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05-01-2009, 09:23 PM | #1 |
Registered User
Join Date: Apr 2009
Location: cedar rapids, IA
Posts: 3
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Mystery drivetrain noise help!
Hi, I have a 71' C30 dually that has me and all my shadetree buddies stumped.
The problem is when driving I'm getting a terrible howl/grinding/scream from somewhere in the drivetrain. (I think) The noise isn't bad in low gears but when I get into fourth and get going 45-55 it screams. When I press in the clutch it stops. I replaced the tranny, a sm420, and the clutch with no luck. Dosn't sound like the rearend, any ideas? Thanks! |
05-01-2009, 10:28 PM | #2 |
Gearhead and audio junkie
Join Date: Aug 2008
Location: nunyah
Posts: 452
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Re: Mystery drivetrain noise help!
I would take a look at your U joints, they can cause a screaming/howling noise if they go bad
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05-01-2009, 10:32 PM | #3 |
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Join Date: Mar 2007
Location: Connecticut
Posts: 581
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Re: Mystery drivetrain noise help!
curious, did you replace the throw out and pilot bearings?
carrier bearing maybe? does the sound change when you let off or step on it while cruising? could be the rear, they can really howl.
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05-01-2009, 10:38 PM | #4 |
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Join Date: Jan 2005
Location: Loveland Co.
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Re: Mystery drivetrain noise help!
Since it goes away when you push the clutch in my first thought would be throwout bearing.
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Chris 74 Custom Deluxe SWB 350/350/3.73’s 99 2wd Silverado RCSB 5.3/4L60/3.90’s http://www.classictrucks.com/feature...short_bed.html |
05-01-2009, 10:57 PM | #5 |
laying low
Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,514
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Re: Mystery drivetrain noise help!
I'd be sure to drain the rear end and look the oil over real good. It probably needs changing anyway. Sounds from the rear end can travel up the driveshaft and sound like they're coming from somewhere else.
Can you put it up on jack stands and make it do this?
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05-01-2009, 11:09 PM | #6 |
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Join Date: Apr 2009
Location: cedar rapids, IA
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Re: Mystery drivetrain noise help!
Yup we replaced the throwout and pilot bearings. (they were shot)
It still makes the noise when i let off but not as bad. And it gets worse the faster I go, but dosn't seem to make a difference if I romp on it at 55. The driveshaft was tight going onto the tranny if that might make a difference I thought it should have had more play in it. Ya I'm thinking we need to put the rear end off the ground and go over it from the tranny back to rear end. Last edited by Korr053; 05-01-2009 at 11:12 PM. |
05-02-2009, 08:28 AM | #7 |
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Join Date: Jul 2005
Location: MISSOURI
Posts: 3,256
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Re: Mystery drivetrain noise help!
Is the clutch disc faced the right direction. as in is it flipped 180 degree. I sen this in a vehicle once.that resymbles the description you describe.
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05-02-2009, 04:15 PM | #8 |
Registered User
Join Date: Apr 2009
Location: cedar rapids, IA
Posts: 3
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Re: Mystery drivetrain noise help!
OK!
We put the rearend up today and found the problem! The rear end is shot. I put a magnet in the rearend and got alot of metal, big nuggets. Thanks for all your ideas! |
05-02-2009, 06:04 PM | #9 |
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Join Date: Apr 2007
Location: King City, Ontario, Canada
Posts: 974
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Re: Mystery drivetrain noise help!
good to see you found your problem!
btw, welcome to the board!
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- Jason If you can turn, Youre not going fast enough. Favorite caption: first car to 200 mph in the 1/4 mile, no parachute, drum brakes all the way around.. ..back when men were men. |
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