Fork chassis, axles, friction: burnishing, chassis alignment, etc...

That fork was awful before it was fixed. 

A few years ago I got all excited to get my fork as good as I could and was going to take it for sizing, but I stripped it down and it was great from the factory. Still running that fork now.

does he say how he realigns them? I agree that chassis alignment is super important, but if you have ever tried to bend a modern CSU or even lowers, you would see how tough it is to make precise adjustments 

You literally just physically bend the lowers, its not complicated at all, just using your hands you can bend the lowers enough to align them.

Do it with seals and everything removed, mount the uppers in a vice at like a 20-30 degree angle (relative to horizontal) and start testing, pull the lowers almost off and just either force the legs together or apart and you can see the difference each time.

Since lowers are cast magnesium there very malleable 

I see a lot of talk about Rockshox fork bushings.  Is this also a "problem" for the other major brands?

Just more people ride Rockshox?
 

Its not a problem per se, its just the reality of a mass manufactured product and tolerance control. 

Other than companies like Intend, the big players simply don't have the labor time to perfectly burnish bushings for their forks, they fit tight bushings to prevent slop, and rely on break-in for it to improve over time. 

But yes, Fox, Dorado etc all have tight bushings from the factory, it is the best choice for their products. 

Chris Porter talks about radial scoring of bushings in order to hold more lubricantion.

Thoughts?

I'm not convinced that grooves on the bushing are helpful - you want the oil film between the surfaces to separate them, and grooves give it a place to be squeezed out of where it should be. When moving, the stanchion should be floating on oil, and only touching the bushing when stopping/starting and at that stage you want maximum surface area to reduce the pressure on the stanchion surface. That why you see forks with vertical grooves start to wear on those grooves - because there is more concentrated pressure there.

Interesting- like honing cylinder walls so piston rings seal and stay lubricated? 

But isn’t all this bending moot after you bolt on the wheel?

shitty chassis kills the forks, that's a fact.. its like a damper trying to lockout on/off during your ride.. I manged to fix one fork with my hands aligning back the CSU/Uppers. Honestly in commercial forks the lowers are very malleable, and a small tolerance error there in alignment is not as bad as in the uppers..

bushing wise, is the last step.

I have just replaced my 170mm Lyrik after 3 years of riding. I live in the Alps so it's had quite a hammering despite my low weight. Regular lower leg services. The bushing play was ridiculous, the front end felt like a noodle. Luckily I scored a deal online on some gen 2.1 charger Lyriks and they feel great. Is there a way to ensure fork/bushing longevity? Or is this just a symptom of whats being talking about with Rock Shoxs poor tolerances?

I believe so, yes

I think he was referring to radially scored bushings, as opposed to the vertical channels in your image.

I am by no means an expert but I think the intent with radial scoring would be that the oil would be more "easily" held in those scores, thus increasing the quantity of oil that interfaces between the bushing and stanchion.

TBH, I've emailed Chris at Mojo Suspension for simple questions on coil weights and he's always been very quick to respond. I would imagine that he would be happy to elaborate. 

I was curious to see if anyone else has done this or has any knowledge of it's effectiveness.

Dimpled bushes to help hold lubricant are pretty common, radial channels might also work.

Are these easily accessible in the aftermarket world for MTB?

I'm usually fine on the technical knowledge of my bicycle, but how do I know if my fork bushings have too much play?

I have an Öhlins RXF38 that has been mostly phenomenal so far but the lowers do have quite a bit of play in relation to the stanchions when the fork is unweighted. Local shop says its fine and according to them Öhlins goes with a bit less tight bushings for better sensitivity, though this is the first time I've heard that.

Should the fork have no play at all, or is a bit of it fine?

I feel like I’ve read before that by design there is some play when unweighted, and then it’s back to normal when cycling through, for the better sensitivity. 

After 2 years in the trenches dealing with fork friction issues, this is what I have found:

In hundreds of forks taken apart and checked for chassis alignment/bushing fit, tight bushings account for maybe 5% of the friction problems.  It is almost always the chassis/CSU alignment causing the issue.

In rare cases burnishing (or opening up the bushings) is the only way to get any improvement, even though the individual fit on each side is good. But in general it is the last resort (unless when testing each leg individually you find a tight fit). 

If the lowers are fully clean/dry with all seals removed, there should be a little play between the stanchions and bushings. They are designed to have a clearance fit which allows for a film of bath oil to remain between the two surfaces. Too tight of a fit and the oil is scraped off which results in more friction. It is important to use a high quality oil like Motorex Supergliss which sticks to the surfaces quite well. 

I kept a tally for a while, and RockShox is far superior to Fox in regards to chassis alignment. It was pretty much 3 to 1. It is imperative to always check with a wheel bolted in the lowers.

Bending or adjusting the lowers is pretty easy most of the time, they are made from magnesium which is pretty soft (ZEB lowers being an exception, those things are burly!). Try to avoid any CSU adjustments if possible as this can lead to the dreaded CSU creak.

As far as adjusting; it is pretty easy to measure the stanchions to see if they are splayed in or out. In regards to the lowers, you just need to try bending/squeezing/manipulating them to see what direction it needs to go. It is surprising how a little squeeze can make a tight CSU drop right to the bottom. Hub spacing can also have an impact, the manufacturing tolerances for hub width can be surprising large.

There are no special tools or secret techniques or black magic involved, just some common sense and trial and error. 

Pull the spring and damper assemblies out, remove the wiper seals/foam from the lowers, get everything clean and dry, and then install a wheel in the lowers. First drop each leg individually to check for tight bushings, then drop them both at the same time to check alignment. If you are lucky, it looks like this (brand new Lyrik);

he definitely has been careful to keep it under wraps, but based on some of the prior pics / vids he's posted, I was wondering if he is facing the dropouts? one of the aspects he's examining is alignment the the hub is clamped in vs not clamped.

here we go, he actually indicated he's facing them in certain circumstances:

"Some of the issues are in the painted drop outs. Uneven paint can cause misalignment. I had a facing tool made so we could skim paint off and face the drop outs. This is not a straight forward process either. I found that you can actually adjust lower chassis alignment by purposely facing the drop outs at an angle. Again non of this is very straightforward and only one of the reasons we will not disclose the entire process."

And you all also want floating bushings that run on two different surfaces... 😬

Old fart dreamin' here: I want bushings that are easily replaced in a normal shop environ without needing a dedicated tool kit to do so, ala the OG Z series Marz & Fox forks. I like the idea Fox had with a long bushing that had holes and grooves connecting the holes to pool lubrication. I've no idea if that was as functional as it seems on the surface, but it seems like a good idea and maybe one that should be explored a bit more. 

Right, like the scoring on the inside of cylinders to catch and hold oil as the piston cycles. 

I really hope not because in some cases it is horrible.

What may be intentional is it seems every RS fork is slightly narrow at the dropouts. If you try the alignment check without a wheel in the lowers, it is sticky. But as soon as you put a wheel in, it spreads the lowers slightly, and alignment is perfect. Perhaps this is done on purpose in the mfg process? The bushing bores in the lowers are machined and located with the lowers in a slightly loaded (spread apart) state?

Fox is often the opposite; alignment feels great without the wheel, but then binds up with the wheel installed and axle tightened. Even with the floating axle setup.