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Discussion Starter · #1 ·
I removed my 2008 ZX-6R's rear wheel to change both the rear sprocket and the rear brake rotor. The old sprocket bolts came out no problem, but the brake rotor bolts were an issue.

The brake rotor bolts are supposed to be torqued to only 20 ft lb, and are suppsoed to have a NON-permanent thread locker (i.e. Blue Loctit versus Red Loctite). They are very small diameter bolts - 6mm - and are quite long.

They also have "buttonheads" with a very SHALLOW hex because the buttonhead itself is very shallow. This means a very small surface area for a hex socket to engage.

In addition, I discovered on the 1st of the 4 rotor bolts that:
  • They had been installed with RED thread locker, not Blue
  • The threads extend BEYOND the thickness of the wheel surface they thread into the "hollow" and open-to-the-environment area of the wheel hub, where they can accumulate lots of dirt and corrosion in 13 years because you cannot get at them to wash them when cleaning the bike
  • The bolts were VERY hard to remove - hard to believe that they had been installed at only 20 ft lb.

Since REAR brake rotors are very seldom actually replaced, I realized that there were probably the OEM installations (maybe "non-permanent" thread locker in Asia is red, not blue??), and 13 years later, the thread locker was REALLY "locked".

With careful work, and preheating of the boltheads with a heat gun, the first 3 bolts eventually came out unharmed, but still coated FULL length of the threads with crusty red thread locker and leaving threaded holes full of thread locker still in place!

But the 4th bolt's hex deformed like butter immediately as I applied even modest torque by hand to its hex.

Gently tapping the hex socket inside the buttonhead before trying again did not help - the socket immediately turned but the bolt did not, further deforming the hex in the buttonhead. In a final desperate effort, I used an impact wrench, applying plenty of downward pressure before pulling the trigger, but no success - the socket immediately spun in the hex.

I have no knowledge, skills, or experience in extracting bolts with stripped heads. And a buttonhead leaves no circumferential surface to grab with vice grips. It is also impossible to get at the exposed ends of the bolts inside the wheel hub; I can SEE them, but cannot possibly grab them in an effort to turn them to break them loose from that end.

I CAN just abandon the effort to change the rotor, by simply reinserting the other 3 bolts, as the 4th bolt IS still doing its job of holding the rotor to the wheel just fine - I just cannot remove it. But, I'd like to get the lighter weight and vastly improved appearance of the new swoopy lightweight rotor. Plus I don't like having disfigured boltheads on my bikes. So, I would prefer to be able to somehow extract the 4th bolt to replace it, and put my new rotor on.

Any advice on how to remove that 4th bolt now withOUT risking creating a situation where it is still not out but no longer doing its part to hold the rotor in place?

Jim G
 

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First of all, don't heat the heads, heat the threads, that's the part locking everything up.

Now that the bolt is deformed, try a torx drive bit slightly larger than the original hex head, hammer it in there, heat the hell out of the threads,
connect an impact driver, and smack it real good with a solid heavy hammer, something's gonna give.

Alternative: Find an accomplished welder nearby, someone with race bike, race car experience. He can weld a
nut onto the head of the bolt, the heat from welding melts the red stuff, then he can remove the bolt with a wrench.
 

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I removed my 2008 ZX-6R's rear wheel to change both the rear sprocket and the rear brake rotor. The old sprocket bolts came out no problem, but the brake rotor bolts were an issue.

The brake rotor bolts are supposed to be torqued to only 20 ft lb, and are suppsoed to have a NON-permanent thread locker (i.e. Blue Loctit versus Red Loctite). They are very small diameter bolts - 6mm - and are quite long.

They also have "buttonheads" with a very SHALLOW hex because the buttonhead itself is very shallow. This means a very small surface area for a hex socket to engage.

In addition, I discovered on the 1st of the 4 rotor bolts that:
  • They had been installed with RED thread locker, not Blue
  • The threads extend BEYOND the thickness of the wheel surface they thread into the "hollow" and open-to-the-environment area of the wheel hub, where they can accumulate lots of dirt and corrosion in 13 years because you cannot get at them to wash them when cleaning the bike
  • The bolts were VERY hard to remove - hard to believe that they had been installed at only 20 ft lb.

Since REAR brake rotors are very seldom actually replaced, I realized that there were probably the OEM installations (maybe "non-permanent" thread locker in Asia is red, not blue??), and 13 years later, the thread locker was REALLY "locked".

