And another muffler question / discussion

[SteveW]

A recent discussion about mufflers and crossovers reminded me that I also have a muffler question to pose...

1973 23 footer. Stock exhaust configuration - two mufflers into one long pipe to the rear. Well... stock except for headers.

The issue is an irritating drone at 1400 - 1600 rpm.

Anyone have any trickery to eliminate it ??

Thanks,

Steve W
Southern California

 

[Carl Stouffer]

> A recent discussion about mufflers and crossovers reminded me that I also have a muffler question to pose...
>
> 1973 23 footer. Stock exhaust configuration - two mufflers into one long pipe to the rear. Well... stock except for headers.
>
> The issue is an irritating drone at 1400 - 1600 rpm.
>
> Anyone have any trickery to eliminate it ??
>
> Thanks,
>
> Steve W
> Southern California

Maybe add a small resonator somewhere in the system? I don't know enough about exhaust system design to recommend placement.

--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging

 

[Jim Hupy]

Nearly all exhaust systems will "drone" or make more detectable to the
human ear, sounds that occur at specific frequencies. Fix? Shorten or
lengthen any pipes in the system. Change diameter of any or all pipes in
the system. Replace mufflers with ones that have different internal
baffling. Add resonator(s). Change pipe hangers to less rigid designs.
Change final drive gearing so you can run at different loads and rpm's.
Turn up the stereo. (Grin) Look for places in the exhaust system where
metal to metal contact is made with the frame of the coach. Safely support
the coach off the ground and crawl under it. Bump the exhaust pipe with
your hand to see and hear if anything is loose or in intimate contact with
frame components. JWIWD.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> A recent discussion about mufflers and crossovers reminded me that I also
have a muffler question to pose...
>
> 1973 23 footer. Stock exhaust configuration - two mufflers into one long
pipe to the rear. Well... stock except for headers.
>
> The issue is an irritating drone at 1400 - 1600 rpm.
>
> Anyone have any trickery to eliminate it ??
>
> Thanks,
>
> Steve W
> Southern California

Maybe add a small resonator somewhere in the system? I don't know enough
about exhaust system design to recommend placement.

--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
Eagles,
Solar battery charging

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[john r. lebetski]

All of what James has stated. You don't say how old your mufflers are, or if stock type replacements or something like a Flowmaster that may be
louder. If stock, they can look nice from the outside, but inside be totally broken down from moisture and acids. The perforated tubes are usually
first to break down, then baffels can become dislodged.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[steve southworth]

You could try inserting an auger muffler in the cross pipe after the mufflers. It had been stated on the net/forum that this had eleiminated a nasty
drone on a three inch system with a rear muffler.. I can't vouch for this as I installed one from the get go on my system.

They are cheap and relatively easy to install so give it a try before spending any significant bucks.
--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

 

[Matt Colie]

> A recent discussion about mufflers and crossovers reminded me that I also have a muffler question to pose...
>
> 1973 23 footer. Stock exhaust configuration - two mufflers into one long pipe to the rear. Well... stock except for headers.
>
> The issue is an irritating drone at 1400 - 1600 rpm.
>
> Anyone have any trickery to eliminate it ??
>
> Thanks,
>
> Steve W
> Southern California

Steve,

As I have a similar coach, I find it hard to believe that what you are hearing is an exhaust note. But it is very easy to believe that the exhaust
system is slightly out of place and so is drumming on the frame somewhere. If that can be the case, it might be hard to find, but it can also be easy
to find if yo spend some time under the coach and look for possible strike marks on the exhaust system.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit