Clunking/Rattling noise from Transmission area?

Janimal444

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Jun 25, 2012
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Salem, NH
Ok, so this noise first started only when driving forward at a low speed. It is a clunking/rattling noise, pretty much goes along to the same exact pace as the "rattle" of the diesel engine when idling, but sounds awful.

Then, the noise started when shifting into drive or reverse, and now even worst when driving at low speeds. It also makes the noise when in park, although not very loud. I tried to trace it tonight, and it APPEARS to be coming from the front bell housing of the transmission, although that is hard to say for sure because I was by myself and the clanking was not nearly as audible when the truck is in Park.

Does anyone know what this noise could be? I have about 5k miles since my trans build. Trans shifts flawlessly, convertor locks up nice, etc. 60k miles on the truck. I will try to get someone else to look at it when I have someone around, so that I can put the truck in gear and listen.
 

Janimal444

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Jun 25, 2012
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Salem, NH
Read around a little more and getting worried could be a broken flex plate :confused::confused:. Is that common at my power level, 500hp or so
 

Mpsoldier

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Mar 10, 2010
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take the cover off the bottom of the trans to look at the converter first guess wound be a converter bolt backed itself out.
 

Mike L.

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Who installed the trans? What did your builder say? You're leaving a lot of info out and we cannot guess.
 

Janimal444

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Jun 25, 2012
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Salem, NH
I did the install myself. It was the third Allison I have done, so I very well could have made a mistake, but it was not a “trial and error” install by any means. I will start by looking for any possible loose converter bolts.
 

blk smoke lb7

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Nov 8, 2010
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Check out the transfercase could be a pump rub going bad.Last year my truck suffered and so did my stepfathers work truck.Good thing i had 2 spares.
 

Janimal444

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Jun 25, 2012
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Salem, NH
Check out the transfercase could be a pump rub going bad.Last year my truck suffered and so did my stepfathers work truck.Good thing i had 2 spares.

I did do the pump rub kit from Merchant as well. You are saying a different issue than the pump actually rubbing through the transfercase, correct? The pump itself actually failed on your truck?
 

blk smoke lb7

<-----Lots of green $
Nov 8, 2010
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I did do the pump rub kit from Merchant as well. You are saying a different issue than the pump actually rubbing through the transfercase, correct? The pump itself actually failed on your truck?
Nope they were virgins never had the kit in ithem thats why they suffered.What made me wonder about the 1 was its 4x4 but never gets drivin in the winter and the transfercase was full of fluid when we drained it so that 1 could have been something else besides pump rub,possible bering failure?

Have you crawled under and checked the shafts for play or anything?
 

Janimal444

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Jun 25, 2012
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Salem, NH
Nope they were virgins never had the kit in ithem thats why they suffered.What made me wonder about the 1 was its 4x4 but never gets drivin in the winter and the transfercase was full of fluid when we drained it so that 1 could have been something else besides pump rub,possible bering failure?

Have you crawled under and checked the shafts for play or anything?

I checked shafts and everything, originally though it was a U joint when it was only doing it in drive, and was not as loud, so checked everything good. I will check TC bolts tonight, and if that does not help I'll try to get a video of the noise
 

Janimal444

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Jun 25, 2012
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Salem, NH

Polaris7x

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Dec 25, 2011
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loves park, ill
thats crazy, mine starting making almost the same noise, so were pulling the trans back out, i ordered a new bd flex plate and my builders gonna go back through the trans, ive got the suncoast with the precision converter, so while the trans is out gonna send the converter back and have them go through it to make sure a fin didnt break or anything
 

Janimal444

Member
Jun 25, 2012
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Salem, NH
Hey guys, luckily ended up just being two loose convertor bolts! Or at least that's what it appears, I tightened them back up and the noise is gone...
 

03Tommy

New member
Jun 2, 2008
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Weston, Mo
You got lucky. I had the exact same sound in my 05, except mine ended up being a broken adapter plate and bell housing. Bell housing wasnt bad until the adapter plate broke completely. Needless to say it is the reason I now own an 08.