USD fork seals

General spannery stuff
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nickst4
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USD fork seals

Post by nickst4 »

While fitting cartridges to my Raptor 1000 forks, I thought I'd change the seals too. The very-low-friction type made by SKF don't appear to be available in sizes to fit our forks, so I opted for what seem like the best of the rest, made by Italian firm Ariete. These apparently have a superior rubber mix and precision forming of the multiple seals (my suspicion is that the SKF ones have only one seal lip instead of two). The code is ARI 118 for the seals and ARI 119 for the outer scraper seals, obtainable from an ebay-uk source for me.

They aren't the cheapest but you don't want to do the job twice, and a tool to push them in safely costs more anyway.

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andybaggies
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Re: USD fork seals

Post by andybaggies »

I also had issues when buying replacement seals see thread http://www.raptorchapter.org.uk/viewtop ... 146#p37146
Fork seal/bush components can got from Brookes Suspension http://www.brooksuspension.co.uk/

Don't do what I did & buy them via the manufacturer/model/year list (05 - 08 ??) as these are too big and are probably for the X-Raptor.

You need to buy them by size which are:

Fork slide bushes - 43.7 od x 20 x 1
Fork guide bushes - 43 id x 20 x 2
Fork oil seal - 43 x 54 x 11 (double spring)
Fork dust seal - 43 x 54.4 x 4.6

I also bought a seal driver which made the whole assembly operation so much easier.
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Re: USD fork seals

Post by shebee »

Nice timing... i need new seals in mine, thanks for the details both of you x
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nickst4
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Re: USD fork seals

Post by nickst4 »

Ahem. Just make sure you fit the seals the right way round!

Go on; ask me why I say this? :( :angry:

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Re: USD fork seals

Post by shebee »

nickst4 wrote: 5 years ago Go on; ask me why I say this? :( :angry:
:haha: :mrgreen:
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Re: USD fork seals

Post by nickst4 »

shebee wrote: 5 years ago
nickst4 wrote: 5 years ago Go on; ask me why I say this? :( :angry:
:haha: :mrgreen:
The plot thickens...

So, oil was gushing out of one fork leg when I took the Raptor for its MOT. Verr' embarassing! Prizing the dust seal off, I could see a garter displaced and the seal lip tucked inwards, so I guessed I'd fitted the seal wrongly and the internal pressure had blown past the seal lip due to it being the wrong way round.

Ordering a new pair of seals, it turns out that they actually have two identical gartered lips (no giggling here) facing in opposite directions, so pressure really shouldn't have displaced the one facing the right way towards the inside. The only clue to orientation that I hadn't noticed before is a minute three-step difference in the outer diameter, presumably to aid fitting, and I know I didn't put them in with the smallest diameter first as now seems logical.

So why did the seal blow? The only possibility I can think of is that I didn't apply as much preload to the Matris cartridge spring as the makers specified, and the resulting excessive sag caused the fork to bottom over some of the awful bumps on the way to the MOT station.

We shall see what happens when I do the forks again... :rant:

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Re: USD fork seals

Post by andybaggies »

Was it on the rebound or compression leg? Not too sure the lack of preload would have done much as the pressures involved when e.g. braking hard have got to be pretty fierce also.

And I have to ask, you did fit them the right way round? from what I can remember (but don't quote me) they go serial number facing outwards see https://www.brooksuspension.co.uk/43-x- ... seals.html

You also have to be really, really careful when initially sliding them over the top of the tube - I wrapped cling film round the top with a bit left over to give them a starter for 10. Use of a proper driver is also recommended.
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Re: USD fork seals

Post by nickst4 »

Hi Andy,

It was the LH Compression leg, for what it's worth. Where I live, road bumps cause much faster and heavier load than my habitually-gentle application of the brakes.

Yes, the lettering on the seal was outermost, mostly because that side has a wider flange for the fitting tool to abut. However, that end has the largest diameter of the OD of the seal entering first which makes no sense.

I did indeed guide the seals on over plastic film as you say, to stop the sharp edges of the bush mounts from damaging the lips, and I bought a pukka tool to push them in.

