I have had my truck for close to 4 years now and ever since I got it, there is this rough grinding turning left or right..
I first noticed the first time I took a long trip, it won't do it unless I drive at least 50-60 miles in a trip. There is nothing until I guess the rearrend gets hot enough? Who knows.. But it is when I come to a complete stop and make a left or right turn, and the whole truck just kinda bumps.. It's never bothered me and I have never had a earl problem with it.. Just wondering if anyone else has had this issue.

I bought my truck with 142k miles and just broke 200k.. I figure if it's done it this long and no problems, I guess there is nothing to worry about... Wouldn't you?

If you figured out what it was or if it gave you any problems I'd like to know!

 

Do you have a ls (posi) rear end if so you might need a new clutch pack

 

I thought they all did.. But maybe you're right.. Just lookin for opinions..

 

All did what

 

had posi rear ends to lock and unlock? You saying maybe it doesn't unlock? Would the clutch pack make it not unlock?

 

Oh no not all trucks have posi but honestly idk exactly what the clutch pack does but i know if it goes bad it can cause the symptoms you started above I would assume that's what it does though

 

Do you hear actual grinding or is it more just the feeling coming from the rear

 

feel.. Now that I think about it.. It's like the same feeling as in 4wd.. Just you can feel it from the rear instead of all around like it would in 4wd

 

Sounds like your clutch pack if you have an LSD differential and it's doing it around corners. At your mileage, the clutches are probably gone.


I don't have the link handy but someone else was talking about the same problem. Check if your rear-end is LSD but that's what it's sounding like.

 

This was the post that came up earlier:


https://www.f150forum.com/f4/rear-end-shudder-237589/


Not sure if the friction modifier will make a difference or not but may be worth a try. Also check your fluid level in the rear diff... make sure your rear axle seals haven't gone and you've lost fluid.