With careful work, and preheating of the boltheads with a heat gun, the first 3 bolts eventually came out unharmed, but still coated FULL length of the threads with crusty red thread locker and leaving threaded holes full of thread locker still in place!

But the 4th bolt's hex deformed like butter immediately as I applied even modest torque by hand to its hex.

Gently tapping the hex socket inside the buttonhead before trying again did not help - the socket immediately turned but the bolt did not, further deforming the hex in the buttonhead. In a final desperate effort, I used an impact wrench, applying plenty of downward pressure before pulling the trigger, but no success - the socket immediately spun in the hex.

I have no knowledge, skills, or experience in extracting bolts with stripped heads. And a buttonhead leaves no circumferential surface to grab with vice grips. It is also impossible to get at the exposed ends of the bolts inside the wheel hub; I can SEE them, but cannot possibly grab them in an effort to turn them to break them loose from that end.

I CAN just abandon the effort to change the rotor, by simply reinserting the other 3 bolts, as the 4th bolt IS still doing its job of holding the rotor to the wheel just fine - I just cannot remove it. But, I'd like to get the lighter weight and vastly improved appearance of the new swoopy lightweight rotor. Plus I don't like having disfigured boltheads on my bikes. So, I would prefer to be able to somehow extract the 4th bolt to replace it, and put my new rotor on.

Any advice on how to remove that 4th bolt now withOUT risking creating a situation where it is still not out but no longer doing its part to hold the rotor in place?

Jim G
Do you own a welder or know someone with a welder because you could just weld a nut on the head that’s stripped and wrench it out
 

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Discussion Starter · #6 ·
Haybaler and Green: Thank-you! I forgot those hand impact drivers exist. I actually owned one in the late 1960s and early 1970s because back then you NEEDED one to get MOST of the very soft bolts out of Japanese bikes when working on them. Even the crankcase covers on the 2-strokes that covered up the ignition points that had to be adjusted (frequently).

I really like that idea for this situation. And if iit does not work, nothing is lost, because the bolt will still be in there and still holding the OEM rotor on along with the other 3 bolts. And the further disfigurment of the hex in the bolt head will not make much difference to appearance. If it does work, I can install the new rotor and use the replacement bolt already ordered.

And those hand impact drivers are not very expensive.

A really neat potential solution. Thanks!

Jim G
 

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If you don’t need the old rotor, grind down the head of the screw maybe drill the head off?

if there’s any thing left after removing the rotor try to use to remove, if not, drill it through and re thread. It’s easier than you think. These materials are pretty soft.
A dremel with at least 3 burr blades will do it little by little. It’s brutal but it will come out, it’s worth the effort.
 

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If you don’t need the old rotor, grind down the head of the screw maybe drill the head off?
if there’s any thing left after removing the rotor try to use to remove, if not, drill it through and re thread. It’s easier than you think. These materials are pretty soft.
A dremel with at least 3 burr blades will do it little by little. It’s brutal but it will come out, it’s worth the effort.
Yes, another method, and probably okay if the bolt is the one shown in parts diagram, 8mm X 30mm,
though I'd be happier doing the drilling on a milling machine; dremel can damage threads and a drill bit can get crooked.

But, OP described it as "They are very small diameter bolts - 6mm - and are quite long."
So, I'm a little confused about the actual dimensions of the bolt.
When he gets it out, maybe OP can post a picture?
 

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Discussion Starter · #9 ·
Yes, another method, and probably okay if the bolt is the one shown in parts diagram, 8mm X 30mm,
though I'd be happier doing the drilling on a milling machine; dremel can damage threads and a drill bit can get crooked.

But, OP described it as "They are very small diameter bolts - 6mm - and are quite long."
So, I'm a little confused about the actual dimensions of the bolt.
When he gets it out, maybe OP can post a picture?
All the bolts are back in the rotor for the time being (so I can ride the bike while I decide if it's worth the risk to try to extract the bolt with the messed up head), so I cnanot measure the diameter of the threads. The hex in the head is 6mm. I THINK the threaded diameter looked more like 6mm than 8mm, but I could be wrong.

Ive pretyt much decided that the hand impact tool is the only thing I will try. My reasoning is that if it works at getting the old bolt out, then great. But if it fails, then the bolt is still in there and the other 3 bolts are as well, so the OEM rotor is secure, and the only "damage" due to trying the impact tool is a slightly MORE mangled HEX, which is only noticeable upon close inspection of the rotor.

