fork oil

[Red5]

Am a fork oil virgin, but am looking to up rate the oil in the trusty Daytona 675. Am experiencing what can only be described as serious chatter under heavy breaking. Looking at the OE specs, it comes with light weight 5W oil. Which for a sports bike of such hype and alleged capability seems a bit wet. Some of you know how I ride on track and road, I'd say on a good day can hold my own in inters on track.

So with reasoning, what would people suggest oil spec wise to go for. Don't need or want mega heavy... but what do most people run in theirs. 10W is listed as medium. Or would people suggest going slightly higher???

[podrick]

It depends how it's been valved, at lot of manufacturers will valve forks to use a thin oil so when it gets hot it isn't a big change.
I would be tempted to just replace whats in there with a good quality 5W oil set correctly. At least that way if it is still wrong you have a known starting point. If your lucky it might be a lot better.
You can also mix oils to change the weight too. 10W + 5W in equal quantities will give you 7.5W I believe.

[MellowYellow]

I believe that the 5w , 10w etc. designations vary in actual viscosity from one manufacturer to another. Also that, yes, you can mix to get intermediate ratings.

[TLS-Moose]

I believe that the 5w , 10w etc. designations vary in actual viscosity from one manufacturer to another. Also that, yes, you can mix to get intermediate ratings.

if the weights/grades vary from oil manufacturer to oil manufacturer, it kind of defeats the purpose, doesn't it? They should have an SAE rating which is a conformity standard.
Yes, oils can be mixed to create intermediate grades.
As Pod says, manufacturers generally valve their forks to suit the grade (or vice-versa), so unless the forks are generally renowned to be weak or the general advice on model specific forums or tuners is to change, id stick with what the manual says.
You can reduce dive by reducing the air gap over standard (adding oil), but to be honest unless the advice is different from the sources mentioned above id return everything to standard and start from there ......

If you plan to dismantle them yourself, forks are fairly simple.things yet surprisingly.easy to f*ck up. You are also likely to need a couple of special tools to complete the job properly .....

[ptolemyx]

Chatter under braking............By all means put new 5W oil in which will improve things but how far from stock do you have your suspension settings?

[Andy900]

I believe that the 5w , 10w etc. designations vary in actual viscosity from one manufacturer to another.

I have also read this several times.

[badgerKDD]

Or alternately just bung 10W in and go for a ride, if its better, job done, if not you know for sure oils not your problem and perhaps set up is the culprit. Btw, when did you last change your oil? If the answer is never, then that could be the simple solution, old, tired, frothy oil!

[DynaMight]

If Triumph fit 5wt as standard then its probably the correct weight for most people & most conditions. You'd be about average weight for a European male.

Sure the discs are not slightly warped? My SP1 had slightly warped discs, would always pass an MOT (with advisory) would feel fine on the road but judder quite a bit on track. If its not the discs, are the forks bottoming out? you got a cable tie on the fork? Usually about 10mm left is what they recommend.

[TLS-Moose]

I stand corrected on the viscosity rating of suspension oils.

An interesting read - http://www.peterverdone.com/wiki/index. ... sion_Fluid" onclick="window.open(this.href);return false;"

[Red5]

Wow, this is all very interesting... To be honest, the oil has never been changed on this one, it's a 60 reg bike. So a few years and a couple of tracks under its belt to.
And yeah, set up has been fettled with by various people, places, Steve(ex peak performance) and several times by suspension guys at track days, so all with the OE equipment and not a million clicks different from OE settings, but feels good riding, with good tyre wear so don't think there's to much wrong, it's just the chatter under heavy breaking.
Probably time for new oil regardless, so no harm in going heavier.
Also, very interesting with the viscosity/ weight ratings. You assume Engine oil specs, ie 10/40W to be a uniform figure so why not Suspension oils?? Unles it's not totally the same with engine oils either.

Discs were changed over the winter, OE spec, they're EBC.

