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Author Topic: How Soft is Soft  (Read 2018 times)

Marrtyn

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How Soft is Soft
« on: September 05, 2010, 02:40:42 PM »
I have noticed that my front suspension on my G5 is quite soft, wether or not it is too soft, I don't know.
Are there any figures for the ammount of compressinon on the fork springs for a given load.  i.e by hanging weights onto the ends of the bars, the suspension lowers by "X" ammount.
Sometimes I feel as though the bike can fold under me if I inadvertantly grab too much front brake, especialy if i am doing a turn, at slow speed. (I do try to balance out the braking, between front and rear)

Ducati Scotty

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Re: How Soft is Soft
« Reply #1 on: September 05, 2010, 04:32:33 PM »
The front suspension is soft.  Not terribly so like some bikes I've had but it is, especially for a 230# guy like me.  I've noticed the same brake dive as you.  I have loosened up the preload a bit on the rear so they match the front better and the bike feels better overall even though it's softer.

Here is the best site I've found on how to set your suspension:
http://www.ohlins.com/Checkpoint-Ohlins/Setting-Up-Your-Bike/Underrubrik_1/

This is technically for a high performance bike and we don't have all the fancy damping settings mentioned BUT getting the right spring rate and sag settings is the majority of getting your suspension tuned properly.  I think the front springs are probably too soft for many people.  You might be able to get by with just adding some preload with longer spacers, but you do have to do some disassembly to do that.  Many people will tell you that you can just add more fork oil or use heavier weght fork oil and you can but they're both kind of a bad cheats.  If you add more oil it's still just as soft at the start of compression but effectively makes the fork more progressive so you're less likely to bottom.  Heavier oil makes the fork slower to dive but does not provide any additional support or spring rate for something like a sustained hard stop on the front brake.  The advantage of these techniques is that they require very little dissasembly.

I don't know the dimensions or spring rate of the front forks but I'll be working on mine this winter and will post what I find.  There are some progressive rate springs available for the RE that many people like.  Progressive rate springs are often great for non-sport bikes and provide better handling and comfort.  On a performance bike they are usually a nightmare if not impossible to get set right.  I prefer regular straight rate springs and if a little preload increase doesn't do it I'll be looking for some this winter.  Also, I should note that I like my bikes set up like many race bikes: stiff springs, little preload, and little damping.  That won't suit everyone.

Hope this helps.

Scott

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Re: How Soft is Soft
« Reply #2 on: September 05, 2010, 05:23:04 PM »
My new C5 soaks up pavement irregularities very nicely and seems fine on spirited (but not yet peg grinding) riding.  One of the stretches I ride used to be a washboard nightmare on the Moto Guzzi and Buell Blast and XB9S.  On the C5 it is not so noticeable. 

So for me the suspension is a positive, at least right now.  Also, my weight is purposely down to 175# (from over 190#) since mid-July.  That helps, too.  (Also helps the blood pressure, but that is for a different forum...   :D)
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Maturin

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Re: How Soft is Soft
« Reply #3 on: September 05, 2010, 06:51:37 PM »
In my opinion the fork is not only too soft but also not very responsible to smaler bumps in the road. I already tried to unload the pressure that could occure while assemlbing it by loosen and tighten all bolts, but the outcome was only little. Any experience with fork oil additives like MoS?
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Ducati Scotty

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Re: How Soft is Soft
« Reply #4 on: September 05, 2010, 11:28:19 PM »
If you feel it's soft and not responsive to smaller bumps you may want to try lighter oil and stiffer springs.  I think they put in engine oil at the factory but I intend to replace it with synthetic fork oil, not sure what weight to use.

I've never used additives in fork oil before.

