XTR M900 crank question: scabbiness, sticky-outyness!?

[TreaderSteve]

Hello,

Firstly, if anyone's got a L/H M900 175mm cranks that is a bit manky they could part with I'd love to know! I did place a wanted add but got no bites.

Anyway, I have a pair that I wish to powdercoat (white ) as they're not that great condition. The LH one is sooooo scabby - like you can get your nail underneath scabby bits and bits of alloy peel off. I guess it's some sort of corrosion - I've had a go with Mr Muscle oven cleaner and Brillo pads - improved slightly, not a lot. I almost need to file off a good layer all over to get to some good metal. Anyone had this before/ know how to cure it?

The LH one is I think too scabby at this point to powdercoat without the scabs showing through. So unless someone's got one they wish to part with, which other LH Shimano crank has the same 'sticky-outness' do you know?! As in if the BB axle hole is placed flat on a bench, another crank that would have the pedal axle hole the same height off the bench.

I see Sheldon's crankset database shows the M900 needs a 107-113mm BB. Would any of the others mentioned be a suitable match, such as M563, M569, M737 or M739 that also appear to need the same BB?

Cheers all,
Steven

 

[legrandefromage]

I think the Shimano FC-M520 matches and I remember a lot of people polished their black Deore M560 LX chainsets to look like XTR

The M900 was the first of the 'low pro' groupsets that used narrower axles but stayed 110 BCD along with LX M560

XT 737/9 was a different BCD (compact 94bcd)

Exage FC-M520 110 BCD

I think, the M560 110 BCD black LX will be about as near as you can get to the XTR look, the M563 94bcd arms are a bit different

 

[TreaderSteve]

Excellent info thanks Bigcheese - there are options out there for me. Cheers!

 

[Magpiegifts]

There was a Lh m900 crank arm on eBay recently for£29.99 or penny more. Decent condition

 

[ishaw]

Re:

Bitd I did the lx paint strip and polish.

If your cranks are scabby, brillo and oven cleaner isn't going to do much. If I were you/I had the cranks and wanted to make them presentable or powder cost them, I'd probably wire brush tgem first to get rid of anything that wants to come off, then hit them with some rough sandpaper to get rid of more and smooth the metal. I'd then use some finer grade sandpaper to start the polishing process and remove scratches, moving to finer grades to get a mirror finish. Once as good as you can get it, some metal polish to get the shine. From there you can either wax to seal your hard work, or powder coat as by this stage, you've created a finish that powder coat will look good on. Clear or colour at this point is your choice.

 

[FluffyChicken]

I'd try as ishaw explains, you have plenty of metal to play with. They are not hollow like modern cranks.

Stick some pictures up too

 

[TreaderSteve]

Re:

Thanks all, looks like I'm saving myself sore fingers - konacarl dropped me a line and is selling me a spare one he has which seems in much better condition.
Perhaps I'll fettle the bad one some time to see if I can get the scabs off and the shine on...but I'm in no hurry now!
Cheers

 

[Bawgixer]

They can be cleaned up even from rough starting