Re-anodising fork stanchions

This is quite a common practice on motorcycle suspension, but as soon as a CSU gets worn on a bike fork we say OH NO, and either bin it or buy a £250+ CSU.

Has anyone done this? Is it possible? Expensive?

Conti

I would guess the issue that with most single crown mtb forks (unlike motor bike forks) the stanchions are bonded in to the crown, hence getting them re-coated is not going to be an easy job….

first result I found on google said;

Unfortunately we don’t have any coating that can be applied to Aluminium Mountain Bike fork stanchions.

so I guess motorcycles tend to have steel stanchions?

Strike, that seems to be the issue, but I have emailed the job to a couple of the top UK hardcoating companies and we shall see!

Someone told me the other day you can get any forks kashima coated.
I know not if he was just gibbering…

Oddly I never thought of looking into this, despite spending tens of thousands on plating in a previous job. We used to get parts masked and dipped, so I would not have thought having them in the crown would matter. Need plugs for the legs through (unless you wanted to coat inside)

Where did you get all of that done?

I think most cheep or classic motorbikes will have steel stanchions that are chromed, so an easy-ish job to re-chrome them. Top end sports/super bike replicas with ohlins etc more likely to be aluminium to save weight, but even then you can get a ti-nitride coating on steel so maybe not?

transapp – Member

Need plugs for the legs through (unless you wanted to coat inside)

Can’t imagine that’d be an issue – Kashima coating ends up inside & out – hence the rear shocks having it on the outside of the can.

“Kashima coating ends up inside & out – hence the rear shocks having it on the outside of the can”
Am I being daft, but whats the air can got to do with the Kashima coating? I assumed the outside colour was just for looks, as theyve no need to coat the inside of the air can as thats where the seals sit?

I think it was a general comment that it doesn’t really matter if the coating is inside and outside the legs.

If you know the material of the fork stantions, then you can get them coated.. :wink:.. Which is done by electroplating I think.

Dual crown forks can def be done, don’t see why singles couldn’t too.

They are a 2010 revelation CSU, aluminium intact otherwise.

James from J-tech says no because you can’t split the tubes from the crown as they are pressed and bonded and removing them to reaffix creates a lot of weakness.

Surely you could just tape the CSU like you would if you were airbrushing and wanted to leave an area blank.

I think dual crown legs is easy, as motorcycle forks are normally ground flat after coating, I imagine having another fork leg and csu would make that difficult as the job is rotary..

The coating is not cosmetic, it makes up part of the tolerance between the inners, outers and bushings. Therefore it needs to be a specific and uniform thickness. When motorcycle forks are rechromed they are first ground down in a special milling machine to allow for the thickness of the replacement chrome plate. The milling machine can only work on individual round pipes so I can’t see how a CSU would fit.
Also the anodised coating is applied by passing a current through the part whilst it is dipped in a solution so masking the crown area probably won’t work.

but bushes need sizing…hence it being a techy job, o rings and fork seals would accomodate the tolerances?…reckon this could be an idea for fox victims…sorry users 😉

but bushes need sizing…hence it being a techy job, o rings and fork seals would accomodate the tolerances?…reckon this could be an idea for fox victims…sorry users

It could work in theory as long as the anodising isnt comletely worn through, if you score the aluminum underneath then the um thicknes of anodising (actualy IIRC doesn’t anodising strip away some material rather than adding it?) isn’t goign to comensate for 0.1mm of wear.

Chrome plating is different, that involves depositing a relatively thick layer of chrome (well, layers of other metals first, then a final top coat of chrome) onto the metal, so can be used to fill pitting caused by corrosion on motorcycle forks.

Anodising on aluminium stanchions is to reduce friction, prevent corrosion
and increace hardness. Chrome plating is to reuce friction, add corrosion resitance but it’s softer than steel.

Think matt24k has it on the nose..

You would have to press the stanchions out of the crown (which may well gall and ruin the crown in the process)
you then have to mount the stanchion in a lathe and grind down the surface back to a perfect tube of bare aluminium again, so you don’t end up with a difference in diameter from the top to the bottom of the stanchion.
you then re-anodise and build up the 20-30 microns or so to just larger than the diameter required and then grind/lap/polish the surface to the original tolerance.

expect this process would reach £250 quite quickly unless you are doing big batches of jobs..

