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      04-19-2019, 11:57 AM   #23
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Quote:
Originally Posted by yco View Post
what was the total cost of changing the diff?
I haven't changed the diff, I'm using the stock diff.
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      06-06-2019, 09:59 AM   #24
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I'd love to see it too. I don't have the funds, nor another vehicle, to experiment with this one for a while to figure it out. I sue mine to tow semi- regularly too, which makes me hesitate to gear higher. But at the same time, I can always let her eat in 5th up highway hills instead of 6th. More than enough power.
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      06-07-2019, 01:19 PM   #25
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Quote:
Originally Posted by richlandforged View Post
Bump... Would love to see someone byte the bullet on this project as could prove to be game changing for the e70 diesel! The torque on this engine is just begging for some more gearing!
I wish BMW introduced the 8 speed ZF transmission as they did in the E70 35i. It would have differently improved fuel economy at HWY
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      06-10-2019, 08:15 AM   #26
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Quote:
Originally Posted by X5-User View Post
I wish BMW introduced the 8 speed ZF transmission as they did in the E70 35i. It would have differently improved fuel economy at HWY
This is the ultimate wish for me too, but alas, need to upgrade to the n57 to get the 8 speed. That's out of the question for me at the moment, but one day maybe I can start thinking about it...

Truthfully, even if the swap only cost me $1500- would I ever see the savings in fuel back on that?
Lets see- fuel by me is right around $3.00, but national diesel average is around3.50, so lets be generous and say 3.50. 1500/3.50=428.6 gallons of fuel. so, how long would it take me to sip 428.6 less gallons of fuel? Lets say my highway is around 30mpg, which is usually is close to. Lets say the diff sway to lower the rpm by 300 nets me a 3mpg increase, which I'm not positive it would. Maybe it would be more though?
3mpg is 10% Savings, so I would have to spend 1500/.10 = $15,000in fuel to make up the difference. 15,000/ 3.50= 4286 gallons, 4286 gallons*33mpg= 141,428 miles. So, I would break even after 140k miles, if my quick "I just got to work and don't want to do my work" math checks out. No guarantee that it does, but I'm 60% confident in my thought process.

So, I think I'm better off using that 1500 on new headlights bulbs , maybe new halo bulbs, and a set of Michelin defender tires that will last 70-100k miles, than swapping out the diffs for $1500.
Or... replacing every component of my front suspension, which would cost right around $1300 how I've priced it out. I can't see this reasonably being worth it, but it would be a cool novelty to get better mpg's, and have a lower RPM running while cruising. I suspect it would be a bit quieter too, which would be the main draw for me to swap the diffs.

Now, If I found a wrecked 50i on craigslist being parted, and was able to snag the diffs for $100 each, would I do it? Probably. That would mean in the ballpark of 30k miles to make it up, and 30k miles is a year of driving for me.
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      06-11-2019, 09:30 PM   #27
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Okladies and men. I've decided to do some light research into this, primarily based on how cheaply I could apparently source the differentials. A lot of factors would have to line up right for me to really have the ability to TRY the swap, but a little research wouldn't hurt, right? I plan on keeping this vehicle hopefully until at least 500k miles, so long term, it could be feasible for me to do this mod, or maybe to another in the future,



So, looking at realoem... the first thing I notice on the differential pages for my 2010 build 35d and a mid 2011 build 50i is that the 35d mentions #6 on the front diff page, which is some sort of centering ring that seats the what I believe to be the front driveshaft, centered with the flange off the frot diff. The 50i specifically omits that. That leads me to the next step, which is to check the part numbers of the tow axles up front, and the driveshafts of both vehicles. I'm hoping the numbers actually match up, because that's the only real way to be sure they'd fit. The mounting bolts for the front diff look to have the same specs, which is a good start.

It's going to be a bit of a process, but I'm all about knowing any useless information I can get, and this seems like information I'll never actually need, which makes it more fascinating!

This research won't happen overnight. I need to think through my organization so that I can do it bit by bit and track the matching process/ not matching progress, probably going to set up a spread sheet.