Scott

gashousegorilla

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Re: How Soft is Soft
« Reply #5 on: September 05, 2010, 11:38:43 PM »
 IMHO, I would start with the basic's,fork oil. The correct amount and the correct wieght for the rider, you may be able to achieve what you are looking for there. The C-5 comes with 10 w 30, thin motor oil. Thats old technology. Try a 15 or a 20 wieght specific fork oil, and you will feel the difference right away. That being said, there ain't nothing wrong with experimenting with that front end either.I'm looking foward to scotty's front end work. I'm sure he's gonna find something that will make it better.
  Also motor oils get bubbley , It  gets foamy. A good quality fork oil will not do that.Can you imagine all that foamy oil being forced through the little holes inside you fork?
« Last Edit: September 05, 2010, 11:56:44 PM by gashousegorilla »
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WillW

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Re: How Soft is Soft
« Reply #6 on: September 06, 2010, 09:27:38 AM »
"......The correct amount and the correct wieght for the rider......"

Do you have any specific reccomendations? I'm feeling it's time to change my fork oil and haven't a clue what's best. Solo rider, 160 pounds. Several bikers I've mentioned changing - even checking - fork oil to have looked at me with amusement and asked "why?"    :-\
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Ducati Scotty

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Re: How Soft is Soft
« Reply #7 on: September 06, 2010, 03:05:13 PM »
Fork oil wears down over time and needs to be replaced.  I was also amused when I saw that it's supposed to be 'checked' at regular intervals in the manual.  If it's not obviously leaking out or past the mileage to change what's to check?

Scott

gashousegorilla

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Re: How Soft is Soft
« Reply #8 on: September 06, 2010, 03:59:41 PM »
"......The correct amount and the correct wieght for the rider......"

Do you have any specific reccomendations? I'm feeling it's time to change my fork oil and haven't a clue what's best. Solo rider, 160 pounds. Several bikers I've mentioned changing - even checking - fork oil to have looked at me with amusement and asked "why?"    :-\
Will, you can't just check the fork oil on these bikes.The fork legs must be removed .Then you might as well change it. It's a time consuming and tricky job. If you have no experience with front ends, this is probably not the one to learn on.But if you have, then go for it. Those guys who rolled there eye's at you don't know what there missing. The correct suspention set up makes a big  difference. Unless you think the front end feels too soft, or your past 7.5 k miles, I would not sweat it. I would think at your weight, that no more then a 15w oil would do. The higher the viscosity, the stiffer it's going to feel. The book states 265 cc each leg. Thats what i put in, and it's fine. I put in 20w, I'm 175 US lbs. and its a little stiff, but I don't get front end dive. I like my bikes to feel a little tighter then the stock set up.Same with the rear.
They will handle better, but at the expence of comfort. And like scotty said,if it has not leaked,and you would know it, your level is probably OK.
Dan.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

WillW

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Re: How Soft is Soft
« Reply #9 on: September 06, 2010, 05:02:42 PM »
Thanks - I was just unsure what oil I actually need to put in there when it comes time to change. I'm at around 6000 miles so no hurry.
I checked the level once, just because I was familiarising myself with the bike and checking everything. I used a straightened out wire hanger as a dipstick. I noticed one side was half an inch lower than the other, but plenty in both so didn't give it another thought.
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Ducati Scotty

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Re: How Soft is Soft
« Reply #10 on: September 06, 2010, 09:03:55 PM »
Half an inch different isn't that bad.  It's quite common for bikes of all makes to be fairly different heights and also common to have very low quality oil.  Changing it out is one of the best low price mods to do.

Scott

Marrtyn

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Re: How Soft is Soft
« Reply #11 on: September 07, 2010, 04:39:55 PM »
Thanks for all the interesting responces.
The manual just states "fork oil" 200m/leg. I suppose they mean 200ml/leg.(no viscosity quoted) and to check every 1000 kms., and replace at 12000 kms.(7500 mls.)
Is the oil just topped up thro the 2 slotted screws at the top of the forks?

gashousegorilla

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Re: How Soft is Soft
« Reply #12 on: September 07, 2010, 05:18:59 PM »
Thanks for all the interesting responces.
The manual just states "fork oil" 200m/leg. I suppose they mean 200ml/leg.(no viscosity quoted) and to check every 1000 kms., and replace at 12000 kms.(7500 mls.)
Is the oil just topped up thro the 2 slotted screws at the top of the forks?
No, you must remove the fork leg to check. I guess it feels too soft for you? How much do you weigh? ( I'll be nice, ::)). The bikes are made for the average customer, You may have to set things to your liking. I would go to the dealer and talk it over with him. He should be able to set it up the way you like it. I would start by going to a 15 w FORK Oil.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: How Soft is Soft
« Reply #13 on: September 07, 2010, 06:57:18 PM »
 I'm pretty sure the service book says 265 cc's.
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Marrtyn

