spares for M950 hub

[Anthony]

Is this what you're after? If so I'm sure I have some of these at work.

That's the one, just the seal really, but I suppose I shouldn't be a cheapskate about £7. There's me thinking a 'good' hub for £15 might be good!

 

[Anthony]

I can only say maybe. On the one hand, you'd think Shimano wouldn't use a different seal with its own part number unless there was a good reason. I did wonder whether it was because the M950 uses 11 balls per side and so has a larger dustcap diameter, but the 7700 is also shown with 11 balls per side, and seems to use the same seal as the 6400 and 738.
Obviously the way to be sure you get what you need is to match the part exactly if you can. Perhaps dbmtb can help, or failing that, surely someone must have replaced their cones at some point and kept the old ones.
If you can't get an exact match, I've got hubs here I can measure when time permits, including a Dura Ace 7700.

Ah! I noticed the 22 balls thing too, but I've only got 20 balls mister. Unfortunately I haven't got a copy of the M950 parts diagram to compare, so I don't know whether I am short on balls or my cone is different. But my cone is 23.3mm as stated there, so I haven't given up hope yet. Any further advice would be very valuable, as always.

 

[one-eyed_jim]

Ah! I noticed the 22 balls thing too, but I've only got 20 balls mister. Unfortunately I haven't got a copy of the M950 parts diagram to compare, so I don't know whether I am short on balls or my cone is different.

Diagram here:

http://www.paul-lange.de/produkte/shima ... B-M950.pdf

from:

http://www.paul-lange.de/produkte/shima ... _archiv/HB

There's actually a discrepancy between the diagram (20 balls) and the parts list (22) while the Dura Ace hub shows and lists 22 balls. I guess if your hub came with twenty, twenty is correct.

Jacques Le Borgne

 

[Xesh]

The other thing to remember is that the M950 hub has an axle diameter of 11mm as opposed to the standard 9 or 10mm.

In fact, now that I think about it, the M950 cone looks a lot like the ones you find in the old XT parallax 110 hubs.

 

[Anthony]

The other thing to remember is that the M950 hub has an axle diameter of 11mm as opposed to the standard 9 or 10mm.

In fact, now that I think about it, the M950 cone looks a lot like the ones you find in the old XT parallax 110 hubs.

Curiouser and curiouser. My M950 axle measures 10mm, even at the slightly fatter central part.

The diagrams do show the axles and cones of the 7700 and M950 as quite different - the 7700 cone is shorter. But that doesn't necessarily mean that the seals are different, he said, more in hope than expectation.

I may never end up with a working hub, but at least I'm learning a few things.

 

[one-eyed_jim]

Curiouser and curiouser. My M950 axle measures 10mm, even at the slightly fatter central part.

From the exploded diagrams, it seems the design of the axle was changed. The earlier "110" hubs, like the M910 and M738 seem to have an 11mm axle with the M11 thread cut down. Later hubs like the M751 and 7700 show a rolled (i.e. larger diameter than the base metal) M11 thread on a slightly slimmer axle. Presumably the change was made for fatigue and thread strength reasons. The M950 was in production for quite a long time (circa 1996 - 2002?) so presumably there was a running change in the axle. The later design should be a hair lighter.

The diagrams do show the axles and cones of the 7700 and M950 as quite different - the 7700 cone is shorter. But that doesn't necessarily mean that the seals are different, he said, more in hope than expectation.

Well, the part number for the 7700 seal is similar to the part number for the 738 seal, and the 738 cone is dimensionally similar to the M950 cone...

I'm not sure how many "similars" we can stack up and still maintain reasonable expectation of interchangeability. Still, I can take measurements.

I may never end up with a working hub, but at least I'm learning a few things.

Likewise.

 

[one-eyed_jim]

Well, it keeps me off the streets, eh?

I've just stripped an XT 738, an XTR 950, and a Dura Ace 7700 front hub and measured the cones and seals, counted the balls in each, and tried various combinations of hub, cone, and seal.

The XT and DA seals are, as far as I can detect, identical. The XTR seal is a little different.

XT/DA:

internal diameter: 12.3mm
external diameter: 18.2mm
thickness: 2.6mm

XTR:

internal diameter: 12.8mm
external diameter: 19.0mm
thickness: 3.0mm

I tried the Dura Ace seal on the XTR cone. With a little massaging it will seat evenly around the base of the cone. Popped into the open cup of the XTR hub it makes good contact all the way round. On balance I'd say it should work as a contact seal on the XTR hub.

 

[one-eyed_jim]

The Dura Ace hub comes, as advertised, with 11 balls per side. The XTR would seem to have ample room in the cup for 11, but only comes with ten. It's obviously designed as such. The axial ridges on the cones are designed to pass between the balls; the DA cones have 11 ridges, while the XT and XTR cones have ten.

The XTR cone seems to work in the XT hub. The XT cone won't fit the XTR hub: the smaller pressed-on dustcap of the XT cone fouls the dustcap of the XTR shell. Neither the XTR nor the XT cones fit the Dura Ace hub, and the Dura Ace cone won't work in either of the other hubs. The dustcaps foul in every combination.

All three axles have rolled M11 threads on a base diameter of just over 10mm.

I found a reliable way to seat the XT seal evenly on the XTR cone is to place the seal gently in the opening of the hub, flatter side inwards, with the bearing balls in place. Then carefully slide the cone into the shell and press it firmly against the balls. You can use the axle to guide it in. If you now withdraw the cone, you should find the seal correctly and evenly seated on the cone.

 

[Anthony]

Well, it's a good job those Shimano designers don't work for me, or else they'd have to explain why they wasted my money designing a fractionally different seal for no apparent purpose and disregarded economies of scale!

And why use ten ball bearings in a bigger space than the other hubs have, when the others use eleven? And why does the later M750 use ten ball bearings with the identical seal with which the M738 uses eleven?

I don't know which is best out of ten or eleven, but one of them must be, so why not use it for all these hubs? And enjoy economies of scale. And don't tell me the XTR uses one less ball bearing to save weight!

Anyway this is hugely helpful Jacques. I had already ordered a Dura-Ace seal and I shall make a copy of your advice and refer to it when the seal arrives. But don't hold your breath, it's not available until December! Many thanks.

 

[cjn1014]

sorry for the old post dig...

had the same "ten per side" issue with a hb-m750 front hub i recently came across. do you think the flutes on the cone dictate number of ball bearings? ten flutes, not eleven (on mine), and it it seems like it would be a huge pain trying to sneak the cone into place on the axle if eleven balls were present.