Broken Sprocket bolts in rear mag, is this a normal issue?

[Chuck]

Hi:

I have a 1980 XS650. When I got it it had all of the rear sprocket bolts loose except for one. When I took it apart the one that was tight broke off. Another was already broken off. To make life easier I bought a used rear mag and it already had 3 broken sprocket bolts. Now I am beginning to wonder, what’s the deal? Is this a normal issue with the mags? Why is the bolt material so soft? How do I get those broken bolts out? I am thinking of taking my used wheel to a machine shop to see if they can get them out as I am extremely bad with an easy-out. Any suggestions? Should I replace those soft bolts with hardened bolts? Thanks in advance! -Chuck

 

[angus67]

they prolly had seized in the hole. the bolt is steel going into aluminum. if you get them out, use anti-seize when u put the bolts back in.
i know it doesnt help rite now,but thats why they broke.

 

[gggGary]

Fortunately this is a very easy job because you can use a sprocket (or two doubled up) and drill bushings to precisely center the drill into the old bolt. this will let you drill nearly out to the threads and make it much easier to remove the remaining part of the bolt. If it's a good, tricky, machine shop they might have a left hand drill bit which may extract the screw part way through the drilling out operation. The only hard part is a mill or drill press with enough column to spindle depth to reach to the bolt centers. Just free thinking but it might be a good place to use a kind of dull drill bit the heat might help break loose the bolt.
Finally as Angus said steel bolts into aluminum are very likely to seize. Aluminum oxide is bigger than aluminum so as the aluminum corrodes it gets bigger seizing the bolt.

 

[xjwmx]

On something like that is it better to use a hand impact driver, or a regular socket wrench? Is one less likely than the other to shear off the head or strip the aluminum?

 

[Kingwj]

Fortunately this is a very easy job because you can use a sprocket (or two doubled up) and drill bushings to precisely center the drill into the old bolt. this will let you drill nearly out to the threads and make it much easier to remove the remaining part of the bolt. If it's a good, tricky, machine shop they might have a left hand drill bit which may extract the screw part way through the drilling out operation. The only hard part is a mill or drill press with enough column to spindle depth to reach to the bolt centers. Just free thinking but it might be a good place to use a kind of dull drill bit the heat might help break loose the bolt.
Finally as Angus said steel bolts into aluminum are very likely to seize. Aluminum oxide is bigger than aluminum so as the aluminum corrodes it gets bigger seizing the bolt.

Genius. Why does shit like this not come to my mind automatically?

 

[MrBillohnooo]

I fitted mine with studs/ nuts after having the same problem about 10 yrs ago.
The SR500 rear wheels come with studs....

 

[Chuck]

Hi All,

The bolts are broken off pretty deep in there. They probably have 1/2 inch to 3/4 inch of thread. I am thinking that it may be easier to pull out the old bearings and if there is a recess, hollow area, behind the bolts maybe I could turn the bolts "in" to get them out. Right now soaking them in "CRC Freeze Out" hoping it kills that corrosion problem.

Thanks, Chuck

 

[Chuck]

Studs is an interesting idea. Can you elaborate on how you did that? Thanks, Chuck

 

[gggGary]

It helps to have fought this battle a bunch of times over the years.
I just got a reluctant spark plug out of a head, same story with some added carbon build up on the inside of the plug threads. Loosen till it starts to bind, stop, douse it with (insert your favorite brand or home brew rust buster here) retighten, repeat taking as long as necessary to remove the thread without (or only minor) damage to the aluminum. On my Sprinter van I spent 3 days getting a glow plug out. Alternative was a new head at about $4,000 I was VERY careful and patient. Dealers typically break them and say oops YOU need to buy a new head. Heat can be a big help. I drove the van between efforts. I like the studs, nuts idea MBohnooo.

 

[MrBillohnooo]

Thanks! on that bike I had the cases, carb flanges, breather, etc, etc attached with studs and nuts. It took some clearance machining in places , but sure looked trick with 12 point shouldered nuts!

 

[xjwmx]

Yeah, I've seen heat do wonders. Also, I've used a nut splitter when the problem was a rusted nut. That's very easy.

 

[Gordon]

A little heat does good to help loosen up the alum. oxide, but too much heat and you will melt the aluminium. And steels' melting point is double that of the alum. You can get a left turn drill bit from Snap-On, or the small extractor kit with left turn bit's and extractor's for a little more money. They usually have them on the truck. Good luck,,,Gordo

 

[gggGary]

DIY sets on fleabay for nearly nothing, 5 piece set of drills and extractors for less $20.00 with shipping. Great IF they don't break off in the bolt. Gulp! The heat and run in out wd are ideas for next time. You are describing the bolts broken off below the surface of the flange, I agree with Gordon scary to try to heat the flange.

 

[TwoJugs]

I am in the process of removing these bolts from a very corroded rear spoke hub. The one advantage I have is that the bolt holes are through to the inside. I can attack from both sides with penetrant and heat. Heat is a great tool for working this stuff loose like mentioned here. The expansion rates are very different and helps to weaken the bite between the two metals. The best approach is to get the bolts to move the slightest bit in either direction. Sometimes you can get them moving first by tightening before trying to loosen them. Also rest in between movements. The friction caused by big movements once they start to give can cause it to bind worse. A little rest and turning the stuck bolt both tight then loose will often do the trick. If all fails go for the drill and take the long route. I try to start with a small hole first concentrating on getting as close to center then step up the drill to the max size just before cutting into the parts threaded section. The drilling heat and vibration helps to get things loose too and the bigger the easy out the less chance of snapping that off too.