Transmissions and Drivetrain Need help with your trans? Problems with your axle?

"Flap-Flap" Noise...Transmission bad? What could be wrong?

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Old Oct 7, 2009 | 07:56 PM
  #1  
tilstad's Avatar
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Joined: May 2003
Posts: 800
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From: New Jersey
Car: 87 Black Formula
Engine: Rollercammed Lg4
Transmission: 700R4
Axle/Gears: 3.23 10 Bolt Locker
"Flap-Flap" Noise...Transmission bad? What could be wrong?

There is a noise coming from the direction of the transmission. It seems to follow engine/tranny rpm, and usually comes on if I use the throttle a little bit. If I back off on the throttle, it usually goes away, and I can keep it away if I drive very carefully.

The noise itself is best decribed as a "Flap-flap" sound. Not too harsh. If one set heater fan to the max, it will deafen it. It's been like this for two weeks or so, but does seem to come more and more often.

I did suspect it could possibly be an exhaust leak, either from the manifold, or from the exhaust under the car. But I didnt find any loose bolts or such. I could not get the sound to come on when I had my head in the engine compartment either, revving the engine. One can usually hear it from inside the car though, even when parked. It does seem to require a lil more throttle then though, which led me to think it could possibly be an exhaust leak.

Since I didnt find any sound in the engine compartment, I'm back to thinking it might be the transmission. Is this a typical sound for transmission issues? What could it possibly be? Converter related? or possibly the lockup clutches? The noise comes on in speeds lower than lockup though. The transmission works perfectly otherwise though.


There is one transmission shop in my country, but they are not close, and I also suspect them of being rather expensive. But I will try them if someone here thinks thats what I need to do.

I would appreciate some input on this issue first though. Any help, hints or comments would be highly appreciated.


(I need to sell this car ASAP, and hence would want this fixed before I do. My new wife is expecting a baby end of november, and I need to fix and sell my two cars, pack up and send all my stuff to the other side of the world by november 1. The money for these cars is supposed to pay for furniture and baby stuff. So, I'm a bit stressed about this now)
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Old Oct 7, 2009 | 08:12 PM
  #2  
Burnout91's Avatar
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Joined: Jul 2006
Posts: 811
Likes: 2
From: 4-22 / 7-25
Car: '91 Z28 L98 G92
Engine: Modded L98
Transmission: Modded 700R4
Axle/Gears: Modded 10-Bolt
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

Have you looked under the car, at the trans / driveshaft / rear axle area?

Once some friends at work installed a large zip-tie around the driveshaft on my pick-up truck....
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Old Oct 7, 2009 | 08:29 PM
  #3  
tilstad's Avatar
Thread Starter
Senior Member
 
Joined: May 2003
Posts: 800
Likes: 0
From: New Jersey
Car: 87 Black Formula
Engine: Rollercammed Lg4
Transmission: 700R4
Axle/Gears: 3.23 10 Bolt Locker
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

No, I havent. But I think the noise would follow the speed then, not the engine rpm like it does now...? I Will have it up on a hoist this weekend though.
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Old Oct 8, 2009 | 03:13 PM
  #4  
tilstad's Avatar
Thread Starter
Senior Member
 
Joined: May 2003
Posts: 800
Likes: 0
From: New Jersey
Car: 87 Black Formula
Engine: Rollercammed Lg4
Transmission: 700R4
Axle/Gears: 3.23 10 Bolt Locker
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

bump
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Old Oct 8, 2009 | 03:19 PM
  #5  
84 z28's Avatar
Supreme Member
 
Joined: Apr 2006
Posts: 1,801
Likes: 21
From: Rochester NY
Car: 1984 z28
Engine: 355
Transmission: 700r4
Axle/Gears: Moser 9" 4.11
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

Check your converter bolts. They might be coming loose.
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Old Oct 8, 2009 | 11:08 PM
  #6  
csimpson1's Avatar
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Joined: Sep 2009
Posts: 78
Likes: 0
From: 47874
Car: 1984 Black Trans Am
Engine: 350 bored .030
Transmission: 700r4
Axle/Gears: Stock. Wanting up grade
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

i had somewhat of the same problem in my bird. found out that the bolts that hold the flywheel on the tranny had come loose. but at a lower rpm mine would be so loud, like the exhaust manifolds were hitting stuff down under there, but then i lifted it on a couple of jacks and then seen a bolt or two were loose. so me and my dad undid the tranny and the flywheel was just rockin around in there. my suggestion would be to take off the bracket to get to the tanny and get in there and see if those are tight or not, but thats IF this is the same problem, sounds EXTREMELY similar tho. hope this helps
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Old Oct 9, 2009 | 02:32 AM
  #7  
punkdude908's Avatar
Senior Member
 
Joined: Apr 2007
Posts: 394
Likes: 1
From: Huntington, NY
Car: 1983 Pontiac Firebird
Engine: LG4 305ci 4bbl
Transmission: 700r4
Axle/Gears: 10-bolt open diff.
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

i had a similar sound coming out of my Bird's 700r4 when i first got it. it would come and go, and usually fade away past 2000 rpm. idk what it was, but a few weeks later, i lost my 2nd gear and had to drive home in 1st with the hazards on @ 15 mph. i ended up having the trans rebuilt- no more weird sounds and solid as a rock. shifts better too.
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Old Oct 10, 2009 | 08:19 AM
  #8  
tilstad's Avatar
Thread Starter
Senior Member
 
Joined: May 2003
Posts: 800
Likes: 0
From: New Jersey
Car: 87 Black Formula
Engine: Rollercammed Lg4
Transmission: 700R4
Axle/Gears: 3.23 10 Bolt Locker
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

I towed the car to a transmissionshop last night. Hopefulle it wont be too expensive. THey charged $3500 for an overhauled transmission there, + installlation fee.

I asked if they please could try do it as affordable as possible though.
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Old Oct 10, 2009 | 08:33 AM
  #9  
84 z28's Avatar
Supreme Member
 
Joined: Apr 2006
Posts: 1,801
Likes: 21
From: Rochester NY
Car: 1984 z28
Engine: 355
Transmission: 700r4
Axle/Gears: Moser 9" 4.11
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

Originally Posted by tilstad
I towed the car to a transmissionshop last night. Hopefulle it wont be too expensive. THey charged $3500 for an overhauled transmission there, + installlation fee.

I asked if they please could try do it as affordable as possible though.
OMG thats a rip off. it should ony cost about $1500. And i dont think theres nothing wrong with your tranny. I'm betting its the converter or flywheel.
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Old Oct 10, 2009 | 08:42 AM
  #10  
tilstad's Avatar
Thread Starter
Senior Member
 
Joined: May 2003
Posts: 800
Likes: 0
From: New Jersey
Car: 87 Black Formula
Engine: Rollercammed Lg4
Transmission: 700R4
Axle/Gears: 3.23 10 Bolt Locker
Re: "Flap-Flap" Noise...Transmission bad? What could be wrong?

Well, I live in Norway, everything is a ripoff here. It's just a choice between the severity of ripoffs really. Hence why we are moving to Texas.

Main reason being, we're getting a 4/5 bedroom house with pool, for the same price as a 1 bedroom apartment of 35 square meters in Norway. Also, if things go as we hope, we're getting out of debt/mortgage at the same time.

Just need to sell these vehicles and I'm done.
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