LCI Manual Rear Diff Swap to Pre LCI 4.4 3.64 Dilemma

[sharocks]

Hi all,

I have an 04 6MT X5 that recently ate it's front diff and t case. Took that opportunity to swap in some low mileage 3.64's out of an 02 4.4 X5. The front fit no issue.

What I learned next is that the LCI manual X5s had large case rear diffs. The 4.4 rear diff is a medium case unit.

I found Green Dragon's old thread about doing the swap and he had mentioned he was successful in getting it done.

His inbox is full and I can't PM him so I'm asking out here, any one know what needs to be done to get the medium case diff to work in this situation?

Of if anyone can reach out to Green Dragon, I'll buy you beer lol

Thread in question: https://xoutpost.com/bmw-sav-forums/...swap-go-2.html

Also I can't access page 3 of that thread, anyone else with the same issue?

[andrewwynn]

Seams to be a bug.

https://xoutpost.com/1008583-post20.html

Change the 20 to 21,22 etc to read the last few posts

[RocketyMan]

Originally Posted by sharocks

Hi all,

I have an 04 6MT X5 that recently ate it's front diff and t case. Took that opportunity to swap in some low mileage 3.64's out of an 02 4.4 X5. The front fit no issue.

What I learned next is that the LCI manual X5s had large case rear diffs. The 4.4 rear diff is a medium case unit.

I found Green Dragon's old thread about doing the swap and he had mentioned he was successful in getting it done.

His inbox is full and I can't PM him so I'm asking out here, any one know what needs to be done to get the medium case diff to work in this situation?

Of if anyone can reach out to Green Dragon, I'll buy you beer lol

Thread in question: https://xoutpost.com/bmw-sav-forums/...swap-go-2.html

Also I can't access page 3 of that thread, anyone else with the same issue?

I did the 3.64 swap on my X5...to my knowledge, none of the E53s came with LSD...so I guess I'm confused as to your inquiry.

Large case? There are differences in the CV axle mounting flanges to the carrier?

I guess I would need some more education on this as well as I'm curious...

[sharocks]

Only LCI manual X5s and 4.8iS got large case rear diffs apparently. I want to know what was needed to get the medium case in lol

[bcredliner]

Since you already have the rear diff you want to install, measure to see if bolt holes are in same locations and if the case is the same length from side to side. If there is a difference the flanges from the installed diff are likely longer to make up the difference. I know that the flange is sometimes different but I have no experience with your specific application.

Unless you are doing a lot of highway driving going from a 4.10 ratio to 3.64 might not improve mileage. What will be very noticeable is your vehicle will accelerate slower.

[sharocks]

Originally Posted by bcredliner

Since you already have the rear diff you want to install, measure to see if bolt holes are in same locations and if the case is the same length from side to side. If there is a difference the flanges from the installed diff are likely longer to make up the difference. I know that the flange is sometimes different but I have no experience with your specific application.

Unless you are doing a lot of highway driving going from a 4.10 ratio to 3.64 might not improve mileage. What will be very noticeable is your vehicle will accelerate slower.

Green Dragon had noted that his MPG actually increased.

This car has an M54. It will never accelerate fast.

I had a 4.8iS prior, and even that thing didn't scoot haha

[RocketyMan]

Originally Posted by sharocks

Only LCI manual X5s and 4.8iS got large case rear diffs apparently. I want to know what was needed to get the medium case in lol

According to Realoem, all LCI 4.8is E53 have the "beefier" rear housing and diff cover. But on the LCI 3.0l, I see both diff P/N listed--so it seems it could be both (maybe if one's a manual vs automatic trans..dunno). It is challenging to see if the dimensions are actually different in terms of the bolt holes location for the front two and rear one.

BUT...when you look at RealOEM P/N's, the rear axle carrier is the SAME in the 4.8is and any other E53.


LCI 4.8is rear carrier: https://www.realoem.com/bmw/enUS/sho...diagId=33_1028

Rear carrier P/N: 33316770459


non-LCI 3.0l rear carrier: https://www.realoem.com/bmw/enUS/sho...diagId=33_1028

Rear carrier P/N: 33316770459


As a side note, there MAY BE a difference in your CV axle drive-flange. I had this issue on mine when I did the swap to 3.64 rear diff. All I did was swap the drive flanges out that was compatible with my rear cv axles, and voila.



You can see slight differences between a 4.8is diff and non.

[sharocks]

Originally Posted by RocketyMan

According to Realoem, all LCI 4.8is E53 have the "beefier" rear housing and diff cover. But on the LCI 3.0l, I see both diff P/N listed--so it seems it could be both (maybe if one's a manual vs automatic trans..dunno). It is challenging to see if the dimensions are actually different in terms of the bolt holes location for the front two and rear one.

BUT...when you look at RealOEM P/N's, the rear axle carrier is the SAME in the 4.8is and any other E53.


LCI 4.8is rear carrier: https://www.realoem.com/bmw/enUS/sho...diagId=33_1028

Rear carrier P/N: 33316770459


non-LCI 3.0l rear carrier: https://www.realoem.com/bmw/enUS/sho...diagId=33_1028

Rear carrier P/N: 33316770459


As a side note, there MAY BE a difference in your CV axle drive-flange. I had this issue on mine when I did the swap to 3.64 rear diff. All I did was swap the drive flanges out that was compatible with my rear cv axles, and voila.



You can see slight differences between a 4.8is diff and non.

Thank you for this, that is exactly what's different in size.

However, the medium case diff in place of the large case (stock) causes about an inch and a half of space between the axles and the diff itself.

So do I need 4.4 axles? Or do I swap parts off the 4.10 large case to make the 3.64 medium case work?

[bcredliner]

Originally Posted by sharocks

Green Dragon had noted that his MPG actually increased.

This car has an M54. It will never accelerate fast.

I had a 4.8iS prior, and even that thing didn't scoot haha

As I posted it may or may not increase mileage depending what kind of driving one does--city or highway, the topography and the speed of the vehicle. Fuel choice can make a difference but hardly ever significant. Increases or reductions in performance that I was referring were based on a given engine, not stating the M54 is a performer when compared any other engine. I have a 4.6 that scoots as in comparison to a stock 4.6 If I go to a higher gear ratio it will scoot less but obviously it doesn't scoot if compared to a supercar that goes 0-60 in 2.8 seconds.

What often happens regardless of the potential acceleration from any engine is that one tends to use more pedal to achieve the same acceleration as was used with the lower gear ratio. More pedal means less mileage. Mileage is usually calculated from longer trips on highways where a constant speed over long distance are achieved. One other factor is that the lower RPMS at any given speed can result in less engine efficiency equating to less mileage. Or, especially with lower HP engine more downshifting.

[sharocks]

Originally Posted by bcredliner

As I posted it may or may not increase mileage depending what kind of driving one does--city or highway, the topography and the speed of the vehicle. Fuel choice can make a difference but hardly ever significant. Increases or reductions in performance that I was referring are based on a given engine, not stating the M54 is a performer when compared any other engine. I have a 4.6 that scoots in comparison to a stock 4.6 but it doesn't if compared to a supercar that goes 0-60 in 2.8 seconds.

What often happens regardless of the potential acceleration from any engine is that one uses more pedal to achieve the same acceleration as was used with the lower gear ratio. More pedal means less mileage. Mileage is usually calculated from longer trips on highways where a constant speed over long distance are achieved. One other factor is that the lower RPMS at any given speed can result in less engine efficiency equating to less mileage. Or, especially with lower HP engine more downshifting.

Fair enough. I only use the X5 to haul the dog around so I'm not really flooring it ever.