My BOS forks and shock will soon be coming up to service time. I know that it is common place to send these forks away and from what I can gather they are not a DIY job but has anyone sourced the parts and done the job themselves?
Was it a hard job or just like doing a set of fox etc??
Cheers
Forks are easy. Just make sure the oil height is spot on.
I used Fox 34 seals & non BOS oil - couldn't tell any difference.
BOS OE oil is supposedly some fancy pants stuff that's more like an engine oil than a fork oil, but various suspension tuners suggested a certain weight oil (think it may have been either 2.5 or 5wt) would be fine & it was.
The Fox seals seem to be better than the BOS ones anyway.
I've serviced a couple of pairs of Deville's using a combination of [url= http://singletrackworld.com/forum/topic/bos-deville-oil-change ]THIS STW[/url] thread and [url= http://www.pinkbike.com/u/bikebert/album/BOS-Deville-Service/ ]THIS PINKBIKE[/url] post. Here's what I've done.
Leaving the forks in the frame and the wheel in the forks, first turned the rebound damping to the slowest as it helps with the bleed later and then bleed all the air out, make sure you compress the forks fully while bleeding air to get as much air out as possible.
Now whip the wheel out and the forks out of the frame and put them in a workstand.
Undo the hex screw holding the silver compression damping adjuster in place and remove the adjuster.
Undo the grub screw holding the red compression damping adjuster in place and remove the adjuster.
Put a bowl under the forks.
Undo the damping footnut.
Undo the air cartridge footnut.
Tap the fork brace with a rubber mallet to break the seal.
Pull the lowers down and watch your old oil drain away.
Pull the lowers off.
Push and pull the compression damping rod to get the last of the old oil out.
Give the lowers a good clean inside.
Apparently it's damned hard to get the seals out but they're also supposed to be pretty durable so inspect them and change if necessary. You could try Jungle or Mad Elk cycles but you can also use SKF seals.
There's a gap beneath the seals that should have grease in it such as Super Slick Honey, Manitou M-Prep, Rock n Roll fork grease or Judy Butter, you don't need to put any grease in here at all and instead can put more 20w oil into the air cartridge leg but I'm not brave enough for such shenanigans. If using grease, don't overfill this gap but make sure there's grease all the way round and then smear grease around the seals.
Re-fit the lowers, just take your time and make small adjustments when getting the stanchions and lowers together.
Turn them upside down in the workstand and put some 20w oil into the air cartridge fork leg. Bos recommend 5ml but if you haven't put grease under the seals then you need between 10ml and 17ml. I've heard various recommendations.
Re-fit the footnuts, then the red and silver compression damping adjusters.
I then re-fitted the forks into the frame and the put the wheel back in. Makes it easier to fully compress the fork.
Undo the hex screw holding the rebound damping adjuster in place then unscrew the rebound damping cap.
Pull the rebound damping cap out of the fork leg.
I got some of the Bos oil but if you have a look at the notes [url= http://www.pinkbike.com/photo/9140852/ ]HERE[/url], there are loads of suggestions of what oil to use.
Fill your syringe and start filling the damping leg with oil, I put about 210ml into the Deville 160's I did.
After every 50ml of oil I push and pulled the rebound rod a few times to bleed the cartridge.
After you've got a good amount of oil in there, fully compress the fork and using a thin tape measure, check how far the oil is from the very top of the Crown Steerer Unit, depending on your travel it needs to be the following distance:
140mm = 60mm
160mm = 50mm
170mm = 58mm
When filled to the correct level, DON'T screw the damping cartridge cap back in, instead re-fill the air cartridge so the forks are fully extended, I had to put 8 bar in there to get back to 164mm between bottom of the CSU and top of the fork leg. Re-fitting the damping cartridge cap before re-inflating can introduce a vacuum that eats travel, I lost 30mm to this initially.
Re-fit the damping cartridge cap.
Let a load of that air out of the air cartridge and then re-fill, remembering to homologate the chambers every now and then.
Drink beer.
Feel like a king.
Ride dude, ride like the wind!!!
That's a fine piece of work. It all reads simply ang logically.. I need to do mine soon too, will be following that.
Thanks, it needs to be simple too, I'm sure Scruff will be along in a mo to explain why. 😉
I'd do them sooner rather than later tho, there are lots of reports of stanchion wear if they're not serviced every 6-9 months.
8)
thered thank you very much for that info, just what i was looking for!!
Will be giving this a go in a few weeks 🙂
scruff - Member
8)
BOOOOOOMMMMMM!!!!!!!!
Thered, good write up there.
I am curious who mentioned to you about not screwing damping cartridge cap back in at end of service until you have fully extended the forks with air. I have never done this although if forks ever cavitated when re inflating had to change o rings on air side. Usually if forks equalised correctly forks extend to full travel as increase the air.
The forks are easy to service - having taken the apart and done mine, there is nothing magical about them at all.
I was told by J Tech to use 7.5w Motul oil - I originally did it with 5w but was told that this is too thin. They did feel better with the slightly heavier oil in them. The Fox 34 seals fitted and weren't too bad to get in at all.
Nice one, very straightforward, other than needing four pairs of hands at the end to compress the fork, lift the piston, squirt in the oil and hold a measuring tape
Cheers to thered for the write up.
HG, you're not wrong, I found turning the rebound damping to it's slowest and compressing the fork to get as much air out as poss at the beginning of the oil change process helped a little but it's still a bit of a faff.
Any one tried servicing a shock?
I can't find any instructions for a BOS Vipr service. I've done a few forks at home but no shocks so wasn't sure where to start with it.
thered - Member
HG, you're not wrong, I found turning the rebound damping to it's slowest and compressing the fork to get as much air out as poss at the beginning of the oil change process helped a little but it's still a bit of a faff.
Used a strap to keep it compressed in the end. and the top half of a cable tie as a wee dipstick to measure.
All seems good, they suck down when deflated, feel fine. Got another set to do now. Was v impressed with what I found inside, forks are a couple of years old, had plenty of use in loads of mud, the grease under the seals was still white, almost no dirt, and the damper oil was clean too - gone a bit cloudy, but no sign of dirt. Sta.nchions perfect
Always dropped mine in with Clive at Next Level Bikes, he knows his way around BOS stuff rather well.
http://www.nextlevelbikes.co.uk/
Always been very happy whenever I'd had my springy bits back from these guys.