Thanks all for your inputs and opinions. An insight into peoples thoughts as always, actually quite an education.

[TLS-Moose]

Has the bike always chattered, or is that a recent issue? If it is only a recent issue, but was previously OK with stock(ish) suspension, why on earth would you do anything but return it to factory stock?

Changing the oil for a heavier one without understanding the cause of the chatter just throws another variable into the equation.

Make a note of the suspension settings as they are now. Carry out proper maintenance, and return to factory settings. See how it feels. If not completely happy, head towards the last known good setting a click or so at a time. If the suspension feels right but the chatter is still there, then (and only then) look to other solutions.

[Red5]

AAARRRGGGHHHHHH!!! Why do you have to say things that make sense Moose... You're not wrong. It's not a sudden new thing, though has developed more on track, ie, harder use and is a track bike now so this extra use will be the norm.
I think I'll sleep on it for a bit. Have a date with Si to see if we can do something.

[menzies3032]

Stop using the back brake when heavy braking that will sort the chatter out

Serious note got my GSXR oil done a few years back and and was upped and did help with feel and diving forks but was not struggling with chatter.

You sure this is suspension and not tyres and tyre pressure's? Have you tested on a road ride and are you getting the same problem?

[Robbo87]

Am a fork oil virgin, but am looking to up rate the oil in the trusty Daytona 675. Am experiencing what can only be described as serious chatter under heavy breaking. Looking at the OE specs, it comes with light weight 5W oil. Which for a sports bike of such hype and alleged capability seems a bit wet. Some of you know how I ride on track and road, I'd say on a good day can hold my own in inters on track.

So with reasoning, what would people suggest oil spec wise to go for. Don't need or want mega heavy... but what do most people run in theirs. 10W is listed as medium. Or would people suggest going slightly higher???

This serious chatter under heavy braking, you're not carrying a pillion at the time are you? That might explain it

A bit late with it, but here's my tuppence-worth - Double, no TRIPLE check the steering head bearings - condition and clearance - as part of your diagnostic procedure. Sounds basic but it was an influence on a similar problem I had on my Aprilia recently; that, coupled with cheap & crappy aftermarket discs gave me the same symptoms as you. Cured it by going back to OEM discs and new taper roller s/stem bearings. I've also recently re-built the forks and upped the reccomended OEM 5w oil grade to Fuchs/Silkolene 10w, that's had a positive bearing on the old Fut's handling I have to say.

[Red5]

Am a fork oil virgin, but am looking to up rate the oil in the trusty Daytona 675. Am experiencing what can only be described as serious chatter under heavy breaking. Looking at the OE specs, it comes with light weight 5W oil. Which for a sports bike of such hype and alleged capability seems a bit wet. Some of you know how I ride on track and road, I'd say on a good day can hold my own in inters on track.

So with reasoning, what would people suggest oil spec wise to go for. Don't need or want mega heavy... but what do most people run in theirs. 10W is listed as medium. Or would people suggest going slightly higher???

This serious chatter under heavy braking, you're not carrying a pillion at the time are you? That might explain it

A bit late with it, but here's my tuppence-worth - Double, no TRIPLE check the steering head bearings - condition and clearance - as part of your diagnostic procedure. Sounds basic but it was an influence on a similar problem I had on my Aprilia recently; that, coupled with cheap & crappy aftermarket discs gave me the same symptoms as you. Cured it by going back to OEM discs and new taper roller s/stem bearings. I've also recently re-built the forks and upped the reccomended OEM 5w oil grade to Fuchs/Silkolene 10w, that's had a positive bearing on the old Fut's handling I have to say.

Cheers for that one, yeah been done now but never heard about the head bearings effecting it. Worth a look at if get it returning. Fingers crossed though, it'll be fine. Si found that there was a good few cc down from what should've been in there, so hopefully is all sorted. Seemed to be with the little time I had at Portimao, but have to look at it when get a full track day under my belt...