Pulsating rear 87 VR

[Pasta Burner]

Only put 100 miles on my new toy and I’ve noticed that the rear brake was pulsing and hot to the touch after a ride. I adjusted everything and got it where I like it and the freeplay where it should be so no more drag. I’m still getting a pulsating brake that is only really noticeable just prior to a stop. In all my experiences this is indicative of a warped rotor, being that these are linked brakes is there an easy test to narrow down front or rear?

[cimmer]

Only put 100 miles on my new toy and I’ve noticed that the rear brake was pulsing and hot to the touch after a ride. I adjusted everything and got it where I like it and the freeplay where it should be so no more drag. I’m still getting a pulsating brake that is only really noticeable just prior to a stop. In all my experiences this is indicative of a warped rotor, being that these are linked brakes is there an easy test to narrow down front or rear?

 

It does sounds like a bent or warped rotor and most likely is the rear rotor and not the front. I believe in theory that the rear brake applies before the left front brake does. One thing to check is to make sure the rear washer is in the correct position on the right side of the wheel. It should be between the wheel and the caliper bracket. I had the warped issue on my 89 VR and ended up replacing the rotor with a used one that was not warped and made sure to test it before riding it and it was smooth when I spun it around by hand.

 

I would make sure to properly bleed the front and rear brakes also. If you dont have one, there is a copy of the Yamaha service manual in the Tech section and it will give you a lot of information on the proper way to bleed the brakes.

 

Good luck and let us know how it goes..

[Pasta Burner]

What is the washer you refer to? Is there a washer for each caliper bolt? I have not pulled the rear caliper. I bled the front handbrake and changed the pads, rear and front left pads are good but I plan to bleed that and the clutch while I have fresh fluid.

[Patch]

Also make sure or check that the rotors are correctly seated. The contact surfaces should be inspected for buildup which could prevent the rotor from seating flat, say if they had been removed and then not cleaned before re installation.

[CaseyJ955]

Another possibility is that the rear caliper could be hanging up causing the pads to drag on the rotor. That would let the rotor get good and hot, maybe hot enough to warp and have some heat discoloration. If this is the case then replacing the rotor will only subject the new rotor to the same heat and warpage. Get it on the center stand, put the bike in neutral, with the brakes warm roll that rear wheel around by hand while working the rear brakes with the other hand, you will then feel if the caliper is causing drag when you let off the brake. If memory serves me correctly, the caliper pistons only need to retract about 0.004" to let go of the rotor, so it wont be really visible to the naked eye, but if it's not properly releasing the rotor when you let off the brake you will feel it dragging and resisting. Even in neutral the rear wheel turns the driveshaft, so it might feel a little heavy that way, but drag from the brakes should have a distinctive feel.

 

On my 99 Vmax they were hanging up also so I disassembled the calipers, cleaned everything up and reassembled (keeping the same pistons and seals with their respective bores) with the old parts. The parts looked good so I cleaned out the sludge and they still work great, I even had to carefully scrape some buildup off the ID of the bores. For a 30+ year old machine it's not outside the realm of possibility that the caliper may need some love. If you DO end up needing brake parts then Mark at Brake Crafters is your guy. He has OEM and cost effective aftermarket, lots of it out of the UK. He refuses to sell Chinese parts anymore because of the problems with them . I've dealt with him a couple times and he's a 5 star guy.

 

Aged or kinked rubber brake lines can disintegrate from the inside out, causing a sort of check-valve effect keeping pressure in the caliper, making it look like the caliper is dragging, less likely but possible. If you experience a dragging caliper out back, crack the bleeder screw on the caliper just long enough to see if it reduces drag of the rear brake(w/o touching the brake pedal) and if the caliper lets go of the rotor freeing up the brakes then the issue is further up the line. If you do end up pulling the rotor remember what Patch said about any matter or gunk getting between the mounting surfaces causing it not to sit true on the rim.

 

The same can be done up front, I just use a floor jack and a pad to gently get the front wheel off the ground while on the center stand, then you can see if there is any real drag up front. On my 89 all the calipers were dragging so I did the conversion to R6 calipers.

 

If there is no abnormal drag in the caliper then your ahead and may now crack open a beer while looking for a replacement rotor. .

Edited April 25, 2020 by CaseyJ955

[Pasta Burner]

Thanks for the info guys. I’m gonna dig into it further and thanks for the tip on how to jack up the front end without a motorcycle jack. Which I still might get anyway. The front right caliper and rotor was like nothing I’ve ever seen. Inside pad was practically gone and outside practically new. Also slathered in grease, like lithium high temp grease. I think maybe the P.O. wife was trying to kill him 🤷*♂️. I didn’t rebuild the caliper in the interest of getting on the road, but I did scrub a lot of crud off and cleaned it up well. Also got some scum out of the inside as the inside pad was so worn the pistons fell out. Coming from a sport bike where my handbrake controls two four piston calipers on slotted, cross-drilled floating rotors; I naturally expect a lot more when I squeeze that handbrake. Will keep you posted with the progress.

