Why does my 727 make noise?
#2199444
11/20/16 04:58 PM
11/20/16 04:58 PM
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Joined: Feb 2003
Posts: 1,665 Milwaukee, WI
Prince_Valiant
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Milwaukee, WI
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The 727 in my 79 LRE has been making noise...really quite soon after it was rebuilt.
It started small, and at first didn't think it was my transmission...it'd occur under very light loads/high vacuum situations, so I actually thought that it was noise from air resonating through my throttle plates...as soon as a little throttle was applied, it would go away, and come back under low load/high vacuum situations again.
After taking my Truck to the Drag Strip though, the sound is unmistakably the transmission. It only happens in 2nd and 3rd gear...but has gotten MUCH louder. Sounds kind of like a loud flat horn...
And again, under light load...when I apply throttle, the noise goes away. If I replicate the same throttle conditions/rpm's in 1st, no noises, load or no load. Trans was "built" with components to race (shift kit, race clutches/bands, high pressure regulator spring, etc)
Transmission otherwise drives just fine...no slipping, good firm shifts.
1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph 1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD) 1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD) 1989 Shelby CSX #500/500
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Re: Why does my 727 make noise?
[Re: Prince_Valiant]
#2199495
11/20/16 06:48 PM
11/20/16 06:48 PM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
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Mass
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From A to Z the problems could be a multitude of issues?, first I'd start with checking the converter flex plate, the bolts, any signs of rubbing/scrapping, weights missing from the converter, etc, etc,...new drive shaft? vehicle been lowered, spring/axle/perch relocation, etc?
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Re: Why does my 727 make noise?
[Re: Prince_Valiant]
#2199500
11/20/16 07:02 PM
11/20/16 07:02 PM
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Joined: Jan 2003
Posts: 25,812 Rio Linda, CA
John_Kunkel
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A "moan", "buzz", "whine" noise is often caused by a rapidly cycling pressure regulator valve, the factory calls it "regulator valve resonance". It's more of an annoyance than a real problem...the recommended cure is to replace the valve body.
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Re: Why does my 727 make noise?
[Re: Prince_Valiant]
#2200230
11/21/16 10:25 PM
11/21/16 10:25 PM
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Joined: Feb 2003
Posts: 1,665 Milwaukee, WI
Prince_Valiant
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Since it was a second and third gear thing, I thought band might be an issue, but John's description sounds the most accurate and makes sense that the noise depends on which gear it's in too. It does shift fine/no slippage....which fits with "annoying...not serious."
Though this one is VERY annoying since it's VERY loud....
Last edited by Prince_Valiant; 11/21/16 10:25 PM.
1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph 1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD) 1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD) 1989 Shelby CSX #500/500
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Re: Why does my 727 make noise?
[Re: Hotwheelsjr]
#2200450
11/22/16 11:35 AM
11/22/16 11:35 AM
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Joined: Feb 2003
Posts: 1,665 Milwaukee, WI
Prince_Valiant
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You're positive it's the trans? I have a '01 Durango with a bad pinion bearing and it makes noise when applying light throttle, but quiets way down when I let off. Sounds pretty familiar... That's a good thought...but 1)the noise definitely doesn't sound like it's coming from the rear 2) Can't find any load/speed conditions when the noise can be repeated in first gear 3) Going into neutral completely quiets it down (I know this changes load conditions so it doesn't entirely rule out bearing) and 4) the noise was present before and after completely rebuilding the rear end.
1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph 1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD) 1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD) 1989 Shelby CSX #500/500
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Re: Why does my 727 make noise?
[Re: Prince_Valiant]
#2201003
11/23/16 02:20 AM
11/23/16 02:20 AM
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Joined: Nov 2003
Posts: 10,693 Surface of the Sun, AZ
Hotwheelsjr
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I Live Here
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You're positive it's the trans? I have a '01 Durango with a bad pinion bearing and it makes noise when applying light throttle, but quiets way down when I let off. Sounds pretty familiar... That's a good thought...but 1)the noise definitely doesn't sound like it's coming from the rear 2) Can't find any load/speed conditions when the noise can be repeated in first gear 3) Going into neutral completely quiets it down (I know this changes load conditions so it doesn't entirely rule out bearing) and 4) the noise was present before and after completely rebuilding the rear end. Cool. Just a thought.
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