LSD Rear Differential Rumble and Binding During Tight Turns Forward and Reverse

I read a few earlier posts about the rumbling noise coming from the rear end in order to determine what was wrong with my truck.

Today, I finally went to the dealer regarding the rumbling noise and I wanted to share the info I learned regarding my 2006 Tacoma. This noise just recently started after having the dealer service the differentials and transfer case at approximately 40,000 miles. Currently, I have 43,000 miles on the truck and everytime I make sharp turns and hit the accelerator, the truck makes a horrible rumbling sound, almost as if the rear differential has a severe bind inside.

After continued driving, the truck also made the same noise in reverse. I decided it was time to go to the dealership today. Fortunately, the dealership replicated the problem with ease. In fact, three different mechancis took the truck for a test drive to try and determine the issue at hand.

After nearly an hour of waiting, I was informed that the dealership was on the phone to Toyota of California (apparently the technician help line). This was simply because they could not determine the fix for this issue. Eventually, the service advisor informed me that Toyota of California recommended that 2 additional bottles of friction modifier be added to the rear differential and that this rumbling noise is "normal".

After hearing this, I disputed the "normal" comment, however I figured I need to jump through these hoop and see what happens. Keep in mind that I have nearly 15,000 more miles of powertrain warranty, or a little more than a year left. So, the dealership added the 2 additional bottles of friction modifier and now the rumbling noise is gone. To be honest, the rear seems to be very smooth now.

I will say that the dealership told me they will not guarantee this fixes the problem, but it is worth a try. This is because Toyota will not simply replace the rear end on the truck without a little bit of troubleshooting.

My frustration is that none of this happened until after the rear differntial was serviced. And, I know for a fact that friction modifier was added at the time of service because the service advisor informed me of it upon handing me the invoice for the work.

I am hoping this corrects the problem. From what I understand, if it reappears, it will do so within about another 4,000 miles. Let's just hope this provides some of you other Tacoma owners with some dealership advice.

I am so happy I had the Toyota dealership do the differential fluid change. That was the first concern of theirs...the fluid needed changed. Too bad it already was changed...by them!

 

That is definetely good to know. so their fix is to dump more additive. Did they change oil for synthethic in your Diff?

 

Did you guys read this thread?
http://www.tacomaworld.com/forum/2nd-gen-tacomas/93117-beware-changing-lsd-lube.html

This has been an issue for everyone. These mechanical LSD's are finnicky and the owners manual is not specific enough about what to use in terms of oils or friction modifiers.

Every situation is different and certain oils/modifiers work fine for some while they don't work for others.

I'm using Mobile 1

$29 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 with the Ford XL3 (Toyota recommended) friction modifier. The first two turns of each day (after the truck sat overnight), I'd get rumbles. After 1,000 miles, the rumbles got better but didn't go away completely, I contacted Toyota and they suggested another bottle of modifier. I just added that 2nd bottle on Friday and did some tight 8 circles in a local parking lot. So far, so good.

Even the dealerships have troubles with this......

 

Search for this thread and read it (rear end growling after dealer chg fluid...!!)

What happens is over a period of time the friction modifier in the gear oil breaks down. The clutch packs on the LSD differentials hardly ever turn as no one makes very many tight turns, thus causing the clutches to basically run "dry". This will in turn cause the clutch packs to start binding and that causes the noises that everyone is hearing. If you will follow the steps I posted in the above thread it will work every time. Just make sure you have the right amount of friction modifier added to the differential fluid (I like the BG product) and you will be good to go. I have done this to many of the LSD differentials and it works every time.
Fred.

PS: Chris, maybe we can make a sticky for this.

 

He just had the rear diff oil changed, so it doesn't have anything to do with the friction modifier breaking down. It's because there's not enough of it (for the most part).

Some folks still have issues with various combinations of oils/modifiers. You should drive in tight 8's or tight circles in both directions, but not everyone 'believes' in that. Some folks try it and it still doesn't help. It's a case by case scenario.

 

Janster,
I understand that he just had the oil changed. The dealer more than likely did not add enough modifier to the gear lube. Same thing happens when the modifier breaks down, not enough to keep the clutch pack from binding. That is why I told him to read that thread where I stated to add some more modifier and then go do the circle trick. And I also know it is a case by case situation but it will work every time to get the modifier worked back into the clutch packs.
Fred

 

From what I understand the dealership had some 2010 models with the LSD rear doing the same thing directly from the factory. Toyota's initial thought process was that the rear end was defective, but after replacement of the rearend, they realized the noise eventually came back and tried the additive.

It seems as though this rear end issue is an experiemental process. I really do not understand why Toyota does not contract a company to make specifically Toyota LSD fluid...fluid that is already mixed with the friction modifier that is necessary. Unless...maybe that is the problem...they do not know how much is really necessary.

 

The 2010 models do not have a mechanical LSD so you don't need the LSD additive, it's a totallt different type of system. The 2010 and 2009 uses the brakes and ecu to mimic a LSD diff.

 

X2

 

Can someone post a video of how to replace gear & axle differential clutches (limited slip) please