Have not come across any motorbikes with aluminium stanchions, all steel with chrome, ti-nitrided, or DLC coating.

Iirc type 3 will only build up to a certain level and it goes both in and out of the substrate doesn’t matter how long you leave in in the tank for after that it just won’t go bigger there are coatings like Saras they use to rebuild fretted high value shafts and bores but I have never seen it done on aluminium A lot of tubes are centre less ground beforehand

http://www.finishing.com/153/54.shtml

I reckon x fusion should just start making replacement uppers for everyone else

So I just got off the phone with one of the largest vacuum coating companies in the UK. He says it’s possible, but due to their materials and run-time the costs would be prohibitive (£450ish) for a better than DLC coating application.

He was very interested in the possibility of reducing this to make it financially efficient; we thought that a process costing approx 100-150 would sell like hotcakes, it might even kill the parts market for CSU’s.

Oh well!

Do Mojo not offer a retro-fit Kashima coating service on Fox forks when you send them in for service?

If they are coating the existing stanchions rather than replacing the entire CSU (I’ve no idea which of these two is actually the case) then it’s obviously possible.

they replace the CSU

http://www.extremeion.com/pdfs/MotorbikeSuspension.pdf

I work for one of the large heat treatment companys in the uk. does anyone have any knacked stanchions i can run some tests on?

i run fox forks but dont have any with wear on.

Dave

yes – email me

http://www.extremeion.com/pdfs/MotorbikeSuspension.pdf

Wallwork do something similar here in the UK

I have a set of Fox Float CSU that are badly scratched – if you wish to play with them i’d be more than happy to let you have them.

Mail in profile – i think.

(Does this mean i might get them repaired?) 8)

I’ve got some totem airs that are just sat in the shed due to worn stanchions. If you want to try a larger size.

I have some Air Revs from 2009 if youd like to experiment on them too. Email is definately in my profile.

And some Fox stanchions here if you want them.

mugbooatgmaildotcom

I can’t understand why somebody cant build a new CSU cheaply enough.

2 straight tubes, a crown & a straight tube with a bump for the crown race.. They could even do different heights of crown to alter your HA.

I am a hairdresser though 😀

Have not come across any motorbikes with aluminium stanchions, all steel with chrome, ti-nitrided, or DLC coating.

The new Ducati 1199 Panigale definately has alloy stanchions. I was reading about how they saved 1kg off the weight of the forks with them in MCN a few weeks ago. That might be a first on a road bike, but is imagine race bikes will have had them for a while first. 🙂

You don’t want to grind the anodising, you will wreck it. A hard anodise with a ptfe seal for lubricity would be what your after but there are several things to take into account. Anodising is not just a surface growth, you eat away your substrate as well. So once stripped, clean, de-ox and etched you can lose a bit on the size, especially on a diameter. I wouldn’t expect it to make much difference on fork stanchions to be honest but you never know!. For a 25um hard anodise film we would use the rule of thumb of 50/50 growth. So 12.5um into the substrate and 12.5um growth on the anodic film. You can’t just keep adding to the film either as the acid used in the process actually breaks it down as your forming it.
Working with virgin Alu is a shed load easier than trying to sort stuff thats been anodised before. We find most of the time that you would need to repolish stripped parts to get a decent finish.

Looking at the Kashima coating it’s just a specific seal, probably a ptfe variation. When you anodise something you build up an oxide film on the surface of the part, this film is a honeycomb like structure with the pore in the combs reaching to the substrate. In order to provide an effective coating these pores have to be sealed, either with something, ie Nickel acetate, dichromate coatings or you can hot water seal which deforms the coating to seal itself. Looks like the kashima coating is a hard anodic film with a developed seal.

Someone on SDH got their Boxxers re-done at a motorbike place, looks awesome – http://ride.io/forum/index.php/topic,263253.0.html

Anyone interested my email is in my profile

cheers Dave

Kashima is TiNi with molybdenum disulphide.