My Lefty has started clonking as it tops out. It feels like there is no damping for the first 10mm or so of travel. Once it is slightly compressed, it feels fine all the way to full compression.
I thought it was low on damping oil, even though there’s no sign of a leak, so I checked the manual, and it looks like it may actually be bearing migration (page 21).
I’ll have ago at resetting the bearings, it doesn’t look too hard, but what about the oil level anyway ? It mentions damper oil and seal change, but no instructions on how to do it.

Oh, yes, it says DO NOT ROTATE THE GOLD DIAL! for the lock out as well. In capitals, in bold and with an exclamation mark.

Just out of interest, what would happen if someone hadn’t read that bit until now and had already rotated the dial ? 🙄

Hi Graham. Almost certainly sounds like bearing migration. It’s a quick & easy job to do, couple of minutes once you’ve done it a few times. Drop me a line if you need any advice.

Just out of interest, how long have you been running your lefty until you started getting these issues? I’ve had mine since March this year and so far no issues, just wondering when to do this. I know what the manual says, but it must really depends upon the type of riding you do.

Ahh yes it happened on mine a couple of times. Bearings slipped, easy fix. I was told to lube them with vasalene, which I did quite reqularly after the first slip’idge.
Ohh and change the boot if you can or at least the zip ties top and bottom.
Never touched the “gold ring” even though I was tempted once, but that was a very loooong time ago. 😆

ooh, I need to do this too 🙂
any tips would be appreciated

It’s dead easy.

— let air out of chamber
— remove PBR (on mine) and rebound buttons with 2mm hex key
— unscrew black top cap (with shimano HT BB tool. Tip – leave it finger-tight in future so you don’t have to use the tool each time)
— remove split ring thingy from top of shaft
— yank wheel down hard a few times
— put it back together, insert air into chamber. Job done.

oh, and mine generally needs doing every couple of rides. I’ve had it serviced by TF Tuned so it’s all running properly, it’s just part of the maintenance with these Lefty’s I think. You can get different thickness needle roller backing plates if they’re slipping a lot…I think the thickness of the plates is effectively the pre-load which can vary due to varying tolerances of the inside diameter of the Lefty. Or at least I’m pretty sure that’s how it works.

Strange. I’ve done nothing to mine since march despite riding every week and in some pretty crummy conditions. It looks easy enough so must start a routine.

Go onto the Cannondale forum over on MTBR. There’s plenty of guides/videos on how to do anything Lefty related.

This is good too…

http://www.mbaction.com/Main/News/How_To_Service_Cannondales_Lefty_Fork_641.aspx

Looks easy peasy and a 15 min job once you’ve done it a few times.

Just done this for the first time. It is really really easy. Honestly. I did it in about 30 mins for a bearing regrease and re-alignment and I was really taking my time being ultra methodical. I reckon you can get this job to around 10mins once you’ve done it a few times. I didn’t clean the air filter because i’ve not got any oil -just ordered some off ebay so will re-visit that once i’ve got it. But boy did it need doing. The fork length measurement in the manual for my fork was 725mm and I was measuring about 670 mm. I was tapping the fork down for about 5 minutes with nothing moving and was getting concerned for a moment but realised you do have to be quite forceful with it. Not violent, but just firm and the bearings knocked into place nicely. The re-greasing job was strange. I applied the grease, cycled the fork, reapplied the grease and just kept going, really not knowing when to stop. But ultimately, if you’ve got basic bike mechanic skills this is a really easy and satisfying job to do yourself. THe fork itself looks like a really simple unit, very well engineered. I reckon, if you can get a kit, a complete fork refurb would be quite easy too. I’ll look into it as a service costs £125 with the inconvenience of having to send your fork off to a specialist.

Thanks for the replies.
Finally got around to doing it today. Overall fork length had gone from 730mm down to 690mm, so it was worth doing.

I’ve got another problem now though.
I thought I’d take the opportunity to regrease the head bearings while I was at it.
However, it seems the steerer tube threads are seized to the stem.
I’ve undone it so far and can’t get it any further or wind it back in without risk my spanner slipping.
I’ll order a proper socket to use with a bar to force it off with a good chance that either the stem, steerer or both will need replacing afterwards.

Where’s the best place to buy Lefty spares ?

I’ve reset the bearings and sorted out the other problem with the seized stem and steerer, but I’ve still got no damping for the top 10mm or so of travel.
With the fork unlocked, the damping works OK until the fork is nearly fully extended.
With the fork locked, there is still about 10mm of free, undamped travel.

It feels as if the damper is low on oil and once the piston rises above the oil level there is no damping or lock out.

Is the oil all contained inside the damper cartridge ?
Is it something I can take apart and service myself ? Qwerty sell seal kits, so I take it I can.
Where do I find instructions on how to do it, how much oil to use etc. ?

Sounds like it could be the damper unit then. Take a look on You Tube. I found a useful video of a guy replacing the damper cartridge in real time. Again, looks like a really simple job, you just need to be methodical. You appear to need a special tool to remove the internals once you’ve got the top cap off, they are avaialbe through Qwerty for about £15. From the video it looked like the damper cartridge was a sealed unit so not sure if you can just replace the oil, maybe it differs from fork to fork as over the years and across models they’ve sourced their internals from different manufacturers like Fox and RockShox.

How old is the damper? My old version has no user/professional serviceable parts and it was £180 to replace it!!