The Autumn from hell....Front drive shaft splines let go!

[TriX5]

So, the last few weeks have been complete misery....after the tension strut bushings, the half shaft boots and the fuel filter/gas pump saga, today the front shaft TC splines let go. What else could go wrong...maybe don't answer that! :-) When the engine was out I cleaned the splines and greased them. Everything seemed ok. Apparently I was wrong.

The best way seems to be getting the Cobra Shaft (length = +1") but according to the write up by ///Monster123 this can't be fitted on the car without slacking off the TC from the transmission by a 1/4". This was also the conclusion of a gent on Youtube (Snake & Fire) who bought the longer splined bit, welds it to his drive shaft thus adding an inch only to find he can't get the shaft back in. He has the 1/4" problem which he overcomes by grinding the weld off and then re-welding with the shaft and splines installed already.

So now I have a choice of three options I guess:

1. Buy the cobra shaft and bite the bullet. It will be properly welded and balanced I guess but requires the removal of exhaust, rear drive shaft and cross member to get to the TC bolts according to ///Monster123's write up.

2. Buy the splined bit and rent a welder to spot weld it on the car. Then go to a shop to get it welded on completely. (Alternative to spot welds is drill it and put two bolts trough as a temporary connection and then get it welded).

3. Buy the splined bit and have a drive shaft shop weld it in 3/4" longer rather than 1" longer, then insert a (quarter inch?) spacer between the flex disc and the diff drive flange. (I'm trying to find the Ebay item but so far haven't found it, nor the thread on XO that refers to it.) EDIT: Here is the 15mm spacer. https://www.ebay.com/itm/25519558026...580262&vxp=mtr

Options 1 & 2 are sort of semi-permanent, any sub-sequent work on the shaft will require splitting the TC from the trans, splitting the trans from the engine or dismounting the diff from the upper oil pan. Option 3 will require finding a spacer or putting in the elbow grease to produce one.

I am weary of the 2-piece shaft, seems a good way to introduce a new failure point or a source of vibrations. Anything else I could do or have missed in the above?

On top of all that; finding a shop in my part of the world that has both the skills and the inclination to weld this item is going to be a nightmare....

[srmmmm]

My original front shaft splines quit at 136,000 miles. Dealership installed a new OEM shaft with a used transfer case with marine grade grease packed in those splines for $4200, ouch. But, never had another problem or any signs or wear for 253,000 miles after that when I sold the E53.

[eskirvin]

The Russians I bought it from don't seem to be offering it on Ebay anymore, but I bought an extended driveshaft and it fixed my issue, which seems to be the same as you describe. They had 3 options for the driveshaft; stock length, an additional 1/2", or a full inch extension. The added 1/2" was able to be installed without removing the TC.

[eskirvin]

Here's the link to their offerings. https://www.ebay.com/usr/vanos-bmwcom

[zener]

165k miles and splines where like new and greased. I added little bit more and put it back.

[andrewwynn]

I vote for the spacer and ³/₄ depth spline addition.

[X5chemist]

Wow! I was considering the two piece shaft option. A spacer is much easier! Adding the option to my parts lists.

[TriX5]

Got it out and the damage is indeed as many have shown. I'll add a picture later but nothing new. We are at a latitude where AC in the summer is a must and the damage was done over many years I guess. The spline engagement is pitiful.....

I am going to order the spline shaft and the spacer (found the listing last night). Once I get the parts I will cut the drive shaft and put a hose clamp where I think the maximum length is. Then do a mock install to check that I can get the parts in to place at the new maximum length. Max length should be 30 1/8 minus about 5/8 for the spacer. So, the shaft should be at 29 1/2" when welded together. That should leave adequate space to install without undoing the TC as Eskirvin posted.

Now off the "fastener store" to find 15mm longer bolts for the flex disc. Also need to swing by a local trusted indy to find out if they have a recommendation for a welder.

[nick325xit 5spd]

What grease did you use? On the E30 iX, the grease selection is critical. Regular axle grease will result in rapid spline failure in a car that is exposed to the weather. (And marine grease didn't do it for the iX, either.)

I've been using Dow Corning Molykote BR2+ on those with great success.

[andrewwynn]

Thanks for finding that spacer. I would definitely do the repair that way on my car.

I'm wondering if the aft seal can be moved so the existing shaft can be moved in 15mm further as preventive measure.

Is the seal/disc welded or just press fit that it can be moved?