There has been a thread on MTBR regarding the return speed/overhaul of the i950 and it was stated that there is a tiny hole on the underside of the post where you can increase/decrease air pressure. Can you shed any light on this? I have been able to pull the post down, and as a bonus, put it back together:thumb: and it still works! But I was wondering if you can assist with any info regarding upping the air pressure to get the post to return to the fully extended position?
I basically cleaned the build up of grease out which had accumulated at the bottom of the inside of the " seat post tube" and put fresh grease around the DU bush at the top of the post. The reason for the pull down was that
a) the post would not descend all the way, at least 10mm+(probably closer to 20mm) of the post was still visible, even when apparently in the fully dropped position(this might have been due to the amount of grease at the bottom of the post, effectively acting like an bump stop(maybe??) and not allowing the post to drop all the way. This has been remedied by limiting my liberal application of grease to the post under the red collar..
and
b) the return speed would not be sufficient to return to full height unless the post was "preloaded" before the cable was released. Even more noticable if the post was only half dropped before being released..
I did also notice that with the red collar off, or unscrewed, and compressing the post, the du bush would "pop" out of its seat and air would escape.. Does this build up in operation of the post and cause the limiting of the dropped distance of the post..
With a few crashes, I have noticed that the head is getting loose, ie: it can be unscrewed. Should I just loctite it and screw it back in?
Sorry about all the questions !! Love the post, and it does seem to be fairly bulletproof, and serviceable..
sorry I missed this ...
Firstly the small hole on the i900/i950 / Supernat / Dropzone carts
Note: Self servicing the cartridge on a KS post voids warranty ! The Service Centre isn't even allowed to re-gas or service the cart.
All that said, there is a one way hole at the bottom of the silver cap in one of the many holes. One customer I know has been servicing his post for about 4 years, so well outside of warranty. Essentially with a ball inflator pin and some blue tack he rams the pin on top of the hole and forces air in. Apparently it works
caution: if you are going to disassemble the puppy ... please remember the internals are under pressure ... wear eye protection and don't lean over the puppy and get all the contents over your face and have the end cap ping off your glasses
Note: I don't know what the internal pressure is sorry - educated guess is 120 to 150 psi max 200psi (you would really want to pancake the nads at this pressure)
Re: a)
The build up of lube between the seal collar and DU washer is usually the cause of a spongy last inch of so of travel (negative spring) ... basically too much slicko around the DU makes it air tight (particularly when dropping its travel) and traps air in the mast. This is common in the older i900/i950s as the red end cap is sealed ... for Supernats and Dropzones the red end cap now has a blow hole ... although that can get clogged with mud / dust especially if you don't clean it at all.
I previously use to advocate for this
but there are too many minuses for the benefits ... so we now say use a thin smear of Slicko more frequently as opposed to packing it as shown.
The cost of a light lube is you will need to reapply more often (monthly or after wet rides) ... but more importantly, you will need to become confident it removing the cart and cleaning out the mast of accumulated crap (usually mud or fine dust) This is not hard and the red end cap doesn't need to be removed ... but removing the end cap just allows for a more thorough clean.
general steps (i900 /i950 / supernatural / dropzone)
i) 15mm socket removes the blue lock nut and compression washer
ii) unwind the red seal collar
iii) at the saddle clamp ... firmly pull so that the stanchion pulls out and knocks the silver DU out of the mast
iv) if you ride in wet conditions welcome to the wonderful world of moldy odors
- check the mast internals and using a bottle brush or lint free rag clean it out as best you can
- focus on the guide rod channels to remove any accumulated blockage what can slow or affect guide rods and the return speed of the post.
worse case ... you have a carbon frame and galvanic processes have started to occur on exposed post (coats all exposed parts inserted in the frame with friction paste) and or regularly remove the post after wet rides of bike wash to ensure frame internals dry out sufficiently to avoid corrosion. (this is for all makes and models of alloy posts)
v) feel the roller bearings for grit and clean as needed
- relube with slicko
vi) looking at the cartridge / guide rods / DU / seal collar
- wipe it down and remove any accumulated gunk
- with a stanley knife extract the brass guide rods
- you can now slide off the DU and seal collar
- wipe down the DU and stanchion ... wipe the seal collar
- for completeness remove the seal using your thumb nail and forefinger ... this takes practice but the seal is pretty robust
- check for wear ... splitting etc
- repack with red carrier with lube and reinstall the seal ... be generous with the slicko here
- Slicko the teflon coat of the DU - reinstall it all and insert into the mast (remember one way roller bearings)
- redo compression washer and nut ... don't forget the black bumper stop
normally takes about 15 to 30 mins
If you keep up the regular relube above and below the seal collar ... you can get away with less regular maintenance, but I recommend always drying your post after wet rides or even bike washes, particularly on carbon rigs it seems.
re: b)
In 80 % of cases all the return speed issues are due to a lack of maintenance where the teflon on the DU has dried out. The next item is accumulated gunk on the guide channels, over tightening of the seat clamp ... and or accumulated gunk in the frame seat tube leading to uneven clamping.
eg If you are getting black streaks on your stanchion then your frame is over clamping on to the mast compressing it on to the stanchion and causing the guide channels to score your stanchion.
