[sluggo1246]

NOW WITH PICTURES!!

Hi Everyone,

I heard all this horrible grinding under the car today so I'm almost certain it's the transfer case. For the last few weeks, I would get intermittent flashes from the DSC light under acceleration but once I let of the gas, it would stop. Last night I thought I heard a clicking sound under the car, but I was in traffic so I thought it was another car. Now I know it was me

I'm clearing out the garage to make room for the project. I've searched through countless threads but I haven't encountered a DIY for the transfer case removal/replacement. I wonder if anyone has some tips on sequence and tools. I was not getting the triad of warning lights people have often reported about and I highly doubt it is the servo motor...or at that isn't all of the problem I heard.

I'm quite good mechanically but I have to add some torx bits to be able to do all things bimmer but any other tips are greatly appreciated. Thanks!

[sluggo1246]

It's not the transfer case but where the front axle connects under the engine...for lack of a better description. I'll send a picture shortly and off to search for the part name.

[sluggo1246]

The bottom of the photo is where the drivers side front half shaft is (you can see it in first pic) and I am looking up at the area covered by the metal belly pan (which I removed). As I rotate the front tires, the shaft going to the transfer case does not rotate all the time and I can hear a clicking coming from the area of this housing. I can grab the halfshaft going to the TC and turn it with the wheels and I hear more clicking. There is fluid all over the place...

I'm looking for diagrams online as well but I'm hoping someone here can tell me the part name...thanks!

[sluggo1246]

It's the front differential. Now who can take a few quick pictures of the Bentley's guide for replacement of this part? I can't have my bimmer laid up for too long and she sure isn't going to the stealership.

[Jeffman]

Originally Posted by sluggo1246

It's the front differential. Now who can take a few quick pictures of the Bentley's guide for replacement of this part? I can't have my bimmer laid up for too long and she sure isn't going to the stealership.

Now wouldnt that be copyright infringement? I see that the Bentley book is about $85, and with 2 day shipping if you have Amazon Prime. But you need help right away...anybody willing to commit copyright infringement for our friend?

[335xi Kevo]

sould be straight forward enough, the front diff is very small. Just take it apart. You need to pull the front axles which is a give and work from there.

[sluggo1246]

and it'll be here on Monday. I'll need it anyway. I thought that if I could get a head start on ordering other parts I might need, that would be useful. I wouldn't want anyone committing a crime for me

[sluggo1246]

It seems that the front differential failure was the result of whatever is wrong and not the problem itself! Here is the problem...often when I step on the gas, I will hear/feel a vibration under the car and the DSC/traction light will flash on until I take my foot off the gas. The CV/axles are fine...can this be a transfer case problem? The only other thing I can think of is the shaft that goes from the transfer case through the oil pan and to the passenger side shaft.

Any tips for diagnosing a bad transfer case? I will certainly check that little plastic motor that goes bad...but what else can I consider? I'm going in for some exploratory surgery but I wish I could just look in one place

[stratplaya06]

PSA: Change the oil in the tcase every 30k miles. Clutchpack material in the fluid (what little of it there is) and the deterioration of the friction modifier makes the car bind and make tons of noise. Change the fluid and I would bet your car will return to smooth and quiet.

I had a bad transfer case in my car, when I pulled into work the car came to an abrupt hault and required substantial throttle to even creep forward. I had a 30k mile transfer case out of a 328xi that I got on ebay and had it put in and the car feels great. I personally believe that the chains in these transfer cases slack over time and with hard driving as the new tcase has taken a substantial amount of drivetrain 'clunk' out of experience.

[sluggo1246]

I pulled out the tcase actuator last night and checked it out and it was fine. I did not change the fluid but I was going to do it. I just didn't want to stop to run out and get more gear oil. My new thought on this after driving it and having the same problem is that it is the front axle pedestal...I can't remember the right name as I write this at work. It is the holder for the front axle as it comes out of the oil pan on the passenger side. When I notice the wobble/problem that causes the DTC light to come on and I let off the gas, I feel the front of the car drop slightly and to the passenger side...weird I know. It is slight but noticeable. The new diff is just fine as are the axles/CVs etc.

I'll let you know when I pull it off to take a look. I'll also change the diff oil.

[stratplaya06]

do NOT use gear oil in the transfer case. The fluid that these units take is sold by the dealer in 1L bottles (you'll only need one) and it contains special friction modifiers that smooth out the clutchpack engagement. It's not cheap at about $50-60 per bottle, but using any other fluid could cause some issues.

[sluggo1246]

And I found out what the problem was. I pulled off the passenger side front hub and look what the CV did....

[sluggo1246]

and I would have never know the CV was bad had I not removed it from the car. No noise...boots looked great...but WOW! So I imagine the bad CV damaged the front differential which caused it to fail. Damn expensive and I wish I diagnosed it before it killed my diff

[rsofronici]

Check your front drive shaft too. Had one seize at the transfer case end and it ruined the front differential which in turn ruined the oil pan.

[sluggo1246]

But after I swapped out the front diff, I noticed the passenger side front axle was bad and went to swap it out too. BMW wanted $608 for it (with a core charge!!) so I grudgingly went to autozone and got their Duralast Gold axle for about $130.

I swapped out the axles and when I took it for a test drive, I drove about a few hundred feet and I heard this horrible metallic pop and grind. I was afraid for the worst...it wound up being that the inner CV separated. I limped it back into my garage and did a post mortem examination on the part.

I could see nothing wrong with it (or my installation) so I went back to Autozone and got another one (no charge). This time, I was even more deliberate about the install to ensure that I was not making some small mistake that was ruining the part. All seemed fine so I made the swap....and the same thing happened! What an awful sound to have the CV snap

I went back to Autozone and after a long conversation, they understood that I was not making a mistake and gave me a refund. I went to another local chain and got a new axle from them. It was a different brand so I thought I was protecting myself from what I thought was a defective batch of parts. BUT...when the part came, it was the same exact part as the Duralast Gold I got twice before! Grudgingly, I installed the part and I recorded my test drive and just as before...the CV snapped before I could even make it out onto the street. The problem as near as I can figure it is that the inner CV cannot move to the same degree as the suspension can so when I go over a bump....POP.

I tracked down a used axle from a nearby used auto part yard and it was in great shape!! The boots looked new and for $135 how could I go wrong? I installed it and all is good...but before I did that...I got on the phone with the company who make the three (what I believed to be) defective axles.

After starting in China and then getting into the USA, I finally found someone who knew about axles and I explained my problem. After waiting on hold for a few minutes, I was told that the director of the parts department (for the manufacturer Suretrack) heard about this problem with the BMW axle and wanted the bad axle I had to go directly to them!

SO...if you are looking to buy an aftermarket front axle for your BMX AWD, do not install anything that has BM-8038 on the axle! And BTW, there is no rebuild kit for the outer joint so you cannot rebuild it yourself.

Glad to be done with this unnecessary odyssey but it had to take so long. All that and I changed out the transaxle fluid to make it feel as new as possible. Well worth the effort.