Rear Brake Disk replacement

[Husafreak]

I was surprised by a premature failure of my rear brake pads resulting in a ruined rear brake disk. Replacing it looks simple enough. Manual says to use new bolts, locktite, 18 N.m torque. Since it uses locktite I should probably heat the screws before removal. But what should I use? Red or Blue strength locktite? Is it really necessary to replace the bolts?

Thanks.

 

FWIW a friend rode my bike and cooked the rear rotor, pretty colors  I did not realize this would ruin the pads. Should have paid more attention for sure.

[Dan M]

Try to loosed the bolts first without applying too much pressure. They'll probably come out. I swapped rotors to my Alpina wheels and had no issues removing them.

If you need heat, I wouldn't use much more than a heat gun. Anything more can damage the finish on the hub.

Clean the threads and apply blue locktite. 

Typically, replacing bolts is only needed in "torque to yield" applications where the bolt is stretched.  Not likely at 18nm.

Edited September 5, 2023 by Dan M

[Alan M]

I haven’t replaced a rear disc on the T7 but have replaced quite a few discs on other models.

 

 I usually heat the back side of the hub first and use an impact driver to remove the socket bolts.

 

These type of socket bolts have a habit of rounding if you just try to torque them off. If you haven’t got an impact driver better to ‘crack’ the bolts than just turning them.

 

 I usually replace the bolts if the hex insert shows any signs of rounding.

[Husafreak]

Thanks guys, I agree that the torque spec is low but Yamaha seems to over tighten everything during factory assembly. I'm concerned about rounding out those hex insert bolts and that's why all the questions. I do have a heat gun so I'll use a little heat and try not to mess up the finish. I have an impact driver too so I'll use that. I don't really know when to use impact drivers, I need to read up on that! And by "cracking" the bolts I guess you mean a sudden yank rather than slow and easy. The dealer said they have bolts on hand if I need them. He also said to use red Locktite or green retaining compound! I thought that green stuff is for permanent assemblies.

 

On a side note I was surprised by that prices and availability of the OEM replacement disc. Out of three Yamaha dealers in my area two wanted $122 for the disc and the other $136! That guy got mad at me and hung up when I told him I'd pass, LOL. Only one had stock though and wanted $15 to ship it. I gave up on them and got one for $95 with free shipping from an internet dealer who had 7 in stock. Prices are so crazy and vary wildly these days, at least here in the states.

[Alan M]

Yeah, quick yank with a good fitting hex bit but an impact driver is better.

 

I normally use blue locktite as Dan recommended.

[Husafreak]

Good grief, has it been two weeks already! No one near me had a disk so I ordered online, waited 10 days. Removed the ruined disk with heat gun and impact wrench. Bolts started out turning slowly but then came right out with no damage   The replacement disk sent to me was the wrong part   I should have looked it up myself but I just searched by bike and Motosport Outlet got it wrong, plus they sent in it a bag, no box! No padding at all. I'm amazed the disk stayed in the bag. Never again with them. Yesterday I drove 160 miles R/T to a shop that had the part. Yamaha itself is out of stock with an ETA in October. I got the correct OEM disk. Aftermarket disk's are more expensive. I decided to use red Locktite for reassembly, it looked like that is what it was assembled with, plus 18 Nm is not much torque at all and I've found that while red definitely is stronger than blue by design if you heat either before disassembly the bolts will come out easily. I learned when to use an impact driver though! Thanks.