Rear Brake Master Cylinder Bolt help needed.

:thumbsup: I was just trying to install my Devol frame guards on my 05. I could get all bolts out fine except for the rear master cylinder bolt. It is the lower allen head bolt. I heated it up, but that thing is not moving. I did not totally strip it out, but it is starting to wear the bolt. How the heck do I get it out? If I end up stripping it will it come out with a easy out, or do I have to freaking drill and re-tap it? That thing is freaking seriously tight, and must have lock tight on it.

Hey dl19,

Its funny you asked this, as I just got finished with removing the stripped piece of chit. I rounded it off and then tried the drill and extractor bit. Yeah, I broke off the damn extractor inside the bolt. :thumbsup: I ended up taking it to a welder and having them mig another bolt onto it to remove it. Best damn 20 bucks I ever spent. (also removed a stripped skid plate bolt) I spent about 20 bucks in drill bits, extractor, etc, and I could of saved myself an hour of work for 20 bucks to begin with. :thumbsup: Live and learn I guess

P.S. I HATE YAMAHA BOLTS - they are soft as butter

I would try this, take a Dremel tool using the cutoff wheel and cut a groove in to the head of the bolt, then go back and heat the crap out of the area and take an impact wrench to it with a big flat bit and bang it out. Nothing beats heat and impact.. I've had the same problem with the same exact bolt, once I got it out I installed a Helicoil... good luck, let us know what happens...


The impact drivers you hit with a hammer are a must for stuck hardware. The best $15 or 20 you could ever spend.

This worked great for me. The bolt head is huge compared to the bolt shank. I simply drilled the head off the shank like a rivet leaving the shank in the brake master cylinder. Twist the master cylinder clockwise (only requires amount of movement allowed by brake line) while holding the top bolt with a allen wrench. Turning the master cylinder loosens the bolt (who freaking knows why), and then simply turn the top bolt out with the allen wrench. Use good quality (not cheap 1.99 or welded/oxy cut) vise grips on the small portion of the lower bolt protruding out the back of the master cylinder. Twist the shank all the way through the master cylinder. I then replaced with SS allen head bolts. Worked perfectly for me.

Good advice from the guys. I run the Devol frame guard and I ended up replacing mine with a hex head bolt and have had no more issues with that soft headed low profile factory bolt. :thumbsup:

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