Grinding noise when coasting (1 Viewer)

[PJCB]

For about the last month or so, there has been a noise coming from what appears to be the front left side when coasting at between 10-40km/h. The noise can sometime be heard when accelerating but easiest to reproduce when coasting. The noise is difficult to explain but its basically a grrrr grrrr grrr. You can feel the grinding through the pedals and floor. It sounds like the dull groan of a huge base speaker making a car vibrate.

When it first started, I looked under the vehicle and saw the left CV boot was torn and grease was coming out. I had replaced the right side a while ago so decided to replace the entire CV on the left side. After doing this, the noise was gone for about a week and I thought that was that... until a few days ago when it started again.

I have driven with the front prop only and the sound persists. Rear prop only and the sound persists. Changing to neutral when coasting also make no difference. I have visually inspected all the break pads and disks and they are all perfect.

Today I stripped down the front hubs to inspect the wheel bearings and although I have not put it all back together yet, I dont think it will make a difference as all the bearings and needle bearings have no pitting or roughness.

Any suggestions as to where to look next or how to diagnose?

 

[12guns]

I would put money on the bearings being bad or needing a simple repack. Did you get that done today? I'd be curious if that helped. Not sure what else it could be, it has to be something moving, which is limited to driveshaft and wheels. Only other thing that comes to mind might be a u joint. Have you greased them up lately? You mentioned you have "driven with front prop only"...are you referring to front and rear drive shaft? How did you seperate the front vs. rear shaft? You would have to pull the yolks and entire shaft one at a time. Since our rigs are full time 4wd, there is a chance there is a bad u joint.
I'll assume the transfer case and transmission are not the issue, but I guess there could be a bearing inside the front diff as well that could be going out. Maybe the new CV shaft being put in place made the noise go away briefly? Don't know if any of that helps, but hope you narrow it down soon.
First step for me would be a bearing repack and lubing up the driveshafts just to rule those out.

 

[AATLAS1X]

I had a similar noise last year and I couldn't locate it, took it to Toyota. Ended up being RR wheel bearing.

Shane.

 

[PJCB]

I drove with the front drive shaft only and rear drive shaft only (with centre diff locked) and could get the noise both times so its definately not the U-Joints.

Last night I was inspecting all the parts again and see that the thrust washers that sit between the hub nuts and outer wheel bearing were badly pitted/worn. Maybe about a 0.5mm indentation rubbed away. Possibly the preload was too little allowing the bearing to turn against the thust washer and making the noise?

I'm waiting for two new spindle bearings that should arrive tomorrow and will then re-assemble the front end and see. I've read a few threads on getting the mystical preload right... I went with the FSM fish scale technique the last time I repacked the bearings... and consensus says that thats way too loose for a used bearing. This time I'll just go with about 50Nm torque on the hub nut.

 

[ntsaint]

Mystery solved. Had the dealer install new rotors a month or so ago. They found a clip on the hub or axle that hadn't been installed properly and had come loose. Replaced that, all good. $0.