Replace The Exhaust Slip Joint Gasket !

LeeWonnacott

My odometer has turned past 105,000 miles now and certain things give me subtle clues that my new bike is no longer new.

Until my trip to California in March I always wondered why everybody was complaining about heat on the heels and around the foot pegs. Well, a broken valve stem on the rear wheel forced a roadside dismount and remount. In the process the metal collar that holds the exhaust pipe flange tight to the muffler pipe broke... I'm sure this has happened to many of you. I bought and mounted an automotive U-bolt as a temporary fix. Heat on that side of the bike was a huge problem for the rest of the trip.

It wasn't until I dismounted the muffler to remove the roadside U-bolt repair that I began to understand why the heat problem can appear suddenly. The slip joint gasket looks like a small roll of duct tape. The center of the joint is wire mesh and it's wrapped with a heat resistant tape material. The OEM gasket can become brittle and melt the mesh. That's when exhaust gas begins to blow by and bake your heels.

Obviously Honda has figured out that the OEM engineering here was not stout enough. I ordered a new assembly from www.RonAyers.com and was pleased to find a wider, much stronger, collar.

The parts you need are the new collar; Honda P/N 18372-MAT-0001
a new slip joint gasket; Honda P/N 18391-MLO-003
and two bolts for each collar; Honda P/N 90103-KCM-620

It's a simple fix and can be done the next time you change the rear tire. BE CERTAIN to clean the inside of the flange before you put the new gasket in, otherwise you won't get the proper fit and seal. Rock the gasket slightly as you insert it to make sure you get it all the way to the proper spot. It's obvious when properly seated. When tightening the collar bolts be sure to snug one first, then the other, till fully tight. Do one all the way before going to the second and it will warp the flange - and you are back to hot gas blowing by the gasket. The process adds maybe ten minutes to a rear wheel tire change.

Took a quick ride - no more baked heel.
 

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LeeWonnacott said:
It's a simple fix and can be done the next time you change the rear tire.
Click to expand...

Now that's handy information. But that first gasket lasted about 100Kmi before you felt the heat? Not bad for a not-best effort on Honda's part. I wonder if/when that became the new OEM at some point in production. Thanks for the pics and the fishing lesson!

Could you provide some background on your bad stem? When was it replaced? TPMS add-on? Too many contortions during air-fills?
 
The bad stem was really the problem of working with a shop I had not previously used. Dunlop had shipped to me a new set or RS III's to try out and I needed them mounted before going to left coast. Regular shop was closed to to illness of the owner. (one man shop). Had to BEG the Yamaha shop to do the mount because I didn't buy the tires from him. That should have been my first clue.

Took him all day to do a 45 minute job. In the process he removed my very expensive all metal right angles and replaced them with what I thought were new all metal right angles. Okay, didn't ask for that, but nice of him to go the extra mile. Didn't know till the rear one failed at 75 MPH and 600 miles away from home that the base of the new right angles were plastic. I should have replaced the front immediately, but figured that I could not be unlucky enough to have both of them go bad.. right?

Sure enough, another 1,200 miles down the road the front one went. Again at 75 MPH, and this time in the middle of the desert west of Las Cruces NM. Luckily enough the Honda dealer at Las Cruces was generous enough to send a trailer out for me immediately. 15 Minutes after unload at his shop I was back on the road...

So, if a stranger offers you right angle stems make sure he understand you have a bike easily capable of triple digits and that you routinely ride hundreds of miles a day on all types of roads. And then tell him to keep his cotton pickin hands off the stems you know serve you well.

The Dunlop RS III's by the way have proven to be EXCELLENT sport-touring tires. I know a lot of rider here had a bad experience with the first RoadSmarts, but Sumitomo has conquered the learning curve. They expect the average rider to get 12,000 miles or more from the rear and about 14,000 from the front. I currently have almost 10,000 miles on the set and they still look really good.
 
LeeWonnacott said:
new collar; Honda P/N 18372-MAT-0001
Click to expand...

Collars are listed but are different parts. The Honda part is 'Band' and for 2010 (my bike) it lists the P/N as 18372-MAT-000. The xxx1 must be the upgraded bit? The gasket P/N is the same as you listed.
 
LeeWonnacott said:
The bad stem was really the problem of working with a shop I had not previously used.
Click to expand...

Geeze that's an adventure all its own! Was there any damage to the seat vinyl?
 
Not really, but it did take two guys with a crowbar to get me off the saddle.
 
ST Gui said:
Collars are listed but are different parts. The Honda part is 'Band' and for 2010 (my bike) it lists the P/N as 18372-MAT-000. The xxx1 must be the upgraded bit? The gasket P/N is the same as you listed.
Click to expand...

Probably so. It is significantly wider than the original part, and the band itself appears to be thicker.
 
Thank you for this. The failure mode with the original clamp band is often frozen bolts that snap off, at least in this forum. Are the bolts still the same at 12 mm?
 
Yes, still 12 MM. And they are easier to work than the originals. Whomever designed the fix should have been in on the original design. I never thought that a gasket like that could melt and deform, but obviously they do.
 
I examine mine every tire change as both mufflers come off. The gaskets are still very tight fit.
 
dduelin said:
I examine mine every tire change as both mufflers come off. The gaskets are still very tight fit.
Click to expand...

The only thing better would be not to remove the mufflers for tire changes and I have modded my mufflers for just that.

Thanks for the post, i think one of mine has been a leaker for quite some time and now I have a reason to R&R that muffler.
 
ZIAMON said:
The only thing better would be not to remove the mufflers for tire changes and I have modded my mufflers for just that.

Thanks for the post, i think one of mine has been a leaker for quite some time and now I have a reason to R&R that muffler.
Click to expand...
It's not a big deal to remove them and does allow loosening the bolts so the threads remain free. Six of one, half dozen of the other, whatever you like.
 
dduelin said:
and does allow loosening the bolts so the threads remain free.
Click to expand...

That's worth a lot. I've never had a bolt break conveniently. And they all been more than an inconvenience to replace.
 
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