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small.planes
09-07-2012, 06:02 AM
Its semi off topic as I had to make a couple of tools to enable me to strip my bottom bracket out, and thats on the same bike ;)

I have a 2004 Specialized Enduro. On cleaning it up after a 20 mile trip round the peaks last weekeknd I decided it finally needed some TLC.
The Forks need a service. By Googling I have determined that the lube oil is simply synthetic motor oil, hurrah I have some of that.
The damper oil *appears* to be a standard hydraulic oil, but I cant confirm that.
Manitou spec 5Wt, which as far as I can tell is slightly meaningless, and could translate to ISO 22 hydraulic oil?
I have various hydraulic oils for my various machines, so going out to buy more would be a silly thing to do.

Does anyone know if they are the same thing?

cheers
Dave

ps:
Shimano splined BB tool, Im currently time rich, money limited.
http://i306.photobucket.com/albums/nn274/small_planes/2012-09-06_15-47-02_363.jpg

shawnspeed
09-07-2012, 09:08 AM
You may be ok with the hydraulic oil , but I doubt it is 5W....more like 15-20W oil, so your fork action will be stiffer& slower....Just go buy some motorcycle fork oil at a good bike shop ....you will have enough for a couple years service.....or you could try the hyd. oil and if it is to heavy switch it out later...Shawn

schoolie
09-07-2012, 09:17 AM
Doesn't exactly answer your question, but this is a useful read:

http://www.peterverdone.com/archive/bikesuspension.htm

Basically, the manufacturer's labeled "weights" don't mean much of anything. Find a suspension oil that matches viscosity and you're good to go. Usually a lot cheaper than buying MTB branded suspension oil as you'd expect.

I ended up going all in and buying a couple weights of redline oils so i could mix to a certain viscosity and modify the damping. Not the most cost-effective route, but fun to tinker with :)

Harvey Melvin Richards
09-07-2012, 10:02 AM
My local bike shop tells me to go to the local motorcycle shop for fork oil. He says he can't buy as cheap as they sell it.

small.planes
09-07-2012, 11:41 AM
According to part of this (http://www.mgaguru.com/mgtech/suspensn/fs110.htm)

ISO 22 = SAE 5
ISO 32 = SAE 10
ISO 46 = SAE 15
ISO 68 = SAE 20

So for a recommended fork oil of 5 WT ISO 22 is the same viscosity.
This is the weight Manitou spec for the damper portion of the fork, for the lube they spec 5W40 motor oil.

It would make sense to me that hydraulic oil is used in hydraulic dampers, but I havent found a definitive yes.

I have ISO 22, 32, 68 and 100 hydraulic oils, as well as ATF (Dextron F IIRC) which is a hydraulic fluid of some sort.
Yes Im being cheap, but I see no need to spend money on repackaged oil that I already have, especially when I dont need very much of it.

Dave

beanbag
09-07-2012, 05:23 PM
Compare the viscosity of the ISO22 with the fork oil by stirring in a small cup. You should check that your hydraulic oils have anti-foaming properties and be tolerant to air exposure.

kendall
09-07-2012, 07:17 PM
According to part of this (http://www.mgaguru.com/mgtech/suspensn/fs110.htm)

ISO 22 = SAE 5
ISO 32 = SAE 10
ISO 46 = SAE 15
ISO 68 = SAE 20

So for a recommended fork oil of 5 WT ISO 22 is the same viscosity.
This is the weight Manitou spec for the damper portion of the fork, for the lube they spec 5W40 motor oil.

It would make sense to me that hydraulic oil is used in hydraulic dampers, but I havent found a definitive yes.

I have ISO 22, 32, 68 and 100 hydraulic oils, as well as ATF (Dextron F IIRC) which is a hydraulic fluid of some sort.
Yes Im being cheap, but I see no need to spend money on repackaged oil that I already have, especially when I dont need very much of it.

Dave

I've always use ATF for forks, works very well and can be obtained anywhere.
On the advice of a mechanic, I tried 5-30 in motorcycle forks to stiffen them up a bit, but found that it was far too stiff, not much better than rigid forks.

Oil viscosity is something I could never seem to get a solid handle on. Viscosity charts I have seen put 30 to 40 motor oil at the same 'level' as 85 gear lube, yet they don't behave at all like they're anywhere near the same viscosity.

kf2qd
09-07-2012, 07:41 PM
5W fork oil is probably very similar to ATF. Motorcycles use oil rated the same way, 5W is standard and you can get 7.5 and 10 and mybe 15. You mix a little 10 with the 5 so your older bike with some wear has a bit firmer ride. After 30 years and 140,000 miles they do need a little help.

M_C
09-08-2012, 06:44 AM
For open bath dampers, I just use whatever suspension oil I can get my hands on that's the right weight, as if it doesn't work quite right, it's not a major issue to change it again. So I'd try the hydraulic oil. Worst thing likely to happen is it aerates and damping goes very unpredictable, or it's too slow.

For sealed dampers/shocks, I use the genuine stuff. Cost isn't that much more in the grand scheme of things, and given the time it takes to strip, fill and bleed closed systems, I don't want to be doing them anymore than needed!


As for lower leg lube, I use transaxle gearbox oil. The latest oils have lots of anti-friction additives designed to handle extreme pressures while being very thin, and a certain well known UK bike suspension company sells a special lower lube oil blend that looks and smells just like MXT oil...