996TT differential troubleshooting question
02-03-2009, 05:52 PM
#1
Rennlist Member
Thread Starter
996TT differential troubleshooting question
Ive been searching the various forums about 996TT Differntial Troubleshooting with little succcess.
There are lots of opinions about the AWD functionality on the 996tt ranging from complete removal for weight saving and parasitic drag to leaving it as Porsche intended. Although it is obvious when there is a catastrophic failure- there really isnt any information about how to determine if your front differential is working, and if so, at what capacity.
The facts are that its an AWD system that can transfer anywhere from 5 to 40% pending conditions / load and that dynoing on a 2WD system (and some AWD models as well) can grenade your differential. Interestingly, there is also specualtion that using the spare can also cause damage which is why it wasnt included on the 997s (hearsay).
Bottom line: Does anyone know how to determine if the front differential is working, and if so, how do we know at what capacity?
Any constructive input appreciated.
Btw, my differential appears to be fine, although I have dynod on an awd system, and used the spare a couple times
There are lots of opinions about the AWD functionality on the 996tt ranging from complete removal for weight saving and parasitic drag to leaving it as Porsche intended. Although it is obvious when there is a catastrophic failure- there really isnt any information about how to determine if your front differential is working, and if so, at what capacity.
The facts are that its an AWD system that can transfer anywhere from 5 to 40% pending conditions / load and that dynoing on a 2WD system (and some AWD models as well) can grenade your differential. Interestingly, there is also specualtion that using the spare can also cause damage which is why it wasnt included on the 997s (hearsay).
Bottom line: Does anyone know how to determine if the front differential is working, and if so, how do we know at what capacity?
Any constructive input appreciated.
Btw, my differential appears to be fine, although I have dynod on an awd system, and used the spare a couple times
02-03-2009, 06:12 PM
#2
As you mention, there are number of threads addressing this topic, including several I've commented on. The facts may state one thing, but I think the general consensus is the viscous AWD differential in the 996 series transfers little if any useful power to the front, at least at low speeds. It does however, seem to add a small margin of stability to the AWD cars. I do know Porsche added an electromagnetic clutch in the 997 turbo and C4 Mk 2 - probably to get a little more function out of it!
02-04-2009, 11:49 AM
#3
Rennlist Member
Ive been searching the various forums about 996TT Differntial Troubleshooting with little succcess.
There are lots of opinions about the AWD functionality on the 996tt ranging from complete removal for weight saving and parasitic drag to leaving it as Porsche intended. Although it is obvious when there is a catastrophic failure- there really isnt any information about how to determine if your front differential is working, and if so, at what capacity.
The facts are that its an AWD system that can transfer anywhere from 5 to 40% pending conditions / load and that dynoing on a 2WD system (and some AWD models as well) can grenade your differential. Interestingly, there is also specualtion that using the spare can also cause damage which is why it wasnt included on the 997s (hearsay).
Bottom line: Does anyone know how to determine if the front differential is working, and if so, how do we know at what capacity?
Any constructive input appreciated.
Btw, my differential appears to be fine, although I have dynod on an awd system, and used the spare a couple times
There are lots of opinions about the AWD functionality on the 996tt ranging from complete removal for weight saving and parasitic drag to leaving it as Porsche intended. Although it is obvious when there is a catastrophic failure- there really isnt any information about how to determine if your front differential is working, and if so, at what capacity.
The facts are that its an AWD system that can transfer anywhere from 5 to 40% pending conditions / load and that dynoing on a 2WD system (and some AWD models as well) can grenade your differential. Interestingly, there is also specualtion that using the spare can also cause damage which is why it wasnt included on the 997s (hearsay).
Bottom line: Does anyone know how to determine if the front differential is working, and if so, how do we know at what capacity?
Any constructive input appreciated.
Btw, my differential appears to be fine, although I have dynod on an awd system, and used the spare a couple times
you can test if it works by putting the car up on the rack and turning the front wheels they should be coupled but I am not a mechanic and I'm sure yours or Porsche would know.
as a follow up at that point for me (also broke my pinion gear) I went to RWD and that is posted entitled building the super transmission.
