garrett376

Very true indeed - it just provides us C4-bashers with rays of hope!

Adrian

I think that the C4 is stronger than people think, BUT and I use a big but, everything has its breaking point.
Go racing on 100,000 mile engines and transmissions, one should actually expect problems.
I believe the fact that many high mileage and relatively old and normally maintained C4s have been club raced and are still going, after what they have been put through is a testiment to the strength and integrity of the design.
I can tell you many of the old Porsche/Ford etc transaxles could not put up with this treatment.
Ciao,
Adrian.

Devils_son

I was talking about massive oversteer. And that is why I assumed that the PDAS was disabled during the braking into the corner, and stayed disabled throughout the corner. On the other hand, it may be that the oversteer was so massive that the PDAS, as it kicked in, couldn't get the car to understeer...

So, is the PDAS working again from the moment the brake pedal is disengaged? And if that is the case, then these moments will probably wear the system out eventually yes...

The other question was: do all of our attempts of reducing understeer mean that PDAS is working harder to compensate for that. And does this mean wear and tear increases when reducing understeer?

garrett376

The PDAS is mechanically disabled by an electrical switch activated by the brake pedal. If you brake into a corner, then floor it while you're still in the corner, you'll be likely locking that rear differential - thus "activating the PDAS" once the brake is off. If you install the light in your dash you will be able to see this, which is fun. My green PDAS light in the dash gauge is on pretty much from the apex of a corner to the corner exit - the whole time I'm on the gas (it's floored).

Depends if you're on the gas, or if you're sliding in such a way that one wheel is going slower/faster than another.


I think you're wearing your tires out faster than any of the transmission components!! Just like a limited slip differential, any time things are slipping (in our case the PDAS is variably locking the differential) something is wearing.

Again, sliding more means PDAS is working more - so in a way, yes! If the PDAS never activated, things wouldn't be worn out much since the differential would be acting like a simple open type differential during non-slip conditions (where wheel speeds are within a certain range - .5mph I think: Adrian knows that kind of stuff! )

I think the bottom line is: if you drive your car hard and especially race, things will wear and tear quicker, whether it's a C2 or a C4.

Adrian

PDAS is only disabled whilst your foot is on the brake pedal. Once your foot is removed it is rearmed. When you accelerate out of the corner it is ready to work and is just waiting for a wheel or a pair of wheels to spin up to 0.8kph faster than the others. PDAS primarily works by monitoring wheel speed.

You CANNOT dial out the understeer caused by the activation of the traction control.
We can only dial out the inbuilt understeer by Porsche in the basic design, which was far far too much.
As I always say, it's best to disable the traction control on the track because it will slow your corner exit everytime if you are really racing. If you can heel and toe you may feel the understeer even more when the centre lock activates. Serious understeer occurs when both locks are activated at the same time.
Ciao,
Adrian.

Devils_son

Is that an easy thing to do? (and I do have your book, so a page nr. would suffice... )

Adrian

Yeah you pull the connector off the control unit and put two bits of black tape over the warning lights whilst you are out on the track. It will take out the ABS as well.
You can also pull fuse 16 or remove relay R34.
Ciao,
Adrian.

klr10

Excuses for reserrecting an old thread. Had this catastrophic failure of the planet gears just at the end of summer last year. After looking at the cost of the new planet gears (£1200) got a used box on fleabay. After fitting discovered it jumps out of second (another story) so currently having the box reconditioned. The centre diif clutch is almost shot so having both diff lock clutches replaced. Looks like the gear jumping issue is a bunch of weak springs. Two questions really, firstly how often should the diff lock clutches be checked or replaced? Secondly is there anything that should be done to ensure this planet gear issue isn't repeated (this car has eaten two sets of planet gears in the last 30,000mls)

meek

So klr10, the second gear issue didn't turn out to be the transmission mount?

klr10

Nope, had to have the box stripped down. Still in the shop, currently having new diff lock clutches. Looks like there are some weak springs, will elaborate more when I find out which ones. I'm just petrified of having another planet carrier explosion...

meek

Sorry to hear that; for you and for me, potentially. Ho hum, something to add to the list. Can you let me know exactly what the cure for the second gear issue is, when you know and how much? It would be very much appreciated, even if the price may make me faint.