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2WD with no transfer case clunks with AWD/4WD easily switched on when needed
So I just thought I'd share this since the other thread was pretty long and this interesting discovery (to me) is buried at the end.
I found out I can easily unplug the transfer case control module under the passenger's seat and have 2WD (and no clunks from my stretched chain). No errors, warnings or anything.
Then if I ever need or want AWD or 4WD, without even getting out of my seat, I can reach down there and plug it back in (after turning off the ignition) and have it all back in seconds.
I did this last night at a sold out Dave Matthews Band concert.
People in trucks and SUVs were driving over curbs and parking precariously perched upon grassy knolls at scary angles... I got excited since this has been my life-long dream as a 4x4-envying sedan owner.
So I put my hazards on, plugged it back up and found some parking.
Actually I ended up parking in the VIP section for free, but anyway it was a good test.
The reason my module is so easy to connect and disconnect is because I never properly extracted the original module, and have a newer spare I bought off eBay (that didn't solve the clunk issue) so I have more access.
Of course the right thing to do is R&R the transfer case, but I like this fix for now. Might even save on gas (?)
Any thoughts? Rotten tomatoes?
I saw the band on TV at the SITW water they had in DC last week. The band was awesome. The heavyset black trumpet player hails from st Thomas and is a friend of a buddy of mine who leads a local band.
I am interested in how this goes.
I have a question. Is it required to have the ignition off to connect/disconnect the control?
If not, I can see it being possible to make a power switch to select / deselect it, which is pretty much what a lot of other 4 x 4's have as standard.
Ha, I didn't even think of that! I'll report back.
Originally Posted by TRINITONY
I saw the band on TV at the SITW water they had in DC last week. The band was awesome. The heavyset black trumpet player hails from st Thomas and is a friend of a buddy of mine who leads a local band.
Yeah that trumpet player had some serious virtuosity... kinda reminded me of Eddie Van Halen the way he hit the keys so fast to fire out some of those fast notes.
Dave's voice was still 100% as far as pitch and power after all the years. I didn't realize he talked so funny. The simple things he said between songs were hysterical in a way where it's like he wasn't trying to be funny but it just came out that way.
Great show.
I am interested in how this goes.
I have a question. Is it required to have the ignition off to connect/disconnect the control?
If not, I can see it being possible to make a power switch to select / deselect it, which is pretty much what a lot of other 4 x 4's have as standard.
Out of respect for my Cayenne, I didn't try to plug/unplug it with the car on but yeah, I thought of the switch idea. It would certainly make things easier.
To update on the burnouts, I finally unloaded my recently mounted and balanced snow tires on 20" rims, which I figured weighed the rear down. Plus I didn't want them jostling around and marking up my tan interior.
Well unless I'm doing it wrong, its a no.
I was forced to get gas at an over-priced station today, so I actually got just a few gallons of regular for the first time just to get home.
Not sure if that makes a difference, but along with the high heat today I'm sure it doesn't help.
(2003 CTT)
Try it on some water. Find a puddle and back into it w/your rear tires, or spray a spot on your street w/a garden hose...see if you get get 'em going in water, then roll out onto the dry with the rear tires a-lit! Just like we do it at the drag track.
Obviously you need to have "everything all off"....or as close to that as this car will let you get.
Yeah, I didn't try any funny stuff yet.
I did turn off the PSM and kinda kept on the brakes slightly first, but I didn't want to abuse my baby after being so nice to me all these years.
With my luck my serpentine belt will go or something (it's due for replacement).
It sure was nice having no clunks though, with all of the Garden State Parkway congestion this weekend -and stop and go traffic looking for parking down the NJ shore.
Me neither.
I'm open minded... I only know for sure at this point that the clunks are gone.
I'm going by this Russian guy's words from this website: http://transfer-case.com/
If your browser doesn't auto-translate to English, here is the translation copied and pasted
How to make sure that it is the transfer case?
Disconnect the electrical connector of the servo drive (longitudinal moment module) on the transfer case housing. Attention: when the connector is disconnected, an emergency indication will be displayed on the dashboard, the front-wheel drive of the car will be completely disabled, incorrect operation of the ABS and stability control systems is possible. At the same time, jerks during acceleration should completely disappear (if the problem has not disappeared, the reason is not in the transfer case).
I unplugged the module instead of the motor, so I don't get any errors or warnings.
I'm sure I can find the single power wire to switch from the schematics.
I don't think I'll do any mod like that though. Even though I'm usually the last owner of all vehicles I've ever owned.
I was curious so I looked into this. I was wrong, RWD only does seem to be an option with this T-case.
We don't have a centre differential at all, just a variable clutch pack which allows the computers to torque bias front-rear on the fly.
With no pressure on the clutch packs, 100% torque would be going to the rear wheels, once enough pressure is applied to the clutches they become locked up for a 50/50 split.
I guess when you turn the car off it "homes" the motor back to no clutch pressure (RWD only) and if you unplug the motor before restarting it will stay that way.
Find a low traction surface and do a burnout! It's the only way to be sure For science!
Next to work out how to lock it up while remaining in high range. Having to be in Low to get proper 4WD is a bit annoying. You could bomb around in 4H "locked" 90% of the time off road and almost never need low range.
You could try it but it would just consume more fuel and tires without any noticeable benefits. There really isn't any use for locked center differential at high speeds. High meaning anything over brisk jogging speed. I cannot think of any situation where a solid 50/50 split torque distribution would be a good thing if You aren't actually stuck or offroading.
But I agree that this is a thing that deserves further investigation. The hardware in drivetrain between Porsche Cayenne/Audi Q7/VW Touareg is 100% same. Yet basic torque distribution is different between these platforms. You can swap a transfer case from a Cayenne to a VW or from an Audi to a Cayenne and it will perform just like the receiver cars original would. The difference in behaviour is in the transfer case control module software. Now all we need is someone with a prommer and couple of hundred hours of spare time and couple of decades of experience and we can reverse engineer the control unit software. After that it's just writing a "100% to the rear at all times".bin and flashing it to the control unit
06-30-2022, 07:54 PM
2WD with no transfer case clunks with AWD/4WD easily switched on when needed
For science!
