Hot rotor on rear brake

[HeckticHaze]

So I got the brake system back together again. I did end up completely disassembling the MC and cleaned it again. The bypass hole was clean. Disassembled the caliper, cleaned it and reassembled it. I did not install the brake pad shims and skimmed the brake pads a little with the belt sander. I did not brake the calipers apart. The caliper pistons went in easy by hand. Bled the system. Just spinning the rear wheel and applying the brake it seemed better.

I took the bike out for a short ride. Applying the rear brake it squeals like a pig. Probably because the shims are out. I tried the last few miles to not use the rear brake before pulling in at home. The rotor is somewhat hot but not fry an egg hot like before. It just bothers me I can put my hand on the front rotors which I was using for braking and they were not hot to the touch.

I have made progress. Not 100% satisfied I have the problem solved. The only thing I have not replaced is the caliper pistons but they really did not look bad. My friend made a suggestion to remove the dust seals but I really did not want to do that. I would think the main piston seal would get crapped up pretty quick without the dust seal in place. I'm out of ideas. Any other suggestions would be appreciated.

 

[Fire-medic]

OK, I forget, did you try replacing the caliper seals, isn't that what Sean suggested? The seals provide some 'pull-back/retraction' for the pistons.

The pistons, if you can move them in and out with finger pressure, I don't believe to-be the problem. Of course mounted on the bike, you cannot perform that.

About the only other thing I can think-of, how is it to bleed the brake? Is it difficult, with a lot of resistance to fluid flowing? You may have a piece of crud lodged somewhere in the system, preventing the free-flow of fluid. Did you blow-out the passageways well, when the caliper was split in-two?

 

[HeckticHaze]

The caliper seals was the first thing I replaced. When I had the calipers apart the first time (and split apart) I cleaned all the passageways. Brake cleaner and compressed air. Ran new brake fluid down passageways before installing seals and pistons. Installed a rebuild kit into the MC. Cleaned it all out good. Checked that bypass hole again. Used rake cleaner and compressed air again.

Bleeding took a while even with the Mighty Vac but I got a good firm pedal. Fluid flowed out the bleed screws fine.

 

[Fire-medic]

The caliper seals was the first thing I replaced. When I had the calipers apart the first time (and split apart) I cleaned all the passageways. Brake cleaner and compressed air. Ran new brake fluid down passageways before installing seals and pistons. Installed a rebuild kit into the MC. Cleaned it all out good. Checked that bypass hole again. Used rake cleaner and compressed air again.

Bleeding took a while even with the Mighty Vac but I got a good firm pedal. Fluid flowed out the bleed screws fine.

If you use a reverse-bleed, the Mighty Vac will then collect dust sitting on a shelf, unused for your VMax. The reverse-bleed solves bleeding issues for VMax front and rear brakes, and the hydraulic clutch.

About the only thing not-discussed is the rear brake tension spring, and the foot pedal. If that was 'sticky,' that could affect your rear brake, causing it to drag. Check your foot pedal, check the spring (fiche part #32) check the mount, make sure what's supposed to be tight is, and what's supposed to be springing-back, easily, is. Make-sure that the brake actuation is NOT dragging.

Spring, Tension (description of the return spring for the rear brake pedal)

90506-18305-00

$3.97

https://www.ronayers.com/oemparts/a/yam/500456acf8700209bc793155/stand-footrest

 

[HeckticHaze]

So I went back and checked the spring attached to the rear brake pedal and the M/C. It looks connect correctly. I do not think it can be put in backwards. Action of the pedal and M/C seem smooth. No binding. The pedal returns to it's starting position when released. I still need to set the pedal height in relation to the peg. It is off but this should not affect the pedal operation. The end of the bolt that connects the M/C to the pedal is within that spec stated in the Yamaha manual. You have to be able to see it inside the side hole of the bolt.

If I get some time this weekend I will try the reverse bleed.

I just read a post from early this winter on rear brake drag on a 2005 Vmax. Talked about alignment of the rear rotor between the brake pads. Interesting use of shim washers between the rotor to the wheel and between the caliper mounting and its mounting bracket. It may require some further investigation.

I'll let you know my results from the reverse bleed.

 

[Fire-medic]

Something needing shims sounds like some misalignment from use of an aftermarket rotor. I've never seen a VMax which needs shims on an OEM rear brake assembly. The factory has no provision for one or the other (shimmed caliper or rotor). I suppose that there could be crash damage where a side blow could have affected something.

 

[HeckticHaze]

No signs of the bike being in a crash or dropped. It was worth asking after reading that other post. I'll look at it again. Maybe they did install a 3rd party rotor on it.

Is this "reverse bleed" something you just perform on the gen1 Vmax motorcycle brake and clutch systems or something you perform on all your different bikes?

 

[Fire-medic]

No signs of the bike being in a crash or dropped. It was worth asking after reading that other post. I'll look at it again. Maybe they did install a 3rd party rotor on it.

Is this "reverse bleed" something you just perform on the gen1 Vmax motorcycle brake and clutch systems or something you perform on all your different bikes?

I don't have anything newer, w/ABS brakes, I do it on my old-school disc-brake equipped bikes, or hydraulic clutches.

 

[HeckticHaze]

So with all the other work going on with this bike I had to remove the rear wheel to get a new tire put on. What a pain. The wheel would not clear the rear finder. Almost an inch or more. Ended up removing the rear fender to get the tire out. Next time drive the bike up on a 2"×12" platform and center stand it on that. Hopefully give me more clearance with the floor.

So unfortunately I found the rear rotor fractured in two spots. I did not see it on the bike. Both the front and rear of the rotor. Must have really heated the hell out of the rotor for this to happen.

Yamaha discontinued the OEM rear rotor. So either it's a used one on FleeBay or a 3rd party rotor. Has anyone got a preference on a 3rd party manufacturer they have used. The only one I have done research on is EBC.

 

[Fire-medic]

You're in Schenectady NY, go see if PCW Racing has anything for you.

PCW Racing
Address: 112 Henry St, Schenectady, NY 12304
Phone: (518) 346-7203

 

[[email protected]]

So with all the other work going on with this bike I had to remove the rear wheel to get a new tire put on. What a pain. The wheel would not clear the rear finder. Almost an inch or more. Ended up removing the rear fender to get the tire out. Next time drive the bike up on a 2"×12" platform and center stand it on that. Hopefully give me more clearance with the floor.

So unfortunately I found the rear rotor fractured in two spots. I did not see it on the bike. Both the front and rear of the rotor. Must have really heated the hell out of the rotor for this to happen.

Yamaha discontinued the OEM rear rotor. So either it's a used one on FleeBay or a 3rd party rotor. Has anyone got a preference on a 3rd party manufacturer they have used. The only one I have done research on is EBC.

Quite a few folks have mistaken the joints in the rear rotors for cracks. See this ebay ad and zoom in and you can see the joints in the rotor surface. Perfectly normal. 1985 85 YAMAHA VMX1200 VMX 1200 VMAX FRONT BRAKE ROTORS | eBay

Also, check out the old microfiche, its visible on there too. Yamaha Motorcycle 1992 OEM Parts Diagram for Front Brake-Caliper | Partzilla.com

 

[Fire-medic]

Quite a few folks have mistaken the joints in the rear rotors for cracks. See this ebay ad and zoom in and you can see the joints in the rotor surface. Perfectly normal. 1985 85 YAMAHA VMX1200 VMX 1200 VMAX FRONT BRAKE ROTORS | eBay

Also, check out the old microfiche, its visible on there too. Yamaha Motorcycle 1992 OEM Parts Diagram for Front Brake-Caliper | Partzilla.com

Yes a good point. There are narrow 'scores' running diagonally, not 90 degrees radially, from the axle hole, in the rotor braking surface.

