Deore XT T780 hubs

For discussions about bikes and equipment.
MikeDee
Posts: 689
Joined: 11 Dec 2014, 8:36pm

Deore XT T780 hubs

Postby MikeDee » 1 May 2020, 8:34pm

pwa wrote:I have one of those rear hubs and it has done a lot of miles with no problems from the freehub. I think I did get some extra lube in it at one point but I do that with all freehubs that have done some miles.


Me too, 780 front and rear hubs, thousands of miles, no problems at all.

I think some of the problem with these freehubs is people running too low of a gear on them and blowing them up. You are not supposed to use lower than a 22x34 gear on a 29er, for example, according to Shimano.
Last edited by MikeDee on 1 May 2020, 8:34pm, edited 2 times in total.

pwu
Posts: 47
Joined: 8 Jul 2019, 2:48pm

Re: Deore XT T780 hubs

Postby pwu » 1 May 2020, 8:50pm

Brucey wrote:I am pretty sure that is not the case; shimano don't even own up to the RH part of the DH assembly coming apart, leave alone that you should use it for adjustment purposes (*).

IME every disc brake hub allows access to the LH cone and locknut once the disc is removed, be it 6-bolt or centre lock type.

(*) and you shouldn't; repeated movements of the RH cone will cause the cone threads to break through the insulation on the wires; if this goes to a dead short the generator is usually scrap.

cheers

On my RM66 front hub I couldn't get a cone spanner in the centerlock side so had to undo from the drive side, the rear hub was accessible on the disc side like normal.

bgnukem
Posts: 565
Joined: 20 Dec 2010, 5:21pm

Re: Deore XT T780 hubs

Postby bgnukem » 4 May 2020, 1:25pm

MikeDee wrote:
pwa wrote:I have one of those rear hubs and it has done a lot of miles with no problems from the freehub. I think I did get some extra lube in it at one point but I do that with all freehubs that have done some miles.


Me too, 780 front and rear hubs, thousands of miles, no problems at all.

I think some of the problem with these freehubs is people running too low of a gear on them and blowing them up. You are not supposed to use lower than a 22x34 gear on a 29er, for example, according to Shimano.



I'm using 26x28 on my commuter. Haven't blown up the freehub body yet but I did have the cone loosening issue and the freehub body is skipping now and seems virtually impossible to clean out and/or re-lubricate.

In contrast I've used the older M750 XT hubs for 20 years now with no hassles, original freehub body - easy to re-grease. Also the older gen M563 Deore LX rear hubs have been fine.

MikeDee
Posts: 689
Joined: 11 Dec 2014, 8:36pm

Re: Deore XT T780 hubs

Postby MikeDee » 4 May 2020, 2:30pm

bgnukem wrote:
MikeDee wrote:
pwa wrote:I have one of those rear hubs and it has done a lot of miles with no problems from the freehub. I think I did get some extra lube in it at one point but I do that with all freehubs that have done some miles.


Me too, 780 front and rear hubs, thousands of miles, no problems at all.

I think some of the problem with these freehubs is people running too low of a gear on them and blowing them up. You are not supposed to use lower than a 22x34 gear on a 29er, for example, according to Shimano.



I'm using 26x28 on my commuter. Haven't blown up the freehub body yet but I did have the cone loosening issue and the freehub body is skipping now and seems virtually impossible to clean out and/or re-lubricate.

In contrast I've used the older M750 XT hubs for 20 years now with no hassles, original freehub body - easy to re-grease. Also the older gen M563 Deore LX rear hubs have been fine.


One of those old Deore LX 8 speed freewheels/freehubs broke on me, so I'm unconvinced that they were any stronger than the newer ones.

pwa
Posts: 13648
Joined: 2 Oct 2011, 8:55pm

Re: Deore XT T780 hubs

Postby pwa » 4 May 2020, 3:08pm

bgnukem wrote:
MikeDee wrote:
pwa wrote:I have one of those rear hubs and it has done a lot of miles with no problems from the freehub. I think I did get some extra lube in it at one point but I do that with all freehubs that have done some miles.


Me too, 780 front and rear hubs, thousands of miles, no problems at all.

I think some of the problem with these freehubs is people running too low of a gear on them and blowing them up. You are not supposed to use lower than a 22x34 gear on a 29er, for example, according to Shimano.



I'm using 26x28 on my commuter. Haven't blown up the freehub body yet but I did have the cone loosening issue and the freehub body is skipping now and seems virtually impossible to clean out and/or re-lubricate.

In contrast I've used the older M750 XT hubs for 20 years now with no hassles, original freehub body - easy to re-grease. Also the older gen M563 Deore LX rear hubs have been fine.

If I remember right, the 780 freehub has a back seal that won't quite come out so, yes, re-lubing isn't as easy as on those where the rubber seal comes out. I ended up slipping a very thin blade down one side of it then dribbling oil around the seal, leaving it to creep down where the blade was, and repeating over time. The oil went somewhere and I hoped it was the right place.

bgnukem
Posts: 565
Joined: 20 Dec 2010, 5:21pm

Re: Deore XT T780 hubs

Postby bgnukem » 4 May 2020, 3:24pm

pwa wrote:If I remember right, the 780 freehub has a back seal that won't quite come out so, yes, re-lubing isn't as easy as on those where the rubber seal comes out. I ended up slipping a very thin blade down one side of it then dribbling oil around the seal, leaving it to creep down where the blade was, and repeating over time. The oil went somewhere and I hoped it was the right place.


That's what I did too. Only managed to get a few drops of oil in though and the thing started skipping and banging afterwards so I guess not enough lubricant.

I also tried immersing it in oil, but the seal being in situ probably prevented any oil passing into the bearings due to an air pocket.

Can't compare the strengths of the 8-S and later freehubs, all I can say is they both seem to be strong enough for my type of riding, which is mostly unladen but featuring a fair bit of climbing, which is neither here nor there. YMMV.

cromo
Posts: 64
Joined: 3 Aug 2009, 9:10am

Re: Deore XT T780 hubs

Postby cromo » 4 May 2020, 3:25pm

As mentioned, the non removable oil seal on these freehubs makes lubrication difficult. I used a piece of earth sleeving (the yellow / green stuff) pushed over the end of a old Wesco oil can. Inserting the flexible earth sleeving between the freehub body and the oil seal and giving the oil can a few squirts quickly injected oil where it was needed.

Brucey
Posts: 42162
Joined: 4 Jan 2012, 6:25pm

Re: Deore XT T780 hubs

Postby Brucey » 4 May 2020, 5:22pm

no need to remove the freehub body or try and force oil past the seal or any of that. Complete waste of time. If you add oil on the RHS as I've described, it gets to where it is needed.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~