exhaust vibration

victortrail · Aug 14, 2013

Two issues

1. Very hard to keep the headers tight. The crowns at the head always seem to be too loose. I can never turn the bend clips to the right point to where the whole assembly does not vibrate and clatter. Any suggestions?

2. The mufflers a also very mobile (move a lot). I purchased the rubber replacement dampers but I am not sure how to tell if they really need to be replaced (and how to do that if they need to be replaced).

Thanks, Nate

rvich · Aug 14, 2013

Throw the clips away! I warm up the bike with the exhaust "rose" just snug, then I unscrew it and put some high temp silicone on the threads, and crank it down. Then I start up the bike and run it up to about 4000 RPM and crank it down a little more. It works (for me at least). Maybe the silicone doesn't last very well with the temps there but it lubes the threads and makes it easier to get it tensioned.

As for the muffler. The rubbers are just a piece of rubber with a 5/16 threaded bolt sticking out of each end. So all you have to do is remove the 1/2 nut from each side and it will come free. Not that it is ever that easy as the whole exhaust system has its own tension and usually you either have to remove more items or force the exhaust to move away from the frame by force to get them out. You decide which is best.

I have one header that extends into the muffler by about 4". The other extends into the muffler about 1.5". The latter rattles all the time regardless of what I do, the former doesn't seem to care if the clamp is tight. I know what I will be doing when I put new headers on!

Russ

Hobot · Aug 14, 2013

Hehe a few way to skin the headers, of course only one way will work on one side and another on the other. After a couple years I gave up on trying to really clamp header in muffer and find my rubber "Lords" mounts last longer if headers are a sliding vibe ignoring fit. The times I've gotten them to really clamp and my buddy too, the headers crack up by the first bend from head. A hnad full of things help save the threads and seal so can grab what's at hand but I've switched to Milk of Magnesia for good retention and release and comments how silly i am, at first. I've heard a few that nip up while running hot but I ain't good enough to keep gripper on the ring bolt or not get burnt on pipes. Norvil or equialent reference says put a 4 ft lever arm on the wrench, but I find a sledge hammer is handier. Don't put anything but special spring retainers to hold rings, no lock tab no saftey wire as can still let some clamp force off so parts jiggle and treads dissolve. I now waist the rubbers to allow less tugging on the front bends. Once I got crude and brave enough for the sickle and hammer treatment its a one time does it task. This is the business end of factory tool - you supply the hammer.

Bernhard · Aug 15, 2013

hobot said:
Hehe a few way to skin the headers, of course only one way will work on one side and another on the other. After a couple years I gave up on trying to really clamp header in muffer and find my rubber "Lords" mounts last longer if headers are a sliding vibe ignoring fit. The times I've gotten them to really clamp and my buddy too, the headers crack up by the first bend from head. A hnad full of things help save the threads and seal so can grab what's at hand but I've switched to Milk of Magnesia for good retention and release and comments how silly i am, at first. I've heard a few that nip up while running hot but I ain't good enough to keep gripper on the ring bolt or not get burnt on pipes. Norvil or equialent reference says put a 4 ft lever arm on the wrench, but I find a sledge hammer is handier. Don't put anything but special spring retainers to hold rings, no lock tab no saftey wire as can still let some clamp force off so parts jiggle and treads dissolve. I now waist the rubbers to allow less tugging on the front bends. This is the business end of factory tool - you supply the hammer.

re;
"Once I got crude and brave enough for the sickle and hammer treatment its a one time does it task."
Where your ancestors Russian by any chance :?: ( I say with my tongue firmly in my cheek :!: )

concours · Aug 15, 2013

Welcome. Peashooters do shake, by design. The rubber mounts can be visually inspected for tears/seperation. I have seen a W I D E variation in durometer of the mounts.

engineering-compromises-leading-exhaust-threads-stripped-t14363.html

rvich · Aug 15, 2013

I thought it was "hammer and cycle"?

Hobot · Aug 15, 2013

Oh cool Rich, yes I like hammer and cycle label much better. I have evolved towards stone ax from using long lever clubs as bike tends to tip over on the loads needed and doesn't impart the shock factor, like air impact, to over come friction preventing full nip up. I've been through 6+ peashooters so far and every single one of a variety of makes breaks its baffle loose in a 1000 miles or so. Rattles to handle any and on slow non paved plodding but not at idle nor on pavement I can detect.
With just levering I found some slack when ever I checked and levered till the wham bam thankyou mam method, one quickie does it. To get to head or primary off I only have to undo the exht roses and just leave the mufflers hanging, headers slip right in/out. Can't remember last time I touch the clamps but on first assemblly a few years ago on Trixie. Due too the crappy angle, dia size and flange thickness of my "last" set of Victory headers, its very hard to get rose started and worries me I'm gonna chew up the initial threads some day. Lords mounts are like tires to me now so keep spares on hand and shave a waist in them before use on hangers or head steady so both last longer and isolate better extremes of vibe and motions.

bmwbob · Aug 15, 2013

I run 1975 header setup on my 1974 and haven't had any problem since. The pre 1975 setup always came loose and ate the head threads!