And for what it's worth, it looks like I'd be able to source a front and rear diff for HOPEFULLY under 200 each, but I'd have to check with these yards to se if I could get milages on the units. Who knows... and e70 diffs aren't known to be the longest lasting in the world.
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      06-14-2019, 08:56 AM   #28
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So, the more I look, the more I think this should work. The rear diff, has all the same seals, so I'm guessing it'll bolt in.
Same hub wheel bearings in the rear, same output shafts in the rear. That means the flanges will be the same.
On the front end of the diff, the nut seems different, by 4 mil, but the seal is the same. So a possible difference in gear size, but the same seal lead me to believe the overall fit would be similar.

This brings me to the driveshaft- the driveshaft has different part numbers. The bolts and nuts to bolt the transfer case are different. which led me to look at the transfer case. the LCI 50i and all 35d's have different transfer cases- 50i has the ATC 450 and the 35d has the ATC 700. I guess the 35d needs it for the torque. Thinking through this, I don't think it'll be an issue on the front of the driveshaft, becasue I'm not changing that. Since the rear bolts and everything are the same, the only thing I'd need to worry about is the length matching up in the right way so that the rear of the driveshaft will bolt up exactly the same.


The transfer cases being different also make me worry about teh front driveshaft, from trans case to front diff. The bolt patterns look the same, but the 35d shaft seems to have a guibo, while the v8 does not. I'm not sure how to figure out the lengths of the two, and I'm not sure an equal length will necessarily mean it'll fit, since the vehicles have different transfer cases.
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      06-14-2019, 09:12 AM   #29
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Quote:
Originally Posted by Spyro235 View Post
So, the more I look, the more I think this should work. The rear diff, has all the same seals, so I'm guessing it'll bolt in.
Same hub wheel bearings in the rear, same output shafts in the rear. That means the flanges will be the same.
On the front end of the diff, the nut seems different, by 4 mil, but the seal is the same. So a possible difference in gear size, but the same seal lead me to believe the overall fit would be similar.

This brings me to the driveshaft- the driveshaft has different part numbers. The bolts and nuts to bolt the transfer case are different. which led me to look at the transfer case. the LCI 50i and all 35d's have different transfer cases- 50i has the ATC 450 and the 35d has the ATC 700. I guess the 35d needs it for the torque. Thinking through this, I don't think it'll be an issue on the front of the driveshaft, becasue I'm not changing that. Since the rear bolts and everything are the same, the only thing I'd need to worry about is the length matching up in the right way so that the rear of the driveshaft will bolt up exactly the same.


The transfer cases being different also make me worry about teh front driveshaft, from trans case to front diff. The bolt patterns look the same, but the 35d shaft seems to have a guibo, while the v8 does not. I'm not sure how to figure out the lengths of the two, and I'm not sure an equal length will necessarily mean it'll fit, since the vehicles have different transfer cases.
Your info matches up with what I found when I was researching this. The ATC700 was the E70 pre-lci TC w/ 6 speed trans. North american 35d never got the full LCI 8 speed drive train which could explain why it is still on the pre-lci TC. Realoem will show you driveshaft length in MM.


Drive shaft assy front L=709MM 04/2010 05/2018 26208605866

Drive shaft assy rear L=1410MM 26107564398
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      06-14-2019, 04:34 PM   #30
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Quote:
Originally Posted by smassey321 View Post
Your info matches up with what I found when I was researching this. The ATC700 was the E70 pre-lci TC w/ 6 speed trans. North american 35d never got the full LCI 8 speed drive train which could explain why it is still on the pre-lci TC. Realoem will show you driveshaft length in MM.


Drive shaft assy front L=709MM 04/2010 05/2018 26208605866

Drive shaft assy rear L=1410MM 26107564398


So what I found was this- 35d is 705mm/1410mm and the 50i is 709/1427. But again, I'm not certain if these differences mean anything because I'm not suer about the transfer case. So, is there a way to see if the transfer cases have different lengths on their flanges? If the differences are because of the difference in the transfer case, then my transfer case and both driveshafts will work fine. If the differences are on the diff flanges on not the transfercase, I'd be looking at having to either replace my transfer case, (not happening), or I guess swapping both driveshafts with that of a 50i.

I guess the driveshaft swap is likely cheaper than the transfercase, but either way it makes it a hair too complicated for me to try on the car I need to drive to work in.

Again, if the difference in length is because of the way the flanges are on the TCase, then everything should both up nicely. If I had a mill and could make an aluminum spacer and use longer bolts, I would go ahead and order the diffs now. But I don't have a machine shop to make spacers for the cost of the aluminum, so I'm not sure how I would guarantee a successful install without knowing where the difference in lengths comes from.

