[Go123]

Just wanted to say I am back. Let go of the E90 at 135K miles last summer and picked up a 2014 335i M Sport this week. I had an Audi in-between but never warmed up to it and had to go back to BMW.

I drove it 130 miles the first day and realized the steering alignment was off. So I brought it in yesterday and they say no problem but there is a campaign out that states my rear differential must be replaced because of a poor batch in production. So now I'm waiting for a new rear differential to be installed, hopefully I get it back by tomorrow.

Should I have any concerns that a new car is already getting major service? I am not sure how often the BMW techs do this type of replacement. Can I expect it to be the same as factory after installation?

Thanks, Go

[X2 Monstah]

Welcome Back. I traded my E92 for a Mercedes C-Class. I hated it. One year later, I was back in a 2014 3 Series. Took a beating when trading the C Class in, but it was worth it to be back in a Bimmer.

Sorry to hear about the problems with your new car. I haven't experienced any issues yet...knock on wood.

[Blubaron79]

I think by law they have to put the same differential in. Also, I wouldn't worry as the old one was faulty anyway; and I'm sure there are no after market ones available yet.

[drob23]

Originally Posted by Go123

Should I have any concerns that a new car is already getting major service? I am not sure how often the BMW techs do this type of replacement. Can I expect it to be the same as factory after installation?

Thanks, Go

It obviously won't be *as good* as the original factory installation, but it should be damn close. I believe the rear diff is pretty easy to get to relative to driveline stuff in the front of the car. Might involve dropping the rear subframe, but I'm not sure. I'm assuming many BMW bolts are stretch bolts (audi does this a lot), so just make sure on the receipt that the mounting bolts were replaced.

http://www.unofficialbmw.com/all/eng...ead_bolts.html

[Go123]

Originally Posted by drob23

It obviously won't be *as good* as the original factory installation, but it should be damn close. I believe the rear diff is pretty easy to get to relative to driveline stuff in the front of the car. Might involve dropping the rear subframe, but I'm not sure. I'm assuming many BMW bolts are stretch bolts (audi does this a lot), so just make sure on the receipt that the mounting bolts were replaced.

http://www.unofficialbmw.com/all/eng...ead_bolts.html

Thanks

[btbossman]

Welcome home!

[mrunner]

The only thing that a typical mechanic doesn't do is setup the gears. Most will outsource that work to a gear specialist. Not saying they can't do it, (my typical mechanic does ) probably anyone who can follow instuctions and do it with paticence and proper tools is able.

For this, I took a quick look at how it might be different to other cars. It looks like it would be possible for almost anyone with tools, and the space. If the differential is the issue, the easiest sceanrio for them is to have a completly setup differentail already in the housing. They'd unbolt the drive shaft, unbolt the axles, unbolt the differential housing with the diff gears inside of it, and then bolt back a new diff housing with gears already setup inside, and bolt the axles, and drive shaft back. The difference here with other cars/trucks is in the simplicity of disconnecting the axles. It appears that they are bolted on to a flange of sorts from the outside, and not direct connected with splines on the inside of the housing into the differential like many cars and trucks are. This means even if the BMW dealer techs have never setup differentials, if they can unbolt and bolt back to torque spec they can do it.

This isn't to say they don't have a gear specialist on staff, or that they wouldn't send the gears out to be setup and reuse you existing housing.

[Go123]

Originally Posted by mrunner

The only thing that a typical mechanic doesn't do is setup the gears. Most will outsource that work to a gear specialist. Not saying they can't do it, (my typical mechanic does ) probably anyone who can follow instuctions and do it with paticence and proper tools is able.

For this, I took a quick look at how it might be different to other cars. It looks like it would be possible for almost anyone with tools, and the space. If the differential is the issue, the easiest sceanrio for them is to have a completly setup differentail already in the housing. They'd unbolt the drive shaft, unbolt the axles, unbolt the differential housing with the diff gears inside of it, and then bolt back a new diff housing with gears already setup inside, and bolt the axles, and drive shaft back. The difference here with other cars/trucks is in the simplicity of disconnecting the axles. It appears that they are bolted on to a flange of sorts from the outside, and not direct connected with splines on the inside of the housing into the differential like many cars and trucks are. This means even if the BMW dealer techs have never setup differentials, if they can unbolt and bolt back to torque spec they can do it.

This isn't to say they don't have a gear specialist on staff, or that they wouldn't send the gears out to be setup and reuse you existing housing.

Thanks, Is it critical they use new bolts as stated above? If I had bought the car a week later this would have all been done before they sold it and I probably would have no idea it was even changed. So maybe I am just creating my own worry.

[mrunner]

I can't confirm if any stretch bolts are used. I'm new to BMWs and so far my service experience has been good. If yes, they should be replaced. And it could be possible that the dealers and techs don't follow that, or are aware.

Quiz them about the typ of bolts they use. If they know what stretch bolts are. If they use them, etc... Kind of setup a trap for them where they'll volunteer info about strecht bolts, and what they are, how they're used, and that they are one time use. Then you can some how manipulate that to insist that the strech bolts will be changed, have them write that in the service write up, maybe that they need to return to you the used stretch bolts. If they say that the bolts will not be changed have that be put in the service write up too if you choose to continue with the work. Or, before you do the work, get confirmation on if those bolts are stretch bolts that do need to be changed. Maybe another dealership. Maybe an independant BMW specialist. or the FSM.

I do this with my other cars all the time. I show up with a TSBs, some pages from the FSM, forum info, and armed with knowledge of what needs to be done, or what I want them to try.

[drob23]

Exactly, it's not necessarily that you are checking to see that the work was done correct, but rather demonstrating that you care and can do the research. It's human nature that they're inclined to do a more thorough job if they know this about you vs someone who blindly hands them keys so they can go test drive the 6 series for their next lease.

[Go123]

I'll update once I know more, I didn't have much choice, the car shouldn't have been sold prior to the replacement. Apparently the seals did not cure in the diff, so I guess it could have cracked with use. They really wanted it back to make the change with a new diff per BMW campaign. Ill inquire about the bolts as well. Supposedly there are many cars that are affected, but they will only replace it if it has less than 300 miles, otherwise I think they just do some form of inspection.

[Go123]

Just spoke with service guy, he said bolts can be reused and he is aware of the kind that can not. He said the key thing is that everything is torqued to the right specs on the reinstall. And now he says friday because the diff is still in transit.

[Go123]

Here is the latest update, still no car. They are still waiting on the new diff to arrive. I am definitely getting frustrated and still pissed they have to do this repair on a brand new car. I started to look into swapping the car but I am getting the usual bs that you bought it and its your car even though I only drove it for a couple hours and a 100 miles.