On the other hand, if I try grind the head and then drill the threaded portion out - tasks at which I have zero skills and experience - a lot of things can go wrong, and I can potentially do a lot more "structural" AND cosmetic damage to the wheel itself. The bike is in way too nice overall condition for me to want to risk that.

So, after the hand impact tool and the replacement bolt have both arrived, I may try to use the impact tool to get the bolt out. But if that fails, the bolt and OEM rotor stay on, and I just have a really nice lightweight brake rotor to use as a souvenir $100 paperweight and to remind me of the dangers of trying to extract small diameter, shallow button headed bolts in 13 year old bikes.

Jim G
 

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Jim, you know I like your approach, but I worry. The reason I worry is because of all the times we looked at parts that snapped,
scratched our heads, and said "how'd that happen?" Sometimes these sessions were held in a rider friend's hospital room.

You said: "But if it fails, then the bolt is still in there and the other 3 bolts are as well, so the OEM rotor is secure, and the only "damage" due to trying the impact tool is a slightly MORE mangled HEX,"
I disagree! I think you may have already damaged the area where the head of the bolt meets the shank of the bolt; wish I could see that piece under extreme magnification. If impact tool fails, it might inflict additional damage at that same point. Then my fear is that you leave the bolt in there, and put in the rest of the bolts, sounds like a good escape strategy, right? But if the damaged bolt decides to crack and let loose at the right moment, the head flies out, jams in the caliper, and you're off for an unauthorized flight, no good! Okay, I'm paranoid, but sometimes escape strategies should be abandoned. It's your decision, but I would commit to getting it properly sorted, even if I had to take it to a machine shop for a proper rescue, sorry to rain on your parade, I'm just sayin'...

"Ive pretyt much decided that the hand impact tool is the only thing I will try."
Friendly Reminder: I would use plenty of heat near the threaded area, and yes, it's possible to snap the head of the bolt (my paranoia at work again)

Welcome to the glamorous world of motorcycle maintenance, Zen my ass!
 

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Discussion Starter · #11 ·
Jim, you know I like your approach, but I worry. The reason I worry is because of all the times we looked at parts that snapped,
scratched our heads, and said "how'd that happen?" Sometimes these sessions were held in a rider friend's hospital room.

You said: "But if it fails, then the bolt is still in there and the other 3 bolts are as well, so the OEM rotor is secure, and the only "damage" due to trying the impact tool is a slightly MORE mangled HEX,"
I disagree! I think you may have already damaged the area where the head of the bolt meets the shank of the bolt; wish I could see that piece under extreme magnification. If impact tool fails, it might inflict additional damage at that same point. Then my fear is that you leave the bolt in there, and put in the rest of the bolts, sounds like a good escape strategy, right? But if the damaged bolt decides to crack and let loose at the right moment, the head flies out, jams in the caliper, and you're off for an unauthorized flight, no good! Okay, I'm paranoid, but sometimes escape strategies should be abandoned. It's your decision, but I would commit to getting it properly sorted, even if I had to take it to a machine shop for a proper rescue, sorry to rain on your parade, I'm just sayin'...

"Ive pretyt much decided that the hand impact tool is the only thing I will try."
Friendly Reminder: I would use plenty of heat near the threaded area, and yes, it's possible to snap the head of the bolt (my paranoia at work again)

Welcome to the glamorous world of motorcycle maintenance, Zen my ass!
I know the bolt is not (yet) damaged beyond the corners of the hex in the buttonhead, as the hex basically deformed like soft butter as soon as I tried to remove the bolt with the hex socket on hand ratchet. Anyhting I did after that, so far, was unable to exert any more force on the bolt due to immediate slippage due to the rounded corners.

But you are probably correct that introducing impact into the equation COULD hurt the integrity of the bolt itself, especially since it has already been proven to be remarkably soft, given that it rounded at supposedly just 20 ft lb of torque having been applied to install it in the first place.

You've got me thinking that I should not even try the hand impact tool, and just cut my losses right now.

Jim G
 

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I will respect and support your decision Jim, because it's your bike, your responsibility, your judgment call.
We disagree, and that's okay.

I suppose I could be crazy, but I would try the heat and impact driver method and accept 1 of 4 possible results:

1. the bolt comes out-hooray!;
2. the bolt head gets more deformed, but doesn't turn;
3. the bolt snaps, then I find the best welder in town to remove what's left of the bolt;
4. the wheel is destroyed in any process, whether by me or the welder trying to save it, then I would buy another wheel.

Sorry I can't be there onsite, but I trust you'll think it through and get it sorted.
 
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