Quote:
Originally Posted by ucsbwsr
Glad I found this thread. I have a few months of ownership under my belt with my new-to-me X5D. I love it but agree the gearing is too short. A ZF 8-spd conversion would be ideal in many ways but improving the gearing with the current 6spd will greatly improve the setup.
I have some experience retrofitting drivetrain so hopefully I can contribute towards achieving this goal. On one of my E61s I converted it from AWD with an auto to RWD with a manual trans, I also fitted complete E60 M5 drivetrain. This did require my modifying my M5 driveshaft but that is because I was mixing an N54 motor with M5 everything else.
RealOEM and I have an intimate and long-term relationship 
In short: E70 50i differentials should work, here is why I think so....
Another member said all rear diff cases are the same, looking RealOEM I would have to agree, with the exception of the 39mm nut that joints the shaft to the diff (X5D= M39x20mm 50i=M39x16.5mm) every other flange, nuts and bolt are the same so there should be no compatibility issues bolting up the 50i diff
Moving up the front end. The X5D and 50i use the same F driveshaft so length and flanges are accounted for there. Looking closely at pictures of the front diffs themselves you can see the part numbers/marking on the cases are identical as are mounting locations etc. so I consider this a confirmation that the front diff will bolt up as well, nice.
X5D F Diff
50i F Diff
Now we move onto the rear driveshaft. RealOEM states 1410mm for the X5D and 1427mm for the 50i. This could be in part to numerous things like size/location of engine, transfer case, or smaller items like flanges. One thing I learned on my M5 drivetrain sway is the M5 transmission flange in addition to being beefier with a larger in diameter, the flange was also about 20mm longer.
Here is a pic of the E60 535i flange vs M5 just for reference.
I looked up pictures of the TC Output flanges and there does seem to be difference in length between the two.
The flanges have a different design and I doubt they can be swapped. To my eyes the X5D TC flange looks to be longer, ~10mm longer? Add that up with the 20mm vs 16.5mm difference in the large nut that joins r shaft and diff and this MIGHT explain the 1410mm vs 1427mm shaft length.
Focusing on the drive shafts (DS) themselves they use the same guibo, center support bearing, and rear nut diameter and thread pitch (slightly different length) so we know it will all bolt up and this suggests that a hybrid shaft is possible.
If the stock X5D DS doesn't bolt up directly to the 50i rear diff then using the front 1/2 from X5D and the rear 1/2 from the 50i should do the trick!
This is enough data for me to take the plunge on the project and I will do it at some point but have some other priorities for the X5.
Hope this helps!
Evan |
Evan,
I seem to find you in just about every form of media that I use- and it really excites me to see you in this thread. While you do have MUCH more experience with swapping the drivetrain from your AWESOME e60 build, it makes me feel pretty great that your research into this followed nearly the same path that I had taken. All of our information lines up too, which further validates my thought process by someone who has accomplished some pretty cool builds. I'm over here like "hey at least my drift car is well built."
Just one thing- I looked and found the front driveshaft to be different lengths. On the driveshaft page, they show 705/709mm- which I assume accounts for the slight difference in positioning/lengths of the flanges on the transfer cases I looked at a ton of pictures and they seem to be mounted in the same places in respect to the different transfer cases.
Another question: How do we know if the transfer cases are geared the same? Are they direct 1:1 ratios? I assume so, since the front and rear diffs show the same ratios on both vehicles in realoem.
I'm going to attempt this sometime soon this summer. I do have a bit of a backlog,
I need to swap my dirtbike's clutch, and I need to get my drift car's starter swapped out, so I have a way to get to work in bad weather should I need to have the X5 down for more than a long weekend. That will all be done before July 4th, because I have a drift event that weekend.
So, I figure come mid July, I should be attempting this. I'm going to start looking at ordering/ picking up the diffs this coming week.