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Re: How Soft is Soft
« Reply #14 on: September 07, 2010, 07:18:24 PM »
No, you must remove the fork leg to check. I guess it feels too soft for you? How much do you weigh? ( I'll be nice, ::)). The bikes are made for the average customer, You may have to set things to your liking. I would go to the dealer and talk it over with him. He should be able to set it up the way you like it. I would start by going to a 15 w FORK Oil.
Thanks gahousegorilla. My weights 175lb.
Does this mean then, that, by rights , according to the book, I have to remove the forks every 1000kms., to check the oil.Surely this can't be right Can it?

GreenMachine

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Re: How Soft is Soft
« Reply #15 on: September 07, 2010, 10:06:43 PM »
I have a 06 iron...All I did was put the bike on side stand...Unscrew the tops of each fork ...I  gently cracked the bottom of fork nut and gently pushed down on front fork using  the handelbar and drained out the old fork oil....Closed bottom fork nut. and fill with fork oil (think 200 ml) sounds right....I remember not muched came out and not much went in but I went ahead and measured for both forks the same exact amount....I believe I may have put the bike on centerstand when I filled both forks...cheers
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gashousegorilla

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Re: How Soft is Soft
« Reply #16 on: September 08, 2010, 03:27:34 AM »
Thanks gahousegorilla. My weights 175lb.
Does this mean then, that, by rights , according to the book, I have to remove the forks every 1000kms., to check the oil.Surely this can't be right Can it?
Believe it or not yes, BUT, if as mentioned before, if you have had no leaks, all should be well.  I am the exact same weight. I have a C-5, and have not ridden the G-5, but I would think that a 15 w fork oil would be good. Still giving you some comfort, but not too stiff.  It all depends on your comfort and riding style. Spent a lot of time doing high speed cornering, ruff roads, Autobahn maybe? you might want a stiffer feel.Then go to 20 w fork oil. It's what ever you like and feel comfortable with. I have been running 20 w in my C-5 for all the high speed stuff I've been playing with, and I like it now, probably too stiff for some, but not me. I run 15 w oil with progressive springs  on my cb750 cafe bike and i like that set up. It will still give me some comfort, with all the weight on my wrists, due to the clubmans. But the performance is not bad either, for practicle all around riding, highways, city, country roads. If  i spent alot of time on a track, things would be different.  Buy I agree with you, the 10 w 30 motor oil is no good, too soft. But some may like that soft comfortable feel. All preference.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

singhg5

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Re: How Soft is Soft
« Reply #17 on: September 08, 2010, 03:51:09 AM »
Thanks for all the interesting responces.
The manual just states "fork oil" 200m/leg. I suppose they mean 200ml/leg.(no viscosity quoted)

I'm pretty sure the service book says 265 cc's.

Both of you have read correct :  

Owner's Manual = 200 ml per leg
Service Manual = 265 +/- 2.5 ml per leg (should read 265 + 2.5 ml)

Owner's Manual = No listed viscosity
Service Manual = SAE 10W-30

This kind of discrepency in two different manuals or sources has been seen in other parameters too.  E.g., tyre pressure.                          
« Last Edit: September 10, 2010, 01:35:35 PM by singhg5 »
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Ducati Scotty

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Re: How Soft is Soft
« Reply #18 on: September 08, 2010, 04:17:04 AM »
Both of you have read correct :  

Owner's Manual = 200 ml per leg
Service Manual = 265 +/- 2.5 ml per leg

Owner's Manual = No listed viscosity
Service Manual = SAE 10W-30

This kind of discrepency in two different manuals or sources has been seen in other parameters too.  E.g., tyre pressure.                          

Any advice from ScooterBob or Kevin which amt is prefred?

