Servicing Ohlins forks

[dlaing]

Dave - Have you got it sorted now?

 

I'm a bit unclear why you were having problems but it sounds like you didn't remove spacer tube that holds spring in compression??? You have to undo the nut under the fork tops that retains these. 1st remove forktop then nut - you will need to make up a tool to hold the tube down against the nut whilst you undo it - a washer to the same width as the tube but with a slot cut in it (so's it'll slide onto the rod). Then you can remove spacers.

 

I used the depth gauge rod on a vernier gauge to measure gap.

 

BE V CAREFUL NOT TO LOSE SMALL NEEDLE VALVE THAT'LL POP OUT OF END OF LONG SMALLBORE DAMPER TUBE WHEN IT EXTENDS AS YOU PUMP FORKS NOW.

 

KB

Thanks Baldini!

I finished the job, ignoring measuring the level.

16 ounces out, 14 ounces in, so, it won't be any worse than it was, unless I miss some of the stiffness of the air spring, but it was nowhere near bottoming with 16 ounces in each leg.

I had trouble because I don't know which instruction to follow and my measurement increased when I pumped the fork, presumably replacing air with oil. INEEDAGUZZI probably had he same problem with trapped air.

I did not remove the spacer tube.

One PDF says to measure with spring in.

Another PDF says to measure with spring and spacer out (therefore making full compression doable)

If it is fully compressed, does it force the air out?

Or do you have to pump all the air out?

Does taking the spacer off allow effortless full compression while keeping the spring in place?

(I imagine removing the spacer might have made draining it go more quickly and easily.)

Thanks in advance....but I am not going to do this again, until next year....

Has anyone asked Ohlins for an FG-313 manual or the "mounting instructions"?

[belfastguzzi]

I did not remove the spacer tube.

One PDF says to measure with spring in.

Another PDF says to measure with spring and spacer out (therefore making full compression doable)

If it is fully compressed, does it force the air out?

Or do you have to pump all the air out?

Does taking the spacer off allow effortless full compression while keeping the spring in place?

From what I remember, no effort is required. Seems that you just didn't disassemble it enough.The 'compression' (again, from poor memory) that you mention, isn't to do with forcing air out – it only sets the tube parts at the correct height, relative to each other. I.e. the outer tube should be slid right down, then the spring set in place (but preload not applied). Spring in or spring out doesn't change the 'effort' as it's just sitting there, not fixed, and so not compressed. The 'pumping' is on the cartridge piston to fill it with oil – doesn't apply to the spring / fork leg tubes.

[Greg Field]

I had Moto I longtime tech jason, who's rebuilt a bunch of Ohlins on Guzzis, Aprilias, and Ducatis show me how when I put stiffer springs in my Ohlins. he measured the gap with the springs on the bench.

 

FWIW: Aprilia sells a revision kit for the Ohlins that has the seals and dust scrapers for two legs for about $60. This seems like a pretty good deal.

[belfastguzzi]

I had Moto I longtime tech jason, who's rebuilt a bunch of Ohlins on Guzzis, Aprilias, and Ducatis show me how when I put stiffer springs in my Ohlins. he measured the gap with the springs on the bench.

 

FWIW: Aprilia sells a revision kit for the Ohlins that has the seals and dust scrapers for two legs for about $60. This seems like a pretty good deal.

He'll be using a figure appropriate for that, which presumably is a bigger gap at that stage than the figure for when the spring is in. The manuals are a bit confusing as there doesn't seem to be one for exactly the fork model that Guzzi's (02) have and the different models' manuals give different advice. Dominant advice is that springs must be in. MG's own manual adds to the general confusion as it gives completely wrong information on where the compression and rebound adjustment is.

Springs in, or springs out, can't be a crucial issue. The correct oil height / air gap for either situation would be the thing that matters.

 

Is the revision kit just the updated Ohlins seal design? The Ohlins tech that I spoke to said that you couldn't keep up with the original seals and that the revised design has been a great improvement. However, controversy as usual: Baldini has said that in his experience the newer seals are no better. So far, my replacements are ok... so far.

 

BTW in an older thread there was mention of the importance of using Ohlins green grease to keep the seals lubricated. Again the manuals are a bit confusing as some say green grease and others say red grease. One is older than the other, I can't remember which way round it is. But the point is --- that Ohlins race people don't use it. They take a dab of whatever they have. It's not important to use Ohlins grease.

 

[Baldini]

Thanks Baldini!

I finished the job, ignoring measuring the level.

16 ounces out, 14 ounces in, so, it won't be any worse than it was, unless I miss some of the stiffness of the air spring, but it was nowhere near bottoming with 16 ounces in each leg.

