where are the Porsche cayenne expo builds?

[Dave Waldo]

This is the centre diff



The rear diff should be able to be locked when the centre diff is in high range if the rear diff controller is independent and does not talk to, or is controlled by, the Porsche smarts so the factory ECU doesn't know the rear is locked or partially locked. I think the rear diff blocking untill after low range is selected is software.

Happy to be wrong here, it's all a bit of a guess so far.

The centre diff has the cam that does the selecting in the pics above, but I don't fully understand it yet. I'm doing a lot of guessing based on the images above but, like you, I'd like to control all the diffs before selecting low range.

It looks like. The motor can move the cam to start loading the clutch before it pushes to engage low range.
Guess 2. Turn the cam 360° and engage low range with variable slip on the clutch.
Wild Guess 3. Turn the cam further again and lock the drive shafts. I can't see how that happens.

It looks like it will need custom controller and a new cam to change this. A bit of a PITA but doable maybe. Have to see one I think.

Do you know if the diff motor and the centre diff motor are the same ?

 

[dreadlocks]

here's the missing piece of that image:

"This cam has a curved inner track that moves a pin, which in turn moves the shifter rail and shift fork..", I believe the locking position on this track is AFTER the shift fork has switched to low range, and thats what would require custom machining to make a new track which allows the stepper motor to go to locked w/out moving the shift fork.

I found a post a couple days ago that discussed why this was not feasable, with better photos.. but I for the life of me cannot find it now.

I'm not sure the center diff's work, the front diff dont have a stepper motor AFIK, so is the low range for the front diff in the transfer case and the low range for the rear is in the diff? I dont have selectable center locker, just a simple auto locker w/no low range.. looks like if I wanted a rear locker, I'd have to get the transfer casee too and figure out how to operate everything externally.

 

[Dave Waldo]

I'd like to see that article if you find it, sounds interesting.

You should be able to fit the rear locker and have an independent controller like I'm doing, you just have to match the ratios from the front diff. We are working on front diff locks too but it's very early days at the moment, we won't know for sure for a while.

Both front and rear diffs are single ratio. The reduction for low range is in the centre transfer case/differential. No motors on the front diffs, there is a lot of talk about if they ever existed but I am pretty sure they didn't. I think it was in planning for the cars but never made it to production.

The motor on the rear diffs only function is to apply locking across the axles anywhere from no lock to full lock.

The rear diff has two round plates with ball bearings between them. The ball bearings rest in the deepest part of ramped groves machined into the faces of both plates. The ramps oppose each other. The motor on the rear diff rotates one plate. As the ramps move relative to each other the ball bearings are forced up the ramps to shallower parts of the groves which pushes the two plates apart. As they push apart they apply pressure on the clutch pack which resists slip between the axles.

 

[dreadlocks]

ah I see, so its the center diff stepper motor you won't be able to lock w/out engaging low range then.. if you keep that unlocked we'll be able to lock the rears.. sweet, yeah so the TDI's always got the same ratios on diffs.. I found a rear TDI diff from an earlier year when you could still get em in Europe for about $800, thats cheaper than fitting most aftermarket diffs.

are you going to try to figure out the stepper motor positions for the center diff too or just the rear? if thats not overly complex mebe I can find a TC too and do a full conversion.. might as well throw all the eggs into the basket when shipping is gonna be so brutal.

 

[Dave Waldo]

In the original design you have to progress the level of off-road capability in this order.
Step 0. On road
Step 1. Low range
Step 2. Low range + Centre diff lock
Step 3. Low range + Centre diff lock + Rear diff lock

I "hope" to make a controller that will allow the rear diff to be partially or fully locked at any time regardless of the state of the steps above, so if you don't have low range or locking centre diff it should still work on the rear.

I doubt I will do anything with the centre diff after looking at it's design. I wouldn't rule it out, but unlikely.

It's interesting to speculate what's involved though.

 

[Lovetheworld]

Well, a bit strange to not have an H4 mode as refered to in old-style 4x4s, but okay, it will work.

@Dave Waldo What do you know about the original controller of the rear diff lock? Couldn't you get it with the diff?
I would assume it either has some simple 12v or ground lines, or vacuum or CAN bus to lock the diff? That would safe you a lot of work.

 

[Dave Waldo]

Well, a bit strange to not have an H4 mode as refered to in old-style 4x4s, but okay, it will work.

@Dave Waldo What do you know about the original controller of the rear diff lock? Couldn't you get it with the diff?
I would assume it either has some simple 12v or ground lines, or vacuum or CAN bus to lock the diff? That would safe you a lot of work.

