Was wondering what the limit of the 996 Turbos Front diff and trans are

 

Hi, first timer! Welcome to the forum. Your question is a bit vague, but many threads rate the parts to over 1000 HP, but with upgrades to clutch etc.

 

I believe the front diff doesn't like anything above 650-700whp. Although the trans can handle much more than that. 1000+

 

so front diff is limited to about 700whp TY for info

 

I only have 530bhp crank. I replaced front diff (and it is leaking again - but this I think is being unlucky with the replacement from Porsche) and I had to replace main shaft tranny bearing (90K miles). If you drive it, if you drive relatively fast and hard (like I am) and pile on the miles, these items will take a beating and will inevitably fail. Yes the items can take it, they can take 800bhp, the only question is, for how long…

 

I had the same question as I was trying to decide if the 997.1 is worth the extra money for the better drivetrain. With all the searching I did it looks like around 700whp is where things go south fast. The case for the front diff is quite thin and cracks. I am sure somewhere before that it will start to deflect and increase the wear on the gears/bearings inside.

 

Front diff?? Whats that?

 

The other day reading a 2010 Turbo review and there was a comment that with the 530hp of the new Turbo S this is why the car is available with a PDK only.

The 6-speed manual was deemed not strong enough to provide the longevity required.

Thus I would hazard a guess anything over 530hp is probably at the design limits of the 6-speed and its clutch.

The front diff only gets 40% of the engine's torque output but it is a smaller (appears smaller anyhow) than the rear diff. And given the lesser weight load it carries the front tires are more likely to spin thus saving (perhaps) the front diff/half shafts from the wear/tear the rear diff/half shafts will have to deal with.

Sure, you can run more HP through the drivetrain but I think one is relying upon considerable margin and not all cars will have this.

Oh just to add: The 530HP figure was given but the torque output is 516 lb-ft between 2100 to 4250. If you bump the HP output up you're also bumping the torque output up and this increase in torque can be at lower engine and car speeds thus the drivetrain experienced prolonged exposure to this increase in output from the engine.

Sincerely,

Macster.

 

A LOT: https://www.6speedonline.com/forums/...-vs-world.html

 

Did you forget you are in the 996tt forum? The 997tt drivetrain is very different, especially the AWD system. And to say the 6 speed tranny can only take 516 ft/lb of flywheel torque (as HP has nothing to do with a drivetrain) is laughable. There are guys on here running over 800 ft/lb at the wheels.

 

Well you have obviously fallen vicitim to beleiving HP is the deciding factor in in this case drivetrain selection. It is torque and the torque curve.

The engine makes its max. HP at a pretty high rpm, but max torque can be available from a lower rpm, in the case of the 996 Turbo at around one half the engine's max. rpm.

Thus when the throttle is nailed the drivetrain receives its max stress (from torque) then.

While the 997 Turbo's drive coupling to the front diff is different having clutches controlled by the DME vs. the 996 Turbo's viscuous fluid coupling the 6-speed transmission of the 996 Turbo could have been used in the 997 Turbo S.

Heaven knows many swear that a manual is the only transmission to have so for Porsche to go against this market demand and offer a PDK only suggests there was a good reason not to offer the 6-speed.

In short it is not up to the demands the 997 Turbo S and its 530hp puts upon it.

This then suggests to me a reasonable limit of 530hp (and I forget the torque number I quoted in an earlier post) is what the 996 Turbo drivetrain could be expected to deal with and deliver suitable long life.

Sure there are those that run much more hp/torque and with no apparent problems.

We hear about this cases like it somehow guarantees all will have the same good luck.

OTOH, there are the occasional post about a ruined clutch or worse -- even for those with stock hp/torque output -- so not all are as fortunate.

Also I have seen more than one mod'd Turbo in for a new clutch or other drivetrain problems so not all owners are as fortunate as the few that somehow manage to skate by.

The OP is certainly free to throw as much hp/torque as his bank balance allows at his Turbo's drivetrain and see what happens.

But my point is that if he ventures above the hp/torque output of the 997 Turbo S he's pushing the 996 Turbo's drivetrain: tranny, and diffs and well everything beyond their design limits.

Sincerely,

Macster.

 

Did you even read my last post? I was talking torque, not HP. Ft/lb is a torque rating. And of course you will have to replace a clutch, it is a wear item just like brake pads. There are many factors that play in to how fast it will wear out and that should be a given. That is true with any platform, not just the 996tt.

Also, I will guarantee Porsche did not consider putting a 996tt drivetrain in the 997.2 as the viscous coupling is archaic by today's standards of computer conrolled AWD systems like the GTR and EVO.

Good manufacturers (such as Porsche) put a large safety margin on their products because they know they will be driven hard. You do realize the GT2RS has a 6 speed, right? The factory has to factor in warranty costs and reputation, they have to take in to account the ham fisted guy that does revs it up in neutral and does a clutch drop. You always design to the lowest common demoninator, not an enthusiast or someone that knows what they are doing.

The choice of the PDK was probably be cause it is fast than the 6 speed. Name the car that is gunning for the 911tt... The GTR has a dual clutch system so the 911tt needed it also. Throw in the cost to develop 2 drivetrain options and the fact they probably didn't want a 6 speed 911 compared to a GTR in a magazine and that is likely the reason right there. Marketing and sales drive product design.

If you think Porsche couldn't design a 6 speed to handle 515 lb/ft of torque then I am shocked you are on here :P

 

Not really mate. The awd system is nearly identical minus electronic drive management versus mechanical (viscous clutch). It allows greater transfer of power % wise to front wheels. I actually don't like this I prefer my car more rear wheel drive biased. Gear box is nearly identical. Some strengthened syncros and the first gear. Of course they are guys running 800ft/lb torque values, I know few personally, however, one friend went through 3 gearboxes already, I guess this is the part no one really likes to talk about!

 

The front diff is not beefier on the 997tt since it can transfer much more power to the front than the 996tt? I have read that it was, but have not seen it myself first hand. I agree that 800 wheel ft/lb is probably getting near the limits, but 516 flywheel ft/lb is not pushing it at all for the tranny. As I said in the last one, driving style can make a huge difference too.

 

997tt awd system OWNs the 996tt one. biggest difference is 997tt one works and 996tt is junk. clutch vs vscious. electric vs stupid etc etc