Scott

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Re: How Soft is Soft
« Reply #19 on: September 09, 2010, 04:31:16 PM »
Both of you have read correct :  

Owner's Manual = 200 ml per leg
Service Manual = 265 +/- 2.5 ml per leg

Owner's Manual = No listed viscosity
Service Manual = SAE 10W-30

This kind of discrepency in two different manuals or sources has been seen in other parameters too.  E.g., tyre pressure.                          


Singh Ji,

In the C5 manual, its 195ml per leg and they reduced the level by 5ml for expansion of gasses as 200ml per leg was causing a bit of bouncy moments.

I got the fork oil changed today and it wasn't easy. Had to remove booth the forks as the drain plug on the bottom was moving without getting loose.

Although a bit surprised to what quantity was drained per leg.
In one it was 150ml and other it was 170ml to the specs of 195ml. I never had any leak so I was a bit surprised to where the rest of the oil went or RE never topped it up at the factory.

I was a bit cautious to put 195ml as my C5 slag in the front was half a inch higher compared to a new C5. So assuming there still be some oil sticking inside the forks, I used Shell 10w30 with 170ml in each fork.

Now I am quite satisfied as I have got just the right handling at front now. Neither to heavy nor to soft. Just the way I wanted all that long.

singhg5

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Re: How Soft is Soft
« Reply #20 on: September 09, 2010, 05:40:25 PM »
Singh Ji,

In the C5 manual, its 195ml per leg and they reduced the level by 5ml for expansion of gasses as 200ml per leg was causing a bit of bouncy moments.

I got the fork oil changed today and it wasn't easy. Had to remove booth the forks as the drain plug on the bottom was moving without getting loose.

I was a bit cautious to put 195ml as my C5 slag in the front was half a inch higher compared to a new C5. So assuming there still be some oil sticking inside the forks, I used Shell 10w30 with 170ml in each fork.

Now I am quite satisfied as I have got just the right handling at front now. Neither to heavy nor to soft. Just the way I wanted all that long.

SSR:

After I read your post, this got me thinking if C5 and G5 have different oil volumes in forks ?  According to the Service Manual, the stroke length of G5 (USA) and Electra (UK) is 15.5 cm and of C5 is only 13 cm (less by 2.5 cm). Any info on C5 vs. G5 oil volumes ?
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SSR

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Re: How Soft is Soft
« Reply #21 on: September 09, 2010, 07:05:23 PM »
You are right about the length of strokes so in fair comparison  G5 vs C5 specs

                                            G5                         C5

Stroke length                      15.5cm                  13mm

Oil volume capacity             200ml                    195ml




My owners and service manual corroborates the specs. I asked the mechanics about the volume and they had never filled any fork with more then 200ml in all the CI bullets in a decade. So I am assuming the volume given in your service manual is either a mistake or they have given the volume 265ml for a fresh overhaul of the suspension(totally bone dry of oil. In which case there will be no oil sticking to the inside of the forks and rods but will 65ml be consumed just to get the inside wet without raising the volume is what I am not clear about.

Ducati Scotty

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Re: How Soft is Soft
« Reply #22 on: September 09, 2010, 07:08:42 PM »
65ml just to get it all wet would be a LOT of oil.  I would suspect it wouldn't take more than 5-10ml.

When I do my forks plan to fill with 195 and then measure the height of the oil with the spring out and the fork compressed.  Oil height is generally considered a much more accurate way of measuring the amount of oil in a fork.  Make sure to pump the fork leg several times to get all the air out and get an accurate reading.

Scott

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Re: How Soft is Soft
« Reply #23 on: September 09, 2010, 07:20:39 PM »
65ml just to get it all wet would be a LOT of oil.  I would suspect it wouldn't take more than 5-10ml.

When I do my forks plan to fill with 195 and then measure the height of the oil with the spring out and the fork compressed.  Oil height is generally considered a much more accurate way of measuring the amount of oil in a fork.  Make sure to pump the fork leg several times to get all the air out and get an accurate reading.

Scott


But Scott, Singh has G5 with a longer stroke of 2.5cm so theoretically it could take the extra 65ml over our stroke of 13cm on C5's.

