2007 Boxxer WC tuning

i'm 125lbs and i run it at 105psi. that's really low if you're setting it at 95psi and still not bottoming it. sometimes there's some pressure that is built up in the lower legs during assembly that acts as additional spring. i was adviced once to keep the lowers compressed while bolting the lowers to prevent that pressure build-up.

also since u mentioned stiction, perhaps u can pack that area between the dust seal and oil seal w/ prep-M. it works amazing on mine– so plush.

as for the left leg.... don't do anything to that. all the oil there are purely for lubrication and nothing else.

btw, how old is the fork... how many runs?

You've got the oil levels wrong.

Basically, the fork has 4 chambers sealed from each other - these are the two stanchions (air leg, damper leg) and the lower leg on each side.

Damper leg (top) = 150ml of 5wt
Air spring leg (top) = 5ml of 5wt
Lower leg (each side) = 15ml of 15wt

The damping oil provides compression and rebound damping, in my experience with the compression adjusters wound out the level of compression damping is ~zero, so unless you want it rebounding faster than it does with the rebound adjuster all the way out too - then changing oil weight here is futile.

The air spring oil provides lube for the sliding o-rings, excess oil in here can clog things up so keep it at the recommended amount.

The lower leg oil provides lube for the bushings, as the oil in the aforementioned air/damping chambers is isolated from the lowers. Posts #29-30 here should be helpful and provide a little more detail on setting/reducing the air pressure in the lowers to make the fork more linear, as well as the lube oil levels in the lowers.

Beyond those things, the other important factor is greasing the seal/wiper area like peachy said. Pull the uppers from the lowers after removing the footbolts, and generously pack the area between dust wipers and oil seals with grease (prep M, judy butter, or any good silicone grease). Grease the stanchions and slide them in, don't forget the oil for the lowers - syringing it in from the bottom after putting the uppers into the lowers is probably the easiest way.

Anyway, do all that right and you should have a pretty soft and active fork. However, having a fork that blows through its travel regularly is definitely NOT the fastest way down the hill, so don't underestimate the impact those pretty blue and gold compression adjusters (as well as running correct spring pressure) will have on your times. But that's another story for another day.

Maybe try slowing down the rebound a tad, sounds like it's pushing off the rocks and all as you go through it.

My guess is the lack of 'plushness' is more related to lack of lube in the system causing stiction (I noticed a fair difference by checking/filling the bushing lube and packing the inter-seal space with grease (I use slick honey), Or air trapped in the lowers. I feel the same as Udi, with the comp adjusters 'off' there is almost as little damping as my old 888 w/o the low speed adj (read NO comp damping).

I am significantly heavier than you at 190lbs (and ride a team) but I run the gate almost closed (two clicks RET IIRC) and a fair threshold. The fork feels wierd (quite 'platformy') in the parking lot, but it is great at speed. Tracks great, hands feel perfect, use all travel, and the best of all, the front does not dive and wallow all over the place. I run the rebound almost full off (maybe two clicks in).

If you want to mess with the damping (after addressing the other more plausable causes), try removing the speed stack to lessen the redundant high speed damping.

davep - do you mean LSC 2 clicks back from closed?
floodgate two clicks back from closed = buckets of HSC + very late blowoff = bad.

for interest's sake my settings are -

body weight: 145lbs
pressure: 110psi
compression: 2 clicks out from closed
gate: 5 clicks in from open
speedstack: removed (blue hex/core left in, otherwise floodgate settings get affected)
rebound: full open. I actually enlarged + chamfered the edges of the rebound damper ports a little to get it faster.

damper oil: silkolene 5wt, 150ml
air spring: silkolene 5wt, 5ml
lowers: silkolene 10wt, 20ml per side

My 07 Teams came with no lube oil in the LHS. It took about 5 runs for it to get sticky and squeeky. But I put oil in the lowers and now its fine. What I'm getting at is have you checked the oil etc.

