Duramax Diesels Forum Truck of the Week
  #1  
Old 05-15-2019, 07:54 AM
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Jacob tomlinson Jacob tomlinson is offline
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Default Help lb7 grinding

I made a post a little over a year ago and still have not been able to find the source, when i get up over 50mph and i coast and barely press on the throttle i get a loud grinding noise but it isnt all the time and sometimes sounds louder or softer i replaced u-joints, center support bearing, took apart transfer-case. I noticed marks all over the torque converter, also a shop told me they think is is my wheel bearing but not sure how the throttle would make it grind.



http://https://m.youtube.com/watch?v=1Ynn0ysVx1k&t=79s
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Old 05-15-2019, 08:45 AM
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Hows the angles on your u joints?
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Old 05-15-2019, 08:50 AM
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What do you mean?
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150 air-dog lift pump
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Old 05-15-2019, 09:36 AM
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It is possible, I've seen it on mine, that it is just the u joints and their angles that is causing it. From what you described, it doesn't happen under load. But only when you are coasting and give a light throttle. For me this was when I matched the engine rpms with the tires so there was little load/torque on the drive line. If I was coasting and the wheels where turning the engine or if I was accelerating it wouldn't happen.

I first I thought I messed up the front differential gears or destroyed a u joint. But after checking everything out I determined it was my front drive shaft angle of off causing a vibration that sounded a lot like grinding.

And since I see you have a 6" lift I thought I would ask about your angle on the u joints. If the angles are too sever or mismatched it will vibrate and make noise that can be interpreted as grinding.

Just a thought
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Old 05-15-2019, 09:45 AM
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Yea i took out the front drive shaft and ran it stoll
Had the grinding sound, how would u check the rear?
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Old 05-15-2019, 12:28 PM
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well from that video i would say its either the drive shaft angle or a broken flex plate. i bet its the angles tho. looks like there is no spacer under your carrier bearing. im sure one is required for the size lift blocks under the springs.
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Old 05-15-2019, 12:36 PM
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See if your u joints are hitting. Not the same joint but you get the idea
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Old 05-15-2019, 01:56 PM
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maybe its an optical illusion, but in the beginning of that video it looks like the front part of the drive shaft is just flopping around in the carrier bearing?

around the 6-10 second range of the video
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Old 05-15-2019, 02:01 PM
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that carrier needs a drop bracket. are the lift blocks tapered or flat? stock leaves?
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Old 05-15-2019, 05:53 PM
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Moved to Chassis/Suspension. Sounds like the guys have a plan....
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Old 05-15-2019, 10:14 PM
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Marks on the converter are from some lazy ass using a screwdriver to pry the engine over instead of doing it the right way.
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Old 05-16-2019, 06:39 AM
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Quote:
Originally Posted by rcr1978 View Post
Marks on the converter are from some lazy ass using a screwdriver to pry the engine over instead of doing it the right way.
Nothing wrong with turning it with a screw driver.
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Old 05-16-2019, 06:24 PM
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how close is the exhaust hanger to the rear driveshaft,,looks like there is a band on the shaft.
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