Fork oil

[mandolin]

How much fork oil do i need for the change, on my sm 610 ie 2009?

 

[Pinepig]

My 2008 took just under one liter to do both sides, I bought two just in case and now have one for the next change.

 

[mandolin]

My 2008 took just under one liter to do both sides, I bought two just in case and now have one for the next change.

what kind of oil are you using?

 

[Pinepig]

I used Motul 7wt, I might try 10wt next time, I still think it's a little soft but I'm 240 in full gear.

 

[Kyle Tarry]

Factory oil weight suggestion is 7.5W. Final fill should not be done by volume, but rather by oil height. The manual states this should be 100mm, 90-130mm is common, depending on desired outcome.

I, for one, am not a huge fan of tuning suspension performance with oil viscosity. Viscosity changes have a nonlinear effect on damping, with a greater effect at low speeds (small orifice sizes) and lesser at high speeds. You also have essentially no control over the shape of the damping curve, which is often just as much of a problem as the overall damping level.

It is far more effective to improve suspension performance with valving changes.

I run 5W oil in my forks, but they have been revalved appropriately.

 

[Fast1]

Redline 5weight is what I'm using in my 630 along with the 610 fork compression adjusters.

I believe the manual states 90 mm air gap. I went to 100 mm.

 

[XLEnduroMan]

Redline 5weight is what I'm using in my 630 along with the 610 fork compression adjusters.

I believe the manual states 90 mm air gap. I went to 100 mm.

Dang it...I have to get the compression adjusters and spring spacers in my 630. I bet Zip Ty has what I would need.

 

[CJBROWN]

I have to put new seals in the little WR yammie so I got an extra quart of Amsoil 'lightweight' fluid which they say is 5wt. Will change fluid in the 630 as well.

Someone suggested I add a few cc's to them to improve bottoming resistence and that worked like a charm. Have not buttomed since. Very happy otherwise - no mods to suspension.

Rear spring is too stiff, would like to deal with that sometime, but it's fine when all loaded down with camping gear so I've left it.

 

[CJBROWN]

Did the fork seals on the WR250F yesterday, piece of cake. Took a whole liter of fluid.

Shop manual for TE630 says 630ml (how quincidence) or .63L per leg. Darn, I only have one liter left, better order another one to drain and fill the zokes.
In looking at the marzzochi manual it's remarkable how similar they are to the showas on the old yamaha. Damper rod type forks, not cartridges.

I didn't have to remove the damper rod to change the seals. That was good news. Same for the husky.

 

[mandolin]

Thank you for your feedback!

 

[Theo]

I’m going to replace my fork oil.
I’ve understood that the fork is a Marzocchi Shiver 45, which has an open cartridge system and not a twin chamber.
In the owner’s maual they suggest the AGIP FORK 7,5 (SAE 7,5), but it’s a mineral oil:
http://www.transdiesel.com/app_docs/AGIP%20FORK%207.5W.pdf (read “2. Composition/information on ingredients”).
So, I’d like to find a similar oil, but synthetic. In this page they wrote: “the viscosity index measures the variations in the viscosity with changes in temperature; the higher the level of the viscosity index, the lower the variation in viscosity at temperature.”
I’m looking for an oil having the same viscosity at 40°C (I think that the suspension works at about that temperature) and an high viscosity index. The viscosity could also be a little higher (but not too higher), because I think that the compression now is too quick, but I don’t want to spend money to replace other parts.
What do you think about it? Should I use only the recommended oil to avoid problems? Could a different one give problems even if its viscosity is similar or a little higher? I've read that some of you have used different oil, like Fast1, who used Redline 5weight... .

The viscosity of the AGIP 7.5W at 40°C is 31 mm²/s; its viscosity index is 163 and its price is about 10-15 €/litre:
http://travel.eni.com/catalog/products/documents/001429_14_en_FR_1_150.pdf
Here are some other oils and their datasheets:

-MOTUL Fork Oil Factory Line 10W: http://www.frontier.ro/files/pdf/Fork%20Oil%20Factory%20Line%208219-18-17-16%20(GB).pdf
Viscosity at 40°C: 36.0 mm²/s, viscosity index: 130, synthetic, formulated for any type of upside/down or conventional telescopic fork, about 15-20 €/litre.

-MOTUL Fork Oil Expert 10W: http://www.motul.com/system/product_descriptions/technical_data_sheets/91/original/Fork_oil_Expert_(GB).pdf?1301482582
Viscosity at 40°C: 35.9 mm²/s, viscosity index: 112, Technosynthese quality (a mix between mineral and synthetic based oils, according to Motul website), specially designed for any type of forks upside/down or conventional, about 15 €/litre

-SILKOLENE PRO RSF 7.5W:
http://www.peterverdone.com/archive/files/Silkolene%20Pro%20RSF.pdf
Viscosity at 40°C: 37.19 mm²/s, viscosity index: 322, utilizing synthetic technology, this racing suspension fluid was developed to exceed the requirements of today’s competition systems, about 15 €/litre

