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Go Back   E46Fanatics > Tuning & Tech > Driveline, Engine & DME Tuning

Driveline, Engine & DME Tuning
Talk about driveline improvements, NA tuning and DME tuning your E46 BMW here. This includes diffs, intakes, exhausts, chips, software and OBD tuning.

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Old 08-01-2010, 12:24 AM   #1
xixixi
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Painful Lesson (awd to rwd swap)

Today I started the first step of my rwd conversion... or so I thought... I started by taking out the front axles. I was about to take out the front drive shaft when I decided to go for a drive. That didn't work out, the car refused to move. I figured it wouldn't, so I pull the traction control fuse. Still nothing at this point I have my car running at the end of the drive way at 12am (headers no cats no muffler true straight pipes) I tried to push the damn thing up my driveway and get it out of the road. It didn't happen, I had to wake up my neighbor to get it back in the garage. A few weeks ago I bought a 99 328 that has 2 drive shafts in the rear seat. It also has the front subframe/spindles/control arms and a 3:46 diff I plan on using. Now I must source a transmission and have it in by tuesday morning. I just wanted to share my story with those that are thinking about trying this swap. It's not easy and so far I'm running into more and more issues... I'm hoping that once the new transmission is in I will be able to disable the traction control (via fuse box) and all will be good! I'm also trying to think of a band aid fix till i can get a tranny. Any out of the box ideas are welcome I was thinking about welding the front diff so it's locked??? I'm going to drown myself in gin
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Old 08-01-2010, 02:20 AM   #2
cnotesdip
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you know you can program the car to be rwd, even if you get a new tranny if the car thinks its awd is going to give you problems
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Old 08-01-2010, 10:08 AM   #3
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well go on tell me how... it's the transfer case that is messing everything up. once that is gone the problems will be gone i can always pull the abs/dsc fuse to ignore the front wheel sensors

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Old 08-01-2010, 01:55 PM   #4
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mmm i'm pretty sure your not the first person to attempt.. but good stuff keep up the work
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Old 08-02-2010, 04:21 AM   #5
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What you experienced was an "open" carrier in the transfer case. It was literally directing all force to the front driveshafts which were absent. I wouldn't say it was a problem, just a PITA.

Good luck with the rest of your swap, getting the transmission back in can be a real pain. I've done it alone, but would NEVER do it again....and that's on a race car that I built to make it easy to change. Get help.
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Old 08-02-2010, 10:22 AM   #6
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Since you are doing a 4wd to a 2wd conversion, I suggest getting a shop manual. Do a bit of reading and you'll see why pulling a fuse does not convert your car to 2wd.

It would be like if I said, "If you pull the ABS fuse, on a 330i, the car will have an open diff." Sounds stupid doesn't it? In reality, it's true. Go put the LR wheel on ice and the RR on dry pavement and try to take off. The ABS/DSC unit will apply the brake to the LR wheel which will transfer power to the RR wheel and the car will move. It's acting like a LSD. Pull the ABS fuse and the car will just sit there slowly turning the LR wheel.

As for a 4wd BMW, if you put the front wheels on ice and the rear wheels on dry pavement. Start to accelerate and the ABS/DSC unit applies the front brakes thus transferring the power to the rear wheels. The car will move. Take out the fuse and the car will just sit there.

On a 4wd system with open diffs, the power is applied to all 4 wheels. My old Audi 5000 Turbo Quattro would get stuck in the snow pretty easy. This was because it had 3 open diffs. If one wheel would get stuck in the snow, all power was transferred to that wheel. At the time Audi had a rear and center diff lock. If you engaged these, then you would have to get both rears and one front stuck to keep the car from moving.

With the advent of advanced electronics, things changed. My old Audi A6 Quattro had a torsen center diff but an open front and rear. When I was in the snow, I could just punch the throttle and the ABS precharge pump along with the ESP would go to work and start transferring power to wherever it was needed. Once I got going, then it drove like a regular car. The problem with my 5000 Quattro was that trying to drive the car around with a locked center and rear diff was a PIA. I had to switch it on and off plus it needed to essentially stop for the diffs to lock.

The XI pretty much operates like an Audi. Now exactly but close enough. The Bosch ABS/DSC system (the 4wd ABS/DSC system is made by Bosch and the 2wd system is made by Teves) just applies the brake to whatever wheel starts slipping. When you are driving the car around on the street, power is delivered to all 4 wheels if you like it or not.

