try to emulate for sure.
Probably more important to most is the state of your steering head bearings, which you’ve just lubed I hope, many here complain of factory dry.
Talk of weave , shimmy and such abounds, some of it due to the massive boxes they fit high and aft of bike, some simply dry bearings, notched and crispy
Or change them like
FWIW....
https://www.youtube.com/watch?v=k4BxjmIwVdY
I'm contemplating doing fork oil on my v85tt way earlier than recommended since I've changed oil on forks of new bikes having only a few thousand miles on them and the oil was filthy gray. The reason for changing oil early on those bike was because the forks were already off for replacement of stem bearings (balls to roller type).
Art
I actually like the modern revival of balls not taper rollers, more appropriate for application imho
But regardless of ball or roller, I hum a tune, sometimes sing it
Grease, your bearings well , and…….
They will love you
Apologies to Neil Young
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Could you elaborate why you like the ball style bearings as opposed to tapered rollers. Less friction?
kk
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Could you elaborate why you like the ball style bearings as opposed to tapered rollers. Less friction?
kk
WAG...cheaper (guzzzi content) and less contact area = less friction, less grease required, less heat :laugh:
My feeble attempt at sarcasm & humor.
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Personally if there is an oil height spec, I only use the volume spec to get close and then measure height - that's the number that matters.
Agreed. Oil height is the way to go. Whenever I've changed fork oil there's always residual clinging to bits inside the forks so you drain less than specified oil volume. That said, and if one presumes the forks were filled correctly, replace the amount comes out and you should be pretty close.
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I know plenty of you folks here know what you're doing. That said, assisting every year at my favorite shop in the entire world in CT I did a lot of fork procedures. Amazing to see how many ways to get it wrong. The best was Gold Valves installed upside down (how did they even DO that?) from "the best shop in Toronto for Triumph" when we had to service the forks. How ya doin'?