[steeneriam]

I couldn't find much on this so I thought I would share what I know. I bought a pair of XTR 960 V's from ebay for my polo bike build, that were not very smooth and I wanted to fix that. It's a good idea to keep one brake together for reference. Here's what I did:

First lift up the rubber cover. The two aluminum nuts are now visible. Next remove the top jam nut by holding the lower nut with a 17mm cone wrench, and use a 14mm cone wrench to loosen it. By unscrewing the top jam nut, it will lift the top of the parallelogram off, which is a press fit piece. Swing the parallelogram out of the way and remove the bottom nut.
The bearings are a two piece set, one having the captured balls and one race, and the other race. Disassemble the brake keeping the two pieces of the two sets of bearings together
(each bearing and race should remain a matched set).

 

[steeneriam]

Now its time to clean the parts. For the small parts I use a tea ball and swish it in a jar of mineral spirits. The rest of the brake parts I used a Q-tip and paper towel.
Once the parts are clean and dry the bearings need to be greased with whatever grease you would like to use. A small amount is enough to lubricate the small bearing balls.
Start the reassembly by sliding one race and one bearing on the brake base. Next insert the base into the brake arm. Then set the other bearing, then race into the brake arm

 

[Major Clanger]

Good post.........

Out of interest, how much play is there on the axle the actual brake pad mounts on to? There's loads on my old bike and I wasn't able to source a re-build kit in GB (product too out-of-date I think). If you had bad play how did you get around it?

Thanks

 

[steeneriam]

Spin the larger bottom nut all the way down finger tight. Snug it up with the 17mm cone wrench but not tight. The base should spin freely under the brake arm. Now install the smaller nut ( relief cut facing the bottom nut). Tighten it against the bottom nut while holding it from spinning with the 17mm wrench. Keep in mind these are aluminum nuts, so err on the lighter side of torque. Slide the rubber boot over the parallelogram. This part is the only tricky part and is where the brake for reference is helpful. Lift the parallelogram over the brake and align the notches. The fit is a press fit so I used a small plastic bar clamp to lightly press the parallelogram onto the brake. Don't go overboard, cause if it's not completely seated, it will press on the rest of the way when it is mounted to the bike. Replace the rubber boot over the nuts. Wipe any excess grease from the brake.
Make final bearing adjustments (preload) when the brake is mounted on the bike. It should move very freely but have no play.

 

[steeneriam]

Good post.........

Out of interest, how much play is there on the axle the actual brake pad mounts on to? There's loads on my old bike and I wasn't able to source a re-build kit in GB (product too out-of-date I think). If you had bad play how did you get around it?

Thanks

Thank you.

There isn't any play in that pivot. I believe I got lucky with these, cause they don't look like they have had a very hard life.........yet.

 

[diveplane]

i like my v brake setup as well , however later on i might swap out to a front disc brake.

 

[What&son]

Nice post! Most people don´t know they are serviceable.
I did that once to my xtr´s too..so much work I didn´t do it again
I believe these are the only V-Brakes you can actually repack, very nice brakes.
Thanks!

 

[Mangrove Jack]

Super. Very well presented and informative.
Regarding the brake blocks - if not used for a few years they (canti / v brake) blocks get hard. If used like that would they damage the rim ? Would appreciate your comments. Thanks. .

 

[gticlay]

They used to sell shim kits for them as well.

I wonder if it would be easier to spray them out with brake cleaner, heat up a little grease and dip them in there then clean it off the outside?

 

[steeneriam]

This is not a difficult task. It took me about two hours total to do two pair, take pictures, and write this thread. Granted, the brakes were not on a bike yet.

Jack- if by blocks you're asking about the brake pads, I've never seen any get hard enough to damage a rim, they just don't work well.

 

[Mangrove Jack]

Jack- if by blocks you're asking about the brake pads, I've never seen any get hard enough to damage a rim, they just don't work well.

steeneriam, thanks. Yes, I mean brake pads. I have started using a bike that was un-used for about 5 years and I find the brake pads have got hard - when you dig them with your finger nail they do not give at all. Besides less braking performance I was wondering if they will wear / damage the rim ? I live in Sri Lanka and good quality replacement pads are not available here - have ordered some but they will take at least 2 weeks to arrive.

 

[SantaAna12]

Can anyone tell me what the positional relationship between the "parallelogram" and brake in aligning the notches? I do have the one set still assembled, but I am not getting the same travel in both (the overhauled, and the reference sets). What mark or reference would one use if he did not have a reference set? Also, is the blue loctite?

 

[breckenridge]

I miss my 1st gen XTR v-brakes. Those plus ceramic Mavic rims and ceramic specific pads were fantastic, even in the wet.

 

[airkewled]

Thanks @steeneriam for the post. I used your directions as a starting point.
I thought I'd mention that I went one step further and cleaned out the tension adjusting and shaft part.

