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Gear oil vs. Shock oil

Sandwich

Sandwich

Pig my fish!
Staff member
May 23, 2002
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borcester rhymes
Question:
I am trying to un-fuck a Suntour Raidon that came out of the box very sticky and extremely linear.

The best way to un-linear it is to either buy an air cap with a volume reducer built in, or to pour oil into the air chamber.

They recommend 80w gear oil. They suggested I not use FOX Gold oil (or RS 15w, or Finish line 10w), which I have in spades and works awesome.

What's the difference between gear oil and high quality fork oil that I should use one and not the other?
 
HAB

HAB

Chelsea from Seattle
Apr 28, 2007
11,589
2,021
Seattle
I haven't taken one of those SR forks apart, but if it's got a negative air spring, the issue you'll have with lightweight fork oil is that it'll gradually seep through the bleed port when the positive and negative chambers self equalize. So it'll work fine initially, but gradually work its way into the negative chamber and stop doing what you want it to.

Gear oil is much more viscous and much stickier, so it should seep through the bleed port a lot less readily.
 
Sandwich

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,790
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har har.

This is on my budget bike kid hauler. It features all of the latest "why bother" in modern techmology, like boost spacing, 35mm bars, and 650b+ because we all hate cross compatibility.

Included in that is this fork. It's OK, one of the best bad forks I've owned, but it's sticky off the top and blows through it's travel.

It has a mechanical negative spring so I don't think cross over is a problem. A suntour rep was kind enough to send me a picture of the internals, but he was insistent on gear oil. I could certainly buy the RC damper, buy the progressive cap, and the external knobs necessary, but I'm trying to keep this ad budget as possible. With more cash, I'd just start with a better fork.

So, I just want to know if I can pour one of my readily available three fork oils into the positive chamber to make it smaller and get a marginally better fork out of it.
 
Udi

Udi

RM Chief Ornithologist
Mar 14, 2005
4,918
1,213
Try the Fox gold, it's pretty sticky. If it doesn't improve the situation you can take it back out.

Edit - actually, Fox doesn't recommend the gold oil for their own air chambers so it's probably worth keeping that in mind - but if these guys are recommending gear oil (which contains all manner of heavy EP additives) then I doubt the gold will be harmful either. If you want to be ultra-safe just try the RS 15w instead.
 
4130biker

4130biker

PM me about Tantrum Cycles!
May 24, 2007
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Fill the spring side with actual un-used root beer. The results will surprise you!
 
Happymtb.fr

Happymtb.fr

Turbo Monkey
Feb 9, 2016
2,066
1,438
SWE
Udi said:
Try the Fox gold, it's pretty sticky. If it doesn't improve the situation you can take it back out.

Edit - actually, Fox doesn't recommend the gold oil for their own air chambers so it's probably worth keeping that in mind - but if these guys are recommending gear oil (which contains all manner of heavy EP additives) then I doubt the gold will be harmful either. If you want to be ultra-safe just try the RS 15w instead.
Click to expand...
Steve from Vorsprung mentioned in one of the Tuesday tune that he found some fox gold had got drawn past seals. Here http://www.pinkbike.com/news/the-tuesday-tune-ep-10-whats-in-your-oil-video.html
" I can't speak for other companies' rationale, but we use WPL oils in all fork services and certain shock services now, including revalving & custom work, simply because they're the best lubricants we've found in terms of reduction of friction. Fox's 20wt gold is also great as a lubricant, on par with ShockBoost 20wt for friction, but we find its adhesive qualities mean that it gets drawn past seals quicker than the WPL equivalent (Fox and several others actually had to redesign their wiper seals when they released the 20wt Gold for this reason). "

@Sandwich i guess that you will be fine with rs 15w
 
Sandwich

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,790
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borcester rhymes
Looks like 80w gear oil comes in at like 68 cst@40 and ~8 cst@100.

I see mention that fox gold is 98 cst and RS 15w/torco 20w is something like 45 cst@40. Maybe 50:50?
 
dcamp29

dcamp29

Monkey
Feb 14, 2004
589
63
Colorado
I'd be cautious using anything other than what is recommended by suntour... Seal swell is a thing and will slowly make your fork more sticky over time.
 
dcamp29

dcamp29

Monkey
Feb 14, 2004
589
63
Colorado
it's more about what o-ring compounds are used vs what oil is added. Some non-approved fork oil can cause seal swell. they are not all the exact same.

we do a lot of testing with our o-rings in approved oil to make sure they don't swell over time. if someone pours random oil in the fork- the seals might swell. Just use whatever is approved/recommended by the manufacturer.
 
Sandwich

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,790
7,047
borcester rhymes
yeah, FLAPS has 80w for $5. I'll give it a shot.

Just wondering if I could get away with not putting money towards something I'm not confident will actually work. 10cc of shit I have on the shelf will tell me if there's any salvaging the performance, or if I'm just going to end up with a sticky feeling fork that is also filled with oil.
 
kidwoo

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
42,149
13,358
Squirtin ketchup n' mustard on charred flesh
Swelling seals, breaching seals blah blah blah
Let me remind you what it says on the lowers: S.U.N.T.O.U.R.

Come on sandwich, drop them drawers, saddle up on that stanchion and let'er rip! It's truly the only safe alternative.
 
4130biker

4130biker

PM me about Tantrum Cycles!
May 24, 2007
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Sandwich said:
GOD DAMMIT EVERYBODY SETTLE DOWN I BOUGHT THE RIGHT STUFF NOW CARRY ON WITH MAKING FUN OF MISSING LINK GUY INSTEAD
Click to expand...
DONALD TRUMP would know how to fix your fork. make your fork great again!
 
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