Minor Brake Rub on Rear

[utadventure]

I'm pretty good about riding with a helmet, mostly because I like tunes as I ride. Tonight I'm away from home assisting tomorrow in the MS150 ride for Multiple Sclerosis, I went to top off the tank and could hear some minor rubbing on the rear brake rotor (only in one spot, not all the tme)

 

Do you think opening the reservoir or the brake line bleeder valve solve the issue?

 

Dave

[friesman]

Mine does that too, and I think it is probably a slightly warped brake rotor. I only notice mine when backing out of a prking stall or out of my trailer. I never hear it at speed and dont feel any pulsing when stopping so Im not too worried about it.

 

My brakes stop fine and i dont think there is a stuck piston in the caliper as it looks like the pads squish against the rotor when I push the lever down. i was going to have a bit better look while the tire is out next week just to confirm before taking down to Cody.

 

brian

[skydoc_17]

Hey Dave,

Your MKII VR has a VERY large "semi floating" rear rotor. The object of the "semi floating" rotor is to allow the segment of the rotor that actually comes in contact with the brake pads, (outer most diameter) to expand and contract independently (due to heat from braking) of the rotor hub. (the part of the rotor that bolts to the wheel) Because of 25 years of stopping your bike, the exposure to heat from the braking process has caused your rotor to "take a set", (remain slightly warped, even when NOT exposed to the extreme heat of the braking process) Normally, if this were a "racing bike", the rotor would be changed out, due to the fact that the "memory" of the metal of the outer diameter of the rotor has been lost because of exposure to extreme heat during braking.

With the cost of a new rotor at close to $400.00, and the fact that the major "downside" of this condition is a slight loss in the number of miles you will get on a set of brake pads due to the constant rubbing, (you will notice one pad getting thinner than the other pad)

AS LONG AS YOUR REAR CALIPER IS FUNCTIONING PROPERLY, (ALL 4 caliper pistons are floating in and out, following the bend in the rotor surface) braking will not be affected.

Because of the extra heat generated by the rubbing pads, you could see a shortening in the service life of the rear caliper until one day, one or more of the caliper pistons will finally start to "drag", the rotor will be overheated and turn blue, and it will be time for a complete rear caliper rebuild. Which is here:

http://www.venturerider.org/classifieds/showproduct.php?product=2443&title=first-gen1986-1993-mkii-caliper-rebuild-21&cat=22

OR here for the MKI VR Calipers:

http://www.venturerider.org/classifieds/showproduct.php?product=2642&title=first-genmki-1983-1985-caliper-rebuild-21&cat=22

Watch your brake pads closely, as one pad is going to wear much faster than the other side. (usually the inner pad, which is harder to see, but it could be either side) If the backing plate for the brake pads is allowed to come in contact with the rotor, physical damage to the rotor will result, and not only will you be buying a new set of brake pads, but a new/used rotor as well.

Do I think you need to rush out and buy a new rotor, Hardly, (my own rear rotor on my 87'VR has been like this for several years) BUT you will need to keep a close eye on the function of the rear caliper and the wear on the brake pads so you don't compound your rear braking issue. If I can help you with rebuilt calipers, pads, or you have other questions about this issue, please feel free to PM me.

Just my thoughts, for what they are worth.

Earl

[Flyinfool]

The other good test is to put the bike up on the center stand and turn the rear wheel slowly by hand. when the dragging gets bad enough to be tight when turning by hand it is probably time to do something.

Mine has been dragging for 5 years now, on the center stand I can just barely feel the spot that it drags, as long as it does not get worse and the brakes work properly I'm fine. I check it every time I check tire pressure.

[utadventure]

Thanks for the responses. They are very much along the line of what I was thinking, but it's always best to check with those smarter than me (which includes all of you).

 

Earl, that's for your wealth of information in your post.

 

Dave