 

[HeckticHaze]

Wow, I did not know the rotor was not manufactured from one piece of metal on each side or it is and they just score the surface for some heat expansion/contraction purpose. That is what I am seeing. My rotor still seems pretty burnt. Its surface is really blackened/blued. To much heat. Have a 3rd party rotor on order. I also ordered the OEM brake pads. Going to pull the rear caliper apart again and go through it once more. Tried contacting PWC Racing twice. Voice mail was full.

 

[gentsvmax]

Something needing shims sounds like some misalignment from use of an aftermarket rotor. I've never seen a VMax which needs shims on an OEM rear brake assembly. The factory has no provision for one or the other (shimmed caliper or rotor). I suppose that there could be crash damage where a side blow could have affected something.

Hey guy's
I really wanted to get in on this discussion since July and have only had time to keep up by reading on my phone.
I too have had this problem but not always. Caliper seems to not open wide enough after release, drags, overheats etc. I have a wide(300) tire/wheel and 5 7/16" stretch, Exactrep V-Line 5mm rotor, not being stock assembly and one-off parts adds to the mix
I can remove the wheel without any issue, it's putting it all back together is when the potential
for miss-alignment rear's it's ugly head.
Though I have a good easy system from start to finish, something just didn't go back the same.
I would sometime get the smell of a burning clutch or brakes when cruising the "strip" .
I would touch the back brake pedal, get normal travel but NOTHING for braking,WTF!
Come to a stop and the smell had been my rear caliper cooking the pads and rotor...
To assemble my non stock set-up I used .008 wave washers between the rotor and hub, one per bolt, perfect alignment and no issues ever with a hot caliper/rotor.
I had the bike apart, as usual, early this year and started having issues back in March and had already tried everything mentioned in these posts.
I had gotten a near new 04 caliper from an ebay vendor, TDCycle, they're located here in Denver
so I could walk-in buy it. That one was worse, my old stock rotor must have been paper thin too to never have had this issue before.
Next and to date I got a Harrison Billet 4 piston caliper from Exactrep ,new longer stainless line and fittings and still had the "hot drags" WTFFFu%KKK!
I have personally rebuilt every inch of this bike, and then some(another post), but I had never done a thing to the rear res, hose and master cylinder. I did an exploratory rebuild and in short order had no pedal at all, by the way I have always reverse bled everything, better, faster. So the idea of going from a stock 1 piston caliper up to the overkill 4 piston and the failure symptoms makes me think the stock master cylinder may not pump/flow enough volume for the new Harrison. TDCycles to the rescue with a new big bore master cylinder from a 05 Triumph 2300cc Rocket III. Configuration and mounting almost identical to Vmax. Once plumbed and mounted
I manually opened completely both sides of the caliper before the reverse bleed, I believe having the pistons at the top of their bore(s) helped in the resulting firm pedal.
The new master isn't really much bigger and as you can see(pics) I had to tap a new hole just above the stock bolt hole location. I also used a new res. container.
The brake light switch is now inline, I kinda like that set-up.
Better yet ,I really like the smooth,effortless rear braking power .

 

[HeckticHaze]

Gentsvmax, I have a question, why a wave washer and not a standard shim washer? I may run into the same issue alignment wise and have to shim the rotor or caliper.

 

[gentsvmax]

Gentsvmax, I have a question, why a wave washer and not a standard shim washer? I may run into the same issue alignment wise and have to shim the rotor or caliper.

Hey HH, the waves are thinner yet(.003) than the S.S. shim washer's(.005-8) I found at True Value.
Why True Value? The store's around here in Denver have a really good fastener inventory.

 

[HeckticHaze]

So I received my new EBC rear rotor and installed it on the rear wheel. Question, when I install the rear wheel back on the bike there is a collar on the right side that goes between the wheel's bearing and the caliper mounting bracket. That collar has a smaller diameter protrusion on it. Does this smaller diameter protrusion face toward the bearing or toward the caliper mounting bracket. I did not write down its orientation when I removed the wheel. Yamaha manual is no help.

