Unicornz0

I changed forks on my mountain bike and I need to adjust the V brakes. On the drive side the pad is tight against the rim, and the brake arm is leaning toward the non drive side of the bike. I removed the brake pad from the non drive side and dropped the washers and spacers, and need to know how to put everything back together. This pad was not fitting properly with the new fork. Since the drive side is not set up properly for this fork, I decided to ask for help.
All help is appreciated.
Thanks,
Uni

operator

Ok. Numbered them here. Start with ... number one obviously. Right after you stack 3, put everything onto the brake arm then continue.

This is *most* likely the correct configuration (the only consideration is whether you need the fat or skinny convcave washer e.g swap 2 in place of 5 or vice versa) to have the arms parallel when it the pads hit the rim. Also note that the curved sections of each washer should fit together in harmony - if you didn't know that already.

Unicornz0

Thanks so very much Cab Horn, how should 3 & 4 be orientated?

operator

The flat side should be against the brake arm.

Unicornz0

Thanks again. Looks like I will be riding tomorrow morning.

desertdork

Uni,

Did you resolve the issue with the brake arm leaning into the rim? There's a small spring tension adjustment screw on each brake arm near the canti mount (see pic). By turning each screw alternately, you're able to center the brake arms. If the springs aren't adjusted right, you'll probably note one brake shoe being pulled into contact with the rim by the opposite brake arm.

Also see Shimano V-brake service docs

operator

Those particular arms usually have the adjustment screw preset so that the arm has no return spring tension at all (sort of annoying) out of the box.

Panthers007

By turning that little screw clockwise, you'll be moving the brake-arm further away from the rim. Turning it counter-clockwise moves it further inward to the rim. You must balance them by going from side-to-side in your adjustments as what you do on one side, also has effect on the other brake-arm. It's easy, be patient and get the hang of it.

Unicornz0

Hello everyone, and thank you so very much for your timely and prompt help. I was able to reassemble the brakes and they work well, and the brake arms are pretty much straight when braking (2nd picture). The drive side pad is still a bit closer to the rim than the opposite pad. On the drive side brake pad, the thinner spacer is closest to the pad, and on the non drive side the thicker washer is closest to the pad. This setup is the only way that I could get the drive side pad far enough from the rim so that it does not rub, and the opposite pad close enough to the rim to brake. The tension adjuster on the drive side is screwed all the way clockwise, and the tension adjuster on the opposite side has been backed off as far as possible. Any suggestions to get the brake arms more perpendicular?
I was able to ride today!

Thanks again,
Uni

MilitantPotato

On the part the brakes screw into, there should be three holes, make sure both brakes have the thin spring portion in the middle hole (spring pre-load setting IIRC.)

Both pads should have the spacers the same, then center the arms via the two very small screws/allen bolts on the sides of the brake arms. Is your wheel centered in your forks? It's sometimes necessary to put weight on the handlebars before tightening the quick release skewer to force the axle into both forks.

Having the spacers different on each side will cause one side to push harder on the rim than the other, twisting the wheel.

https://www.sheldonbrown.com/canti-direct.html

I'd highly recommend taking the bike into a shop if that site makes no sense, having brakes that aren't properly set up isn't a good thing. I'd not think they'd charge more then 5-10 dollars.

operator

It is also possible that the wheel is out of dish.

MilitantPotato

True, but less likely and since the arms are at crazy angles that'd be a severely fubar'd dish. Although from the angle the pictures are taken it was hard to tell if the wheel is leaning or off centered, but on a second look, it doesn't look like it is. I'm guessing he's got the springs in different holes and/or the adjustment screws are way off.

operator

That is not correct.

Sometimes it is the fork/brake brazeon mounts itself that is off even if the wheel is

a) seated properly in the fork
b) in perfect dish

You cannot claim that the spacers HAVE to be equal on both sides. Having the sapcers different on each side DOES not automatically cause one side to "push harder". The adjustment screws can be adjusted to compensate for that.

Unicornz0

There must be a adjustment problem, or a problem with the fork brake mounts. At present, there is about the same amount of space from the rim to the brake pads on both sides. The brakes and wheel where fine before I installed the new fork. Based on my above description, what can I do to move the non drive side pad closer to the rim without moving the drive side pad closer to the rim? There is only one position for the tension spring on the fork. The wheel is centered, true, and I'm sure not out of dish, as this problem only occurred when I reinstalled the brakes on the new fork. Please help me get these brakes adjusted properly.
Thanks again,
Uni

operator

You cannot assume anything.

1) CHECK that the wheel is actually in dish
2) Put the bike on the ground. Open and then close the QR. This is enough to seat the wheel properly in the fork.
3) Squeeze the brake once
4) Take a picture (two) from the front of the bike that shows us the pad distance (both drive and other side) from the rim and post it.

The biggest problem right now is that we cannot see what the setup currently looks like.

Unicornz0

I'll post a picture shortly. I just have to get enough light on the bike for the picture to be worthwhile. The dish could not have changed with the installation of the new fork. The bike was not rode, the wheel was not dropped, etc. Only the installation of the fork has changed. The design of this fork is vastly different from the previous fork. That is why I had to change the spacers.
Thanks again.

operator

You know for sure the wheel was in dish before... as well? That's what i'm getting at. You can't assume this just because it worked on your old bike.

MilitantPotato

They don't HAVE to be equal (note that I said should,) but it does change the mechanical advantage the arms have, swapping the spacers around can have a very noticeable affect on clamping force. If one arm squeezes harder than the other, I'd think it would overpower the opposite arm, bending the wheel a little.

The brazeons would need to be off by a lot for that kind of difference, if that's the case the fork needs warrantied.

operator

It does not affect anything.

This type of repair has been done a billion times in the shop already (note: if necessary) The 'rim' is pushed to aside in all cases. You cannot get the brake arms to hit *exactly* the same time. You can get it close enough that it's not apparent visually.

Unicornz0

I don't know for sure that the wheel was in dish before changing forks, but it probably was, as there were not any apparent problems prior to replacing the fork. I measured the distance from the brake mounting posts to the rim. Both sides are measurably the same.

Here are the pictures, drive side, non-drive side.
Thanks again everyone for the help.

Unicornz0

Here is the inverted view, drive side on the right.

Unicornz0

When I adjust the tension screw clockwise on the drive side brake pad it moves that pad away from the rim. How does it affect the non drive side pad?
Thanks in advance,
Uni

desertdork

Currently, you have the thin washer adjacent to the pad on the drive side and the thick washer adjacent to the pad on the non-drive side. You also have the spring tension screw cranked down on the drive side and the tension screw completely backed off on the non-drive side. Nothing about this seems balanced. Isn't it possible that you made these setup decisions prior to having a good understanding of how to install/setup/adjust these brakes?

How about just going back a few steps to get things started better? Make certain the wheel is installed correctly. Loosen the cable pinch bolt and equalize the spring tension screws so there is some (but not excessive) spring tension on each arm. Using your thumb to move each brake arm toward the wheel will give you an idea of the amount of tension. Switch the DS washers so the thick washer is next to the pad (as it is on the NDS). Set the pads for correct contact with the rim and connect the cable.

Now you're ready to fine tune the brakes via the spring adjuster screws (see the post by panthers007) and the barrel adjuster. In the absence of an possible issue with wheel dish or the fork itself, this should be quick and painless.

operator

This is good. Make both sides have the same spacer arrangement and go from there.

Unicornz0

Thanks to everyone for your help. I took the brakes apart and started from scratch. Set both tensions screws about the same, same washer pattern on both sides, thin closest to the pad. I reinstalled the brakes, and after getting both arms perpendicular and only minor pad rub, I started on the adjusters. Eventually, everything lined up and now is perfect, with every one's help, and the grace of Jesus.
Now, I intend to go for a ride! Whew!
Thanks again,
Uni