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+--- Thread: Which fork oil? (/showthread.php?tid=61122)
Which fork oil? - darrsi - 06-12-12
I've been getting a slightly unnerving feeling through my steering for a while, which i can only describe as similar to having a tyre with low pressure.
The thing is the tyre pressure is okay (36f-42r), and the tyre's only a few months old, so i reckon it's going to be something to do with the fork oil.
There's no leaks or anything but i can't really think of any other explanation?
It's mainly noticeable at low speeds too.
My question though is what are your views on 15w fork oil, rather than the recommended 10w?
Is there any major difference in feel?
My forks are just standard one's with no mods or anything, in fact they're older than my bike, without the adjusters on top.
Any comments appreciated as always.
Thanks, Darren.
Re: Which fork oil? - CRH - 06-12-12
hi darrsi, i changed mine after replacing fork seals, and used 15w and noticed a big difference !!..feels realy planted now!...i have the preload adjusters but havnt had to touch them since switching to 15 either?
Re: Which fork oil? - darrsi - 06-12-12
Cheers CRH, that's a good start.
I changed my forks when i was going through my issues with braking just to eliminate them, and a friend stripped and re-sprayed the ones i have on now so when i realised it wasn't the forks causing the problem i just left them on and sold my original ones.
I've always preferred firmer suspension because i take the occasional passenger on board.
I just hope that that is the problem?
**Nice job with the fancy forum by the way**
Re: Which fork oil? - CRH - 06-12-12
yes darrsi!, defo makes a diffrence 2up! no wallowing on bends or forks bottoming out under heavy braking!
Re: Which fork oil? - unfazed - 07-12-12
I upgraded the front with Hagon progresive springs, but kept the fork oil a 10w. If you have standard springs then the upgrade is worthwhile. Ensure you keep the oil level correct to maintain the correct air gap on both fork legs as this also affects the fork compression.
15W is a good option if you have very smooth roads otherwise it can be bit to stiff,
Check the static sag on the forks, 20 to 23 mm is a good start point, more than 25 will make the front feel like you have a soft tyre. Since you have no adjusters use washers on top of the spacer to correct it.
Re: Which fork oil? - Fazerider - 07-12-12
If it's steering rather than ride quality that is the problem it may be worth checking the head bearings and that none of the cables are binding or causing a problem with the free movement of the bars.
I find the best way to check is prop the bike so the front is clear of the ground and remove the front wheel... its sheer weight make it much harder to feel notchy bearings.
Re: Which fork oil? - kebab19 - 07-12-12
Other possibilities...
Are you sure its not something tyre related? Are your tyres standard sizes?
Or have you moved the fork tops up through the yokes?
I didnt think the fork oil would make *that* much of a difference...unless there wasnt any in the forks
Get some preload caps off a Fazer with bent forks, or a TRX850 - worked for me on a '99 bike with no adjusters.
Re: Which fork oil? - darrsi - 07-12-12
Head bearings and wheel bearings are new, and steering moves freely on centre stand.
No movement at all from head bearings, and wheel spins okay.
Tyre is a new(ish) 110, same model i always use, and air is correct.
Forks are flush at the top.
It's a mild feeling but it's definitely there.
Another way of describing it is when you square a tyre off and ride over white lines, but it's obviously not that?
Another thing i should add is that when i had the forks with the adjusters on i normally had them set around the 2nd notch which was quite firm, which is why i was asking about the 15w oil, to maybe compensate for a standard set up on the forks i've now got with no adjusters.
Re: Which fork oil? - Fazerider - 07-12-12
Ah well, hope the fork oil solves the problem, though the oil will be thicker anyway now temperatures have dropped.
How new is that tyre? It always takes me a long time to get used to a new one. It's not just the breaking-in period, the handling changes a lot having gone from a weird stepped triangular profile to a circular one.
I seem to be getting worse at adapting to the change too... took me about 800 miles to get happy with the feel of it after changing the tyres a couple of months back.
Re: Which fork oil? - darrsi - 07-12-12
I changed the tyre in monsoon season, or 'summer' as we call it. :lol
I could understand if i was trying out a new brand but it's the same as i normally use and i've not had this feeling before!
Re: Which fork oil? - darrsi - 07-12-12
So, i was just getting on the bike this evening, and thought i'd check a few things, albeit in the dark, and after checking the general side to side feel of the steering again it didn't feel as free as i first thought.
There's no cables causing the issue so i'm wondering if the nut needs slacking off by 1 or 2mm and see if that solves it.
There's no grittiness or anything so that's a good sign, but there shouldn't be anyway as the bearings were only changed this year and heavily greased.
I'm wondering now if the 'wobbly' feeling is being caused by me not being able to move the steering quickly enough side to side to keep a good balance at low speed?
I'll investigate tomorrow and let you know what happens, i wanna get it sorted before the damn snow sets in :'(
Re: Which fork oil? - darrsi - 10-12-12
Had the steering lock nut 'loosened' by a few mm and it's certainly made the steering feel a bit lighter and responsive, i'd say there's a 70% better feel to it overall. There's no movement in the head bearings at all so it's all still good as far as that's concerned. And there were no cables causing a nuisance at all.
I may still go for the 15w fork oil anyway when i get some free time though just to give it a try.
I didn't put the oil in my last forks i had on and i'm wondering if they had the 15w oil in, and i'm feeling a difference to the 10w that i have in these forks?
But that's just a guess, i'll never know now?
Re: Which fork oil? - Fazerider - 10-12-12
Glad that sorted it. :thumbup
As for fork oil, it's always a tricky compromise between a compliant ride and a wallowy one. What works best for you depends on the nature of the road, your riding style and how heavily laden the bike is. I'm skinny and travel light so found 10W to give a stiff enough ride that the bike remains controllable around the weird lumpy roundabouts in my area at the expense of horrible jarring sensations over the potholes. :lol
The ideal solution would be cartridge forks. I'm still tempted by kebab19's modification, but it's not reversible... might give it a shot if I can get a spare set of fork lowers cheaply.
Re: Which fork oil? - darrsi - 10-12-12
To be truthful the bike is mainly used just for work.
I'm no lightweight, my large top box is always half full of stuff, and i take the occasional passenger, so it all aims towards being a bit firmer on the front i reckon.
Worst scenario, if i simply don't get on with heavier oil at least i can always change it and say i've tried it out, and give my opinion.
I have a good feeling that i will prefer it though.
Re: Which fork oil? - darrsi - 02-01-13
I'm fairly certain that i've got to the bottom of my wobbly bike problem.
I eventually got round to changing the oil in the forks today to 15w rather than 10w, and when i was looking at the manual on how much air gap to leave between the top of the fork and the oil it suddenly dawned on me that i've replaced my forks with one's from a 98/99 bike, but my bike is a 2000 model.
It was then that i noticed in the book that the older forks need more oil than the newer type with the adjusters on, presumably as there's a bit less metalwork inside each leg.
Easy mistake, as i always read the book for the 2000 model, 'cos that's what the bike is!!
So it seems i never had enough oil in the forks before, and although it wasn't a huge amount, it was very noticeable when corning, and general handling at low speed.
After taking it for a short ride it felt much more stable than before, and i think i'm going to prefer the 15w oil as well.
I didn't ride for too long as the weather turned on me but i'm confident it's all sorted now.