[Closed] Reaming out a seat tube

Get a KS Lev.

halving the seat tube wall thickness right where it joins the seat stays and top tubes doesn't sound like a good thing.

removing well over 1/3rd of the thickness of the tube?

One that gets all sorts of off axis loadings from the seatpost (and the rest of the frame).

Get good insurance, make sure someone follows you with a camera.

Or get a new frame with 30.9 (or 31.6) seat tube.

Even if you managed to get that done at all concentric, which is doubtful, you'd be left with a wall thickness of 0.55mm, and a potential stress riser where the reamer stops cutting.

So not a good idea then.
@wwaswas I've got a Lev, it's mince too, unless you can tell me how to increase the pressure in it.

Mines been fine for two years.

Think pressure can be changed during a full service but what's the issue you have - not returning quick enough - that can be down to 'string' length inside the post being set a tad long?

Yeah, not returning and generally being as a slow as poo in the neck of a bottle.

Tried it with a 501 frame years ago. It didn't end well.

I'd look at the string thing - if you can pull the end that sticks out the top of the post with a pair of pliers and it goes up fast then it's not pressure etc - whether you have too much slack in the cable to the lever or the string inside the post is a tad too long is next thing to check.

Is your seatpost collar too tight?

some lev 27.2's are very slow at returning.. its a fairly common fault with them even from new..

They can be re-pressurised.. but it is a [b]MASSIVE[/b] pain in the backside to do.. (ive just managed it after about 3 weeks of faffing about.. and even that was somewhat of a bodge)

Its so much of a pain to do with any sort of reliability.. that the guy who services levs at south coast suspension doesn't do them anymore, and just replaces the whole oil cartridge..

It is also possible to replace the oil in 27.2 Levs without de-pressurising the air side.. so you could replace it with something really thin.. i used redline 2.5W which would speed the post up..

but again.. its a bit of a pain to do even that..

Or you could just get a new oil pressure stick for the LEV from South Coast.. theyre about £80 i think..

Didn't Thomson do a 27.2 post?....

I'd seen something before about the Kevlar string length being critical, will have to check that.
Spacey, how and where did you find the place to repressurise, I know someone who has the nitrogen kit for shocks which I believe may be relevant.

Nobeerinthefridge, I don't know if I can bring myself to spend the kind of money they're asking for the Thomson one, to see if it's any better.

if you dismantle the post..

in the bottom where the shaft enters the air section of the oil pressure stick... there is a [b]tiny[/b] little hole that you can insert a needle in to pressurise it..

some of them apparently dont have this hole at all though.. so cant be re-pressurised at all!

the hole in mine was about 1mm and no needles would fit and stay air tight.. so i had to use a micro drill bit and make it 1.2mm..

theres an o-ring inside that blocks off the other end to 'seal' it.. but it wouldnt seal on mine no matter what size o-ring i tried..

so my bodge was to put a bit of PU sealant under the o-ring.. put the post back together.. inflate quickly.. leave the needle in for a bit.. take it out.. and the air pressure then forced some sealant into the hole and blocked it..

it will mean i might not be able to pressurise it again.. but its working for now and holds air..

have a look here..

[url= http://www.peterverdone.com/ks-lev-27-2-rebuild-and-speed-increase/ ]Peter Verdone - Lev Rebuild[/url]

and here..

[url= http://forums.mtbr.com/components/ks-lev-diy-cartridge-rebuild-899659.html ]MTBR Lev rebuild thread[/url]

but be aware it really is a pain to do... id try changing the oil first to something much thinner and see if that solves the problem..

I wonder what the wall thickness's are on the 30.9 posts.. could you machine the outside of the post down to fit into frame instead...?
id be running all of the post inside the frame though if i did that!

a friend of mine machined a 31.6 dropper post down to just above 30.9 (took off just enough so the whole post was a very good snug fit) to fit his bike and has been using if for a year or so now without issue..

the difference here though is that the 31.6 and 30.9 posts use the same 'internals' with just a different sized lower section so there was probably material there to spare in his case..

You definitely can't ream it. There will have been some distortion when originally welded so it will end up less than 0.55mm wall in some places (plus you need about 0.1mm clearance on the 30.9mm post. My first frame was slightly reamed 0.8mm wall tube and that cracked. I now build everything with a 1mm external sleeve in that area.

I run a Thomson post as it was the only 27.2 option with enough head angle adjustment at the time. Works beautifully but must admit never use it in UK filth (just goes on for holidays in Alps etc).