[cimmer]

What is the washer you refer to? Is there a washer for each caliper bolt? I have not pulled the rear caliper. I bled the front handbrake and changed the pads, rear and front left pads are good but I plan to bleed that and the clutch while I have fresh fluid.

The washer is on the rear axle and goes between the wheel and the caliper bracket. I have see where people put the washer between the swingarm and the caliper bracket and this force the caliper out of alignment with the rear rotor.

Hope that helps.

 

Rick F.

[CaseyJ955]

Thanks for the info guys. I’m gonna dig into it further and thanks for the tip on how to jack up the front end without a motorcycle jack. Which I still might get anyway. The front right caliper and rotor was like nothing I’ve ever seen. Inside pad was practically gone and outside practically new. Also slathered in grease, like lithium high temp grease. I think maybe the P.O. wife was trying to kill him *♂️. I didn’t rebuild the caliper in the interest of getting on the road, but I did scrub a lot of crud off and cleaned it up well. Also got some scum out of the inside as the inside pad was so worn the pistons fell out. Coming from a sport bike where my handbrake controls two four piston calipers on slotted, cross-drilled floating rotors; I naturally expect a lot more when I squeeze that handbrake. Will keep you posted with the progress.

 

From it being on the center stand you will notice that it's very easy to lift the front and let the rear wheel touch down, teetering on the center stand. I take just a plain ol' automotive floor jack and slip it under the oil filter housing (almost no weight on it) area and give it a couple pumps by hand until there is light under the front wheel. If you still have that lower fairing I think it's 4 screws and it pops off exposing the underbelly and filter housing. Thats how I lifted the front w/o a motorcycle jack to service the steering head bearings, front brakes and the forks. When I pulled the wheels to go into town and have new tires put on, it was there with just the center stand and a floor jack.

 

If you got some pistons jumping out on one side then the other side probably has the pistons seized in there with gunk. R1/R6 calipers are an easy conversion if your existing calipers are too far gone.

Edited April 26, 2020 by CaseyJ955

[BlueSky]

Brake rotors should be hot to the touch after a ride. Brakes convert kinetic energy (energy of motion) into heat. That's what they do. If you check the rotors temperatures with an infrared thermometer and one or more is very hot, then it's highly likely that the caliper is sticking.

Edited April 26, 2020 by BlueSky

[Flyinfool]

Rotors only get hot if you are in stop and go traffic and riding aggressively. My daily commute of 22 miles one way in city traffic would have all 3 rotors up to about 15-20°F above ambient temps. And that is with 300 lbs on the bike (me plus all the junk I store in the bags).

 

It is also a common issue to over fill the rear master and when the fluid heats up and expands with no where to expand to, it will grab the rear brake. This can be relived if you have a wrench to fit the bleeder with you and if the rear is dragging just crack and re-close the rear bleeder to relieve the pressure. This is one of those runaway things, the hotter it gets the more the fluid expands and the more the fluid expands the harder it drags and the hotter............ This can progress to the point that it locks the rear wheel so that you can not move the bike at all. Crack the bleeder and all is good again.

 

This itself will not cause pulsing, but the heat from dragging can warp the rotor and cause pulsing.

[Pasta Burner]

Thanks for all the replies. No update as I’ve been consumed in housework this weekend. I did walk past it about 200 times today and thought about messing with it. The dreaded center stand stopped me. I had my right knee reconstructed and a ligament replaced less than a year ago; it’s very painful to get it up on there and was already bothered from yard duty. I will get to this within the week though.

[CaseyJ955]

I forgot to mention on jacking the bike up that I used jackstands under the highway bars just in case.

 

Also it might be easier to pop it up on the center stand with a bit of extra air in the shock, I find it a real bear to do as well.

[Pasta Burner]

I forgot to mention on jacking the bike up that I used jackstands under the highway bars just in case.

 

Also it might be easier to pop it up on the center stand with a bit of extra air in the shock, I find it a real bear to do as well.

Good to know. I cut a piece of 2x6 to keep in the saddlebag, the only way I can get it on the center is to put the rear tire on the board first. And yes I’ve found more air helps, but not enough.

[Marcarl]

What might also help is t make sure the center stand is well lubed.

Also, when you go to set it up, right foot on the center stand, one hand on the handle bar and one on the side rail,,, now push down on the stand using your hand on the side rail to help give he needed push, then pull back slightly on the handle bar for rearward movement encouragement. Focus needs to be on the foot that is working the stand.

[Pasta Burner]

The washer is on the rear axle and goes between the wheel and the caliper bracket. I have see where people put the washer between the swingarm and the caliper bracket and this force the caliper out of alignment with the rear rotor.

Hope that helps.

 

Rick F.

 

seems I’m doing more work than riding but for sure the washer is between the swing arm and caliper bracket. Changing tires I’m putting it back together as you suggest.

[Pasta Burner]

Only went out for a handful of miles to scrub in the new tires and just finally get back on two. I wasn’t paying attention fully for a pulse as I was more concerned with if I balanced the new rubber sufficiently. But I’m pretty sure moving that washer to the inside did the trick. No noticeable pulse that I recall.