View Full Version : Fork Oil Change
Old Git
11-03-09, 09:59 PM
Is it possible to replace the fork oil without a complete dismantle of the forks?
Can the tops be removed & the oil siphoned out like petrol from a fuel tank?
I have read numerous threads about changing springs etc.etc. but have neither the confidence, funds, ability or knowledge at this stage, think maybe with an old curvy a fork oil change may help if I can make it a relatively easy job.
Thoughts & comments from experienced spanners will be read with interest.
Thanks OG
fizzwheel
11-03-09, 10:01 PM
In my albeit limited experience, I dont see how you'd get all the old oil out without taking the forks off the bike and turning them upside down.
If your going to do that, you might as well change the springs whilst you're at it. Spring change isnt a massive job.
plowsie
11-03-09, 10:02 PM
Yes they can, you can remove the top caps and the oil can be poured out AFAIK. Obviously if you take them out of the yokes...
I wait with eagerness for a spanner person to come along and correct me cos I nay be wrong.
Stu.
yorkie_chris
11-03-09, 10:12 PM
Yeah just remove the top caps. Pour old oil out.
You only need strip the whole leg if you are doing seals/bushes/whatever.
Out of curiousity what oil weights are available as fork oil?
plowsie
11-03-09, 10:19 PM
5 (prob useless)
10
15
20(for the bigger man, AKA me :D)
yorkie_chris
11-03-09, 10:20 PM
Everything from Red Line clear stuff at 5cSt, to spectro golden american 4 20w50 at 155cSt.
Usual viscosity for SV is a 10w at 30-45cSt. (those viscosities are at 40deg C.)
P.s the w rating doesn't tell you how heavy the actual oil is. There are some "5"s that are higher viscosity than other "10"s.
plowsie
11-03-09, 10:22 PM
Everything from Red Line clear stuff at 5cSt, to spectro golden american 4 20w50 at 155cSt.
Usual viscosity for SV is a 10w at 30-45cSt. (those viscosities are at 40deg C.)
P.s the w rating doesn't tell you how heavy the actual oil is. There are some "5"s that are higher viscosity than other "10"s.
Interesting that.
I was told that my Matris cartridge emulator kit was supplied with 7.5 weight oil. There was no indication on the can and am curious to know if the weight exists.
yorkie_chris
11-03-09, 10:31 PM
I was told that my Matris cartridge emulator kit was supplied with 7.5 weight oil. There was no indication on the can and am curious to know if the weight exists.
Pj1 fork tuner
Agip
Silkolene pro RSF
All make a 7.5, or most makes you can mix 5w and 10w to get same.
http://www.pvdwiki.com/images/a/a7/PVD-ISO-Viscosity-Data.gif
Luckypants
11-03-09, 11:36 PM
Seen that table before Y-C, but what do all them numbers mean? Is the relative 'heaviness' of each oil relative to it's position in the table? Further down the table = more damping? I'm a bit confused by what it all means.
yorkie_chris
11-03-09, 11:37 PM
Higher the viscosity = higher resistance to flow.
So the further down the table, the thicker it is.
plowsie
12-03-09, 07:47 AM
I've got some Motul for mine 2nd lowest in its position in 20w section in the table...does that necessarily mean its ****e for what it is? Intrigueing this stuff.
Mr Speirs
12-03-09, 08:30 AM
Is it possible to replace the fork oil without a complete dismantle of the forks?
Can the tops be removed & the oil siphoned out like petrol from a fuel tank?
I have read numerous threads about changing springs etc.etc. but have neither the confidence, funds, ability or knowledge at this stage, think maybe with an old curvy a fork oil change may help if I can make it a relatively easy job.
Thoughts & comments from experienced spanners will be read with interest.
Thanks OG
I don't think you will get all the old oil out by just siphoning it out as there will be loads left at the bottom where you can't get to.
When I did mine even hanging them upside down for 5 mins still had dribbles coming through.
The other problem is then making sure you have set the correct air gap. You won't be able to do this properly with springs and residual oil left in the forks.
