I've read a few diff threads but I'm not 100% sure.. I can rather easily light up my rear tires in 1st gear. Stock turbos, 1 bar. It feels like a RWD car to me. What's the best way to check front diff functionality? Do you think a fluid change may help?

 

The rear of our cars does not have an LSD, so one tire can spin, even when the fronts are pulling the car.

I am surprised you're have traction issues. What kind of tires are you running and how old are they?

Later, Steve

 

the more lsd you have in these cars the less wheel spinning you should feel. also from a standstill/launch i wouldn't expect more than the minimum 5% to the front which is hard to "feel" under any condition. as to fluid, i would treat the front diff as i would the gearbox oil regarding changing it.

 

Tires are Hankook Evo V12's 295/30/19. About 2 years old, 85% tread. Maybe they suck? They were a 'cheap' option.. Maybe I need 305s? To be clear, the car can hit 1.2 bar when temps are low and car is happy.


Car is tip.. LSD is not an option, right?

 

! I've never known the answer to that. i wouldn't think so?!

 

Maybe the car was converted to RWD....just kidding.

1) Tires that suck
2) road surface
3) I'm sure front diff would make noises
4) it means you have no boost leak and car runs like a monster

for example: with a good tune, and crappy road surface, on my end,... car runs like its on steroids and it slides sometimes from second gear.. im on winter tires and roads are cold.

.

 

The silicone fluid viscous coupling is permanently sealed, can't change it. The front diff gears are bathed in oil, that you can and should change once in a great while. But it has zero effect on torque transfer.

 

If you actually converted the car to RWD you'd be able to tell the difference. It's working but just enough to keep you out of the ditch. If you're trying to compare it to a suby, Talon or Audi (I've had a few of each) it's not the same at all.

 

If you can't hear the diff its working just fine.

My car's front diff is fine (I can't hear it) and I can light up the rear tires easy if I want even with a stock 03 Turbo.

The max torque transferred is 40% but my info is this only occurs at 150+ mph. Starting out from a standstill only 5% (and it may be less based on how hot the viscous coupling is) gets transferred to the front wheels and this is not enough to limit rear wheel/tire spin.

The front diff is no different than the rear diff in that it should have regular fluid services. The scheduled change is 90K miles I think. But I have had my Turbo's front (and rear) diff fluid service done now twice in 125K miles.

 

my understanding, exactly. though if it were me, i always cut porsches fluid service intervals in HALF! i think they like that "drive to workshop" dashlight. but call me crazy lol

ps. i dont think it's EVER less than 5% to the front, based on its design. that cardan is always spinning.

 

v12's suxor, especially in the cold. So if it's like sub 40 up there in boulder it's not surprising.

 

Thanks for the info everyone. With no diff noise, seems my car is probably working as it should. Looks like I'll roast through these tires and get some better rubber.


So I guess this car will be awful in the snow?

 

If that's the case it's pretty impossible to light up all four tires, but this makes sense. when I went to the track I went around the water and did a quick rev and clutch drop to clear the tires. I swear it felt like a Regular rwd car but some folks said I should have lit up all tires.

 

drew, a word ( or two lol ) about tires.

you might want to re-think putting hankook v12 tires on when you're ready to replace all four. that v12 is ( as far as i'm concerned ) the very worst tire that one could choose for this car. so bad, in fact, they may even give a distorted notion of how the car should/does drive.

i'm not kidding, but admittedly that's like just my opinion man

 

No direct experience -- well, 40 some odd miles of direct experience in snow on summer tires -- but the car should just be fine in the snow with proper snow tires.

There are a number of Turbo owners who drive their cars year round and report the car is just fine in the snow, albeit a bit short of ground clearance so forget about blazing path through deep snow. But if the snow is shallow enough or the roads plowed the car will be just fine.

It is not going to be a Jeep though and you can't rely upon the front tires pulling the car out of ditch.