Never lose your muffler!

[vonspyder]

When I first got my tank sporty 150 DE, i had bought it used from a guy who obviousley had no business up on two wheels as he had been pretty rough with it (hence the steal I got it for). I heard horror stories from other scooter owners that the muffler clamps are prone to snapping, which made me think with all the vibrations from the road wont that snap the exhaust? so to play it safe I went and bought a 4" plumbers pipe clamp (its a screw clamp thats just barely as big as the muffler) i slapped it on and affixed some high tensile wire through it and connected the other end of the wire to the frame.

sure enough one day the exhaust pipe snapped, but my muffler sling held it in place so I didnt lose it and got it to a muffler shop for rewelding and put on a more sturdy muffler clamp. You never know whatll happen out there so I would definitley reccomend doing this to yours if you can! ill get pictures up shortly!

[earlwb]

Well as some of you know I had several muffler straps break on my scooter. I remember reading about some others having their straps break on them as well.
I tried a length of metal bent and curved into the proper shape, but it lasted about two weeks before it broke too. That lead me to studying the problem more, and as I see it, there is a horizontal resonant vibration mode that sets up, causing the muffler to move back and forth at certain RPM's. The muffler is normally only held on with two straps on the first one fourth of the heavy muffler, with the other three fourths of the muffler hanging in the air. So the straps get too much strain on them, and they develop metal fatigue and break

Basically, if you study the two standoffs on the swingarm bracket, you'll see that there is a sharp edge on the ends of the standoffs. So as the muffler vibrates, it starts a stress riser on the strap where the edge of the standoff on top meets with the strap. The stress riser evcentually turns into a full blown crack and grows until the inner part of the strap lets go. The angle iron serves as a reinforcement, it changes the resonant frequency dynamics, and keeps the straps away from the standoffs, so they don't form stress risers and crack and break off. You only need to attach a length of angle iron drilled to match the standoffs, and you are in business. But if you want you can attach a couple of spare straps too. I used old scrap leftover bicycle inner tubes for the rubber spacers on the straps.
Anyway this has been there for over 6 months and not one strap broke on it ever since.

Important the photo shows the straps on the wrong side of the angle iron, the straps need to be on the outside of the angle iron. I was testing my stress riser theory and yes a strap will break if you do it this way. So put the straps on the outside of the angle iron so the angle iron is in between the standoffs and the straps.

So viola! The four strap mounting adapter:

[hjn97]

I like the angle iron idea. I've broken about 5 or 6 straps, so it's time to do something to prevent it.

I just got done installing a new exhaust pipe, one strap, and welding the bracket that has the standoffs.

[wh]

Any more info on this? Pics?

Earlwb I'm not sure what you mean when you say the straps were on the wrong side of the angle iron.

[earlwb]

See the pic, the straps are on the inside between the two standoffs and the angle iron. The straps need to be on the outside so that the angle iron is between the straps and the two standoffs. it doesn't matter on the two extra spare straps.
When you bolt it all up, the angle iron goes on first, and then the straps.

[wh]

Jul 7, 2008 6:02:35 GMT -5 earlwb said:

See the pic, the straps are on the inside between the two standoffs and the angle iron. The straps need to be on the outside so that the angle iron is between the straps and the two standoffs. it doesn't matter on the two extra spare straps.
When you bolt it all up, the angle iron goes on first, and then the straps.

Would the angle iron that came as the crate material around the scoot make a decent piece to use? I just got the scooter so I'd rather put a fix in place before it becomes a problem.


I've got one of these:



Do you think your application would work with it? It only has one bolt location on the bottom side of the muffler where your's looks like it has two which might make it more sturdy.

[windbreaker]

to WH
That muffler settup does not have the two stand-off bolts. It is suspended from the exhaust
port, (use lock washers or double nuts) and the Axle mounting plate. The weak link on that system are the bolts attaching the axle mounting plate to the engine. My fix was to drill out
both of the engine mounting tabs, and replace the bolts with grade 8 bolts, long enough
to extend through the engine mount tabs, and again long enough to accopt lock nuts.
This procedure may cause problems that I am not aware of, but I had no problems.

[earlwb]

wh,
Like windbreaker stated, my method for preventing muffler straps from breaking will not work on that muffler design that you have there on your scooter wh. Yours uses a different muffler mounting design.

[wh]

Jul 7, 2008 14:18:14 GMT -5 windbreaker said:

to WH
That muffler settup does not have the two stand-off bolts. It is suspended from the exhaust
port, (use lock washers or double nuts) and the Axle mounting plate. The weak link on that system are the bolts attaching the axle mounting plate to the engine. My fix was to drill out
both of the engine mounting tabs, and replace the bolts with grade 8 bolts, long enough
to extend through the engine mount tabs, and again long enough to accopt lock nuts.
This procedure may cause problems that I am not aware of, but I had no problems.

Do you have a picture of your modification?

[earlwb]

Here is a better example picture of how to bolt on the muffler straps and the length of angle iron that I used.

[danw]

I see the beginnings of rust...
Would some silcone hi temp grease be good on the bolts?

["Big Guy"]

Overseas they like to use Vaseline... It's cheap and it works.


-Rich

[earlwb]

Its Chinese, everything rusts.
Of course not riding in the rain would probably help a lot too.

[wh]

Jul 9, 2008 20:13:58 GMT -5 earlwb said:

Its Chinese, everything rusts.
Of course not riding in the rain would probably help a lot too.

It's the mix of metals that's encouraging it.

[nikolai]

I broke my exhaust straps (both !) more than twice over the last six months, and I used the method of earlwb successfully (but only used two straps.) My wife (who is a frequent passenger) also noticed that the bike was somehow quieter and smoother ( I never told her about the modification, she just noticed the difference.) So far, so good, and I'm now confident the straps will no longer break, and I just have to move them to the outside of the angle bar.

I dabbed some roofing sealant over the nut and bolt threads to prevent rusting, it seems to work okay.

[earlwb]

You want to move them to the outside as soon as possible as the sharp edges on the standoffs will break them off pretty quickly.