The more I think about it, the more I'd really like for this to be possible. Just wish someone had done it before!
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      06-15-2019, 09:08 AM   #31
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Quote:
Originally Posted by yco View Post
not sure its a good idea.. if the goal is to make some economy just change the car mate not the diff..
Lol, people with this logic crack me up....

Do you buy a new house when you have an issue with an appliance?
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      06-15-2019, 10:33 AM   #32
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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.
X5D



50i



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
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      06-15-2019, 11:28 AM   #33
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Additionally I have played around with running larger tire sizes. My X5D came with OEM Style 335 19x9 255/50 square. Rolling diameter is 29.1" which means the motor is at 2,300rpm at 80mph.

I was 100% set on running style 612M wheels on my E70. I love the look, they are light, and strong (forged). The downside is limited tire choices. They came off an F85 X5M with the stock Michelin PSS 325/30 in the rear. This is a 28.7 rolling diameter so as I sit now at 2,300rpm I am at 78mph, a little down from stock.

I am a big fan of upsizing the aspect ratio of tires since it offers better ride quality and a beefier look, WIN-WIN in my book but tire clearance and rubbing become a consideration. AFAIK BMW x-drive systems detect wheel slip based off wheel speed sensors so you need the rolling diameter variation to be <1% between front and rear.

Stock X5M tire sizes are 285/35/21 F and 325/30/21 R. My goal was to stuff 285/45/21 F and 325/40/21 R. Unfortunately that didn't pan out up front with lack of clearance with the upper ball joint/spindle. :/

Here are some pics on what I test fit:
STOCK 285/35


285/45


This issue


I came to the conclusion that I needed to settle for a more modest 275/40 F 315/35 R.
But now I run X-Delete and my X5 is in RWD all the time, I live in San Diego so there are not negative repercussions for doing this, I can flash back to AWD in about 90 seconds if needed. The reality is if I ever NEED AWD it will be for a mountain trip to the snow and I will have an extra set of wheels with aggressive all season or dedicated snow tires so no worries about my X5 being in AWD with the 21" X5M wheels.

This is important as it allows me to toss the rolling diameters out the window for my street setup. Where the 285/45 didn't fit up front, I don't see there being an issue with it's matching 325/40 in the back so I am thinking of running 285/40 F 325/40 R. This will give me added cushion I am looking for but also offer a larger rolling diameter out back. Let's see how that would look:

Rolling diameter jumps to 31" which means at 2,300 rpm I will not be at 84mph (+4pmh compared to stock and +6mph compared to my current setup). Conversely going 78mph would now only require 2,125rpms (down from 2,300).

Swapping 3.64 gearing for 3.15 would really stretch the legs of the X5D, especially with taller tires. Here is some info:

325/30 + 3.64 + 2,300rpm = 78mph
325/40 + 3.64 + 2,300rpm = 84mph (78mph = 2,125rpm)
325/30 + 3.15 + 2,300rpm = 90mph (78mph = 1,975rpm)
325/40 + 3.15 + 2,300rpm = 98mph (78mph = 1,850rpm)

My goal is the bottom setup. Once my X5D is deleted and tuned I don't foresee there being any acceleration issues as it will be making gobs of torque and I am really optimistic about the fuel efficiency with the longer gears and larger tires. The drivetrain would be under greater stress from the longer gearing + greater torque so I would keep an eye on that stuff.

Evan
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      06-15-2019, 11:39 AM   #34
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Quote:
Originally Posted by ucsbwsr View Post
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.
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Last edited by Spyro235; 06-15-2019 at 11:54 AM..
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      08-31-2019, 07:46 AM   #35
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Spyro,
Any further developments/intentions on this front?
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      02-08-2020, 10:59 AM   #36
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So I went ahead and took the plunge on this. Bought a 50i 3.15 diff off ebay, $150 shipped w/ 60k on it, very reasonable IMO.


E70 3.64 to 3.15 Differential Swap:
Initial Impressions

I have driven ~500 miles with the new 3.15 diff installed and I wanted to share some initial thoughts. Here is a collection of observations in no particular order.

Noteworthy mods on the X5: RWD (XHP), Malone 2.9, ATM IC, custom intake, Sutphin Trans Tune, and HPR fuel.

- In short, it is working out how I had hoped. The actual swap was straight forward and there have been no hang-ups with the process so far.