It is not as hard a job as you might think. The haynes manual helped me do mine so if you have one of those by your side you shouldn't have a problem.
cowboy racing
12-03-09, 08:40 AM
cant you just crack of the allen bolt at the bottom of the fork legs ,the ones that hold the internall sring locators,drain out into a mearsuring jug over night ,then refill next day ,dont forget to support the front of the bike with a ratchet strap to the garage ceiling or the forks will sink ! ! ,you can either refill to wats been remove or measure down from the top of the stansion 120mm with the srings removed and the forks depressed/sunk down,
plowsie
12-03-09, 08:53 AM
cant you just crack of the allen bolt at the bottom of the fork legs ,the ones that hold the internall sring locators,drain out into a mearsuring jug over night ,then refill next day ,dont forget to support the front of the bike with a ratchet strap to the garage ceiling or the forks will sink ! ! ,you can either refill to wats been remove or measure down from the top of the stansion 120mm with the srings removed and the forks depressed/sunk down,
Does that not hold some sort of rod in at the bottom?
Correct me if you please...
Does that not hold some sort of rod in at the bottom?
Correct me if you please...
It does, this is not a drain bolt, it secures the damper rod in place. You may be able to remove it and put it back later, but if not you just made a simple job harder.
Please just take the forks out and do it properly ;)
Jambo
Luckypants
12-03-09, 10:30 AM
Higher the viscosity = higher resistance to flow.
That much I do know! but this table does not seem to state a 'viscosity' value. Besides which, I thought viscosity was the W rating e.g. 5W is thinner (less viscous) than 10W and multi-grade oils cover a range of viscosity to cope with large temperature range e.g. 10W-40.
So the further down the table, the thicker it is.
Thanks.
yorkie_chris
12-03-09, 12:40 PM
I've got some Motul for mine 2nd lowest in its position in 20w section in the table...does that necessarily mean its ****e for what it is? Intrigueing this stuff.
No, just that it's a different viscosity. It may be that they behave differently under high shear rates. (just to confuse things even further!)
cant you just crack of the allen bolt at the bottom of the fork legs ,the ones that hold the internall sring locators,drain out into a mearsuring jug over night ,then refill next day ,dont forget to support the front of the bike with a ratchet strap to the garage ceiling or the forks will sink ! ! ,you can either refill to wats been remove or measure down from the top of the stansion 120mm with the srings removed and the forks depressed/sunk down,
No, as you risk the damper rod just spinning around when you try to tighten it up. And the crush washer not re-sealing properly.
That much I do know! but this table does not seem to state a 'viscosity' value. Besides which, I thought viscosity was the W rating e.g. 5W is thinner (less viscous) than 10W and multi-grade oils cover a range of viscosity to cope with large temperature range e.g. 10W-40.
cSt = centistokes = mm^2/s = unit of kinematic viscosity.
The "w" rating is viscosity, but a different and non-SI unit. I don't know why it doesn't agree with measured viscosity results. Probably something to do with the manufacturers ideas of numbering systems and what temperature they test/design for as a straight 5w oil would have a very low VI (big changes in cSt with temperature).
I'm not sure of the test for SAE viscosity, which is where engine oil weights come from. So either the oils behave differently at SAE test temperatures to the tests on that chart, or fork oil is tested differently to SAE procedures or not by any set standard.
Multi grade oil, like 10w40, means it behaves like a 10w when cold and behaves like a 40w when hot. This is caused usually by polymer additives in the oil, which uncoil themselves when hot, increasing viscosity.
http://en.wikipedia.org/wiki/Viscosity_index
Luckypants
12-03-09, 01:32 PM
Cheers Chris.
Dicky Ticker
12-03-09, 04:05 PM
I do like Cowboy says. You have to undo the top to fill them anyway and if it does spin use a long piece of wood dowling to hold it back in position. The same piece of dowling can be used as a measure of the old oil level before you drop it out,giving you an indicator as to the level of the new oil.