-ÖHLINS Front Fork Fluid #10:
http://www.protouchsuspensions.be/PDF/Ohlins%20oil.pdf
Viscosity at 40°C: 40.0 mm²/s, about 25 €/litre

-AMSOIL Shock Therapy Suspension Fluid #10 Medium:
https://www.amsoil.com/shop/by-product/other-products/suspension-fluid/shock-therapy-suspension-fluid-10-medium/?page=%2fstorefront%2fstm.aspx
Viscosity at 40°C: 31.8 mm²/s, viscosity index: 206, synthetic, recommended for front forks and shocks on snowmobiles, motocross and cruiser motorcycles, ATVs and other racing and recreational use vehicles, as well as cars and trucks that require their suspension systems to perform in the most extreme conditions, about 9 €/litre.

I’d like to go for the Silkolene, mainly because of its high viscosity index. What do you think?

 

[Kyle Tarry]

I think you're over-analyzing it.

I run 5W in all my forks. However, my stuff is all revalved, so it's sort of set up for that. The difference in damping between 7.5W and 5W is noticeable, but it's not drastic.

I would just go and buy a 7.5W in whatever brand you prefer, if you're worried about it. Otherwise I would run a 5W. If the damping isn't right with a 5W, adjust the clickers or revalve.

 

[CJBROWN]

Yep, what Kyle said.
You wouldn't be able to tell one from the other. Any of the oils you listed will work.

My preference for everything oil is amsoil, so mine will get the 5w shock oil. I put new seals in the little yamaha (WR250F) with the 5w amsoil and it works perfectly. No doubt the husky will too.

I did find adding a couple of cc's stopped the bottoming I was getting, thanks to the gang here.

 

[Theo]

So, there's no need to get a specific type or brand.
You know, it's the first time I replace the fork oil and I'd like to make sure that I'm not going to do something wrong.
Thank you for the replies!

 

[CJBROWN]

It's more important to get the fluid level set right. If you haven't invested in some kind of fancy gauge a couple of zipties will work. Zip one thru the other half way and mark the leg with the height range. Measure with spring out, fork compressed.
I can't recall if the manual has detailed level setting instructions.

Did a quick browse, from the shop manual:

Fork oil level​

For regular fork operation, both legs must be provided with the necessary oil quantity.​

Remove the fork legs from the fork to check the oil level. Work as follows:​

- remove the damper rod caps;​

- remove springs from the legs letting the oil drain into the legs;​

- bring fork to stroke end;​

- check that the level is at distance “A” below the upper limit of damper rod.​

Oil quantity in each fork leg​

- TE: 630 cm3​

- SMS: 600 cm3​

A=80mm (3.15 in.) - TE​

A=90mm (3.54 in.) - SMS​

So you need two quarts to have enough (630cc in each leg). Raising the level by about 3-4 cc's up to 10 will help prevent bottoming. I have no idea what mine have in them but will measure height before I dump the old oil so I can get back close. My forks have worked flawlessly without any any aftermarket mods. But I'm an 'average' sized rider.

 

[Theo]

- check that the level is at distance “A” below the upper limit of damper rod.​

Oil quantity in each fork leg​

- TE: 630 cm3​

- SMS: 600 cm3​

A=80mm (3.15 in.) - TE​

A=90mm (3.54 in.) - SMS​

On my worshop manual there's written to set the level at A=100 mm from the slider top. Probably it's like setting it at 90 mm from the upper limit of the damper rod.

I have no idea what mine have in them but will measure height before I dump the old oil so I can get back close.

Good trick!

 

[Kyle Tarry]

Also, note that oil level can be tuned to your preference. I am on the lighter side (170 lb), still have stock fork springs (a bit stiff), and have revalved my forks for a more progressive damping setup (active mid), so I can run my oil level lower for plushness because I don't need as much bottoming resistance. I think my oil level is at like 120-130mm on my 610. I generally would recommend starting low and raising as/if necessary to avoid bottoming.

Make sure that you pump as much oil out as you can, and also make sure you completely refill the cartridge via pumped before you set the oil level. Definitely don't want to set the level with a bunch of air hidden away down in the cartridge. When you pump the damper rods to get the air out, it will be very obvious.

 

[Theo]

I'll start setting the level at 100 mm as suggested in the manual, but probably later I'll add a little more oil, because when I'm wearing my gear, I weight about 180 lb and when I land after a jump, the fork almost bottom. What if I improve and I start jumping higher? I'm a beginner of jumps, so that's possible.
I want to use the whole stroke of my fork, but now it seems a little too soft to me. What I don't like about the feeling is that when I brake, the front end stoops too quickly. It doesn't stoop too much, just too quickly.
Maybe I should re-valve, but the problem isn't so serious and I've got used to it, so IMO a little more damping given by the oil level could be enough to solve it and could help the fork not to bottom.

 

[Kyle Tarry]

Well, where are your clickers set?

 

[Theo]

Unfortunately I have only the clickers to adjust the rebound and not the ones for the compression.