It's all very odd...

Nick
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Re: USD fork seals

Post by nickst4 »

Andy,

I looked at the Brook Suspension site you mentioned and couldn't see any fitting details. What was surprising though was that they list Raptor 1000 seals as for years 03-05 and 06-08. So what about my 01 bike??

The old seals on my forks (which didn't leak, of course :roll: ) are branded Marzocchi as well as NOK, the brand Brook recommend.

I'm rather expecting to put the new seals back in exactly as I had them before, wind the spring preload up and hope for the best.

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Re: USD fork seals

Post by andybaggies »

Yeah, my first reply on this thread mentions to buy them by size & not the model/year as the listing is wrong as well as sending the wrong sized items.

All I can think is that either the seals were faulty or, as you say, could you have perhaps had everything wound down that the forks bottomed out and popped the seal?

Remember adjusting the preload only alters the sag/ride height it doesn't change the spring rate i.e. it doesn't make it harder or softer.
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Re: USD fork seals

Post by andybaggies »

From what I remember I set the preload to around 3/4 clicks less and the damping to the Matris recommendations and adjusted from there. The sag was pretty much bob on at this point so it was just a case of tuning the damping - wind them down until it gets a little 'loose & bouncy' and then back 'em off a couple of clicks.

Your never really going to be able to tune them for the worst of our roads - for that you'll need a big traillie with 7 inches of travel and 2 grands worth of electronic suspension trickery. And hey presto you'll then have a bike that will be so remote from the road it'll suck all the excitement out of riding the damn thing.
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Re: USD fork seals

Post by nickst4 »

andybaggies wrote: 5 years ago From what I remember I set the preload to around 3/4 clicks less and the damping to the Matris recommendations and adjusted from there. The sag was pretty much bob on at this point so it was just a case of tuning the damping - wind them down until it gets a little 'loose & bouncy' and then back 'em off a couple of clicks.

Your never really going to be able to tune them for the worst of our roads - for that you'll need a big traillie with 7 inches of travel and 2 grands worth of electronic suspension trickery. And hey presto you'll then have a bike that will be so remote from the road it'll suck all the excitement out of riding the damn thing.
Thanks for the support, Andy. I've not stripped the leaky leg yet but I don't now think I assembled it wrong.

As for a big traillie with long-travel suspension; I already have that in the shape of another Cagiva, the Gran Canyon 900 and it's a gem of a bike to ride! Not as powerful as the Raptor of course, but a real pleasure that should be tried by anyone who has the opportunity. Of course, you need longer legs than are required by the Raptor! :thumbsup:

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Re: USD fork seals

Post by nickst4 »

Just a follow-up to my problem with a newly-replaced seal leaking: the seal in question was fitted the right way round but the lips had become displaced. There's no way that that happened during my careful fitting, so I'm 99% sure the seal blew because of the leg bottoming-out over what are unintentional sleeping-policemen on the way to the MOT in Diss. Since replacing that seal (with the same brand) I've added a great deal more preload on the Matris cartridges to reduce sag and increase the effective stroke, and the oil is staying inside and the forks feel nice in their action. :thumbsup:

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Re: USD fork seals

Post by andybaggies »

Good to hear you got it sorted - & lesson learnt.

The old zip tie round one of the fork legs is a good idea as it provides a quick visual of how much fork travel you are using. I forget the exact amount but I think that normal day-to-day riding should leave summat like 1/4 to 1/3 of it's travel unused as reserve for emergency braking, large potholes etc.
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Re: USD fork seals

Post by nickst4 »

andybaggies wrote: 5 years ago Good to hear you got it sorted - & lesson learnt.

The old zip tie round one of the fork legs is a good idea as it provides a quick visual of how much fork travel you are using. I forget the exact amount but I think that normal day-to-day riding should leave summat like 1/4 to 1/3 of it's travel unused as reserve for emergency braking, large potholes etc.
Yes, I put a zip-tie on after re-doing the leaky leg and increasing the preload and that's just about where it's sitting now. I wish I'd put it on before!
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