[nazali]

Hi,
Trying to understand AWD, in so far as fluids.
So rear wheel drive you have the fluid to change in the rear diff, which may be a different oil from the auto transmission box, which is in 2 separate places

BUT how does this work in AWD's , I've heard of a "transfer case" in a automatic, is there automatic tranny fluid to change do you have a rear diff to change, how does the transfer case come into play, ?

essentially on an auto awd, when you talk about changing the fluids what and where and what type of fluids are you changing and using

thank you

[freakystyly]

I'm pretty sure it's just witchcraft.


From what I understand there's 2 differentials (front/back) and a transfer case (near front) and then whichever transmission.
Google realoem, it can tell the story better than I can..
I hope for you get many miles before anything actually needs servicing.

[celsdogg]

Originally Posted by freakystyly

I'm pretty sure it's just witchcraft.


From what I understand there's 2 differentials (front/back) and a transfer case (near front) and then whichever transmission.
Google realoem, it can tell the story better than I can..
I hope for you get many miles before anything actually needs servicing.

this is exactly it. you'll see when you get the car in the air. there's the trans, on the back of that the transfer case from which a drive shaft will go forward to the front diff and a drive shaft to the rear diff. in xDrive, there are 4 fluids to change for the drive train.

it's a royal pita to change the fluids in everything but the front diff and trans. they are the only ones with drain plugs.

[Shovelman]

So the shaft going forward and the shaft going back are also separated bu a differential? Seems like that must be the case since the rear tires travel a shorter total distance in a turn.

[nazali]

txs guy's

makes sense, so 4 fluids,
tranny, transfer case, front and rear
wow, life just got complicated LOL

thanks again all

[celsdogg]

Originally Posted by Shovelman

So the shaft going forward and the shaft going back are also separated bu a differential? Seems like that must be the case since the rear tires travel a shorter total distance in a turn.

the front and rear are separated by the transfer case (BMW also sometimes calls it a power divider). the drive shafts have differentials at the ends of them. the inside wheels travel shorter distances in a turn and the differential handles this difference in rotation. the transfer case is going to expect the same distance traveled between the front and rear. this is why staggered wheel setups must pay attention to the overall wheel diameter and have them be as close as equal as possible.

[celsdogg]

Originally Posted by nazali

txs guy's

makes sense, so 4 fluids,
tranny, transfer case, front and rear
wow, life just got complicated LOL

thanks again all

good luck man. your gonna need it. changing drive line fluids is a messy job to begin with and BMW made just a touch more.

I just did this work, here are a few notes:

-I used Redline MTL and 75W-80 in the rear diff.
-i used BMW DTF1 (83222409710) in the transfer case and BMW 75W-80 in the front diff (83222413511).
-the drain plugs have a rubber seal built in. get 4 (2 front diff, 1 transfer case, 1 rear diff, 33117525064)
-unless you plan on removing the transfer case and rear diff, you are going to need a pump to suck out the fluid. I got 1/4" copper pipe and bent it into a U (with a pipe bend tool) and attached rubber tubing to it. you won't get much out of the transfer case and it's a pita to get the pipe in. it doesn't have much fluid in it to begin with.

[nazali]

mine is a 2020, but I was looking at maintenance outside of this, just to be sure, my first AWD, so wasn't sure what was involved,looks like a lot, YIKES

Originally Posted by celsdogg

good luck man. your gonna need it. changing drive line fluids is a messy job to begin with and BMW made just a touch more.

I just did this work, here are a few notes:

-I used Redline MTL and 75W-80 in the rear diff.
-i used BMW DTF1 (83222409710) in the transfer case and BMW 75W-80 in the front diff (83222413511).
-the drain plugs have a rubber seal built in. get 4 (2 front diff, 1 transfer case, 1 rear diff, 33117525064)
-unless you plan on removing the transfer case and rear diff, you are going to need a pump to suck out the fluid. I got 1/4" copper pipe and bent it into a U (with a pipe bend tool) and attached rubber tubing to it. you won't get much out of the transfer case and it's a pita to get the pipe in. it doesn't have much fluid in it to begin with.

[Shovelman]

The front wheels do travel further than the rears in a turn so this must be accommodated by a third differential or a slip clutch of some kind or by tire slip. If 'snow mode' locks up the driveline accommodation it will improve traction. I think this is why tight turns feel crunchy on pavement.

[freakystyly]

They're all open differentials, I highly doubt even the SUVs have a diff lock that 4WD trucks have (4WD not the same as AWD). Other option is LSD (two in this case) which maybe the new AWD M cars get. These aren't great off road vehicles like land rovers.

https://www.caranddriver.com/feature...-drive-system/ has a good write up. It's quite complicated.

[nazali]

AWD's have LSD ? Didn't think that was possible

Originally Posted by freakystyly

They're all open differentials, I highly doubt even the SUVs have a diff lock that 4WD trucks have (4WD not the same as AWD). Other option is LSD (two in this case) which maybe the new AWD M cars get. These aren't great off road vehicles like land rovers.

https://www.caranddriver.com/feature...-drive-system/ has a good write up. It's quite complicated.

[freakystyly]

It's possible to fit them in these differentials but not really necessary for your average AWD driver. If you really want one, just put one in the rear since these cars are RWD biased. Subaru STIs have had multiple LSDs for decades.

[dradernh]

Originally Posted by freakystyly

It's possible to fit them in these differentials but not really necessary for your average AWD driver. If you really want one, just put one in the rear since these cars are RWD biased. Subaru STIs have had multiple LSDs for decades.

Who sells LSDs for BMW's 2 Series AWDs?

[freakystyly]

I'm not going to search it too much...

https://diffsonline.com/bmw-f2x-228i...ming-soon.html
https://diffsonline.com/bmw-f2x-m235...erentials.html

I'm not sure if these guys are forum sponsors but I have seen the occasional post mentioning this company. I'm sure there are others kicking around.

I haven't had the chance to get a good look, are our differentials welded from factory on these cars? if not a good shop and swap the guts pretty easy to a LSD using the same pumpkin.

[dradernh]

Originally Posted by freakystyly

I'm not going to search it too much...

https://diffsonline.com/bmw-f2x-228i...ming-soon.html
https://diffsonline.com/bmw-f2x-m235...erentials.html

I'm not sure if these guys are forum sponsors but I have seen the occasional post mentioning this company. I'm sure there are others kicking around.

I haven't had the chance to get a good look, are our differentials welded from factory on these cars? if not a good shop and swap the guts pretty easy to a LSD using the same pumpkin.

I'd call Dan and speak to him directly before assuming that https://diffsonline.com/ is offering LSDs for xDrive BMWs.

That's especially true if I was imagining that diffsonline was offering both front and rear LSDs for 2 Series AWD cars.

I'm looking forward to hearing what's available in the marketplace for 2 Series AWD BMWs as far as both front and rear LSDs goes.

[Shovelman]

Well the Car and Driver article is good but it leaves me thinking that the optimum would be a 4 motor electric vehicle.

[cristo]

Originally Posted by freakystyly

They're all open differentials.

I believe that the transfer case works like
an LSD with an electronically controlled
clutch pack.