Next question, the yamaha manual torque value for the rear axial nut is stated at 110 ft-lbs. That seems way to high. I read some older posts stating people were only using 40-50 ft-lbs. Is this lower torque rating ok for the 2007 Vmax model? I think the Yamaha front axial torque rating was 42 ft-lbs. Is that value to high in the manual and what should I use?

Waiting on new OEM brake pads and I have to get some 10mm shim washers.

 

[Fire-medic]

Sean ro CaptainKyle can probably answer that 'which-way does it fit' question off the top of their heads, you should be able to figure it out, because the collar is probably the spacer for the grease seal. It should fit snugly into its intended position, and you should be able to try it one-way and then the other, and it will immediately become apparent which way it's supposed to face. One way, everything should align nicely, the other way, you'll have an interference fit and things won't line-up.

I suspect the small portrusion will face the wheel, to provide spacing for the seal. The small portrusion edge should line-up with the inner bearing race edge. With the spacer properly installed, and the wheel and rear axle properly torqued, the rear wheel should rotate smoothly: no binding, no drag, no interference, and proper alignment of the caliper and rotor.

About the torque for the rear wheel, you cannot go-wrong with the stock specs.

the yamaha manual torque value for the rear axial nut is stated at 110 ft-lbs I don't know where that came-from I just checked the Yamaha Service manual and it says, 85 ft/lb. (attach.) If there is somewhere that it says 110 ft/lb. I think you're OK with the lower value.




It's shaft drive so it's not as-critical as it is on a chain-drive bike, where the rear axle needs to be torqued down to hold the chain tension, and to hold the final drive in position. I'm sure there are many old riders on-here who can tell you about what happens to the chain adjusters if you don't have the rear axle properly-torqued. The adjuster brackets end-up looking like potato chips, and you can throw a chain. The early SOHC Honda 750's had issues with throwing chains, as bikes of the time were sub-50 RWHP bikes, and the SOHC 750-4 would break the cases when it threw a chain. Manufacturers quickly realized the spec for OEM and replacement chains needed an upgrade, and that proper chain maintenance played an important part in avoiding catastrophic damage like broken engine cases. The use that a bike received was also a factor, a person who didn't ride his bike hard but who maintained the chain well, cleaning and lubricating it and tightening it properly, who pays-attention to worn sprockets needing replacement with the chain, would probably not have issues; where someone who regularly 'dropped the hammer' and who abused the bike, not-performing periodic chain cleaning and lubrication, and possibly not properly torquing the rear axle nut, is going to be the rider who has the chain jump worn sprockets, slam-into the cases, and break them.

I think a Harrison caliper in the rear is 'way-overkill, but it's your bike, so you get to install whatever you want. I suspect that such a powerful rear binder will make it harder to modulate your rear brake, causing frequent lock-ups. There's a thread on here about how-to choose a master cylinder, based upon the number of pistons and the bore of the master cylinder, I think Max Midnight was the first person who posted that. It's worthwhile to read, it will help you to know if your choices are correct, or what you can change to make the rear brake system operate optimally, once you begin to change components from OEM.

 

[HeckticHaze]

Right now I am only changing the rear rotor. I am still using the Yamaha caliper. An issue I just found is the EBC rotor is billet steel and requires an organic or what they call a V brake pad. I have to find out the materials used in the Yamaha OEM brake pads.

 

[02GF74]

The other thing I noticed was the difference in distance between the brake pads and the rotor when reinstalled the caliper (not centered). I did not think anything of it because I thought as you bleed the system the pistons will extend outward until contacting the brake pad and rotor then retreat back when the brake pedal is released.

Have you checked the run out of the rear disc? I had same on a z1000 - replacing the disc sorted it.