Fork seals - how tight?

hiswitsend

Got Suntour XCR Magnesium on my Kraken and while out at the weekend, noticed their action becoming quite notchy - lots of sticktion(?).

Have the lowers off the bike and the action of the spring side and the damping side seem smooth enough, but put the lowers back on and the seals seem to be dragging a little; is this normal; do i just need to grease everything in sight, or could it be the wrong seals?

Was also wondering if it would be worth fitting gaiters to these forks, if they are prone to water/dirt ingress?

While I'm here, what the best way of cleaning out the lowers, have tried rag and rod, but was thinking about either spray, like fs85, or just running hot water through them, and then the 85 stuff.

Cheers in advance

nicklouse

Gaiters are pointless. More likely to be worn bushes.

But a good luring ay help.

hiswitsend

The resistance to movement is just sliding the lowers back over the stanchions, so no movement of the internals involved.

Had a brain wave and went back, one leg runs smoother than the other, infact the 'lockout' leg is a bugger to get on - what is the best way to remove the seal from the lower and is it reusable - am thinking that maybe it isn't seated correctly

hiswitsend

Got the seals out and the plastic guides/bushes; all cleaned up - the locking tab on one was sitting slightly proud as it must have moved when I had rag down there trying to clean it and felt something move.

Tab now sitting correctly

Neal_

IIt seems like you can put oil in the lowers rather than just grease them so my advice is to put full synthetic engine oil in the lowers which should make them much smoother. I've just done a service on my Reba's using synthetic engine oil in the lowers and the difference is impressive.

See here for further proof oil is ok http://singletrackworld.com/forum/topic ... ost-870860

bails87

Neal_ wrote:

IIt seems like you can put oil in the lowers rather than just grease them so my advice is to put full synthetic engine oil in the lowers which should make them much smoother. I've just done a service on my Reba's using synthetic engine oil in the lowers and the difference is impressive.

See here for further proof oil is ok http://singletrackworld.com/forum/topic ... ost-870860

Engine oil in rebas? Why not use...erm....suspension fluid?! Especially as that's what Northwinds post on STW is referring to.

nicklouse

Neal_ wrote:

IIt seems like you can put oil in the lowers rather than just grease them so my advice is to put full synthetic engine oil in the lowers which should make them much smoother. I've just done a service on my Reba's using synthetic engine oil in the lowers and the difference is impressive.

See here for further proof oil is ok http://singletrackworld.com/forum/topic ... ost-870860

LOL

have fun. I see you did not read the topic.

and I would be stripping your forks down now if I were you.

Dirtydog11

+1

What's the advantage of engine oil, I'd have thought it would have been full of detergents?

Unless you can you guarantee it's not going to attack the seals/ O rings then I'll stick with fork oil thanks!

Neal_

bails87 wrote:

Engine oil in rebas? Why not use...erm....suspension fluid?! Especially as that's what Northwinds post on STW is referring to.

You could use suspension fluid, which is usually recommended, but as it is for lubrication not damping it makes sense to use a lubrication oil rather than a damping fluid.

See page 14 of this PDF (http://www.enduroforkseals.com/sitebuil ... l_air3.pdf) which reccomends fully synthetic motor oil in the lowers. Also here are a couple other of threads discussing using engine oil (http://forums.mtbr.com/shocks-suspensio ... 15257.html & http://forums.mtbr.com/shocks-suspensio ... 01950.html) and why it is better than suspension fluid for lubrication, basically it is slippier and clings to parts better. Just to be clear you shouldn't use engine oil in the damper.

nicklouse wrote:

LOL

have fun. I see you did not read the topic.

and I would be stripping your forks down now if I were you.

Why should I be stripping my forks? There is nothing in fully synthetic engine oil that will damage the seals or any other part of the fork.

I did read the topic and the first post where the op asked...

Hiswitsend wrote:

...do i just need to grease everything in sight...

...so after seeing Northwind had used oil in the lowers of his Suntour XCR's I suggested using synthetic engine oil.

hiswitsend

I presume that this is just a small amount of oil that is then splashed about internally as the fork compresses and rebounds?

Probably need to add a little bit of blue hylomar to the bolt/washer at the base to seal it, and stop th eoil leaking straight out.

The links directly above seem to refer to forks that have oil in them to play an active roll in the operation of them, rather than pure lubrication; they seem closer to motorcycle forks, where as the XCR magnesiums are not. there will be some compression of the air in the fork lowers, with any excess pressure being vented passed the seals, where as if there was oil in there, then the pressure would build up quicker due to the reduction in volume of compressible air for the same fork travel, no?

Neal_

Hiswitsend wrote:

I presume that this is just a small amount of oil that is then splashed about internally as the fork compresses and rebounds?

That's exactly right, the oil in the lowers is just splashed about for lubrication.

Hiswitsend wrote:

Probably need to add a little bit of blue hylomar to the bolt/washer at the base to seal it, and stop th eoil leaking straight out.

It the bolts don't have crush washers that's not a bad idea as long as you're sure it won't require much torque to undo.

Hiswitsend wrote:

The links directly above seem to refer to forks that have oil in them to play an active roll in the operation of them, rather than pure lubrication; they seem closer to motorcycle forks, where as the XCR magnesiums are not. there will be some compression of the air in the fork lowers, with any excess pressure being vented passed the seals, where as if there was oil in there, then the pressure would build up quicker due to the reduction in volume of compressible air for the same fork travel, no?

