Deore V brakes seem to self-adjust

[Chuffy]

Argh!
My slicked up mtb commuter has Deore Vs. Recently they've been rubbing on the rims after almost every ride. Both the front and rear brakes do this. I've re-centered them each time, they work for a bit then they go back to binding on one side. The cable doesn't appear to be the problem as the arms don't seem 'stuck'. Normally when that happens they spring apart if you give them enough of a nudge to overcome the 'stickiness'. It's almost as if they are re-adjusting themselves on the limit screws.

• I've stripped the outers off, cleaned the cable and sprayed WD40 down the outer
• I've WD40'ed the pivot points

Any other sensible ideas?

 

[Crackle]

Move the binding side one spring hole out. Wheels straight, right?

 

[Chuffy]

Move the binding side one spring hole out. Wheels straight, right?

Wheels are straight enough. I also check each time I readjust the brakes.

Not sure about moving them onto a different 'ole.
I'm not sure that it's doing it consistently on any given side. Will attempt to remember each time and check.

 

[Crackle]

Well I just fitted Deores in replacement of my Dia Compes which did exactly what you describe. In the end I got fed up with them and bought the Deores. I also replaced all the cables, inner and outer, at the same time.

Not too many things it can be. Cable run, sticky cables, which you've addressed, springs weakening......levers possibly, pad alignment as a remote cause. Beyond that, dunno. Might be the outers. Even oiling them doesn't help once the internal coating breaks down.

 

[fossyant]

If V's cable is too long ? - too much pressure on one side.......

Have you checked the tension adjust screw - usually on one calliper ?

 

[Chuffy]

If V's cable is too long ? - too much pressure on one side.......

Have you checked the tension adjust screw - usually on one calliper ?

That's the bit that I end up fiddling with after every ride....

I might try a cable replacement, I can't figure out what would actually go wrong with the arms themselves.

 

[summerdays]

Have you checked to see that the spring (not sure if that's the correct word for it), is fine. I have had two brakes fail where the spring metal was failing ... the second time I even saw a small line on it... whereas the first time I only realised when it totally snapped. But it wasn't front and back at the same time.

 

[mickle]

Are the blocks so worn that they have hooked under the wim?

 

[MartinC]

Increasing the return spring tension by hooking the spring into a different hole on the boss may help. If the tension is low then all the other factors like cable drag etc. can have a bigger effect and affect the adjustment.

 

[Mr Pig]

If V's cable is too long ? - too much pressure on one side......

That's probably it. Moving the spring will get around it though.

 

[HLaB]

The rear brakes on Sirrus (I think there Deore too) behaved similary I overcome it by taking them apart, cleaning and greasing things and reinstalling on the tighter return spring setting.

 

[Chuffy]

Ok. Thanks all, some good advice on offer. I'll give them a full strip-down at the weekend and see if that cures it. Failing that....I'm going shopping.

 

[Mr Pig]

There's no way you won't be able to fix that, it's a very simple fault.

 

[Moose]

Are the blocks so worn that they have hooked under the wim?

I had this problem (or something similar). The blocks were so worn they were getting caught either on the rim or the sidewall of the tyre (can't remember which one it was)

 

[P.H]

The tensioning is pretty crude, the screw is simply pushing against one end of the spring, when that interface (sorry can't think of a better word) becomes worn the spring can come alongside the screw, having exactly the symptoms you describe. I’ve had it on two sets of Deore Vs. If it’s the screw that's worn, just replace it with anything, I think it's 4mm. If it's the end of the spring that's worn, it's probably easier to replace the brakes.
The spring also become lazy over time, to increase tension just bend them. Unhook from the retaining pin, put something like a small spanner between the spring and the brake and push, it doesn’t take much and you won’t snap it. With well tensioned springs, the adjusting screws won't need to be screwed in so far. I like to adjust my brakes with the screws backed right off, then use them solely for centering.
Or it could be something else…