According to the shop manual, 38% of the torque is applied to the front. I have a feeling when you get to worst case scenario (front wheels are off of the ground) that 38% turns to 0%. It's like having a torsen diff. Jack one wheel up and it acts like an open diff. As long as the other wheel has some sort of resistance, then it'll transfer much more power than an open diff.

I still suggest doing some reading and see how these systems work. With a bit of knowledge, you'll find out that just doing things like "pulling a fuse" does not do what you think it should do.
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Old 08-02-2010, 10:53 AM   #7
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I'm off and running on removing the T case now and getting a new rear section of my tranny to finish the swap... however I'm having issues dropping the T case I'm not sure if i need to drop the exhaust and all that or what? anyhow back to the garage. I should be done mid week!!! Great posts keep em coming!!
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Old 08-02-2010, 10:57 AM   #8
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Good luck with the rest of your swap, getting the transmission back in can be a real pain. I've done it alone, but would NEVER do it again....and that's on a race car that I built to make it easy to change. Get help.
I bet this is very true. AWD to RWD swap just sounds scary as FCK!

Y are you doing this anyway?
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Old 08-02-2010, 11:07 AM   #9
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i've spend thousands on the D/T since i've owned the car. It's always something c/v joints vibrations etc etc. It never stops just to pull the oil pan on my car is about 10hours you have to drop the entire front suspension front axles subframe everything. I'm sick of working around it and It's coming out. Not to mention all the weight savings What put me over the edge was the front diff was leaking which is another 10 hours of labor to replace a 20 dollar part.. I'm over the awd system period!!! anyone know how to drop the T case??
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Old 08-02-2010, 11:48 AM   #10
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Originally Posted by xixixi View Post
Today I started the first step of my rwd conversion... or so I thought... I started by taking out the front axles. I was about to take out the front drive shaft when I decided to go for a drive. That didn't work out, the car refused to move. I figured it wouldn't, so I pull the traction control fuse. Still nothing at this point I have my car running at the end of the drive way at 12am (headers no cats no muffler true straight pipes) I tried to push the damn thing up my driveway and get it out of the road. It didn't happen, I had to wake up my neighbor to get it back in the garage. A few weeks ago I bought a 99 328 that has 2 drive shafts in the rear seat. It also has the front subframe/spindles/control arms and a 3:46 diff I plan on using. Now I must source a transmission and have it in by tuesday morning. I just wanted to share my story with those that are thinking about trying this swap. It's not easy and so far I'm running into more and more issues... I'm hoping that once the new transmission is in I will be able to disable the traction control (via fuse box) and all will be good! I'm also trying to think of a band aid fix till i can get a tranny. Any out of the box ideas are welcome I was thinking about welding the front diff so it's locked??? I'm going to drown myself in gin
Why would you attempt to convert your car to rwd when you do not even know how the awd works? Welding the open center diff in the tcase is the only way you will get power to the rear wheels, and IMO you are asking for trouble with that. Welding the front diff will do nothing at all, and neither will pulling the tcontrol fuse. You should do it right and get the rwd drivetrain. You can easily pay for it by selling the tcase, front diff, axles etc. The only bandaid fix would be to somehow keep that front driveshaft from spinning.
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Old 08-02-2010, 12:05 PM   #11
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I guess you failed to read my post.. and you missed the part where I said I FIGURED it wouldn't work. either way to stay on topic i'm about to remove the T case now had to drop the exhaust and the rear drive shaft. I am doing it right I was hoping that I could do the swap in two parts first the front then tackle the T-case/rear end. It didn't work that way so I have to do it all at once. Maybe my post was misleading. I have every intention of doing this the right way. however I wasn't 100% sure how it was all going to work out. I'm learning as I go. However if you have some knowledge to give I'd love to hear it. Not interested in the bullsh!t

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Old 08-02-2010, 12:44 PM   #12
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What are you going to do about the ABS/DSC system? They are not the same from a 2wd to a 4wd.

Maybe it's just me but why not clean up the 4wd BMW and sell it? Then buy a good used 2wd BMW. The market for a 4wd BMW is usually not that bad in colder climates. Since there are tons of 2wd BMW's out there, you can take your pick.

