Rear Diff Dead

[angler]

Hi:
I have a 135i cabrio, 29 months, 26k on it. Several weeks ago my car started making a whining noise from the back on de acceleration. It also was making a ticking noise while making a u turn or gong around corners. Brought the car to dealer they were able to duplicate the noise and said it was coming from the rear diff. They sucked out the rear diff fluid and filled it with SAF- XJ rear axle fluid booster. Gave the car back to me told me to drive it for another 100 miles and if the noise didn't go away they would replace the rear diff. The noise never went away actually got worst. Called dealer told them the it didn't get better, they ordered part and replaced the diff yesterday. On the service notes it states, "When emptying diff fluid from noisy diff metal flakes could be seen in the fluid." They also found "Lack of lubricant on rear input shaft flange, lubricated flange and clunking was gone when shifting." Dealer was great through the whole process!

My question is what makes a rear diff go with so few miles on the car. My lease is up in March and I was planing to buy the car should I now be taking this into consideration when making this decision? Many thanks,

[dtla1]

I've had ticking noises while turning before. Tried re-tightening everything, changing clearance to dust shields everything. Maybe next time I'm in for service I'll mention the rear diff as a problem.

[Bama335]

In any mass produced part with tolerances, there's always a chance you get a bad unit. Or maybe throw in some human error on not adding enough fluid and you might need a diff at 26K miles. The good news is it's under warranty.

With a new diff installed, that will likely be one fewer thing to worry about when you buy it. If you plan to keep it a while, might as well do a break-in service and change the factory fluid at about 1200 miles - it's easy and wont cost you much to DIY

http://www.1addicts.com/forums/showthread.php?t=409293

[champignon]

Originally Posted by Bama335

In any mass produced part with tolerances, there's always a chance you get a bad unit. Or maybe throw in some human error on not adding enough fluid and you might need a diff at 26K miles. The good news is it's under warranty.

With a new diff installed, that will likely be one fewer thing to worry about when you buy it. If you plan to keep it a while, might as well do a break-in service and change the factory fluid at about 1200 miles - it's easy and wont cost you much to DIY

http://www.1addicts.com/forums/showthread.php?t=409293

The truth is, hardly anyone here has the background or experience with this stuff to evaluate whether this is worth doing, beyond what BMW provides and pays for. The cited thread (not the rest of your post) may show competency in how to do a procedure in a home garage, but it doesn't give any proof that it is worth doing. Lots of things in cars (as in life) look bad when you look at them without the requisite experience or knowledge to know what is important and what is not.

The world is full of backyard experts on just about any topic, and lots of them post on internet forums. Is this important or not, is this worth doing or not, at least some will honestly say, "I don't know."

[Olgeezer1]

I've always gotten light metallic clanking noises from the rear end of the car on takeoff. Not every time but often enough. Sounds to me kind of like a noisy LSD working, except we don't have those. Saw another post on the subject of rear end noise and several guys chimed in that they've had similar experiences in various manual trans. BMWs. It's pretty common and they consider it "normal". This noise though is certainly not what's described by the OP.

[Bama335]

Originally Posted by champignon

The truth is, hardly anyone here has the background or experience with this stuff to evaluate whether this is worth doing, beyond what BMW provides and pays for. The cited thread (not the rest of your post) may show competency in how to do a procedure in a home garage, but it doesn't give any proof that it is worth doing. Lots of things in cars (as in life) look bad when you look at them without the requisite experience or knowledge to know what is important and what is not.

The world is full of backyard experts on just about any topic, and lots of them post on internet forums. Is this important or not, is this worth doing or not, at least some will honestly say, "I don't know."

To each their own - I agree with your statement that we can't prove it's worth it, so it comes down to preference.

I tend to agree with Mike Miller's guidelines, and for the cost of a quart of gear oil and the satisfaction of doing it right yourself, I'm in.

[Dackelone]

It was probably due to a manufacturing defect. What causes a diff to go bad so soon is the wrong pinion depth. It was probably the tolerances being too "tight" and the pinion just ate up the ring gear's teeth.

I would pay your dealer to change the diff fluid in 2K miles and take a look at the old fluid for metal. Have them use a magnet. But I think your car is fine for the long term - so I would not worry about buying the car when it comes off its lease.

Dackel

[Solo_M_Tech]

My rear diff is on it's way out as well. Tons of pinion bearing gap. You can grab the driveshaft right in front of the pinion nut, and wiggle it up and down almost 2mm, watching the pinion shaft move. No crazy noises yet, just some vibration under load and decel.

