Rear disc Cover/Plate

[stutrump]

Hi folks.
Not sure what it is called but that Rear Disc cover/plate thingy has been warped on my bike for a while and now it is cracked. My question is would I be able to remove it and ride temporarily whilst I wait for a new one? Thanks for any advice. Photo should be attached.

 

[Juan]

How on earth did you manage that? Are you sure the rear pads are not sticking? The rotor looks pretty used. I'm not sure you can ride without the cover, so I'll let others advise you on that.

 

[EricV]

Sorry, I'm not seeing the issue in your pic. Are you referring to the rear sensor housing? #22 here LINK

Or the finned disc plate, #3 here? LINK

If the disc plate, I don't see any issues with riding w/o it other than it's very common to damage the brake rotor bolts when removing them. Use an impact driver, it helps a lot, but it's still common to damage them. I average 1 or 2 every time, even with the correct tools.

As others have said, the sensor housing that holds the ABS sensor needs to be there for ABS to work. IF you tied the ABS sensor up out of the way, (I'd wrap it in padding and put it in a plastic bag, then tape it up before zip tying it to the bike), you'll have an ABS fault, but the bike should be rideable w/o the cover. More chance of contaminates getting to the bearing and the sensor plate being damaged, but if you avoid water crossings and mud, probably not too big a deal, imho.

 

[WJBertrand]

Why wouldn't you just leave it in place until the new part arrives? No sense in doing the work twice.


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[Checkswrecks]

Why wouldn't you just leave it in place until the new part arrives? No sense in doing the work twice.


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::026::


You will probably also need to replace the disc. Check it for run-out.

 

[stutrump]

Thanks folks.
EricV: It is the No.3 thing.
Everyone else: I have to use my bike every day and Im worried that cracked part which is also warped will catch on the caliper hanger as it turns. Probably need a new disc too! Thanks for your help folks

 

[WJBertrand]

Thanks folks.
EricV: It is the No.3 thing.
Everyone else: I have to use my bike every day and Im worried that cracked part which is also warped will catch on the caliper hanger as it turns. Probably need a new disc too! Thanks for your help folks

If you're talking about the hub plate that holds the ABS sensor, it does not rotate with the wheel.

 

[EricV]

If you're talking about the hub plate that holds the ABS sensor, it does not rotate with the wheel.

He's not talking about the hub plate that holds the ABS sensor. It's the finned disk plate that is really just a piece that fits over the brake rotor. I have wondered in the past what the point was to that piece. you don't see it on other Yamaha wheels, or other motorcycle wheels in general. I don't know if it is intended to help clean out mud, or offers any cooling benefits to the rotor, but it's just sandwiched between the bolts that hold the rotor to the wheel. For all I know, it's purely decorative!

 

[Don in Lodi]

He's not talking about the hub plate that holds the ABS sensor. It's the finned disk plate that is really just a piece that fits over the brake rotor. I have wondered in the past what the point was to that piece. you don't see it on other Yamaha wheels, or other motorcycle wheels in general. I don't know if it is intended to help clean out mud, or offers any cooling benefits to the rotor, but it's just sandwiched between the bolts that hold the rotor to the wheel. For all I know, it's purely decorative!

::026::
And I'd like to know how all that got done to the part; warped, cracked... It bolts flat through the rotor, the rotor is held flat to the hub. Nothing there to warp. With the bolt still in place holding the two halves of the break down, it shouldn't be possible for it to lift enough to contact anything. There's just a hollow space behind it with the bosses for the rotor cast in along the edge of the dish. It does protect the edges of the sensor hub. I see some of that infamous UK corrosion...

 

[EricV]

Just a guess, but aluminum heats up faster than steel. I'm guessing a lot of rear brake use, or dragging rear brake, (which we have seen with crud on the pivot or mis-adjusted foot pedal). I suspect the heat simply transferred to the aluminum plate from the rotor and the expansion speed caused it to warp before it normalized across both materials.

 

[stutrump]

Thank you folks...especially EricV who must have a crystal ball that understands my ramblings very well. You're spot on EricV. In the hope that it doesn't lift any more I will just leave it on until the new part arrives. Yes..uk corrosion! Theres more salt on the roads here than on my chips...sorry...fries! Roll on summertime when it rains every day to wash the roads down. We should get a medal for living in this bloomin climate!! Thanks all.

 

[EricV]

@Stutrump - We're a community that helps our mates. ::012::

Considering the wonders of the salt air of your island, I would order a full set of brake rotor bolts before swapping parts out, just in case. I have found decent ones at the breakers for cheap. Poke ebay UK or your local bike breaker and see if you can score them for a reasonable price before going to Momma Yamaha. Part number for the rotor bolt is 90149-08029-00, but R-1s use the same size, as do many other bikes. Just be careful as different years sometimes have a different amount of threads. Yamaha wants around $2 usd each.

 

[Checkswrecks]

Excellent thought about replacing the bolts when replacing the plate. My other thought is that the photo makes me wonder if the bolts were previously over-torqued or unevenly torqued. Either way, torque stretches bolts, and a heating disc will make that aluminum plate expand yet more. Be careful about torquing the new ones and don't add a little extra oomph.

 

[stutrump]

Thanks checkswrecks and thanks EricV. You must have heard about me EricV because I probably will shop around before going to Momma Yamaha. Cheers

 

[Sean1400]

Just seen this post while looking for a replacement cover, mine warped and cracked the same as Stutrump

 

[EricV]

@Sean1400 - That looks ugly! Rotor itself looks ok from this angle. Have you double checked the brake rotor for run out/warping? Just a quick and dirty with the wheel on the bike and some fixed pointer near the rotor to see if it wanders would be enough. Good on you to read through this thread. Extra points M8 for searching the forum!