HoytUSA

As the title states, when I turn I can hear a rumble or vibration in the rear end. Truck has 114k miles on it. I bought it with 107k miles on it. I have no idea if the differential has ever been serviced. Anyone had this problem before? How big of a deal is it to service the differential?

homer

Do you have a limited slip rear end? If you do, it sounds like the clutch packs going (normal wear most likely at that mileage).

Easy to service but if the clutches are gone it's not worth draining and filling with oil as it won't help. Additionally, you need to have the additive.

HoytUSA

TTT

Saltlife

Is it when you are making sharp turns or at anytime coming out of center alignment?

If you just hear it and not feeling it than homer is more than likely right your clutch packs have gone bad. It's a known issue with these trucks.

Bad thing is a shop is going to charge you a lot to open and replace. I would stick to a dealer because they know the amount of additive that is needed for the rear.

corey_lax

I'm guessing they didn't add a friction modifier when they changed the fluid. I would change the diff fluid before servicing it. It's cheap and at least you will know afterwards if its the clutch packs or just the fluid. The limited slip diffs absolutely need the friction modifier.

HoytUSA

I just talked with my mechanic. He said it is likely just that servicing the diff will solve it. He has seen this before. He knows to add the modifier and the amount. If it is the clutch packs, is that a pricey repair?

homer

Personally... I'd be sure on that, maybe ask another shop a quick opinion (never hurts to get two)... I know here, it cost me $30/quart and it was 3-4 quarts of oil to change that rear end fluid... then the additive (I don't think it's much). I think I was around $120-130 or so to service the diff but only in fluid costs (not including your mechanics labour). I did mine myself, not hard to do. I had to do my axle seals thus the reason for pulling mine apart (also, doesn't hurt to check if those are leaking!!! - may be lower on fluid). I would hate to see someone spend $250-300 to service their rear diff to find the problem didn't go away... I'm not sure how difficult it is to check with the cover off (while changing the fluid) personally.

Saltlife's comment is good. Corey_lax also makes a good point, someone may have serviced it and not put the additive in. I've heard that's a common mistake made and noticeable.

The clutch pack I *think* could be around the $800 or so mark. Others may know, I haven't had to change mine on this truck quite yet (and I hope not to yet either haha). I think it's more though from past posts I've read.

HoytUSA

$240 later and the shudder is gone. The rear diff had never been serviced and the fluid was milky colored....had some moisture in there. Had the front diff and transfer case serviced as well.

homer

Glad to hear that's all it was! Much cheaper than replacing the clutches haha

beantown617

I get a vibration/rumble, mostly at 20-30mph, but also at about every 20 mph increment after that. Ujoints dont seem loose. It feels/sounds like something is slipping and does a quick squeek or two when accelerating from a stop at slow parking lot speeds. It seems like rear diff issue but i dont have it any worst when turning which is weird. Did u also get a jerk/skip/squeek when accelerating from a stop? Or was only when turning?

Mine is a 2005 f150 5.4 4x4 screw cab with limited slip diff