Best way to refurb M900 cranks without polishing

[wadsy]

Clear anodising will dull the polished finish anyway. Pics of cranks I did in a Muddy Fox restoration. Link below...

1987 Muddy Fox Explorer - Resto/build

I've recently completed this restoration / rebuild for Tom sfsr He posted a thread asking for help with this project and kindly entrusted me to undertake this for him.... Recommendations for someone to restore my '87 Muddy Fox Explorer Every component has been stripped down, cleaned...

www.retrobike.co.uk

 

[d8mok]

Clear anodising will dull the polished finish anyway. Pics of cranks I did in a Muddy Fox restoration. Link below...

1987 Muddy Fox Explorer - Resto/build

I've recently completed this restoration / rebuild for Tom sfsr He posted a thread asking for help with this project and kindly entrusted me to undertake this for him.... Recommendations for someone to restore my '87 Muddy Fox Explorer Every component has been stripped down, cleaned...

www.retrobike.co.uk

Would the M900 have been silver anodised or clear anodised when new?

Our plan was to go silver.

 

[wadsy]

My thought would be polished and clear, but probably best to show your anodiser the finish you're trying to reproduce and taking their advice.

If you look in the photo album for the Muddy Fox, you'll see the cranks after polishing and then assembled after clear anodising.

 

[d8mok]

My thought would be polished and clear, but probably best to show your anodiser the finish you're trying to reproduce and taking their advice.

If you look in the photo album for the Muddy Fox, you'll see the cranks after polishing and then assembled after clear anodising.

Yes I saw the pics mate. They look more like a M737 crank type finish rather than the duller and more silver M900

Heading up there tomorrow hopefully to drop them off. He said silver when I saw him.

However I do have a second pair which I want to do different. So maybe a clear on those would work rather than black.

 

[Tootyred]

Anodising is always duller than polish. I thought the shimano stuff was basically clear anno. I doubt shimano polished them to that degree prior. More likely cast them dropped into an acid bath to clean, degrease and flatten the surface before going in.

But anodising is not my specialty....that's why i polish them!

The last set i did, was more like original....full polish, then cut back. But, they take more looking after than anno. But, once your surface goes with anno, your back to sq1. But that will take some time!

Interested to see how they come out....

 

[Dr Dremel]

As I´m also a fan of OG finishes I gathered some info over the last years sending parts to 2 different companies for anodizing. Happy to be corrected of course, I´m not a chemical engineer.

Silver/clear ano is one and the same, it´s just anodizing without colouring afterwards. It usually goes like this: Surface treatment (polishing- brushing etc), etch bath in NaOH or similar to prep the surface (can also be used beforehand to remove old ano), anodizing to the preferred surface thickness, colouring ("silver" is not a colour).

Aluminium does develop an oxide layer just being exposed to air. Ano is just thicker and a much more robust oxide layer. The etch bath is mandatory before ano not only to remove contaminants but also to get rid of the "natural" oxide which does nearly nothing in terms of resistance to scratches. The longer the part is exposed to the bath, the duller the finish will get. So even a fully polished part will get a bit duller. This can be corrected afterwards to some degree, but you can´t polish too much. That´s why it´s important to have clear communication with the chosen company.

The XT 730 cranks are just anodized from factory, as far as I know the XTR 900 have an additional clear coat (lacquer). I think the latter could also be coloured in a light grey? Not sure as I never compared them. The XTR logos should indeed be lasered. There is no way the cranks came directly from casting (thought they were also forged?) to anodizing without polishing. Every tiny scratch will show up afterwards, even more so as the oxide layer is partly growing on the surface. IIRC 1/3 of the layer grows "outwards", 2/3 into the surface.

The XT cranks I had done came back a bit duller than factory as I thought I had to prep the surface to the desired end finish and cut the polished arms with some fine 3M.

The results after ano can also vary depending on the alloy the part is made of. In my experience the Shimano cranks give no problems here.

De- anodizing at home. Cranks were silver, turn black-ish in NaOH


Surface after etch bath. White residue is grease to protect the threads


Polish&cut back


Slightly brushed finish in the end, but happy nonetheless


Deerhead crank fully polished beforehand, but some small surface defects possibly due to alloy


Sorry for the massive post, but I struggled myself to get some on-hand info before attempting this.

Eager to see how your XTR cranks turn out @d8mok!

 

[d8mok]

Done some running around today to drop parts off here and there.

The anodiser showed me an example of silver ano and an example of clear. The silver is darker for sure and not near to the m900’finish. So we have gone with a clear ano in the end.

He is hesitant as he doesn’t like anodising used parts as they show every small imperfection and this is apparently worse with clear too.

However I’ve come this far so I’ve told him to try. If it comes out looking bad we may try a ceramic clear on them or even anodise them black. I’m keeping an open mind.

 

[ishaw]

Bitd the lx cranks looked the same as m900 but with the black coating. In a moment of madness, keeping up with some rich kids who had GT rts-2s and were miffed when me, Mr poor kid also got one, the result of an insurance claim pay out on new for old when I had 2 bikes stolen, one a beautiful giant with pearlescent purple/blue/pink flip paint and full deore dx, and a road bike, Peugeot aravis 531 with 105 SC groupset. I bought the giant new, paper round savings plan with my lbs, and 50% off as last year's model, and the Peugeot a swap for my previous giant MTB which was second hand and not a lot of money. Probably about £ 400 all in, but new for old left me with £1350 in the claim, and could only be spent on bikes. When I rocked up to my Saturday job on the same bike as they owned (they were the sons of the owner), they were miffed and upgraded their bikes to show me who was rich, xtr, Judy's, even got their frames anodised gold for extra bling.

I was poor, I owned a bike way out of my social class, but felt compelled to try and keep up.

One option was to make my lx cranks look m900. Paint stripper removed the black coating, but finish was rough underneath so a lot of wet and dry later I had shiny cranks. Too shiny. So using a less fine grade knocked the shine back to a more m900 looking finish while still being smooth and nice looking. Car polish to give them a bit of protection, they looked good for ages and were passable as m900 look a likes.

Couldn't afford much else, but a flite copy and some blingy qrs. I think I also stripped the paint off the stem and gt post.

Anyway, I've rambled. To summarise, don't overdo the sanding to a super fine grade to avoid mirror shiny cranks for that m900 look.

 

[d8mok]

So whilst the cranks are away at the anodiser being done I had another pair of M900 cranks polished.

So this second pair I’ve had a while and had a bad polish job on the front and cracked lacquer on the back.

These I’ve decided to have them shiny for the build as it should tie in with the polished rims well. . So they’ve been polished and had the logo lasered on.

 

[d8mok]

With chainrings