Jump to content
Sign in to follow this  

04 YZ250F chain slack adjustment bolt broken

Recommended Posts

Hi there,

We bought a used 04 250F and everything is in pretty good shape but we note that the chain slack adjustment bolt on one side of the swing arm is broken off with only about 3/8" left sticking out of the swingarm.

Does anyone have any experience removing something like this? It is quite rusted and I have started lubing it with some Fluid Film but I have a feeling this will be a tough one. I can just barley grab it with a pair of vice grips and it will not turn (at least not yet). I'll likely have to drill it out...

Also, does the chain slack adjuster bolt actually hold the wheel in place or is that largely accomplished by the axle nut? In other words, if there is no chain slack adjustment bolt on one side will the rear wheel stay in place under operation or will it eventually give way on that side?

Thanks,

Barry

Share this post


Link to post
Share on other sites

it keeps the axle located, it is needed. As for pulling it out, use a little heat and it should come right out..... Heat the swingarm where the bolt installs and the thing should back right out.

Share this post


Link to post
Share on other sites

+1 on heating up the swing-arm where the bolt threads in. I would spray the heck out of it with PB Blaster. If heat and lube don't work get an Easy-Out kit ( I guarantee you will use it again someday, so buy the little kit from sears it has multiple sizes) drill the hole you need and use the easy-out with reverse threads to bite the bolt and back it out.

Share this post


Link to post
Share on other sites

Heating is up is a good idea, but I think it would be hard drilling and getting an easy out in there because the space is limited at that position in the swingarm.

I'd try heating it up well, and then using a good pair of vise grips to try and remove it.... Sometimes people use the oldest, rustiest vise grips with all the teeth worn off - that will just round your bolt down and prevent you from taking it out. Make sure the teeth are sharp. Also the small vise grips might work better there. I find the brand name vise grips are tons better for this type of stuff too.

Share this post


Link to post
Share on other sites

Thanks Guys. I had thought about heating but then was concerned about heat and an aluminum swingarm. Heat and aluminum don't usually mix. At any rate, I have been talking to the Yamaha dealer here and they may be able t oremove it for a fairly reasonable flat rate ($30.00 or so). If that is the case I will go with that. If not I will try and get it out myself and if I really destroy the swingarm I guess there is always Ebay.

Barry

Share this post


Link to post
Share on other sites

i would heat and cool it at least twice and it will come out easily.

quenching is very effective at breaking the bond between the two items.

the heat you are putting in will not be sufficient to cause any structural changes in the aluminium.

Share this post


Link to post
Share on other sites

An Update:

It didn't matter what I did, the adjust bolt was in there to stay. Heat, easy out, Fluid Film, etc., did not work. So I ended up drilling it out. The bolt itself is mode of soft metel so it was not too difficult, but I ended up with an oblong hole that would not be easy to tap, so I had a look at the Swing Arm Buddy product for inspiration and made my own replacement.

http://www.protekk.com/index.php?manufacturers_id=12

On the inside of each side of the rear fender is a threaded piece of metal about 1" x 1.5". A bolt goes through the subrame and screws into this to hold the fender in place. I "borrowed" one of these threaded pieces from one side of the fender and used this in place of the threaded portion of the swingarm. This and a metric bolt and nut now rest between the swing arm and the axle plate. The end of the bolt fits in the hole made by drilling out the old adjuster bolt. Just like the original, turning the bolt adjusts the chain tension. Once everything is tighted down everything remains solidly in place. The only thing I will need to watch for is when the axle nut, etc. is loose as the new tensioner bolt and threaded piece will come right out unless everything is tightened down. Seems to work great now though.

Cost of repair: free! Well, there were actually a couple of beer to be had after the repair, but that's another story...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×