[angler]

Originally Posted by Dackelone

It was probably due to a manufacturing defect. What causes a diff to go bad so soon is the wrong pinion depth. It was probably the tolerances being too "tight" and the pinion just ate up the ring gear's teeth.

I would pay your dealer to change the diff fluid in 2K miles and take a look at the old fluid for metal. Have them use a magnet. But I think your car is fine for the long term - so I would not worry about buying the car when it comes off its lease.

Dackel

When I bought the car I had them change diff oil at 1500 miles as I always intended to buy the car out of lease. Will do the same around 2k again. If they find metal in the oil again what do you suggest? Many thanks,

[Dackelone]

Originally Posted by angler

When I bought the car I had them change diff oil at 1500 miles as I always intended to buy the car out of lease. Will do the same around 2k again. If they find metal in the oil again what do you suggest? Many thanks,

IF they find lots of metal bits... that diff is bad too.

Did they install a new unit or did they rebuild it themselves. I thought BMW only had reman/rebuilt gearboxes and diffs as replacement parts. Maybe you could insist on a new unit... if you continue to have problems. Maybe even get the diff oil tested.

[angler]

Originally Posted by Dackelone

IF they find lots of metal bits... that diff is bad too.

Did they install a new unit or did they rebuild it themselves. I thought BMW only had reman/rebuilt gearboxes and diffs as replacement parts. Maybe you could insist on a new unit... if you continue to have problems. Maybe even get the diff oil tested.

They told me they put a new one in.

[ShocknAwe]

Sorry to hear yours went so soon. Mine is a ticking time bomb at this point. Tons of gear whine in the back. Had my indy take a look at it, he said it's still within normal limits of operation and perfectly safe, but it's going to fail sometime within the next year or so. And when it does? I'll put a proper limited slip diff back there. Can't wait!

[Dackelone]

Originally Posted by ShocknAwe

Sorry to hear yours went so soon. Mine is a ticking time bomb at this point. Tons of gear whine in the back. Had my indy take a look at it, he said it's still within normal limits of operation and perfectly safe, but it's going to fail sometime within the next year or so. And when it does? I'll put a proper limited slip diff back there. Can't wait!

WHEN does your diff make noise ? Only on light gas pedal/cruising ? This noise is caused by the car not adhering to BMW's break in procedure. In other words.. IF the car was driving hard with still new(under 2K miles) and IF it was driven faster than 170 kph... there is a good chance that is what is causing this (diff) noise.

BMW AG use to write that into the owner's manuals... but not anymore. But still - doing a few hard V-max pulls while the car is still brand new... can cause diff noises down the road.

Of course its also possible the supplier for BMW who makes the diff's... had a batch of diff's with bad tolerance issues. I wonder IF you guys VIN number's are close ?

Dackel

[ShocknAwe]

Originally Posted by Dackelone

WHEN does your diff make noise ? Only on light gas pedal/cruising ? This noise is caused by the car not adhering to BMW's break in procedure. In other words.. IF the car was driving hard with still new(under 2K miles) and IF it was driven faster than 170 kph... there is a good chance that is what is causing this (diff) noise.

BMW AG use to write that into the owner's manuals... but not anymore. But still - doing a few hard V-max pulls while the car is still brand new... can cause diff noises down the road.

Of course its also possible the supplier for BMW who makes the diff's... had a batch of diff's with bad tolerance issues. I wonder IF you guys VIN number's are close ?

Dackel

nah it whines all the time. Just hard to hear it at times other than when I'm at low throttle or off throttle. 2nd owner so no idea how it was treated during break in. But the whine has only gotten really bad recently, so gonna order up some new MT fluid and some gear oil and change the diff fluid when I do the 6MT.

I sincerely doubt my and the OPs VIN #'s are close, as the OP has a 2013 1er.

[angler]

Mine was only whining on de-acceleration.

[Chunner]

Originally Posted by champignon

The truth is, hardly anyone here has the background or experience with this stuff to evaluate whether this is worth doing, beyond what BMW provides and pays for. The cited thread (not the rest of your post) may show competency in how to do a procedure in a home garage, but it doesn't give any proof that it is worth doing. Lots of things in cars (as in life) look bad when you look at them without the requisite experience or knowledge to know what is important and what is not.

The world is full of backyard experts on just about any topic, and lots of them post on internet forums. Is this important or not, is this worth doing or not, at least some will honestly say, "I don't know."

Big +1