Even a friend of mine bought a theft recovery 2003 330i last year for $3500. It needed a hood, front fenders, bumper and headlights. So for around $2000 in parts and some paintwork, he has a really nice car. A $5500 6 speed 330i with $75K on the clock seems to be a pretty good deal to me. It has a salvage title but he'll probably keep the thing so long that it isn't going to make a difference. Now he has a car that he can spend some money on and do some mods.
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Old 08-02-2010, 02:15 PM   #13
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not gonna use abs/dsc i will disable it and go without abs. I've driven many cars without abs and i never drive with the dsc on. This car is my car there are many like it but this one is mine I can't part with my car. Besides It's almost impossible to find a steel blue 330 sedan. Color combo everything is what i want minus the awd system it's a royal pain. Update: T case out working on taking the ass end of the tranny off now and I will start putting things back together I still need the front subframe/Motor mounts off my parts car. I should have most of this done by midweek/ the weekend!!!
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Old 08-02-2010, 03:12 PM   #14
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i've spend thousands on the D/T since i've owned the car. It's always something c/v joints vibrations etc etc. It never stops just to pull the oil pan on my car is about 10hours you have to drop the entire front suspension front axles subframe everything. I'm sick of working around it and It's coming out. Not to mention all the weight savings What put me over the edge was the front diff was leaking which is another 10 hours of labor to replace a 20 dollar part.. I'm over the awd system period!!! anyone know how to drop the T case??
sell the car get a rwd...much easier and cost effective and no headaches
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Old 08-02-2010, 05:07 PM   #15
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anyone even know what this is costing me? less than a grand. I doubt it can get much cheaper than that i'm not selling the car and buying a rwd. the entire D/T is out of the car and I have a transmission coming from car-parts dot com. The tranny is the most expensive item i bought a whole car for 200 bucks to get the 3:46 diff and drive shaft it also has the front subframe and spindles small update for anyone that is wanting to do this above and beyond the subframe/drivetrain/spindles/control arms you will also need motor mounts and a ground wire must be relocated. You need a 330i oil pan and the oil pump. The ground wire is connected to the passenger side axle housing coming out of the oil pan. If I can keep the xi Oil pan and make it work I will. The XI pan has a capacity of 8 quarts of oil. Thats all for now

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Old 08-02-2010, 08:34 PM   #16
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It really comes down to what you want to spend your time on. For example, I'd love to convert my Eurovan from a gasser to a TDI. It might make sense as VW never sold a TDI Eurovan here in the states. I'd have something unique and it would give better fuel mileage.

On the other hand, if I converted my Jetta TDI to a VR6, that would just seem silly. I can sell the TDI and buy a VR6 ready to go.

If you were going to convert your 330Xi to a diesel, I can see that. Unique vehicle not available in the states. Plus you can upgrade that diesel to make plenty of power. If I was going to do a BMW project, then it would be converting a 330Xi Wagon to a diesel.

So creating an extremely rare vehicle does has it's merits. A Steel Blue 330i is extremely rare. A Steel Blue 330i without ABS and DSC is probably a one of a kind. So, I'd be taking out full coverage on it. If someone steals it and takes it on a joy ride, they will certainly lock up the rear brakes (as a BMW without ABS has too much rear brake bias) and total it.
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Old 08-03-2010, 11:48 AM   #17
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It's fully covered
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Old 08-03-2010, 12:07 PM   #18
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I guess you failed to read my post.. and you missed the part where I said I FIGURED it wouldn't work. either way to stay on topic i'm about to remove the T case now had to drop the exhaust and the rear drive shaft. I am doing it right I was hoping that I could do the swap in two parts first the front then tackle the T-case/rear end. It didn't work that way so I have to do it all at once. Maybe my post was misleading. I have every intention of doing this the right way. however I wasn't 100% sure how it was all going to work out. I'm learning as I go. However if you have some knowledge to give I'd love to hear it. Not interested in the bullsh!t
I was not trying to get on your case. I just did not understand how it was a painful lesson if you had expected the outcome. I am glad you got everything figured out.
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Old 08-03-2010, 12:31 PM   #19
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anyone have a picture of an 01 unibody from a 330i? i think the unibodies were different?? I should have checked before I tore it down

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Old 08-03-2010, 01:34 PM   #20
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anyone have a picture of an 01 unibody from a 330i? i think the unibodies were different?? I should have checked before I tore it down
What part of the unibody are you looking for?

If this has to do with the front of the car, there are some different part numbers for various unibody parts (2wd vs 4wd). Take a look at realoem and you'll see at least which specific components are different.
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