Forking about. (MTB)



Marx SS

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Jun 8, 2004
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Isn’t always the way, I upgrade to a new rig fitted with a good pair of forks (Rock Shox Pilot XC/SL 03) which give me capable & dependable service of 3 yrs through all sorts of trouble & strife, but eventually a fork seal goes & it’s time to take them to the LBS for a service. Then the troubles begin.

No problem at the time, the LBS knows of a bloke who specialises in bike forks – especially Rock Shox of which they are - & send them on. A week later they return resplendent with new seals & oil.
I fit them on again & do a MTB event the following week. The action feels alittle fast so I utilize the only adjusting knob I’ve got for rebound damping at the base of the right fork leg & turn them slightly to firm them up, and ride again. I find that turning the knob doesn’t give the sort of change I previously felt, but I can’t be sure, it’s been 3 weeks since I rode the bike last in similar conditions so I carry on.
That evening back home I check out the adjusting knob & find that previously I was able to turn it clock & counter-clockwise through it’s 1/3 of a turn range in a smooth action. Now I distinctly feel a notchy action, as if there are 3 to 4 notches between full fast & full slow action. The first thought I have is that the rebound mechanism has jammed & the adjuster rod/shaft has spun out or gouged through the plastic damping mech which is what is giving this notchy feel with apprant no change.

Due to work & play commitments another week goes by without addressing my fork issues & I’m fronting up to another event on the MTB. During the course of this event I start experiencing another funny thing from my forks. On big hits the damping works, but on little hits while it’s at the top of it’s travel – climbing seated over rough terrain for example – there is no damping, the fork is springing back at full speed. This also occurs while cornering - exiting corners - which makes the steering vague & very unpredictable, I started getting abit of arm pump which I haven’t felt since I was MXing.

So more than a month after getting the forks serviced and over 20hrs offroad riding time I’m standing in the shed looking at my Stumpjumper wondering how rocking into the LBS with my forks in hand & dissatisfaction all over my face will go.
My leaky fork seals was never this bad.

Like any regular person faced with the prospect of a useless confrontation with a LBS where I get most of my parts/accessories from, I opt to fix it myself.
www.Rockshox.com/ Gets me the exploded diagrams & service instructions for my Rock Shox Pilot XC/SL 03 forks, so off I go.
I suppose the biggest thing about doing something for the first time correctly, is not so much what to do, because the instructions are pretty straightforward, but how to do it – the feel. Things like to know how tight to do up the bolts/nuts, how hard to push the rods through the oil seals etc, especially when you have a combination of alloy & plastic components. Oh yeah, also having the tools required goes a long way, but sometimes you can ‘get by’ without the specialised tools by improvisation.
Of course there are things like pulling the lower forks out without taking into account the remaining damping oil as it pours all over the floor & remembering to ‘grease-up’ the seals & shafts before reinsertion.
But after ½ an hour the suspect HC2 Rebound Damping shaft (part #11.4307.393.000) is successfully retrieved.
Inspection of the rebound damper did show that the plastic inner damping assembly had gouged as a result of the damping adjustment knob shaft being turned beyond the allowable range which was 1/3 of a turn. With the fork fully assembled & fitted to the bike it’s not possible to rotate the damping adjustment knob beyond the 3rd of a turn as the fork’s front axel mount on one side & the protruding skewer on the other restricts movement beyond this 3rd of a turn. Hmm.
Luckily the LBS can supply a replacement (@ $59.59) which arrives the following day.

Assembly always takes longer than disassembly , but surprising not so much in this example. Measuring out the replacement 5wt damping oil (did you know that cc is the same measurement as ml ?) which I had left over when I previously purchased for my motorcycle fork, took the longest. Unfortunately I didn’t have anything small enough to get the 30cc & 20cc amounts I needed so I used some cooking utensils from the kitchen to meter out the amounts (it’s OK, I’ve washed them well afterwards, my fiancée - she’ll never know).
I did notice that even though I did spill a considerable amount of damping oil in the disassembly, there seemed to be a very small amount removed compared to how much I was replacing as directed by the instructions.

With the fork assembled but before I fitted it to the bike, I exercised the fork through it’s action on various damping settings & it feels great, fast is fast & slow is slow. Didn’t get enough time to ride test it, but Dirt Crits is Thursday so we’ll see how we go then.
:D

Hopefully I wont be later adding to this post with a ‘grumble grumble’ reply. :eek:
 
I recently overhauled my forks - Manitou Blacks with SPV. Got some very good instructions from the Enduro fork seals web site, which are much clearer than the manuals from Manitou.

For measuring up the oil I got a 60ml syringe from Super Cheap Auto for about $7 when I got the 5w-40 oil I needed. For straight 5w oil, the LBS filled up an empty drink bottle out of their drum. They also filled a patch kit box with Slick Honey grease for me. A big jar costs heaps and I only used a few smears here and there.

To the syringe I fitted the plastic hose that came with it and then I cut it to the length matching the oil level required as per the Enduro instructions. For the lube oil, I used a 10ml syringe.

I managed to crack the travel adjust dial which was never accurate anyway. Should be able to replace it, but I can just count turns or adjust the travel by feel.

And there is a little oil leaking out from one leg. Might just have to tighten it up a bit.

Otherwise, it's all working fine. It's amazing how instructions make sense after you've done the job.
 
On 2006-03-29, slaw (aka Bruce)
was almost, but not quite, entirely unlike tea:
....
> I managed to crack the travel adjust dial which was never accurate
> anyway. Should be able to replace it, but I can just count turns or
> adjust the travel by feel.
>
> And there is a little oil leaking out from one leg. Might just have to
> tighten it up a bit.
>
> Otherwise, it's all working fine. It's amazing how instructions make
> sense after you've done the job.


All in all, suspension sounds far too tricksy.

Should just go rigid :)

--
TimC
Five is a sufficiently close approximation to infinity.
-- Robert Firth
 
"Marx SS" wrote:

> So more than a month after getting the forks serviced and over 20hrs
> offroad riding time I'm standing in the shed looking at my Stumpjumper
> wondering how rocking into the LBS with my forks in hand &
> dissatisfaction all over my face will go.
> My leaky fork seals was never this bad.
>
> Like any regular person faced with the prospect of a useless
> confrontation with a LBS where I get most of my parts/accessories from,
> I opt to fix it myself.


Good to here that you were ale to do the job. Always a lot of value to be
gained in DIY bike maintenance.

However, if you are a regular at this LBS, I'm sure they would want you to
come back to them if their work was not correctly done, and they would
correct the problems with the fork. If they don't look after you it may be
time to look for a better LBS - essentially it is a warranty issue, the job
was not correctly completed. Next time check with the shop, then DIY if you
have problems with them. Just my 2c.
--
Cheers
Peter

~~~ ~ _@
~~ ~ _- \,
~~ (*)/ (*)
 
That's true, but I suppose with the time left since the service & the milage done it may be a difficult proposition to put forward.
Also the suspect fork action is difficult to discern. Having the fork send off again might lay the bike up for another week or so as well.

Some bike shops arent all that gun-ho about bending over backwards either (as it may not mean that much to them, it's not like I buy a new bike every year), so it'll mean I would have to go further for parts/accessories if things don't work out for me after I had approched them about my fork problem.
 
Woo hoo, the forks worked a peach.
:)
In the dry, fast FGP dirt crits course last night at Westgate had some loose sandy corners & hard packed pot-holed sweepers which my forks soaked up & tracked through nicely.
A technical section down the back had 2x 180degree tight corners that had a loose sandy exit, with the first 2 laps though there on the wheel of the rider ahead, they ploughed & washed out their front ends & I was able to track inside & around.
Also in some of the faster hard packed potholed single-track I getting so much confidence in railing the corners, running the wheels to the edge on lipped berms & staying off the brakes, maintaining momentum, & saving pedal stokes in awkward going.
Looking back at the results I managed my fastest average to date of 22.11kms/hr , even though it was a ‘fast & short’ course. Finishing 11th in a field of 31 starters doesn’t sound too impressive but many in the top 6 places where bringing in times which would be competitive in B grade. A case for sandbagging maybe?

Westgate Dirt Crits results 30th March 2006
:D

I ran the rebound adjustment halfway btwn the rabbit & turtle. My tyres at 45psi - Specialised Roll-X 2.0, tubed.
 

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