Agreed, I'm not sure why they made it back to front to the conventional sequence. I have tried to work out if there is a good reason for it, the only reason I can think of is that they don't want people accidentally driving on road with it in 4wd and stressing the drive train.

They can be made to work with the factory controller, you need to buy and fit a wiring harness as well as the controller. I am thinking about doing it, maybe have both options. There is a guy in the US that has worked out how to activate the factory software to make it plug and play and a guy who makes a piggyback wiring harness. I'll find their details and post them up. I am not sure if this will make the diff active in on road driving like PTM+ or just able to be locked in off-road setting. If it is active on road it should improve the car on road as well as off road. The down side is you will have to follow the sequence above and only use the rear diff lock in low range which isn't ideal for me. Maybe have both ?

 

[Dave Waldo]

This is the guy who does the factory activation - dave(at)racecarsforyou.com

I don't know much about it, I only just found out about him and just started talking with him on email.

 

[dreadlocks]

on the VW/Audi's we can use ross tech vcds to re-code all the modules to support the diff/tc can modules, Ive found em all just browsing around.. Porsche uses its own software for interfacing w/the can bus and reconfiguring em.. Ive never used it so I dont know its capabilities and limitations.

The Tregg guys have this swap totally worked out, several robust threads on club touareg.. if you get the rear diff, the can module, and the new selector switch its just hooking em up and performing the module recoding.. I cant fit a selector switch so I'm keen on dave's findings.. Ive read others figured out how to operate the rear locker on a bench but they didnt share the info unfortunately.. its just a stepper motor so I'll make my own circuit board w/a simple micro proccessor to move the motor from locked to unlocked off a momentary switch, mebe a led output to show status.. tha'll be like $20 in parts and an afternoon of coding.. I'll build it with an extra motor controller circuit incase down the road I get a hair up my ass and try to swap the TC.

 

[billiebob]

Porsche, 1957..



is this not one of the best rear lounges ever

 

[Mr. Merk]

Those are so rad. A lot of 356 parts there. A must have for the best Porsche collection.

 

[Dave Waldo]

I pulled the rear diff control motor apart today, it's a nice design. The motor is a high torque 12Vdc motor - not a stepper motor. it is probably controlled by a PWM controller to ramp up and slow down the motor speed.

The alloy housing doesn't contain any gear reduction it is 1:1, the gear is fitted directly onto the motor shaft.

In the housing is a

• PCB,
• a star shapped washer,
• an electro magnetic clutch.

The PCB has two switches that count the teeth on the washer as they go past so it knows how many revolutions the motor has done.

The clutch (or more correctly it's a brake) holds the motor in place when it stops and releases when you want it moved.

It will be quite simple to make a crude lock/unlock controller but I'm hoping to be able to make a variable control which will require some smarts and programming. I'm not sure which way to go, maybe just to get it up and running; simple is the best. I'll have a think about it.

 

[dreadlocks]

awesome, glad your making progress.. thats interesting its got teeth counters on it, hopefully that PCB handles all that.. sounds like a blown up servo motor tho really.

So I did a thing last weekend, omg its soo awesome tuned.. butt dyno says at least 2s were shaved off 0-60.


It spent a month at the dealer, but they fixed a leaky rear main seal, a leaky upper oil pan, a leaky timing chain cover, and a leaky EGR cooler.. they also threw in a new water pump, all new fluids, and a fresh alignment.. engine is better than its been in a long time, now I'm fitting a 1Micron filter w/water drain and trying to figure out how to install a disaster prevention plate on the HPFP since I can get rid of the EGR valve thats in the way.

 

[dreadlocks]

Got the webasto installed and working, no big problems with the retrofit, was a super fun project.. its configured to automatically come on to assist engine warm up under 41F and can be activated manually or through a pre-defined timer through infotainment system for heating.. I'm going to add the remote and module to turn it on from up to 1800ft away before next winter.

documented the whole webasto conversion, now that the VW and Audi been figured out I think if someone wanted to tackle this for the Porsche they will find most of the path paved for em, its all the module coding and stuff that is gonna be a mystery with the different computer systems between VW/Audi and Porsche.. here it is: https://docs.google.com/document/d/...VxoXUqovySmzFmaBZggVGSl5Xox38505vZMDlay-G/pub

Next up need to bulletproof the HPFP and then hopefully by the time that's behind me I'll have a pretty damn good idea what its gonna take to put a locking rear diff in this thing.

 

[marcantoine77]

I'm looking to order this
What do you think?





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