But again slicko is the answer ... pop the cart out as above ... and relube the stanchion above and below the DU washer ... you should quickly notice if the Du is tight (it should move freely up and down the stanchion) ... if its sticky, slicko above and below the DU and move it up and down the stanchion in a twisting motion ... don't be shy with the slicko here
whilst the cart if out of the mast ... check the roller bearings the the guide channels. if you can imagine the guide rods have to slide freely up and down these channels so if there is blockage then it will slow the return speeds and create a crunchy action.
As a worse case and you are out of warranty a replacement cart is approx $100 to $120. If in warranty send it into Pushie (info(at)pushie.com.au)
Now ... I'm not sure what preloaded means here soz ... does it mean it would rise better if you sat on the saddle then triggered it ?? but under its on weight it wouldn't raise as fast when triggered ?? Not too sure here as we haven't experienced this ... maybe there is trapped air in the mast and thats helping to over come any stiction (ie, two wrongs make a right type scenario I guess ??)
focusing more on the trigger this time ... maybe there is a slight delay in the trigger versus actuator ?? * grasping. What I have seen is that the trigger is only slowly moving the actuator ... or the actuator button is sticking slightly causing slower responses ... or stopping the post locking. This doesn't seem to be your problem sorry ... but to clean the actuator action
i) remove the saddle and saddle hardware
ii) remove the red actuator lever (i900 /i950 / supernatural / dropzone) ...
-in the i900 / dropzone ... there is a well where a silver button or bud is located ... this often collects mud or fine dust ... with either a very small bottle brush or a tooth brush with long bristles ... clean it out.
- for the Supernat / i950 the well is just slightly smaller, but similarly clean the puppy
- I jam slicko in there in an attempt to slow down the accumulation of crap or better displace some of the crap with slicko ... but you will all know the slicko will eventually be overwhelmed to converted to crap /// so pluses and minuses here
re: popped DU
Yep, with the DU out of position, air can release easier out the top of the post as there is more space ... compared to the bottom and out the red end cap (see above comments)
to help visualise ... with the cartridge in the mast ... and the guide rods in the guide channels ... you can see that you effectively have a plunger. as you drop the cart down its travel ... and with lube filling any cavities ... the mast becomes pressurised as the plunger drops reducing the available space so the air pressure builds up and starts pushing up on the bottom of the cart ... creating compression, stopping the cart from using its full travel and or creating a spongy action in the last inch or so of travel.
so too much lube and the air can't get out ... not enough lube, then the seals and DU ware prematurely and lets mud and crap get in the mast and or dries out the teflon coating of the DU.
(edit: for the LEVs this is sometimes why you lose your red KS cap at the remote housing ... the air escapes out the actuator well and pops out the cap)
So in short to answer your question ... depending on how easy air can escape the mast ... it can suffer from trapped air which then ramps up and can stop the post getting full travel
- possible solution. we have stock of the new red end caps with the air hole in it ... rrp is $14 (we have a special tool to install these, but you can use a point spanner or whatever they are called that fits into the holes ... or I have also seen people use needle nose or round nose pliers (note this tends to damage the guide holes as the alloy is pretty soft) use caution here.
Lastly re: loose saddle head clamp.
Yep the saddle heads screw in for all the models above ... again we have a specific tool that is model specific to tighten the heads ... but with a dropzone / i900 you can use big arse adjustable wrench on either side of the saddle clamp head. (beware sometimes this can score the sides of the clamp head)
Bit harder with the Supernat and pretty much in 100% of cases where we didn't use the specific tool, we've scored the head clamp, which is fracking annoying and costly ... so user beware.
We use red loctite ... out of the factory KS uses an epoxy on the threads which normally requires heat and a mutha lever to get it loose ... so pretty surprised you've worked this loose, but I guess it was an awesome binner :laugh:
We are happy to sell spares for your KS posts direct as part of our after sale service and to reduce lost trail time! or feel free to order via your fav LBS.
We can also do a basic service as above for about $35 plus postage and parts if needed (normally no consumables other then slicko which is inclusive).
sorry for the novel ... feel free to email me if you really want to nerd it up and or if I haven't responded to your questions on here soon enough :wave:
