GT3 LSD Performance Comments
02-14-2011, 11:09 PM
#91
Nordschleife Master
Missing from the formula is D: Cost of goodwill lost by not doing a recall.
Since D is the great unknown (look at Toyota: How much did they suffer? What about Audi, way back when?), who's to say what the actual cost is/will be?
Since D is the great unknown (look at Toyota: How much did they suffer? What about Audi, way back when?), who's to say what the actual cost is/will be?
02-15-2011, 10:34 AM
#92
Burning Brakes
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With the coolant hoses we have a real issue.
Porsche is lucky that the media will not pick it up because the cars and their use are in a very small niche that nobody can relate to. Of course, the media will not pick it up because it's true. Reporting on real issues is not what they do. Playing on emotions makes more money. Any time I read a news report on any subject I am intimately familiar with I get horrified at the level of misinformation. Only specialist publications can provide some level of coherence, sometimes.
02-15-2011, 12:41 PM
#93
Nordschleife Master
Sadly Andrei, you are absolutely correct. Same with me and aviation, which I am "intimate" with.
That is why the Excellence article can help the cause; it disseminates the info to the "masses".
That is why the Excellence article can help the cause; it disseminates the info to the "masses".
02-17-2011, 03:32 PM
#94
Rennlist Member
Since my car is not a GT breed I can't comment on the factory LSD, but I've read complaints from a lot of people. All I can say is I am extremely happy with my Guard 40/60 LSD! 
02-20-2011, 11:43 AM
#95
Instructor
If you put one wheel on grass/gravel and the other wheel on normal tarmac, then pull away quite aggressively, surely if the LSD is not working the wheel on the slippery surface will just spin, and the car will struggle to move off ??
If it's working properly the car will move off easily as the traction is shared with both wheels ??
At least thats how I used to check if a car had an LSD or not.
If it's working properly the car will move off easily as the traction is shared with both wheels ??
At least thats how I used to check if a car had an LSD or not.
07-22-2011, 04:05 AM
#96
Rennlist Member
Update on an old thread:
I have now 3,500 miles on my 997.2 RS, majority of which are tracked. (Yeah I started tracking it at 500, whatever theory about a soft break-in certainly didn't get thru my thick skull).
When the car was new, the tail was absolutely planted under hard braking. Same feeling of a "settled" rear end when I had with the Guard LSD in my 997.1 RS.
As of last weekend, I started getting a slight waggle, very much similar to my old car before its Guard upgrade. Not yet a full-on waggle, but definitely felt in the steering.
I didn't like this one bit. If this is within PAG's definition of a working diff I guess it just ain't good enough. For amateur drivers like me, this waggle makes it harder for the car to take a set, at the moment when I need the car to be settled the most.
Will likely put in cup car clutch pack when I drain the tranny fluids next month... Porsche Porsche when will you learn???
I have now 3,500 miles on my 997.2 RS, majority of which are tracked. (Yeah I started tracking it at 500, whatever theory about a soft break-in certainly didn't get thru my thick skull).
When the car was new, the tail was absolutely planted under hard braking. Same feeling of a "settled" rear end when I had with the Guard LSD in my 997.1 RS.
As of last weekend, I started getting a slight waggle, very much similar to my old car before its Guard upgrade. Not yet a full-on waggle, but definitely felt in the steering.
I didn't like this one bit. If this is within PAG's definition of a working diff I guess it just ain't good enough. For amateur drivers like me, this waggle makes it harder for the car to take a set, at the moment when I need the car to be settled the most.
Will likely put in cup car clutch pack when I drain the tranny fluids next month... Porsche Porsche when will you learn???
Not with Kussmaul here, based on personal experience.
My 997.1 started showing the same symptoms at 6k miles--loose tail on hard braking plus inside wheel spinning when I mucked around in powerslides... put in the Guard clutch pack and the symptoms were immediately gone. Even transformed the car from mid-corner understeer to mild oversteer. It was THAT obvious.
I remember Mike at Guard at some point commented that the Gen 1 and 2's share the same diff+clutch pack so it'll only be a matter of time before the problem resurfaces in the 997.2...
Pete: on a GT2RS I can only imagine the diff to fail even sooner... you might as well preorder one from Mike now
My 997.1 started showing the same symptoms at 6k miles--loose tail on hard braking plus inside wheel spinning when I mucked around in powerslides... put in the Guard clutch pack and the symptoms were immediately gone. Even transformed the car from mid-corner understeer to mild oversteer. It was THAT obvious.
I remember Mike at Guard at some point commented that the Gen 1 and 2's share the same diff+clutch pack so it'll only be a matter of time before the problem resurfaces in the 997.2...
Pete: on a GT2RS I can only imagine the diff to fail even sooner... you might as well preorder one from Mike now
Last edited by CRex; 07-22-2011 at 11:11 PM.
10-25-2011, 03:06 PM
#97
Rennlist Member
Not with Kussmaul here, based on personal experience.
My 997.1 started showing the same symptoms at 6k miles--loose tail on hard braking plus inside wheel spinning when I mucked around in powerslides... put in the Guard clutch pack and the symptoms were immediately gone. Even transformed the car from mid-corner understeer to mild oversteer. It was THAT obvious.
I remember Mike at Guard at some point commented that the Gen 1 and 2's share the same diff+clutch pack so it'll only be a matter of time before the problem resurfaces in the 997.2...
Pete: on a GT2RS I can only imagine the diff to fail even sooner... you might as well preorder one from Mike now
My 997.1 started showing the same symptoms at 6k miles--loose tail on hard braking plus inside wheel spinning when I mucked around in powerslides... put in the Guard clutch pack and the symptoms were immediately gone. Even transformed the car from mid-corner understeer to mild oversteer. It was THAT obvious.
I remember Mike at Guard at some point commented that the Gen 1 and 2's share the same diff+clutch pack so it'll only be a matter of time before the problem resurfaces in the 997.2...
Pete: on a GT2RS I can only imagine the diff to fail even sooner... you might as well preorder one from Mike now
10-25-2011, 04:14 PM
#98
How do you feel about these observations per Roland Kussmaul and Porsche Powertrain Engineers?
"The mechanical LSD in the GTx streetcars has no preload on the discs. That means, you cannot find out if the LSD works correctly by just jacking the car up and turning the wheels manually! Nothing will happen in that case because the diff isnt working.
The reason for having no preload on the system is because the car would be a lot less manouverable in park-in situations and would therefore lose some of its "everyday driver" characteristics.
The LSD of a Cupcar has preload on the discs and therefore reacts differently on the jack, although the hardware is very similar.
To find out if the LSD is in good working condition choose a long 3rd gear curve (or a big enough space to drive a neutral 3rd gear circle), go with partial throttle and play with the accelerator (more load/less load). The car will change its radius noticeably because of the diff working. (On overrun its 40% and on throttle only 27% lock).
On all GTx projects of the past the LSDs where all still within spec after 30.000 km of hard racetrack use. On dissassembly there was no critical wear and tear on the discs or on the ramps."
Matt (GTGears) your input is valued and appreciated especially?
"The mechanical LSD in the GTx streetcars has no preload on the discs. That means, you cannot find out if the LSD works correctly by just jacking the car up and turning the wheels manually! Nothing will happen in that case because the diff isnt working.
The reason for having no preload on the system is because the car would be a lot less manouverable in park-in situations and would therefore lose some of its "everyday driver" characteristics.
The LSD of a Cupcar has preload on the discs and therefore reacts differently on the jack, although the hardware is very similar.
To find out if the LSD is in good working condition choose a long 3rd gear curve (or a big enough space to drive a neutral 3rd gear circle), go with partial throttle and play with the accelerator (more load/less load). The car will change its radius noticeably because of the diff working. (On overrun its 40% and on throttle only 27% lock).
On all GTx projects of the past the LSDs where all still within spec after 30.000 km of hard racetrack use. On dissassembly there was no critical wear and tear on the discs or on the ramps."
Matt (GTGears) your input is valued and appreciated especially?
06-08-2013, 09:46 AM
#99
Instructor
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ive got a motorsport DIFF with switchable ramps.
the car feels AMAZING in high speed turns, but in low speed on ramp/off ramp situations, the car pushes really really bad .
i am on my way to a cup car team right now with my mechanic to get some advice.
we may flip the ramps and see how the car feels
997 turbo on gmg springs and gmg sways set to middle setting both front and rear.
the car feels AMAZING in high speed turns, but in low speed on ramp/off ramp situations, the car pushes really really bad .
i am on my way to a cup car team right now with my mechanic to get some advice.
we may flip the ramps and see how the car feels
997 turbo on gmg springs and gmg sways set to middle setting both front and rear.
06-08-2013, 10:26 AM
#100
ive got a motorsport DIFF with switchable ramps.
the car feels AMAZING in high speed turns, but in low speed on ramp/off ramp situations, the car pushes really really bad .
i am on my way to a cup car team right now with my mechanic to get some advice.
we may flip the ramps and see how the car feels
997 turbo on gmg springs and gmg sways set to middle setting both front and rear.
the car feels AMAZING in high speed turns, but in low speed on ramp/off ramp situations, the car pushes really really bad .
i am on my way to a cup car team right now with my mechanic to get some advice.
we may flip the ramps and see how the car feels
997 turbo on gmg springs and gmg sways set to middle setting both front and rear.
my guess is that some of the following will help:
1) turn your 4wdr car into a 2wdr
2) after you have done (1) put your front camber to -2.5 and rear camber to -1.7
3) cut the cup diff's pre-load in half
4) run a 245 255 front tire
5) put your front sway to soft
6) slightly raise your rear ride height or drop the front slightly
- you may also get lucky and if the race shop has a really knowledgable setup guy that significantly altering the diff may help a lot just on it's own
- my guess is that a cup diff will not work in your car as you are finding
- your car and a cup car are just too different in setup
- that said, the very first thing I would do is contact Matt at Guard Transmission and ask for his opinion
http://www.guardtransmissionllc.com/dealers/