- My tuned X5 never struggles to accelerate and driving is effortless in all conditions like it was before. You can leave from a standstill in 2nd without much fuss.

- In general the engine and trans seem to be handling the different gearing fine, shifting behavior seems normal but there are some times when the trans is holding onto a gear (close to downshifting) and with the 3.15 those RPMs are even lower and the engine is falling out the power brand. The motor and trans find themselves in the "RPM troughs" but maybe Rod can adjust these gear limits so the trans is a bit quicker to downshift?

- With the taller gearing WOT from a dig isn't as "exciting" ..which is to be expected but the decrease in straight line performance is most exposed at these 0-60 0-80 WOT periods. Acceleration at high speeds such as highway pulls, passing, etc. seem very similar to before except there is less shifting.

- The main goal was to give the X5 longer legs so the diesel motor isn't humming at more than half its redline at freeway speeds and the 3.15 delivers, if you reference the 2nd photo you can see I am doing roughly 80mph at 2,000rpm, wonderful. This is down 550-600rpms compared to before

- At highway speeds the powerband is very useful since 65-80mph buts you between 1,600-2,000prpm. Only if you get down to 60mph and are going uphill would you really need to downshift.

- My favorite part of the whole swap is how much more relaxed the X5 is in the 70-80mph range, There is less NVH and the X5 cruises along with less drama. IMO this is a pleasant surprise I wasn't expecting.

- Addressing fuel economy: Doing 60-65mph will net you similar fuel consumption as with the stock 3.64 diff. What's different is in the 65-75mph range where the 3.15 returns similar numbers but the 3.64's efficiency drops off quickly >65mph. In this 65-80mph range is where I am seeing my predicted +3-5mpg bump.
*I haven't done any 80+mph highway testing yet.

- My X5's digital fuel economy readout is usually optimistic but not by much, usually less than 1mpg variation. I the X5 had some urban driving prior to this road trip so unfortunately I wasn't able to get accurate hand-calculated numbers but .....

- I drove from San Diego to Orange County, driving flow of traffic 71-72mph. On the drive up I recorded 32.2mpg and this included 10 miles of urban driving to a shop. Return trip yielded 35.1 mpg. So let's call it 33.5mpg over 180 miles out-n-back. Nice

- Overall I am very happy and consider this swap to be 85% positive and 15% negative, well worth it IMO. If you care a lot about drag racing this might not be the swap for you, for the rest of the time it's a welcomed change.

- In terms of fuel economy I think there is more to be gained as well. I have some audible contact between a brake pad and rotor, this certainly isn't helping anything and the X5 doesn't seem to coast as well. The plan is to bleed the brakes and lube the caliper pistons. With the rubbing resolved I wouldn't be surprised if there is another couple MPGs to be had.




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      02-08-2020, 11:20 AM   #37
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Quote:
Originally Posted by ucsbwsr View Post
So I went ahead and took the plunge on this. Bought a 50i 3.15 diff off ebay, $150 shipped w/ 60k on it, very reasonable IMO.
Thanks for being the first to test this out. I am going to do the same swap but on a stock E70. Just for the rear dif for a test. I see you have XHP, is your front driveshaft still connected? If possible, I will test with the transfer case module disconnected. thanks
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      02-08-2020, 11:57 AM   #38
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Quote:
Originally Posted by smass View Post
Thanks for being the first to test this out. I am going to do the same swap but on a stock E70. Just for the rear dif for a test. I see you have XHP, is your front driveshaft still connected? If possible, I will test with the transfer case module disconnected. thanks
Yes, front shaft is in place.
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      02-08-2020, 01:56 PM   #39
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Very Nice! I was actually revisiting this thread today after seeing your IG post.

I would think that those of us who have NOT removed the front driveshaft but still have xDelete would need to do both diffs if we go back into AWD at any time.

*edit*misread above post, thought you had removed the front shaft a while ago.

Impressive work and results Evan.
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      02-09-2020, 12:07 PM   #40
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Interesting the E70 35d is geared so much lower than the 335d. The 335D is 2.81 diff ratio.

My 335D would cruise at 100mph in 6th at 2650 rpm. I don't remember what 80 was.
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      02-10-2020, 07:29 AM   #41
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Originally Posted by Thecastle View Post
Interesting the E70 35d is geared so much lower than the 335d. The 335D is 2.81 diff ratio.