Much easier than removing the forks
timwilky
12-03-09, 05:18 PM
From memory, when I did a mensuration module in the 70s, so may be wrong
viscosity of a fluid is measured by how long it takes a bearing to fall through a tube of the fluid. Obviously the diameter of the bearing/tube are fixed.
So as others above have it is really a measure of the shear capability of the liquid, the ability of liquid to move. "Thickness" and weight are not really an indication of viscosity. Weight as applied to fluids is the SAE interpretation of viscosity.
edit, whoops the above is for the stokes unit so is the drag. the viscosity is measured in poise and is the ability of the liquid itself to flow through a tube.
yorkie_chris
12-03-09, 05:32 PM
From memory, when I did a mensuration module in the 70s, so may be wrong
viscosity of a fluid is measured by how long it takes a bearing to fall through a tube of the fluid. Obviously the diameter of the bearing/tube are fixed.
So as others above have it is really a measure of the shear capability of the liquid, the ability of liquid to move. "Thickness" and weight are not really an indication of viscocity. weight is the SAE interpretation of viscosity
Yup I've done that. I've seen apparatus that measures it with a cylinder rotating in a cylinder, torque required for a certain rpm, and from that you can find viscosity. There are other types that use flow through an orifice, or a rotating cone and plate. I don't think the ball bearing method is in common use, but I'm not sure.
Drag is connected to viscosity. Definition of viscosity is resistance of a fluid to shearing.
timwilky
12-03-09, 05:40 PM
<snip> I don't think the ball bearing method is in common use, but I'm not sure.
A quick google, remember I did this in the 70s found this
(http://www.youtube.com/watch?v=xc9phVhP59E&eurl=http://www.kittiwake.com/Default.aspx/ProductSection/75/ProductSubSection/86/ProductSubSubSection/181/Product/416&feature=player_embedded)
I do like Cowboy says. You have to undo the top to fill them anyway and if it does spin use a long piece of wood dowling to hold it back in position. The same piece of dowling can be used as a measure of the old oil level before you drop it out,giving you an indicator as to the level of the new oil.
Much easier than removing the forks
Is this possible?
Bikes only done emm around 8-9K, and the front is goosed.
Going to change the oil first, as the springs shouldn't need changed at this low mileage.
What is the cubic capacity of each fork?
My mechanic is doing this, as I don't want to make a mess of anything les than 2 weeks before the GMII.
yorkie_chris
16-06-09, 11:13 AM
It's measured by air gap generally.
The springs don't realy wear, but unless you are very light they'll probably be the wrong rate.
plowsie
16-06-09, 11:22 AM
Wow, how weird, I did a search for this thread this morning to look at that table, and now it has been reborn :shock:
A 1L bottle of fork oil is enough to do both forks, as they contain just under 500ml each but as yorkie said, its the air gap you worry about.
Forgot I bought a Haynes.
488cc per fork.
mechanic guy is taking them off..
I got confused.
Got 10W oil and still the OEM springs..
Wrong side of 14 stone, so not light :)
I have 15W oil in mine (was 10W) and its still the same springs after 70,000 miles, don't stress to much.
Stress?
:|
Naaa it'l be fine, they need to be fixed.
7.5K miles, forks are fully screwed down, and can still bottom them out easily.
The past owner left the bike sitting from Sep to March with no use.
Maybe the oil went off then?
yorkie_chris
16-06-09, 06:18 PM
The oil is too thin when new.
How much you weigh?
Wrong side of 14 stone.
Around 5'10-6'0 if that makes any difference.
Mechanic brought 10W oil, I did ask for 15, but he said the manual says 8W..
yorkie_chris
16-06-09, 06:25 PM
Tell him to stick his manual and use what works. I can't stand folk who blindly follow orders.
Anyway, you have wrong rate springs, get some maxton/racetech replacements and some 15w.
I did some research, and worked out I thought I needed 15W and some uprated springs.
Was going to do the springs after the GMII, as I didn't know if they would come in time.
I couldn't find that racetech calculator you were going on about, couldn't see it on their site..
15W and uprated springs, thats what I thought.. :(
How long for springs to come usually if anyone knows...
And Can I just replace the springs, or do I need to change other things, apart from oil + springs?
