Resonating cab problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

/<eystroke · 09-24-2003, 02:53 PM

My old rusted out cab with it's one inch "ventilation slots" in the
floors, resonates badly at about 900-950 rpms. Will this get any better
when I replace the cab with a solid one? I'm planning on using sound
deadener everywhere I can get it and removing the fuel tank from
inside.
I know the aqustic properties of these small cabs are not very good for
sound systems. But what can be done to muffle the resonating? More bracing?

Thanks.

guypm · 09-24-2003, 03:01 PM

You can undercoat the inside floor as well as the undercoat the outside. I put double sided foil with the plastic air bubbles as insulation everywhere I could, then put some sound deadener on the floor then carpet. Mine is fairly quiet. It would be even quiter if i didnt have turndowns on my exhaust at the rear axle. Hope this helps,
Guy

/<eystroke · 09-24-2003, 03:48 PM

Do you notice the rpm range where the cab resonates? Mine is very noticeable at 900-950
rpms (crusing at 20-25 mph) it is impossible to not notice the deafing sound. I was just
wondering if I do the sound deading to a solid cab will it still be noticable?

Thanks.

Hooter · 09-24-2003, 04:13 PM

spraying undercoat or dynamat in a can will cut down 65-100% of the resonation, unless it is resonating because of loose body panels, then the fix would be to tighten up those panels.

**breeh** · 09-24-2003, 05:03 PM

If you are running Flowmasters then get rid of them. They resonate alot.

jay6891 · 09-24-2003, 09:16 PM

People who ride with me always ask why my truck make that noises. I tell them that it is my seatbelt warning signal. I pick the buckle up out of the floor and the noise usualy quits. No floor mats or carpet. 40 series flowmasters.

SWEET7T · 09-24-2003, 10:45 PM

Breeh is right in a way. It could be your exhaust. My cab is in really good condition, but just above idle mine is LOUD. But I'm running 50-series Flowmasters, and I know that it is just my exhaust resonating.

lukecp · 09-24-2003, 11:02 PM

Mine reasonates for some strange reason too.....

Proably the 40 Series Flows dumped before the rear axle

Seriously though,
If you want a temp. fix, buy a tube of caulk and a $9 Wal Mart auto carpet. One of my friends has a '76 Chevy beater, and the floorboards were swiss cheese and letting exhaust fumes come in, and the made alot of road noise. He caulked up all the holes, and put a cheap Wal Mart carpet over it. It made the truck much more confortable to ride in, and cut the wind noise down by about half. Not a permant fix by any means, but it will work until you can weld in new floor panels.

/<eystroke · 09-24-2003, 11:32 PM

I never thought about the mufflers resonating, but I'm very sure it is the
cab doing most of the buzzing. But I do have dual mufflers (with cutouts capped
off) with turn downs sitting under the cab. Maybe if I move those out under
the bed that will help.

09-24-2003, 02:53 PM	#1
/<eystroke Registered User Join Date: Jul 2003 Location: North Texas Posts: 265	Resonating cab problems My old rusted out cab with it's one inch "ventilation slots" in the floors, resonates badly at about 900-950 rpms. Will this get any better when I replace the cab with a solid one? I'm planning on using sound deadener everywhere I can get it and removing the fuel tank from inside. I know the aqustic properties of these small cabs are not very good for sound systems. But what can be done to muffle the resonating? More bracing? Thanks. __________________ '69 C/10 Short Wide 350/400/AC/Tilt/Tach

09-24-2003, 03:01 PM	#2
guypm Registered User Join Date: Feb 2002 Location: orange, tx usa Posts: 167	You can undercoat the inside floor as well as the undercoat the outside. I put double sided foil with the plastic air bubbles as insulation everywhere I could, then put some sound deadener on the floor then carpet. Mine is fairly quiet. It would be even quiter if i didnt have turndowns on my exhaust at the rear axle. Hope this helps, Guy __________________ guypm 1971 SWB Fleetside/350 performer rpm heads &intake/ holley 750dp/1.5roller rockers/MSD6a/700r4 1650stall/one piece driveshaft/3.73 open/dynomax ceramic coated headers/3chamber flowmasters/