Udi said:

davep - do you mean LSC 2 clicks back from closed?
floodgate two clicks back from closed = buckets of HSC + very late blowoff = bad.

Click to expand...

Yes, you are correct.

Udi said:

for interest's sake my settings are -
rebound: full open. I actually enlarged + chamfered the edges of the rebound damper ports a little to get it faster.

Click to expand...

Nice, the ports on both rebound and comp pistons are quite square/sharp edges. I wonder what effect this might have at the oil velocities they see. My guess is just the rebound 'might' be effected.

Unless you're blatantly ignoring what at least four people have stated in this thread, then your first point of attack should be LUBE.

Check the bushing lube oil in the lowers, pack between the wiper and seals with a good grease, make sure air pressure in the lowers is minimal (as per the post I linked to earlier). Beyond that, remove the speedstack. Why? Because.

Not being rude, but we've been through all this before (many times) so it's really not a matter of guess+check anymore.

Once you've sorted that stuff out, then it will be worth toying with more LSC damping, because the compression damping circuit can then work as intended (and there won't be other factors adding stiction like lack of grease/oil for the stanchions/bushings/seals). But yeah, first things first.

udi, is there a thread where u break down the removal of the speedstack? i got the parts to convert my team to a WC and i wouldn't mind getting to that while the fork is apart.

also has anyone found a fix yet for leaking motion control, from underneath the lo speed adjuster? i sent my fork back and although they replaced the lowers they didnt have the moco parts in stock.

Yeah it's in the long speedstack thread. Here's the post.

As for the topcap seal, it's pretty simple to look at yourself. You just have to remove the circlip/LSC adjuster (with the cartridge out), and them remove the black topcap from the plastic spring tube. This is reverse thread, so gently clamp the plastic tube in a softjaw vice or something, and undo the topcap (reverse thread!).

Taking the speedstack out first will make things easier from here on. After the topcap is off the spring tube, pull the adjuster assembly up - you'll see a black pressure seal. Inspect this carefully, it may have been improperly installed (and that could have caused a tear in it etc). If it's in good shape, carefully reinstall (make sure everything stays straight, use some silicone grease etc).

If the seal is correctly installed and isn't damaged then there won't be a leak. If leakage is from the floodgate, there's another thread about that by me - do a search or something. It's best to do both fixes at once.

No worries. I emphasize the importance of the lubing because often there is very little grease under the wipers from factory, and while all my forks have had the correct amount of bushing oil - as top_dog suggested that can be missing too in rare cases. So waiting until service intervals to check things out (on any fork) is IMO just asking for trouble, or at least poor performance.

Personally I give a new fork 10-20 pumps to let the original oil clean out anything that needs it and then rebuild with nicer oils and greases.

Good luck with it anyway, I'm sure you'll get it working nicely. Couldn't be happier with mine.

UDI, i was wondering...... i took apart my motion control today and looked for the blown seal, first i slid off the lsc, then undid the 1/2 blue nut then reverse threaded and pulled the blue piece out.

after i got the c-clip off the top the top cap under the blue lsc adj. slid off and i could see the seals, there were two of them one large and one small one. they both were intact so i greased up the whole deal. so thinking the problems solved i go and put the fork back together and when im bleeding the excess air out of the moco side see oil dripping coming from the adjuster AGAIN. so now ive at least narrowed it to being the seal thats on the very top of the rod how the hell do you get to it???????

aside from that i got my solo air in my fork today,

all i can say is wow.
the fork functions a lot better, the fork feels alot smoother and is way more active on stutter bumps. i think the fork feels better because there not as much built up pressure in the lowers, using a spring you can get any of the pressure in the left side out unless you use a air top cap as a bleed valve . i kinda feel that even with a higher spring rate (im using around 150psi[blown moco FYI]) the fork stays very planted over stutter bumps and feels alot plusher and smoother than my team did with the same sag.

one thing i wonder about is using 150psi this seems like alot for someone my size, but this could be because there is alot of negative pressure in the lowers and my moco unit is blown. i was using a soft spring before.


i think setting the amount of negative air in your fork is an essential part of tuning it and should be tried before you think the fork is sticky and feels like ****.

Can you see where the oil is coming from? Is it between the gate and LSC knob, or from under the LSC knob? If it's the former, this thread should help.

Also, an easier method (than what's listed in that thread) is just to find a drillbit that goes in the hole in the bottom of the floodgate knob (the exact same size) and drill a hole right through the top. You can then reinstall the floodgate knob, and it will sit a bit lower (hold it down while you re-tighten the 1.5mm grub screw). This will do the same job as the fix in my thread, as the knob will hold the sealing o-ring down by sitting lower. I go for this method on all my new boxxers as there's no parts required, but go with whatever suits you.

But yeah if the leak is from under the LSC knob I can't really help you without seeing it myself, there must be SOMETHING wrong with those two seals you inspected - can you get any pictures of the area once disassembled?

Also - why is the MC "blown", what's wrong with it?
Oh yeah and I agree on your points about the WC running nicer than the team, there's just less stiction because you only have 2 tiny sliding o-rings in the air cartridge as opposed to a spring with long rubber isolators rubbing inside the stanchion.

i tried using a washer under the gate knob and the fork is hissing a lot less and im getting a fair bit more compression than i used to (locks out now at full lsc) im gonna try and find something to put some more pressure on that seal.

how do you remove that seal to inspect it anyway? i cant figure out how to remove it.

by blown i mean leaking give no compression,

Ah good, that must have been where the problem was then.

To remove the seal, just get a pick or a pin and pull up what you see around that little silver shaft that the gate knob sits on. There's an o-ring around it, hard to see.

Anyway, I'd suggest ditching the washer and trying the drill trick I suggested, because it means the little "lip" on the bottom of the floodgate knob sits lower and compresses that o-ring, which is the best fix possible IMO. You can do it neatly and it looks sweet, I can get a pic i you want.

Hey Udi, have you thought of shortening the shaft a mm rather than drilling the knob?

Udi, please post pictures/diagrams. can't imagine this somehow. very curious about this fix.

peachy said:

Udi, please post pictures/diagrams. can't imagine this somehow. very curious about this fix.

Click to expand...

The top of the shaft bottoms into a blind hole in the gate knob. Because the knob does not go on far (enough), the o-ring can move up out of its seat. The solution is to be able to move the knob down on the shaft to press against the o-ring, keeping in its place.

Drilling the blind hole through the knob allows it to be slid further onto the shaft, against the o-ring.

BmxConvert said:

I must note that my bushings were essentially dry. They had a little bit of the crusty RockShox lube(Judy Butter?), but not enough for me to call it lubed. I will be using SlickHoney upon reassembly.

Click to expand...

I think you will find that this was the cause of your problems. Pack the space between the two seals (seal and wiper) on each side of the lowers with that slick honey. Then slide the lowers on about 1/2 way and add 20ml of oul to each side. things will feel much better.
When you put the lowers back on, compress the fork about half way and 'burp' the air out of the bottom foot nut...then tighten the nuts whith the fork compressed ~1/2.

BmxConvert said:

Any way, I have a question for you Udi.
When you say remove the speed stack components B. to I. That does that include I. right? Meaning the only piece going back in is the blue hex correct?

-Kevin

Click to expand...

I cant find Udi's labeled pic, but yes you want to remove the shims and keeper nut...then reinstall the blue aluminum 'core'. I did not notice much diff with this mod, but it is simple and reversable..so with a try. I think the lube in the lowers will make a much bigger difference though.

davep said:

Hey Udi, have you thought of shortening the shaft a mm rather than drilling the knob?

Click to expand...

Yeah never really thought about that, would do the trick for sure.

As for all the other questions I think they've been fielded!