Here's how I did it.
The shaft is also press fit onto the adjusting section much like the pivot arm is on the top side. Mark/scribe it before removing it. Then using a 3/4" socket you can place the shaft upside down and use a small flat blade screwdriver to lightly tap on the aluminum shaft interlocking fingers driving it off.






It was pretty crunchy in there

All cleaned with mineral spirits

I used a small clamp to press it back together. Careful to line up the scribed parts.


Lastly I removed the small allen screw from the upper pivot shaft and put a drop of dry lube in there. Putting the screw back in, squeezed out the lube along the shaft ends.


:thumbsup::thumbsup:

 

[airkewled]

OP, thanks for the detailed instructions. I used your post as a starting point but thought I'd mention that I went a little further and cleaned out the post and tension adjuster part.
Here's what I did

Set the post in a 3/4" deep well socket

Fits in there like this. The post part is free to drop in the socket but the adjuster base is supported.

I scribed the adjuster base and the post to make sure I'd get the press fit finger joint back together in the same spot then used a small flat blade screwdriver and hammer to very lightly tap the aluminum shaft out of the adjuster base.

Once apart I was glad I did it as it was very crunchy inside.

Cleaned all the pieces with mineral spirits

I used a small clamp with an 8mm socket to press the parts back together making sure to align the fingers up they way there were.

And lastly I removed this small allen screw on the upper pivot shaft and put a drop of dry lube in the hole. Screwing back in the allen screw forces the lube out the shaft ends.


:thumbsup::thumbsup:

 

[bby]

Fantastic write up, cheers for that.

Adding some keywords:
BR-M950
BR-M951
notchy
stiff
brinelling
detents


misc ramblings:

Upon opening them up, you may find that enough sand/grit/crud has entered the bearings to cause the feel of detents or brinelling, or that a previous rebuild job has left the nuts overtightened.

If the grit intrusion is severe, removing the bearings from the cage may be necessary.

Suggestion:
Count the ball bearings before disassy.
Work in a water-filled container (e.g. shoebox size or such) of sufficient size and have a magnet present therein. Working in water is to prevent the ball bearings from flying throughout your workspace. Use the magnet to pull any trapped ones from old grease, then to collect loose ones fallen to the bottom of container.

You may choose to replace the ball bearings after lightly oiling the cage, or not. Picking them up one at a time by jamming them under your fingernail seems to work, and allows for a tactile release mechanism. Grease applied subsequently may likely cause the bearings to climb out of the cage. Work slowly and deliberately. Toothpicks better than Q-tips.

Once a single bearing is cleaned and rebuilt, you should be able to counter-rotate the metal washers that sandwich the cage. (yes, tough with big hands) You will feel any remaining grit. If present, strip and redo (reclean) that bearing unit until you feel no more grit.

 

[Steveroot]

I've just overhauled one of my brake arms that was a little reluctant to move. I have done this once before, about ten years ago. After the first one, I was planning to make a photo "how-to" record of the second. Luckily, I looked on the web and found this excellent journal. My experience is exactly the same as the OP's. I used the exact same tools, though I prized up the castellated end of the parallelogram linkage with a small screwdriver. I like the OP's technique better, as it's less likely to damage the little engagement teeth. I recommend doing one arm at a time so that the linkage end cap can be replaced in the proper relationship to the base; remember that the two arms are mirror-images of each other. Also... watch them little bearing balls!!

 

[Central Scrutinizer]

Thanks @steeneriam and @airkewled for this tutorial - very helpful. Like @Steveroot, I just rebuilt a set for the second time.

I don't know if this has been posted anywhere else, but makes sense to put it here - instructions that come with the tune-up kit. These are for XT v-brakes, but they're the same except for the color of the axle caps. Maybe it's possible to source suitable washers or shim material and DIY it?

 

[flynlow]

Just thought I'd add some info to this great thread. I've owned a set of XTR BR-M950s since new. I just rebuilt them again. Earlier versions of the parallel push linkage Shimanos like mine do not have the spring between the shoe fixing link and the arm like most of the images in the thread. Over time clearance opens up between the shoe fixing link and the arm. Referencing the rebuild kit instructions in this thread, you can source shims, and reduce this play significantly. What you need are 10mm O.D. x 5mm I.D. shim washers. I got mine from McMaster-Carr. $7 plus S&H for a pack of 25. I opted for the stainless steel. The thinnest they offered was .10mm, which is what I got. If anyone finds any .05mm that would be even better. Once you have removed the pin that holds the shoe fixing link, you can use a feeler gauge to get an idea how much play there is. Most of mine measured between .1 to .225 mm.

 

[flynlow]

Also, the set screw that holds that pivot pin in is an M4 x 4 mm.