Grinding noise coming from drivetrain when decelerating (1 Viewer)

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Wanted to ask on the forms and see if anybody knew what this sound was. Whenever I am driving at approximately 60 miles an hour and let off and let it fall to around 30 I hear an odd grinding/vibrating sound. I just greased my Berfield joints, so I think I’m going to grease the rest of the drivetrain. If anybody knows what this is or what it could be please let me know. Thanks.
 
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Does it happen the entire time you're decelerating? If you add throttle for a moment, does it stop until you coast again?
 
U-joints first
Then check pinion bearings and slop
Then transfer case input and output bearings.

May need to put it all up on jack stands and use a stethoscope to listen to the bearings.
 
Did you recently do a suspension lift? Pretty common side effect of 2.5”+ lifts.
 
Does it happen the entire time you're decelerating? If you add throttle for a moment, does it stop until you coast again?
Exactly. Sometimes it does, sometimes it doesn’t. Only when I start coasting and sometimes it doesn’t even do it at all. I am taking this thing 6 hrs away tomorrow. I wonder if it’ll be alright
 
Never had this issue until the 3 inch lift was put on. How big of a side effect ?
Did you do proper caster correction? Try cleaning and greasing the front driveshaft ujoints. It might help. You will probably need a double Cardin driveshaft to fix it.
 
Exactly. Sometimes it does, sometimes it doesn’t. Only when I start coasting and sometimes it doesn’t even do it at all. I am taking this thing 6 hrs away tomorrow. I wonder if it’ll be alright

If you have a cdl switch installed you can lock the center diff and pull the front shaft. Id bet the grrrr goes away if you do.
I went through the same thing after I installed a lift. I lived with the decel growl for a long time. Then i did the locked center diff 2wd thing for a while. I decided to get a landtank driveshaft when I saved up the money.
 
If you have a cdl switch installed you can lock the center diff and pull the front shaft. Id bet the grrrr goes away if you do.
I went through the same thing after I installed a lift. I lived with the decel growl for a long time. Then i did the locked center diff 2wd thing for a while. I decided to get a landtank driveshaft when I saved up the money.
Thanks for the advice! Issue is I’m gonna be needing 4wd. Laying under it right now looking for grease points while on the forum lol
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Did you do proper caster correction? Try cleaning and greasing the front driveshaft ujoints. It might help. You will probably need a double Cardin driveshaft to fix it.
That’s the next step asap. Caster correction. Watched a few videos and figured it would be okay for a while without it because it’s only a 3 inch lift from Dobinsons. Guess that’s what I’m gonna have done next. Am I damaging it by running factory caster angle?
 
Thanks for the advice! Issue is I’m gonna be needing 4wd. Laying under it right now looking for grease points while on the forum lol View attachment 3249281
There are (3) zerks on each driveshaft.

Make sure that you grease it with the driveline unloaded. THis means chock the wheels, set the parking brake, place the transmission in NEUTRAL. This allows the grease to penetrate even where the high pressure areas are.

You'll also need a "needle" type grease gun end to get to the U-Joint zerks.
 
That’s the next step asap. Caster correction. Watched a few videos and figured it would be okay for a while without it because it’s only a 3 inch lift from Dobinsons. Guess that’s what I’m gonna have done next. Am I damaging it by running factory caster angle?
I’ve not heard of just that causing damage. BUT Improper caster is a safety concern. It can affect steering, stability, etc.
 
did you go from std suspension to 3" or from 2" to 3"?

when lifting the caster changes as mentioned however vague steering is the usual symptom - can you post a pic of the angle of the front driveshaft where it joins the diff?

id be looking for lateral movement in the uni's - particuarly the rear one at the diff - this can cause a grinding / growling sound upon decellaration

also, upon lifting the tailshafts will extend a little from where they would have been sitting previously so might be in need of a little more grease (not too much though) as it may be binding on a dry section of the splines
 
did you go from std suspension to 3" or from 2" to 3"?

when lifting the caster changes as mentioned however vague steering is the usual symptom - can you post a pic of the angle of the front driveshaft where it joins the diff?

id be looking for lateral movement in the uni's - particuarly the rear one at the diff - this can cause a grinding / growling sound upon decellaration

also, upon lifting the tailshafts will extend a little from where they would have been sitting previously so might be in need of a little more grease (not too much though) as it may be binding on a dry section of the splines
Yep. From stock to a 3 inch. Crawled under there today in Greased the fittings on the shafts. But Like somebody mentioned, I could not reach one or two of the fittings because I needed a narrower grease gun.
 
I have the exact same issue as described above - 2.5" OME lift with caster correction, and after some time the grinding ensued and has become worse upon deceleration (the car is also pulling fairly strongly to the left even after alignment and work on wheel bearings). Has anyone found the magic bullet to solve this? I'm not a mechanic , but the car has spent a decent amount of time at the shop trying to solve, so appreciate any further advice (in addition to the above) that I might share with the shop based on outcomes.
 
I have the exact same issue as described above - 2.5" OME lift with caster correction, and after some time the grinding ensued and has become worse upon deceleration (the car is also pulling fairly strongly to the left even after alignment and work on wheel bearings). Has anyone found the magic bullet to solve this? I'm not a mechanic , but the car has spent a decent amount of time at the shop trying to solve, so appreciate any further advice (in addition to the above) that I might share with the shop based on outcomes.

Ditto. Replaced the u-joints with Toyota. 2.5" lift. Caster is corrected using offset rubber bushings. Recently serviced front and rear axles. I am in the process of refreshing all the control arm/panhard bushings, but wondering what the issue could be. Mine is present at 62-75 MPH, is there on coasting/deceleration and goes away when I accelerate.

I am not a fan of the stink bug I have and have considered leaving the 2.5 on the front and putting .75 on the rear to level it out. Wondering if it will also solve the buzzing noise.
 
Each rig is different, for me proper caster correction (I used plates) and a DC front driveshaft was the answer.
 
Fix caster.
New OEM or Matsuba uni joints all round.
Or DC front shaft

A 2 or 3" lift is enough to charlnge the range of movement in the uni joints because of a change in driveline angles. Worn in needle rollers will be riding on ridges from previous normal position.
Uni joint bearings don't roll round and round, they rock back and forth in a narrow range and can wear in pronounced grooves and ridges. Even a subtle wear pattern will create noise when that shifts with a change in driveline angle
 
Did the same lift, same vibration noise as you described - installed new u joints. Got better but still there - tried getting castor fixed .....never could eliminate it.

Got new front DC shaft installed - vibration noise eliminated!
 

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