We C5 owners cant go over 195 and you lads can run a bit higher volume to 195 as you got better and less bouncy roads where as we down here cant afford to be bouncy all the time.

Its a good way of measuring oil height but how much will be too much in our case then?

Ducati Scotty

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Re: How Soft is Soft
« Reply #24 on: September 09, 2010, 07:53:32 PM »
If you take the numbers above as correct that's still 65ml over 200ml recommended for teh G5.  Neither fork (G5 or C5) should take that much to 'wet down'.  If you want to add more oil that's your choice and a fair amount of fine tuning can be had that way.  I'm just stating that 65ml over recommended (a 33% total increase) sounds like a bit too much to me.

Scott

gashousegorilla

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Re: How Soft is Soft
« Reply #25 on: September 10, 2010, 02:51:40 AM »
 Guy's, not to further confuse things. But my sercice manual clearly states 265 cc + 2.5 cc each leg. Not  + or -. . Now that is not explained , but it could be a typo. Or it may mean, like a Honda or harley service manual will, be giving a higher volume,+2.5, for a complete disassembly and rebuild. Which I think is more likely. My service manual also lists the same volume for both the C-5 and G-5. I did see in the owners manual the listing of 200 ml's. But the owners manual also gives mention to an oil tank? So when I changed my fork oil i put in 265 cc. And it's fine. I'm not blowing out the seals, like you would when over filled.And I can bottom the front suspention when compressed. Now I would tend to trust a service manual, over the owner's manual. Like Singh said, there are discrepencies. I do know that the owners manuals came out first, The service manual much later, last year when the UCE's were introduced. I would hope that the service manual would have been well edited by the Engineers? Maybe the listing of 200 ml's is left over from the older Bikes? I don't know? And correct me if I'm wrong, a cc and ml, or both the same unit of measure? I usually deal in ounces. ::)
« Last Edit: September 10, 2010, 03:23:12 AM by gashousegorilla »
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Ducati Scotty

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Re: How Soft is Soft
« Reply #26 on: September 10, 2010, 04:13:27 AM »
Now I would tend to trust a service manual, over the owner's manual. Like Singh said, there are discrepencies.

And correct me if I'm wrong, a cc and ml, or both the same unit of measure? I usually deal in ounces. ::)

Yes, service manual is a better reference. 

I deal in ounces too.  12 at a time every day after work :)

Scott

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Re: How Soft is Soft
« Reply #27 on: September 10, 2010, 04:20:00 AM »
 ;)
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gashousegorilla

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Re: How Soft is Soft
« Reply #28 on: September 10, 2010, 04:35:13 AM »



In the C5 manual, its 195ml per leg and they reduced the level by 5ml for expansion of gasses as 200ml per leg was causing a bit of bouncy moments.

uote]
 I that because they are using motor oil instead of fork oil?
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

SSR

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Re: How Soft is Soft
« Reply #29 on: September 10, 2010, 08:15:20 AM »



In the C5 manual, its 195ml per leg and they reduced the level by 5ml for expansion of gasses as 200ml per leg was causing a bit of bouncy moments.

uote]
 I that because they are using motor oil instead of fork oil?

I dont know how much difference between the oil will make if they are of same grade.

singhg5

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Re: How Soft is Soft
« Reply #30 on: September 10, 2010, 01:40:46 PM »
Guy's, not to further confuse things. But my sercice manual clearly states 265 cc + 2.5 cc each leg. Not  + or -.
GHG - My astigmatism needs seeing eye dog.  My optometrist keeps sending me remineders to visit them for eye exam.  I looked again and you are right.  It is 265+2.5 cc each leg.  For our purposes ml is the same as cc - in terms of volume - and interchangeable.
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gashousegorilla

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Re: How Soft is Soft
« Reply #31 on: September 10, 2010, 01:43:52 PM »
I dont know how much difference between the oil will make if they are of same grade.
I think what the difference may be, is that with motor oils propensity to airate, foam, and bubble.Fork oils do not. They have to allow room for release of that compressed gas from those bubbles, in a sealed chamber. In a hot climate, it may be worce? It's not an issue when motor oil is used in a motor, because of the crank vent.I know when I changed my stock oil it had light colored apearence, as if frothed.
 So when fork oil is used, a higher volume can be installed? Less likely to foam,and  build  pressure? The added benifits are maybe the need to check and replace your fork oil less often? Also maybe less likley to pop a fork seal? Around here, motor oil costs about 3-4 bucks a QT. Fork oil about 7-8 bucks a Pt. Now if I'm gonna go through all the effort of pulling that front end apart, I would spend the few extra bucks for the better product.
  If you use fork oil or motor oil, will it change the rotation of the earth, no. Both are probably just fine.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

gashousegorilla

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Re: How Soft is Soft
« Reply #32 on: September 10, 2010, 01:46:15 PM »
GHG - My astigmatism needs seeing eye dog.  My optometrist keeps sending me remineders to visit them for eye exam.  I looked again and you are right.  It is 265+2.5 cc each leg.  For our purposes ml is the same as cc - in terms of volume - and interchangeable.
I have been delaying my appointments as well my brother, LOL. The older I get, the more I must squint :D
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.

Ducati Scotty

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Re: How Soft is Soft
« Reply #33 on: September 10, 2010, 03:02:50 PM »
There wouldn't be any gases released from motor oil, frothing is just churning it a making air bubbles in what's already there.

I agree, go with real fork oil and use synthetic.  It behaves better as the cold weather comes.  Traditional oil makes  a fork very stiff as it gets colder, synthetic less so.

Scott

gashousegorilla

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Re: How Soft is Soft
« Reply #34 on: September 10, 2010, 04:11:48 PM »
There wouldn't be any gases released from motor oil, frothing is just churning it a making air bubbles in what's already there.

I agree, go with real fork oil and use synthetic.  It behaves better as the cold weather comes.  Traditional oil makes  a fork very stiff as it gets colder, synthetic less so.

Scott
Yea, I'm not sure scott, thats why I put the ?. there. But I do know that petrolium products will release vapors, especialy when heated. Also, those bubbles must be entering the oil from some sort of compressive force. And air and fluid will expand when heated. Think of a boiler or water heater, they have relief valves and expansion tanks. Now I know the fork assembly ain't no boiler, But the principle should be the same? Maybe thats why they make synthetic oils? Were only talking a few cc's here.
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Ducati Scotty

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Re: How Soft is Soft
« Reply #35 on: September 10, 2010, 04:29:45 PM »
All of that is valid but I wouldn't expect any huge differences in gases coming out between engine and fork oil.  And, a plunger with tiny holes being forced through oil is a great way to make froth and exactly what's inside our fork.  You can create bubbles in a fluid without off gassing.  Think ov cavitation on a boat propeller.

The reason to go with synthetic is that it behaves more linealy across different environmental temperatures.  With dino oil, it gets thick when cold and this makes the fork very stiff.  The damping effect of the oil goes up exponentially as temperature goes down.  This can make the fork so stiff it is unconfortable or even dangerous.

Synthetic oil still gets thicker when cold but not nearly as much as dino oil.  Dino oil behaves exponentially, synthetic behaves more closely to a linear increase.

Scott

gashousegorilla

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Re: How Soft is Soft
« Reply #36 on: September 10, 2010, 04:51:23 PM »
All of that is valid but I wouldn't expect any huge differences in gases coming out between engine and fork oil.  And, a plunger with tiny holes being forced through oil is a great way to make froth and exactly what's inside our fork.  You can create bubbles in a fluid without off gassing.  Think ov cavitation on a boat propeller.

The reason to go with synthetic is that it behaves more linealy across different environmental temperatures.  With dino oil, it gets thick when cold and this makes the fork very stiff.  The damping effect of the oil goes up exponentially as temperature goes down.  This can make the fork so stiff it is unconfortable or even dangerous.

Synthetic oil still gets thicker when cold but not nearly as much as dino oil.  Dino oil behaves exponentially, synthetic behaves more closely to a linear increase.

Scott
Yup, makes goods sence.
An thaibhsí atá rattling ag an doras agus tá sé an diabhal sa chathaoir.