Servicing 7900 hubs - ball retainers

Workshop tales, trials and disasters.
Maintenance tips, techniques and myths.
Technical discussion, description and outright lies

Servicing 7900 hubs - ball retainers

Postby bprb » Sat Oct 27, 2012 12:25 pm

Some of the ball bearings in Dura-Ace 7900 hubs are enclosed in plastic retainers:
http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/FH/EV-FH-7900-2875A_v1_m56577569830728255.pdf

Can anyone advise on the best option if I want to put in new balls when servicing the hubs?
e.g.
(i) Buy new retainers + balls (are these even available?); or
(ii) Remove the old balls from the retainers and push new balls into the old retainers (I haven't tried it to see how feasible this would be); or
(iii) Ditch the retainers and just put in loose balls?

Many thanks if someone has experience they can share.
bprb
 
Posts: 60
Joined: Wed Sep 15, 2010 8:32 pm

by BNA » Sat Oct 27, 2012 4:33 pm

BNA
 

Re: Servicing 7900 hubs - ball retainers

Postby jcjordan » Sat Oct 27, 2012 4:33 pm

The bearing in Shimano Hubs are of a very high quality and unless there is ovious signs of pitting I would not bother to replace them. Just give them a good clean, along with the race, pack in some good grease and put it back together.



Sent from my Transformer Prime TF201 using Tapatalk 2
James
Veni, Vidi, Vespa -- I Came, I Saw, I Rode Home
jcjordan
 
Posts: 1040
Joined: Sat Nov 08, 2008 2:58 pm

Re: Servicing 7900 hubs - ball retainers

Postby bprb » Sat Oct 27, 2012 9:31 pm

Thanks James, that's what I did the last (and so far only) time I serviced them — wipe out the old grease and put in fresh stuff. I guess I was just swayed by articles I've read previously that suggested putting in fresh balls when servicing cup and cone hubs. But maybe if it aint broke, don't fix it.

As an aside, I was impressed by the seals on the 7900 hubs. Despite quite a bit of riding in the wet, the grease was quite fresh and seemingly uncontaminated, compared to what I was expecting from my previous experience with 6600 and 6700 hubs. The 7900s were also a pleasure to reassemble — I enjoyed not having to fiddle with cone spanners to leave just the right amount of looseness in the lock nuts.
bprb
 
Posts: 60
Joined: Wed Sep 15, 2010 8:32 pm

Re: Servicing 7900 hubs - ball retainers

Postby jcjordan » Sun Oct 28, 2012 11:54 am

bprb wrote:Thanks James, that's what I did the last (and so far only) time I serviced them — wipe out the old grease and put in fresh stuff. I guess I was just swayed by articles I've read previously that suggested putting in fresh balls when servicing cup and cone hubs. But maybe if it aint broke, don't fix it.

As an aside, I was impressed by the seals on the 7900 hubs. Despite quite a bit of riding in the wet, the grease was quite fresh and seemingly uncontaminated, compared to what I was expecting from my previous experience with 6600 and 6700 hubs. The 7900s were also a pleasure to reassemble — I enjoyed not having to fiddle with cone spanners to leave just the right amount of looseness in the lock nuts.


the new step guide on the cones for the 7900 are a dream for the mechanic and make home servicing so much easier.

That being said i think that the old 6600 and 7800 are also really good. Have a set of 6600 that are on my everyday wheels and all I do is service the hubs with new grease every year. I have had these wheels since 2055 and I replace the bearing for the first time this year.
James
Veni, Vidi, Vespa -- I Came, I Saw, I Rode Home
jcjordan
 
Posts: 1040
Joined: Sat Nov 08, 2008 2:58 pm

Re: Servicing 7900 hubs - ball retainers

Postby Reman » Mon Oct 29, 2012 7:37 pm

I wonder why Shimano decided on bearing frames, when all their other hubs use free bearings...?
Reman
 
Posts: 240
Joined: Mon May 28, 2012 8:15 pm
Location: Inner West, Sydney

Re: Servicing 7900 hubs - ball retainers

Postby jcjordan » Mon Oct 29, 2012 8:28 pm

Reman wrote:I wonder why Shimano decided on bearing frames, when all their other hubs use free bearings...?


It's meant to make the bearing sit better during hard corners but requires a higher tolerance in matching the race to the bearing.

Sent from my HTC Sensation Z710a using Tapatalk 2
James
Veni, Vidi, Vespa -- I Came, I Saw, I Rode Home
jcjordan
 
Posts: 1040
Joined: Sat Nov 08, 2008 2:58 pm

Re: Servicing 7900 hubs - ball retainers

Postby Reman » Mon Oct 29, 2012 8:41 pm

On my 105 hubs with free bearings I can definitely hear a different bearing sound when cornering.
Reman
 
Posts: 240
Joined: Mon May 28, 2012 8:15 pm
Location: Inner West, Sydney


Return to The Shed

Who is online

Users browsing this forum: Duck!



Support BNA
Click for online shops
Torpedo 7 Torpedo7 AU
Ground Effect Ground Effect NZ
Chain Reaction Cycles CRC UK
Wiggle Wiggle UK
Cycling Express Cycling Express
Ebay Ebay AU
ProBikeKit ProBikeKit UK
Evans Cycles Evans Cycles UK
JensonUSA Jenson USA
JensonUSA Competitive Cyclist