My 335D would cruise at 100mph in 6th at 2650 rpm. I don't remember what 80 was.
The x5d is also like 1200lbs heavier and it's meant to be used as a "truck" to tow things and have payload. They drive quite different though, I find myself staying lower in the gears like 4th-5th in my 335d rather than in my x5d where I'm probably in 6th already while cruising lol. Also in my 335d Normal acceleration Doesn't need more than 1,700rpm to get going, where my x5d likes to rev up to something like 2,300rpm-2,500rpm before it'll get going like that.

Maybe I'm exaggerating but the gearing difference is noticeable. This is probably the perfect modification after deleting an x5d to make use of the power and torque you get. I'm interested to see the fuel mileage gains from this.
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      02-10-2020, 10:40 AM   #42
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Rear diff has been ordered. Now I am looking for a front one. Everything looks good except for my early style front driveshaft/flange. Mine has a triangle/3 bolt flange on the diff input. 3.15 diffs all have the round 4 bolt flange. I can swap parts but I am concerned that I will need to reset the bearing preload in the diff. I have rebuilt a few non-BWM diffs where the flange nut held the pinion bearing preload.

For seal replacement, TIS says to mark the position of the nut vs shaft which is appropriate if the same flange is re-used. Since I would need to swap flanges, this method would only work if the 2 flanges were the exact same size. No torque value is listed in TIS.

https://www.newtis.info/tisv2/a/en/e...ential/FoIYi2V

The easiest option is to just swap in 2012 or 2013 front driveshaft. That will avoid the 2011 recalled ones. They are $100 shipped. Did the new style driveshaft get rid of the flexible disk?

Thanks and feel free to let me know if I am going in the right direction or not.
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      02-11-2020, 09:20 AM   #43
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Looking forward tot eh front half update- I can't afford to lose awd! Thanks again for experimenting on this, I'm sure there are at least a few of us that will be following suit. I just realized that the n55 35i's use a 3.15 too, and that the differential seems to be the same partnumber. The side brace seems to be different though, so I'll be sticking to finding a 4.4L front, or really whatever ucsbwsr confirms to work. Prices look like I can get the rear for $130ish and the front for $150ish in NJ, with prices closer to $100 if I decide I'm good with spending a bit more time driving. I'm looking forward to this modification, as I would cherish less noise and less RPM at highway cruising. Removing the front diff looks a bit more involved than the rear, but not all that hard regardless. Apparently there's an special tool to remove the front half shafts, and I'm curious what happens there if we don't have the tools.

Just want to point out- lets say the diff swap is costing me $325- I've calculated out that for my personal vehicle, if I got a 3mpg gain from the change, it would net me about a 1.2 cent savings per mile. This means it would take me about 28k miles to break even as far as pure cost of this modification. To me, that's 2/3-1 year of driving, to someone who only drives 7-10k a year, I can't imagine efficiency mods will be worth it.
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      02-11-2020, 12:46 PM   #44
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Quote:
Originally Posted by Spyro235 View Post
Looking forward tot eh front half update- I can't afford to lose awd! Thanks again for experimenting on this, I'm sure there are at least a few of us that will be following suit. I just realized that the n55 35i's use a 3.15 too, and that the differential seems to be the same partnumber. The side brace seems to be different though, so I'll be sticking to finding a 4.4L front, or really whatever ucsbwsr confirms to work. Prices look like I can get the rear for $130ish and the front for $150ish in NJ, with prices closer to $100 if I decide I'm good with spending a bit more time driving. I'm looking forward to this modification, as I would cherish less noise and less RPM at highway cruising. Removing the front diff looks a bit more involved than the rear, but not all that hard regardless. Apparently there's an special tool to remove the front half shafts, and I'm curious what happens there if we don't have the tools.

Just want to point out- lets say the diff swap is costing me $325- I've calculated out that for my personal vehicle, if I got a 3mpg gain from the change, it would net me about a 1.2 cent savings per mile. This means it would take me about 28k miles to break even as far as pure cost of this modification. To me, that's 2/3-1 year of driving, to someone who only drives 7-10k a year, I can't imagine efficiency mods will be worth it.
Is the drone bad on the highway? I know my 335d deleted gets loud at 2,300rpm. Kind of makes me nervous about deleting my x5d because I don't want no damn muffler on it. I drive nearly 30-40k a year so I'd break even in no time on this mod lol. Also curious on the results for mpg though
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