2WD convert possible? - Page 2

oldskewel · #1 10-10-2019, 12:26 PM

I'd be happy to learn something and be corrected, but my basic understanding of how these early (~pre-2004) x5's work is:

- the transfer case works just like a dumb differential. Constant torque split front to rear (38% / 62%). Just gears, no sensors, no actuators, no clutches, etc.

- the traction control works just like ABS. Detects wheel slip / lockup and adjusts braking accordingly.

For the experts, is that simplification still accurate enough for me to keep believing? I'd gladly throw a switch and be done with the front wheel drive, but am not interested in complicated mods. So I just need to know enough that I can understand how it basically works for driving or diagnosing purposes.

Bmwtvboy · #2 10-10-2019, 12:29 PM

That's what I thought.. that's why I prefer the pre 2005/X5, 3.0's , they were practically bullet proof. My thought was to just cut stuff out. Imagine the weight loss when dumping the front diff, axles, driveshaft and the entire transfer case, minus the spline/cut between transmission and rear driveshaft. Cut n paste. RIGHT? Lol....

andrewwynn · #3 10-10-2019, 12:30 PM

Don't understand the emergency brake comment. Are you saying you can pump the brakes to control understeer?

I thought that could be the case until I had trifecta in a snow storm. In a way you are correct I think: once converted to RWD, you could drive X5 without DSC but in a slippery environment, with three open dif, the X5 is nothing but dangerous, you can't guess when you'll get engine braking and it will put you in random uncontrollable spins. With Rwd, you can at least let off the gas and still steer.

You said you have trifecta but everything works. That is contradictory. Usually when trifecta won't go away and all the parts are in apparent good shape the problem is the abs module.

$200 or so to send that in to have the wiring leads re welded. It's a pretty well known issue with the Bosch abs brains of the early 00s.

Bmwtvboy · #4 10-10-2019, 12:40 PM

Ok, what I meant was. My brakes work just fine, but yes, in e.brake situation I can lock them up to skid. I too had a snow storm issue. Years ago, I climbed a steep hill and could feel the entire system take over,it was truly amazing. Then, some years ago,I was in CO and tried driving with the trifecta and you're right,it was scary to say the leasts. I drove around 10-15mph. Paid $1000 to have it fixed and within a year back in FL, trifecta was back on. SO, I am going to check n clean all four speed sensors, then, pump, then go to the supposed new abs module. THey were supposed to have changed out the Steering angle sensor. Im in FL, so I don't really need the AWD.

Fifty150hs · #5 10-10-2019, 12:57 PM

Quote:

Originally Posted by Bmwtvboy

Ok, what I meant was. My brakes work just fine, but yes, in e.brake situation I can lock them up to skid. I too had a snow storm issue. Years ago, I climbed a steep hill and could feel the entire system take over,it was truly amazing. Then, some years ago,I was in CO and tried driving with the trifecta and you're right,it was scary to say the leasts. I drove around 10-15mph. Paid $1000 to have it fixed and within a year back in FL, trifecta was back on. SO, I am going to check n clean all four speed sensors, then, pump, then go to the supposed new abs module. THey were supposed to have changed out the Steering angle sensor. Im in FL, so I don't really need the AWD.

Run it for codes. It could be a steering angle sensor. If it is a speed sensor it will usually give you a code as well.

Bmwtvboy · #6 10-10-2019, 01:38 PM

I am trying to source an old PC with Window 10 so I can run INPA software pack. Then I can do some great information.
That S.A. sensor was replaced about 4 years ago, can't imagine it went already.
AT this point I just want to keep it going for as little $$ as possible, as it is so old n 250K miles is great with all original engine/drivetrain except front axles. I know I can physically test those s.senors besides code out.

andrewwynn · #7 10-10-2019, 04:13 PM

You need to read codes to know vs guess. Any part can fail any time there is no "should still work", but I've seen plenty of times things can get confused especially if there is a voltage drop.

I've had an sas error that happened twice I think and I just recalibrated and right as rain.

Bmwtvboy · #8 10-11-2019, 12:33 PM

Absolutely, codes are invaluable ,but I find if there is a physical test to add, it can be helpful for a more precise diagnose. The trifecta is a royal Pain. But at least here in FL I don't have to stress over it not working. Just practice safe, stable driving attitude like they taught us in BMW driver training.

Bmwtvboy · #9 10-11-2019, 12:37 PM

One nice feature of driving these steptronic systems is you can lock into a lower gear and keep the engine rotation closer to traction needs. I used to do it all the time when first learning to drive manual in the brutal cold, snowy winters in Maine. And some years later had a wild experience driving my E30 manual around in 2nd n 3rd gear through the power band in the upper revs. I miss that thrill. But youre right, gotta eventually, when it cools off here, get that darn Trifecta issue resolved, but probably not swap into a 2WD, don't have the time or the money.

andrewwynn · #10 10-11-2019, 12:51 PM

Wife's car just started having a trifecta. When I pulled the codes it flagged the right rear sensor.

I just replaced the right rear bearing.

Cannot be a coincidence. I figured either the old sensor just doesn't want to listen to the new tone ring or I damaged the sensor by leaving it in when I knocked off the hub with the slide hammer.

Replaced with a knock off sensor because it was $20 v. $90 and I wanted to see if it was actually the abs module and the $70 savings is 1/3 of the module repair if needed.

So far no trifecta. The sensor takes all of 20 minutes to replace so I wasn't too concerned about using a branded part. I'll post my lack of wisdom on that should that part fail quickly.

I had a knock off fuel pump fail after 10 months but they replaced under warranty and the replacement is working fine. I also bought an OEM pump as a backup since I have a pair of X5 and eventually one of the pumps will fail and I want a quality pump that takes most of a week to deliver. Now I just need to have somebody bring me the pump from my house. (I'm rarely ever more than 90 minutes from home)