Rider Weight: 198.238 lbs.
FRONT FORK SPRINGS
Recommended Fork Spring Rate for Street: 0.868 kg/mm (use closest available)
Stock Fork Spring Rate: .670 kg/mm (stock)
Thats what it says, so .85 kg/mm springs and 15W oil should suit me better than the stock set up?
Also, how long if its coming from the US, will it take?
yorkie_chris
16-06-09, 06:53 PM
Why order from US? Ask maxton.
Also lots of places stock racetech bits over here, ask robw#70 (PDQ suspension)
Would Rob be able to supply me with the springs?
I thought you could only get from Us.. :(
*Bike retard*
yorkie_chris
16-06-09, 07:11 PM
There are loads of suspension places! Ring around and ask, he works for PDQ. Also try Ktech, maxton, google :-P
Sorry for the PM then..
Was just seeing if you reccomended anyone first :rolleyes:
Sally,
Give Hagon a call... it was 2-3 days to get them delivered, price was around 60 quid, with 15W oil.
They have 1 rate for springs and I believe they are thought to be ok with the org. I certainly liked mine.
Think about a gsxr front end with your riding, or just get a TL like ad553 did :D
With my riding, whats that supposed to mean? :rolleyes:
Do you know what rating they sell by any chance dizzy?
You're not exactly slow :) you'd benefit from a suspension upgrade.
I did the same with mine, first the springs and oil, then a zx636 shock for the rear, brilliant.
Give Hagon, K-tech a call tomorrow, ask about springs and oil for your weight and delivery times, if they have them in stock and someone will fit them for you, you should be ok for the GM.
It will be a noticeable improvement as now you can almost bottom your forks out whilst standing still, as you showed me last time.
They are terrible, theyre fully screwed down as well, had some hairy moments on my local 'track' too.
Fitting won't be a problem.
A day and I could be finished with some help.
I need 15W oil and .85 kg/mm springs.
Linear or Progressive?
yorkie_chris
16-06-09, 07:24 PM
Linear. Progressive only come in "one size fits none" which is a big improvement but I prefered linears.
I think us mere mortals (well me at least) won't notice the difference.
Most people say progressives, that's what I had.
EDIT:
Linear. Progressive only come in "one size fits none" which is a big improvement but I prefered linears.
D'OH!!!
Cheers everyone.
15W oil, .85 kg/mm springs and they should be linear.
To fit, take forks off, open up, pour oil out, replace springs, fill with oil?
Is there any crush washers or rings I should be replacing when doing this?
Cheers.
yorkie_chris
16-06-09, 07:29 PM
No, some places supply you with a different spacer (maxton do) ... it is literally pull it in bits ... replace all the bouncy bits and slippy stuff (snarf). Don't undo the bottom bolt!!!
Go find a gallon of paraffin or diesel to flush all the old crap and sludge out. Leave them upside down for 20mins to all drain out.
The bike was sitting for ~6 months before I bought it, just the front has got worse and worse.
Have a feeling I may be needing some help from the org or spearies before the GMII.
YC and dizzy, al give the places a phone tomorrow, thanks for all you're help.
When I was prepping my bike for the track last year I ended up following advice from RaceTech using recommended spring rates for my weight on the SV and 20W oil.
I rebuilt the forks, added RaceTech emulators etc and made up my own spacers to set the preload. For spacers I used a steel table leg tube from B&Q (perfect diameter and about 4 quid).
When I first put the forks together and tried them pushing them to the floor I thought I had made a major **** up as they were so stiff. On the track however they are sublime. RaceTech advice was spot on.
Luckypants
16-06-09, 10:50 PM
Cheers everyone.
15W oil, .85 kg/mm springs and they should be linear.
To fit, take forks off, open up, pour oil out, replace springs, fill with oil?
Is there any crush washers or rings I should be replacing when doing this?
Cheers.
You got that right. I was about 14.5st when I fitted .85 racetech springs, 15wt oil and racetech gold emulators. The transformation was immense, especially under braking as the forks were not on the stops. :smt077
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