Looking at the exploded view of the XCR below (there's loads of them so I doubt this is the exact fork but they're all very similar) they seem quite similar to other forks I've seen so a bit of oil in the lowers shouldn't cause such an increase in air pressure that it blows past the seals. Reba's take 15ml in each lower leg so you could try this amount or PM Northwind to ask him how much he put in his when he did it.

http://preview.srsuntour-cycling.com/cu ... -DS-LO.pdf

supersonic

Fully synthetic can still contain synthetics that swell seals and o rings.

How does the viscosity of this stuff change with temp?

Neal_

supersonic wrote:

Fully synthetic can still contain synthetics that swell seals and o rings.

Perhaps, it's difficult to know exactly what is in any oil really without contacting the manufacturer. There seems to a preference for using Mobil 1 synthetic engine oil which according to Mobil doesn't contain seal swellers/conditioners but I used Halfords full synthetic 10W40 as it's what I already had, based on what the guy from Enduro Seals has said below I'm confident it'll be fine.

Chris2fur wrote:

http://forums.mtbr.com/7643150-post155.html

For the splash bath in the lower legs, multi-viscosity synthetic oil seems to stick to the parts better than anything else I've used and continues to work well in a broad range of temperatures. Just to emphasize, what goes in a sealed damper or what is used in the leg of an open damper system is a dedicated fork oil, not the same as splash bath/semi-bath lubricant.

Chris2fur wrote:

http://forums.mtbr.com/7676920-post204.html

For those sceptical about using multi-viscosity synthetic motor oil as a splash bath lubricant, it's not a new idea. A little historical perspective: We tend to call the closed damper/separate bushing/seal lube "splash bath," but Manitou really pushed this system initially and called it "semi-bath." They even sold "Semi-Bath" lube that was packaged for them by Motorex. What was it? 5w-40 synthetic motor oil.

Chris2fur wrote:

http://forums.mtbr.com/7679048-post208.html

The only thing we've ever seen really attack the seals was automatic transmission fluid. For some reason, some people are determined to use it in place of damper fluid.

supersonic wrote:

How does the viscosity of this stuff change with temp?

It's very stable over a wide temperature range. The first number of the multi-viscosity engine oil is the SAE viscosity it performs like at cold (W=winter) temperatures and the second is the SAE viscosity it performs like at engine operating temperatures (100C) therefore 10W40 is like 10 SAE when cold and 40 SAE when hot. At lower temperatures synthetic is thinner than a normal mineral engine oil yet clings better due it having higher film strength.

http://www.bobistheoilguy.com/motor-oil-103/

http://www.bobistheoilguy.com/motor-oil-104/

bails87

Why not use suspension fluid? I'm sure suspension fluid is manufactured with the needs of suspension forks in mind.

Neal_

bails87 wrote:

Why not use suspension fluid? I'm sure suspension fluid is manufactured with the needs of suspension forks in mind.

You can and as it is what the manufacturer recommends you should use suspension fluid if you're at all worried about using something different.

Just to clarify again for the damper you should only use suspension fluid but in a semi-bath/closed damper fork as the fluid in the lowers will not mix with the fluid in the damper you can use a different oil that will perform better as a lubricant. Have a read of this thread (http://forums.mtbr.com/shocks-suspensio ... 75922.html) which discusses the pros and cons of various fluids and how they swell seals. Suspension fluids are designed to have high shear strength and also lubricate so aren’t a slippy as engine oil, also some suspension fluids such as Silkolene Pro RSF which are great for dampers are even worse as lubrication for the lowers because they become sticky and gum up increasing stiction. A multi-viscosity synthetic engine oil (e.g. Mobil 1 0W40) won't gum up, is slippier, clings to parts better and is more stable over a wider temperature range therefore reducing stiction and making the forks smoother.

We want the best performance from our suspension and some pay a lot of money for the latest kit and stanchion coatings so it makes sense to investigate what else can be done to increase performance and in this case it’s a cheap option. It’s up to the individual to make the choice on what oil they use but I’ve linked a lot of info so people can make an informed decision themselves.

WMB_Su

Hi Dave,

We passed your query on to Owen Coutts, WMB's latest tech guru and the person to ask for advice. Here are his thoughts...

"Good work on giving your forks a rebuild. In most cases doing what you’ve done by greasing the sliding surfaces and bushings can help smooth out a fork’s rough action. It sounds like the bushing on your fork might need replacing though. For new bushings and other parts you can find your local dealer through the SR Suntour website – http://dealers.srsuntour-tuning-base.com/uk.html.
Fork gaiters can keep some muck away from the seals but also allow grit and mud to get trapped between the seal
and the stanchions, and make cleaning a real chore.
As for cleaning the lowers, we would recommend using some citrus degreaser and a general bike cleaning spray, rather than GT85 or WD40. Yes, they can both break greases down but a dedicated degreaser will do the job much better. If the grease and grime is really set in, remove all the seals and bushings then soak the lower overnight before cleaning. Good luck! Owen"

Cheers, Su

hiswitsend

That's great, thanks Su 8)