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CSpaced
07-07-2010, 02:34 PM
While checking over my Freya, I noticed that I had lost one of the four cap head bolts that hold my muffler in place. As I started taking it apart, I thought that the bolt had come loose and had fallen off. What I found was that where the muffler bolts in to, the threads had been stripped out of the plate. The fix was pretty straight forward, and I wanted to share my solution with the rest of CrackRoll.

The plan was to re-tap the aluminum plate for a slightly larger cap head bolt. After going through my spares box, I found a suitable replacement. I already had a nice little metric tap set, which I had picked up from a local hardware store, and the bolt I had selected matched one of the taps that I had.

The first thing I did was to tap the aluminum plate that connects the muffler. I decided to go ahead and re-tap all four bolts, because I wanted to only use one wrench to tighten them rather than having to use two. After I tapped the plate, the metal spacers that go through the rubber gromets on the muffler also had to be tapped. This was because the new bolts were slighly larger than spacers, but only enough that tapping the spacers was sufficient. Tapping the aluminum was very easy, as the metal is fairly soft, and I only had to use the handle on the tap towards the end of the operation.

That is pretty much it! The pictures tell the story, and when I assemble the muffler I will use thread lock on the new bolts to make sure that they stay in place. I think that the reason the original bolt stripped out is because I over tightened it. As I mentioned, the aluminum is fairly soft so I'll make sure I don't over tighten the next time around.

I remember the first time I stripped out a bolt, it felt like the end of the world! I hope this helps some of you if you ever have the same problem.

CSpaced
07-07-2010, 02:46 PM
Here you can see one of the original bolts, which because of the fact that the threads were gone could just slide in and out of the hole.
http://www.crackroll.com/forums/attachment.php?attachmentid=9682&d=1278531990

Here's a close up of where the threads used to be!
http://www.crackroll.com/forums/attachment.php?attachmentid=9683&d=1278531990

This is the tap that I used, plus the old and new bolts.
http://www.crackroll.com/forums/attachment.php?attachmentid=9684&d=1278531990

Tapping the aluminum plate. The tap itself usually finds its own center for getting a straight tap, but I always try to keep it as straight as possible anyway.
http://www.crackroll.com/forums/attachment.php?attachmentid=9685&d=1278531990

All done! The new larger bolt fits perfect.
http://www.crackroll.com/forums/attachment.php?attachmentid=9686&d=1278531990

This is the tap set that I picked up from the local hardware store for less than $20.
http://www.crackroll.com/forums/attachment.php?attachmentid=9687&d=1278531990

NighthawkF-117
07-16-2010, 08:27 PM
Cool, mods should make this a Sticky for other people who run into this problem to see.

TMoore
07-20-2010, 11:48 PM
Good job on the fix.

Thread lock won't help you in a high heat environment like a muffler. The point at which most Loctite types start to crystalize is 350F. It would be better to Helicoil these holes if you really want to repair the thread while maintaining the stock thread sizes.

TM

NighthawkF-117
07-21-2010, 05:59 PM
I agree about the thread lock. Ive heard of people using thin CA.