I have a 2007 HD Sportster 1200 Custom. I tightened the nut way too much on the bolt that keeps tension on the drive belt and it snapped right off. I rode down the road and now the bolt loosened itself more and more causing the drive belt to lose tension making it unrideable. I'm unsure on how to fix this problem.

 

This is what it looks like now.

 

#1. You should post this in the Sportster forum.

#2. Do you mean the axle adjuster?

#3. Are you saying that you tightened this until it snapped, and then decided to ride it anyway?

 

I believe it's the axle adjuster but I'm new to motorcycles and obviously trying to do the work myself doesn't always work out. I rode it because I was told it wouldn't affect the belt very much.

 

Were you trying to change the belt tension when you tightened it, or were you just worried that the bolt was loose? I'm not a Sportster expert (although there are many in the Sportster section of this site), but if you had reason to believe the belt needed to be adjusted, you would need to loosen the axle nut itself before turning the adjuster. It is true that the axle shouldn't move if it's properly tightened regardless of the position of the adjuster. But if your belt tension changed when riding, the axle nut may be lose (which would be very dangerous while riding). Now that you have little or no belt tension, there may be no tension on the broken adjustwe nut. You may be able to grab the end with a pair of vice grips and remove it, after which you can replace the broken bolt and properly adjust the belt.

You should definitely invest in a factory service manual. You'll be able to perform all sorts of maintenance properly with the correct manual. You should also start using the Sportster section of the forum instead of the Dyna section!

Good luck, and welcome to the site. Lots of helpful people here... I've been saved by others many times!

 

Good god... "Doesn't always work out" in the motorcycle world is about a half step from crashing and burning.

If it ain't right, don't ride it.

The adjuster screw is less than half of the axle fixing mechanism. Aside from having a broken/missing asjuster it sounds like you also have a loose axle nut.

You need to remove the adjuster block and get the broken adjuster screw out of it. Details are in the service manual.

 

These guys are on the money. Really solid advice. As far as getting the adjuster out, if you cannot get it with a pair of vice grips because it's in there too tight, pickup a set of EZ OUTs from amazon. Looks like you may have to file that sucker flat before doing that though.

Keep the rubber side down

 

It isn't a bold you destroyed...it's the threaded end of the adjuster (see image below)
Here's what you need to fix this issue:
Item #7: 41573-05 ADJUSTER, rear axle (2, 1 left and 1 right) (for HDI models in Japan, 1 for the left)
Item # 26: 41623-05 ADJUSTER, rear axle, right (for HDI models in Japan) (not illustrated)
Item #3: 7766 LOCKNUT (2)
Item#25: 89579-91 CAP, protective (2)

 

FXD2003Rider has given you the best advice. You will need to remove the rear axle to replace this. Then set your belt tension and make sure that the rear axle is square to the frame, then tighten the rear axle nut to specs. If you are unsure how to do this you need to either use a service manual and/or get someone with experience to help. Otherwise take it to a independent shop to perform this repair.

 

OP; Get the bike "trailered" to a motorcycle service shop (HD, or Indy)...if you don't know what you're doing...this could be recipe for disaster.