09-24-2003, 03:48 PM	#3
/<eystroke Registered User Join Date: Jul 2003 Location: North Texas Posts: 265	Do you notice the rpm range where the cab resonates? Mine is very noticeable at 900-950 rpms (crusing at 20-25 mph) it is impossible to not notice the deafing sound. I was just wondering if I do the sound deading to a solid cab will it still be noticable? Thanks. __________________ '69 C/10 Short Wide 350/400/AC/Tilt/Tach

09-24-2003, 04:13 PM	#4
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,078	spraying undercoat or dynamat in a can will cut down 65-100% of the resonation, unless it is resonating because of loose body panels, then the fix would be to tighten up those panels. __________________ MEMBER DISCS UP FRONT CLUB 69 custom camper/cst 10 70 monte carlo 383 stroker with a 700r4 77 fully loaded silverado (back in the backyard for a little while longer) 1980 BMW 320i (back in the garage finally) 1981 f@*d f150 4x4 (Robert red ford) tried to kill me 1972 Honda ct 90 trailbike Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com AC/DC RULES!!! First generation Monte Carlo club pictures of my life

09-24-2003, 05:03 PM	#5
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	If you are running Flowmasters then get rid of them. They resonate alot. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

09-24-2003, 09:16 PM	#6
jay6891 Car Knocker Join Date: May 2001 Location: jefferson,arkansas Posts: 664	People who ride with me always ask why my truck make that noises. I tell them that it is my seatbelt warning signal. I pick the buckle up out of the floor and the noise usualy quits. No floor mats or carpet. 40 series flowmasters. __________________ 68 c-10,91 sportside bed,350 .030 over,4 bolt,10-1 comp,2.05 intake/1.94 exhaust,1.6 Harland Sharp roller rockers,edelbrock rpm cam and intake w/750 carb, 700r4, 3.73 gears,Jacabbs Electronic Igntion w/Accel HEI distributer and super coil. ZR-1 roll pan, filled tailights. Blazer tank. Hidden hitch. 2 1/2" Flowmaster 40's. Parts bought but not installed>> ford 9" posi with disc. CCP front and rear lowering kit 4/5. Cab corners,foor boards,rockers, cab braces, Phatom grill, Painless wiring kit.

09-24-2003, 10:45 PM	#7
SWEET7T Try spinnin 4 rear tars Join Date: Sep 2003 Location: Salt Lake City, Utah Posts: 757	Breeh is right in a way. It could be your exhaust. My cab is in really good condition, but just above idle mine is LOUD. But I'm running 50-series Flowmasters, and I know that it is just my exhaust resonating. __________________ SWEET7T 1970 C10, 2wd, LB, 307/TH350/3.08. PS, PB

09-24-2003, 11:02 PM	#8
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Mine reasonates for some strange reason too..... Proably the 40 Series Flows dumped before the rear axle Seriously though, If you want a temp. fix, buy a tube of caulk and a $9 Wal Mart auto carpet. One of my friends has a '76 Chevy beater, and the floorboards were swiss cheese and letting exhaust fumes come in, and the made alot of road noise. He caulked up all the holes, and put a cheap Wal Mart carpet over it. It made the truck much more confortable to ride in, and cut the wind noise down by about half. Not a permant fix by any means, but it will work until you can weld in new floor panels. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

09-24-2003, 11:32 PM	#9
/<eystroke Registered User Join Date: Jul 2003 Location: North Texas Posts: 265	I never thought about the mufflers resonating, but I'm very sure it is the cab doing most of the buzzing. But I do have dual mufflers (with cutouts capped off) with turn downs sitting under the cab. Maybe if I move those out under the bed that will help. __________________ '69 C/10 Short Wide 350/400/AC/Tilt/Tach



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