I had trouble because I don't know which instruction to follow and my measurement increased when I pumped the fork, presumably replacing air with oil. INEEDAGUZZI probably had he same problem with trapped air.

I did not remove the spacer tube.

One PDF says to measure with spring in.

Another PDF says to measure with spring and spacer out (therefore making full compression doable)

If it is fully compressed, does it force the air out?

Or do you have to pump all the air out?

Does taking the spacer off allow effortless full compression while keeping the spring in place?

(I imagine removing the spacer might have made draining it go more quickly and easily.)

Thanks in advance....but I am not going to do this again, until next year....

Has anyone asked Ohlins for an FG-313 manual or the "mounting instructions"?

 

Dave,

 

I don't think you got all the oil out. 16oz (US) = approx 475cc? Ech leg holds up to 550cc depending on air gap. You'll drain 475cc w/o disassembling any further but I think you need to release compression so as to bottom stanchion to purge cartridge of remaining oil. I found another 50cc or so was only released at this point.

 

When they say spring in, they don't mean under spacer in compression, they simply mean that the spring is in the stanchion & therefore accounting for some volume.

 

IME you have to pump the forks with compression released & to full extent of travel to purge all the old oil & then the air when you refill. Taking the spacer off allows you to do this.

 

Good luck! KB

[Baldini]

....The manuals are a bit confusing as there doesn't seem to be one for exactly the fork model that Guzzi's (02) have and the different models' manuals give different advice. ....Springs in, or springs out, can't be a crucial issue. The correct oil height / air gap for either situation would be the thing that matters.

 

Is the revision kit just the updated Ohlins seal design? The Ohlins tech that I spoke to said that you couldn't keep up with the original seals and that the revised design has been a great improvement. However, controversy as usual: Baldini has said that in his experience the newer seals are no better. So far, my replacements are ok... so far.

 

BTW in an older thread there was mention of the importance of using Ohlins green grease to keep the seals lubricated. Again the manuals are a bit confusing as some say green grease and others say red grease. One is older than the other, I can't remember which way round it is. But the point is --- that Ohlins race people don't use it. They take a dab of whatever they have. It's not important to use Ohlins grease.

 

As it came mine had about 85mm gap w/springs in, which was also as rec'd by 2 Ohlins techs I spoke to. I used that as starting point. Did you measure yours as stock?

 

BFG, as you say re seals. The latest (ext lip) ones I put in the supplier said he would adjust them, by which I took him to mean that he would tweak the spring a little. I also took notice of Martin's suggestion re leaving the bike on the s/stand could cause the seals to take on a set. I now leave it on w/shop stand. we'll see.

 

Ohlins tech sold me red grease - saying green was older spec. But he didn't seem too fussed about what was used to lube the seals.

 

I clean off the exposed areas of the stanchions after using the bike. I also fitted an RSV1000R 'guard which offers a little more protection, but I'm pretty much resigned to frequent seal replacements. Least it keeps the oil fresh.

 

KB

[belfastguzzi]

As it came mine had about 85mm gap w/springs in, which was also as rec'd by 2 Ohlins techs I spoke to. I used that as starting point. Did you measure yours as stock?

Unfortunately I didn't. From what I can make out, the older Ohlins manuals recommend springs out, while the newer method is spring in.

 

I measured with spring out, because

1) I looked at the older manual

2) it's hard enough to see the level accurately, even with the spring out. It's more difficult to measure down the side of the spring when it's installed.

 

When refilling I filled to 165mm (spring out).

 

Somewhere in a manual, stock seemed to be 170mm. That can't be right, as you have measured stock gap as 141mm w/o spring (? = 85 with spring in ?).

 

I found the volume of oil in a leg to be slightly over 500ml.

When refilling to a gap of 165mm I didn't use as much as 500ml.

 

The various figures that I have noted, from the other suspension thread in particular, don't all equate to each other properly. Could some more people post figures, to get a better picture of what the gap measurement range is? What gap(s) is used at MI (springs out)?

[Alex-Corsa]

 

But the point is --- that Ohlins race people don't use it. They take a dab of whatever they have. It's not important to use Ohlins grease.

 

 

Don't look what the racing people do, cause.

1. They do service in every race (or change forks every time)

2.Racing conditions are different than street.

3. Racing Öhlins forks are different than the ones used on MG or most other street bikes.

 

 

[belfastguzzi]

Don't look what the racing people do, cause.

1. They do service in every race (or change forks every time)

2.Racing conditions are different than street.

3. Racing Öhlins forks are different than the ones used on MG or most other street bikes.

It's a good point Alex, but the advice was given by an Ohlins mechanic, in relation to general street bikes even though he used the race mechanics as an example. I will use Ohlins own oil in the forks, but as far as greasing the legs / seals is concerned, I'm happy with Castrol or whatever other brand of general grease that I already have.

 

Does anyone know otherwise? Has anyone got the Ohlins Red and is aware of any significant difference?

[dlaing]

 

When refilling I filled to 165mm (spring out).

 

Somewhere in a manual, stock seemed to be 170mm. That can't be right, as you have measured stock gap as 141mm w/o spring (? = 85 with spring in ?).

 

I found the volume of oil in a leg to be slightly over 500ml.

When refilling to a gap of 165mm I didn't use as much as 500ml.

 

The various figures that I have noted, from the other suspension thread in particular, don't all equate to each other properly. Could some more people post figures, to get a better picture of what the gap measurement range is? What gap(s) is used at MI (springs out)?

FWIW The fourteen ounces (411ml) resulted in about a 300mm airgap with spring and spacer installed, but not compressed.

Compression will raise it by the length of the stroke, 120mm.

So if I had gotten rid of the air(I doubt I got it all out) and the uncompressed displaced about half as much as a compressed spring(a gross assumption) then the theoretical compressed measurement would be about 80 mm. More air expelled would raise that number. A compressed spring would lower that number. So, guessing is pretty pointless.

But it seems to work well, and give me a little softer ride compared to the sixteen ounces per fork leg.

Could it be that some are blowing seals because their fluid level is too high? (air gap to small)

Fear of seals blowing is one reason why I went with the 14 ounces.

The other is because on a good hard ride I was an inch away from bottoming.

Sorry about the speculative conjecture.

I really need to measure it properly if we are to compare notes.

[dlaing]

Because I had so much trouble reading the PDF instructions, and because you guys gave such excellent help, here is my work in progress instructions:

(PLEASE IMPROVE ON IT)

 

Changing the fluid
1
Loosen the
upper triple clamps.
2
Using tool 797-04 (or a 17mm wrench on the preload adjuster) Loosen the
top nut assembly about two turns
3
Loosen lower triple clamps and Remove the fork leg from the motorcycle.
4
Remove the top nut assembly from the slider and drain much of the oil.
5
Remove the top nut assembly from the rod by doing the following:
Undo
the nut under the fork tops that retains these. 1st remove forktop then
nut - you will need to make up a tool to hold the tube down against the
nut whilst you undo it - a washer to the same width as the tube but with
a slot cut in it (so's it'll slide onto the rod). Then you can remove
spacers.
6
Remove the slider
7
Remove the Pre-Load Tube.
BE VERY CAREFUL NOT TO LOSE SMALL NEEDLE VALVE THAT'LL POP OUT OF END
OF LONG SMALLBORE DAMPER TUBE WHEN IT EXTENDS AS YOU PUMP FORKS NOW.
8
Extract remaining oil by inverting and pumping.
NOTE!
Discarded Öhlins products should be handled
over to an authorized work shop or distributor for
proper disposal.
9
Clean slider and grease fork seals with appropriate grease
10 Replace slider
11 refill with 13901-01 to the proper level (somewhere between 80 and 110)
Compared to conventional type of front forks, the
upside down front forks are very sensitive to
variations in oil level. Therefore, adjust the oil level
with special care.
A change in the fork oil level will not affect damping
force in the early stage of fork travel, but will have a
great effect in the later stage.
When the oil level is raised:
The air spring in the later half stage of travel is
stronger, and thus the front forks harder.
When the oil level is lowered:
The air spring in the later half stage of travel is
lessened, and thus the front forks are softer. The
oil level works most effectively at the end of the
fork travel. Air spring characteristics shown, refer
to the chart description in the PDF Manual to facilitate understanding
of the difference when the oil level is
changed.
It is best to measure oil with fork compressed and springs in place because
it better describes the real life air gap.
12 
Replace Pre-Load Tube
13
Replace Topnut assembly on rod
14
screw topnut assembly on to slider
15
Reinstall fork
16 
tighten everything properly

[belfastguzzi]

Could it be that some are blowing seals because their fluid level is too high? (air gap to small)

No. Quite sure it's just wear.

 

Fear of seals

not a common complaint, but you're not a common guy

[dlaing]

not a common complaint, but you're not a common guy

http://www.darkness.de/images/product_imag..._sevenseals.jpg

thank you?

Seven Seals failing is a Guzzichondriac's worst nightmare