Grinding sound when I let off the gas?

[Maverick26]

It has been doing it in the buggy almost every time I go out. It really is bad when I am going fast and then let off the gas it has a gravelly grinding sound then when I stab it again it goes away. I thought it was my front driveline not being strait but last night I took it down on the lathe and made it right... went out for a test drive and it still does it. On the road it feels like it could be my rear driveline now. It was balanced by a shop. Could it be U joint angle? My rear DL and axle yoke kinda look like they are really strait in line. Any ideas? Its hard to find the problem cause I am chasing a sound... I can kinda feel a vibe in the pedal but thats it.

 

[chainsaw]

Put it on jack stands and rotate the tires by hand?? Im just think you could maybe isolate it that way..

 

[TreeClimber]

A too-steep rear driveline angle will sometimes create a odd sound (kinda growly-vibration) that sounds like the bearings in the Tcase are shot, but only makes the noise in the engine RPMs between accelleration and decelleration. That little window of 'coast' is where the noise occurs.

Had it happen on my CJ. Typically at highway speeds.

 

[lethe]

if your driveline angle is pretty bad check the u joints before you tear anything apart.

 

[Maverick26]

if your driveline angle is pretty bad check the u joints before you tear anything apart.

Well the DL angle is not bad, its just that the pinion and the drive line look like they are inline... All my joints are new, everything is tight, got lubed, nothing is obviously wrong... Its just sounds like its gonna grind something right off when its does it.

 

[nevada]

can you tell if its from the front, or the rear?

the last time i heard something like that, the rear pinion nut was loose.

 

[Eric]

My 4runner had that sound when my rear ring and pinion where on their way out.

 

[boardbysled]

My rig has that kinda sound because the front slip on the DL is very loose. Is your slip tight?

 

[Maverick26]

The slips on both are really tight... like I need a hammer to get them in or out. I thought it was the front at first but after the test drive last night I now think it could be the rear.

 

[Hip]

not being there im assuming you feel this in the seat of your pants... im guessing coast side of ring gear, please tell me thier not yukons:corn:

 

[Maverick26]

not being there im assuming you feel this in the seat of your pants... im guessing coast side of ring gear, please tell me thier not yukons:corn:

Yes, it feels like its under me.. The guts of the axles are what was in them when I got them and I was told they where stock. Dodge dana 60 front, dana 70 rear, 4.88 gears non yukon, and I did the weld jobs. I never messed with anything in there. Not saying there could not be an issue.

 

[Boonie Buster]

Have you checked all the u-joints themselves?

I had a pretty nasty sound from the front d-line when i let off the gas and the front end was locked up.

 

[CHOP SHOP]

If you hvae no angle or a straight junction at the rear axle pinion yoke and no CV at the tcase then thats your problem.

If you have any angle at the upper joint the lower needs to match it unless you have a cv.

Those slips needs to move freely, if you need to tap them it or out thats not good.

Also make sure they are timed properly. both ends in phase with each other.

 

[Maverick26]

If you hvae no angle or a straight junction at the rear axle pinion yoke and no CV at the tcase then thats your problem.

If you have any angle at the upper joint the lower needs to match it unless you have a cv.

Those slips needs to move freely, if you need to tap them it or out thats not good.

Also make sure they are timed properly. both ends in phase with each other.

I think this is my problem. When setting up my links I pointed the rear pinion at the T case output. I should have pointed it more downward so it gave the U joint an angle to ride in. What about when the axle is at full droop?

 

[CHOP SHOP]

What about when the axle is at full droop?

Are you going to feel a vibe at full droop? Is your rig ever at full droop when at a speed to feel the vibe? NO.

Set the rig to work at ride/drive height.

I would get the shaft out and add a CV at the top instead of dropping the nose of the pinion in the dirt and rocks.

 

[Maverick26]

Are you going to feel a vibe at full droop? Is your rig ever at full droop when at a speed to feel the vibe? NO.

Set the rig to work at ride/drive height.

I would get the shaft out and add a CV at the top instead of dropping the nose of the pinion in the dirt and rocks.

Well when I was with S&N they told me to not run a CV and just point the pinion at the output.

 

[Pat]

Those slips needs to move freely, if you need to tap them it or out thats not good.

I would look into this.

It will push/pull on your transfer case, make noise, vibrate, especially when momentum shifts during accel/decel. It will pretty much do everything you described.

Pretty soon the transfer case output seals will be leaking, then you will know for sure.

All you need to fix it is drill out the (probably plugged up) hole in the end of the driveline where the excess grease squirts out.

Wait... the slips could be rusted also, then you will need more than to drill a little hole. But either way its bad they need to slip freely.

 

[Maverick26]

I would look into this.

It will push/pull on your transfer case, make noise, vibrate, especially when momentum shifts during accel/decel. It will pretty much do everything you described.

Pretty soon the transfer case output seals will be leaking, then you will know for sure.

All you need to fix it is drill out the (probably plugged up) hole in the end of the driveline where the excess grease squirts out.

Wait... the slips could be rusted also, then you will need more than to drill a little hole. But either way its bad they need to slip freely.

They are new.. Not rusty, fresh grease, They just need to be tapped to get in and out.. they are not sloppy and worn out like your sister. :flipoff: Just kidding man... Im sure she is nice.

 

[Binder]

Well when I was with S&N they told me to not run a CV and just point the pinion at the output.

That's correct for your setup. What Chopshop describes is true for typical rigs but this isn't the problem with yours, the angle at your T case isn't enough to cause problems. You do however have to have the U joint phasing right..

 

[Maverick26]

That's correct for your setup. What Chopshop describes is true for typical rigs but this isn't the problem with yours, the angle at your T case isn't enough to cause problems. You do however have to have the U joint phasing right..

This is what I thought.. all my stuff is in phase... It is kinda of a random vibration/grind sound... I am gonna keep looking around under there and see if I can find what is up.