britpak · Aug 15, 2013

There are a number of variables that need to be correct for the exhaust nuts to stay tight:-

1. Mechanical fit of exhaust pipe into silencer. The system will only stay tight and rattle free if the exhaust pipe/silencer assembly is rigid. Pattern exhaust and silencers vary a lot in quality in this area . The fit can be improved with some metal shimming. The silencer clamp is important. There are a number of types available. My experience is the simple clamp with a through pinch bolt will not stay tight, and eventually bends after repeated tightening. They tend to compress the sides of the pipe, rather than a more constant pressure around the pipe. The clamp type with two "D" washers work better. They do a far more effective job of compressing more of the periphery of the pipe. I have not tried it, but a conventional hose clip does a good job of spreading the compression loads around the pipe - the issue I expect is the limited clamping force that is available before the threads strip.

2. Exhaust thread quality. As others have pointed out, the roses need to be very tight, and best tightened when the engine is hot.

3. Bronze Roses. These are available from Norvil (among others I believe) and have a closer expansion coefficient than steel to the cylinder head. My experience is they do stay tight.

So, if you can keep the exhaust/silencer joint rigid, and the exhaust roses have good threads and are tight, you will have a number of benefits. Firstly, the roses tend to stay tight, secondly, the silencers stop rattling, and thirdly there are less stresses around the silencer mounting bosses. This means there is less chance of vibration cracks.

Onder · Aug 15, 2013

Bmwbob,
what is the difference twixt the 75 and the 74 header pipes?

concours · Aug 15, 2013

...and another thing, the elders didn't mention to JETTISON the rattle rings until AFTER my first try. Ditch 'em!

Bernhard · Aug 16, 2013

hobot said:
Oh cool Rich, yes I like hammer and cycle label much better. I have evolved towards stone ax from using long lever clubs as bike tends to tip over on the loads needed and doesn't impart the shock factor, like air impact, to over come friction preventing full nip up. I've been through 6+ peashooters so far and every single one of a variety of makes breaks its baffle loose in a 1000 miles or so. quote]

re; “I've been through 6+ peashooters so far and every single one of a variety of makes breaks its baffle loose in a 1000 miles or so.”

Sounds like you want to make your own silencers/muffers with extra internal welds to stop it shaking itself to pieces :?: :idea:

bmwbob · Aug 16, 2013

Onder said:
Bmwbob,
what is the difference twixt the 75 and the 74 header pipes?

Totally different head pipe and exhaust nut locking system!

http://www.ebay.com/itm/Norton-Commando ... 0954276370

concours · Aug 16, 2013

Onder said:
Bmwbob,
what is the difference twixt the 75 and the 74 header pipes?

Spherical seats, have a look at www.oldbritts.com

Old Bloke · Aug 16, 2013

hobot said:
Hehe a few way to skin the headers, of course only one way will work on one side and another on the other. After a couple years I gave up on trying to really clamp header in muffer and find my rubber "Lords" mounts last longer if headers are a sliding vibe ignoring fit. The times I've gotten them to really clamp and my buddy too, the headers crack up by the first bend from head. A hnad full of things help save the threads and seal so can grab what's at hand but I've switched to Milk of Magnesia for good retention and release and comments how silly i am, at first. I've heard a few that nip up while running hot but I ain't good enough to keep gripper on the ring bolt or not get burnt on pipes. Norvil or equialent reference says put a 4 ft lever arm on the wrench, but I find a sledge hammer is handier. Don't put anything but special spring retainers to hold rings, no lock tab no saftey wire as can still let some clamp force off so parts jiggle and treads dissolve. I now waist the rubbers to allow less tugging on the front bends. Once I got crude and brave enough for the sickle and hammer treatment its a one time does it task. This is the business end of factory tool - you supply the hammer.

I've used this tool for decades, and never had trouble tightening the nuts, or had any damage to the nuts/fins

Stillson wrench Record 18. Also useful for any other "problem" fittings!

Hobot · Aug 16, 2013

Yep me too for a time in even bigger size just not no more and will not work on Peel's delicate alloy fin roses. I don't beat mine off until head heated to pretty hot to touch over some minutes to actually expand enough. Different strokes for different folks.

Old Bloke · Aug 16, 2013

Hear what you are saying, if I had these nice alloy/brass/stainless roses, I'd be more careful too!

ashman · Aug 16, 2013

In the last 33 years I have never had a exhaust pipe come lose, hang on, thats when I hard mounted my 850 into a Featherbed frame with a ballanced crank :shock:

Ashley

Hobot · Aug 16, 2013

Hear what you are saying, if I had these nice alloy/brass/stainless roses, I'd be more careful too!

I used pile wrench or drift and hammer on Peel's steel roses but got the Norton tool in time to use on Trixies brass rings and plan to use springs to hold Peel's alloy rings on. Use what ya got long as don't come off or get trapped lose to begine the beatings. I didn't start out as such caveman club torquing fend but evolved into it from failures of more timid civilized approach on many fasteners.

exhaust vibration

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