LSD thoughts?
11-17-2015, 07:24 PM
#31
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I think the cynical answer is that the stock diff is not worth saving. Assuming no electronic systems incompatabilities nor warranty issues, getting an aftermarket LSD is not something to delay if you intend to seriously track the car.
11-17-2015, 08:28 PM
#33
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I am afraid that will be the case. The GT4 was meant to be the weekend/track toy. Not money pit #2...I already have one full time track car lol.
11-18-2015, 01:41 AM
#36
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Not surprised by this. GT3 owners have been dealing with diff's dying premature deaths for a long time now. I think my stock GT3 diff lasted all of 5 track days before it was gone. I had it rebuilt with Guard internals back then and it's still going strong. In the grand scheme of making my GT3 track worthy, the only mods ever needed were the diff rebuild and pinning the coolant lines after 4 yrs/25k total miles (maybe 4K all in).
While the diff solution doesn't appear as simple on the GT4, i think spending a few K to make the car bullet proof on track is reasonable for a 90K car. I don't want to even think about what I spent making other less expensive cars anywhere near as reliable.
If you thought you bought a car that can be tracked hard and regularly without spending a dime to prep it, I think that's a little naive.
While the diff solution doesn't appear as simple on the GT4, i think spending a few K to make the car bullet proof on track is reasonable for a 90K car. I don't want to even think about what I spent making other less expensive cars anywhere near as reliable.
If you thought you bought a car that can be tracked hard and regularly without spending a dime to prep it, I think that's a little naive.
11-18-2015, 02:08 AM
#37
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Needless to say, dropping a few $k to replace/repair a diff after a handful of track days goes beyond basic prep. I thinks that's a little naive to think otherwise
.Now don't get me wrong I am okay spending a dime(s) when needed. Luckily the GT4 doesn't need much to make a great track day "toy"
. I do however expect 90k GT P-car to be have a better diff than a 15 year old Honda lol. Sad to say the least but glad to hear we have options.
11-18-2015, 02:46 AM
#38
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In theory you could cut the lateral accelerometer out of the equation so that it kills the PSM entirely like we used to on the 987.2s BUT you have a button already on the car for doing this; it's called TC off. Turning off the ESC limits the yaw control while cutting off the TC turns off the "traction control" which is what controls the wheelspin and activates the rear ABD (automatic brake distribution.) So, run the TC off and you will get less of the ABD intrusion in the rear at corner exit. Given how much drifting i have seen in the road test videos and how much rotation i see out of the 991s and 981s on track at the limit, i don't think there is any reason whatsoever to go cutting out the PSM like we used to, just push the button.
Correct. The GT4 has the same LSD as what came on all 2011 and newer 987.2s and all Cayman Rs; it is a mechanical locking LSD from the factory with carbon lined clutch discs that will last about 10 weekends on track. Once it goes, you're toast and you're not going to get it replaced under warranty. I think Matt quoted the lockup % early but the factory Cayman GT4 LSD is a 22/27 locking mechanical diff.
Matt and I talk about this often and ponder as to why more LSDs haven't sold but I think that we can all agree that the more you guys and gals go on track with the car, the more you will burn up your stock one and the more apt you will be to buying a Guard LSD. I refuse to run anything BUT Guard transmission products in our cars for obvious reasons, not just because Matt and I like to discuss old re-runs of Miami Vice and the A-Team.
Correct. The GT4 has the same LSD as what came on all 2011 and newer 987.2s and all Cayman Rs; it is a mechanical locking LSD from the factory with carbon lined clutch discs that will last about 10 weekends on track. Once it goes, you're toast and you're not going to get it replaced under warranty. I think Matt quoted the lockup % early but the factory Cayman GT4 LSD is a 22/27 locking mechanical diff.
Matt and I talk about this often and ponder as to why more LSDs haven't sold but I think that we can all agree that the more you guys and gals go on track with the car, the more you will burn up your stock one and the more apt you will be to buying a Guard LSD. I refuse to run anything BUT Guard transmission products in our cars for obvious reasons, not just because Matt and I like to discuss old re-runs of Miami Vice and the A-Team.
TIA
Regards
Ed
11-18-2015, 04:30 AM
#39
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Thread Starter
I recall some (GT3 owners) have gotten it replaced under warranty, however, it might be categorized as a wear item.
11-18-2015, 04:50 AM
#40
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11-18-2015, 07:18 AM
#41
Could be...but that would be a bit of a stretch. While all parts on a car do wear over time a Diff/LSD is not considered a high-wear item like brake pads or a clutch which are designed to wear down as part of their function. To make things more complicated, PAG does accept the use of this car on the track. Unless it specifically mentions the LSD/Diff on the warranty book it's going to be difficult for a dealer or PAG to exclude it from warranty....specially in the US.
What could happen is that they give you the first one under warranty or goodwill but if you come a second or third time they will have a case to justify denying the warranty under abuse/track use/ misuse, ect...
Maybe someone can chime in on this from a past experience?
11-18-2015, 08:56 AM
#42
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So just to confirm... 10 track weekends (obviously abuse dependant) and the diff is pretty much toast...
I am very concerned. I assuming you have pulled apart a fair number of diffs to confirm the wear/tear you mentioned. While the fix is a new/upgraded diff. What kind of cost are we talking about and what kind of life can I expect out of one which sees 12+ events a year?
Needless to say you have struck a nerve.
I am very concerned. I assuming you have pulled apart a fair number of diffs to confirm the wear/tear you mentioned. While the fix is a new/upgraded diff. What kind of cost are we talking about and what kind of life can I expect out of one which sees 12+ events a year?
Needless to say you have struck a nerve.
It seems like after 2 years though customers come to us to buy the LSD because they're tired of their calipers going from PCNA red to "root beer" and they're feeling more and more wheel spin in slow corners. The balance of the people are saying "if we're doing a motor swap or bolting control arms and shocks on, i want an LSD too if you're going to be pulling the car apart."
Could be...but that would be a bit of a stretch. While all parts on a car do wear over time a Diff/LSD is not considered a high-wear item like brake pads or a clutch which are designed to wear down as part of their function. To make things more complicated, PAG does accept the use of this car on the track. Unless it specifically mentions the LSD/Diff on the warranty book it's going to be difficult for a dealer or PAG to exclude it from warranty....specially in the US.
What could happen is that they give you the first one under warranty or goodwill but if you come a second or third time they will have a case to justify denying the warranty under abuse/track use/ misuse, ect...
Maybe someone can chime in on this from a past experience?
What could happen is that they give you the first one under warranty or goodwill but if you come a second or third time they will have a case to justify denying the warranty under abuse/track use/ misuse, ect...
Maybe someone can chime in on this from a past experience?
I could see 1 dealership saying "that's not right, you shouldn't see this thing fail after X weekends on track, we will warranty it." I could also see another dealership saying "you have monoball toe links, control arms and an ECU flash and therefore we will not warranty your LSD because you have modified the car."
If your car is stock and you burn up the LSD, in my opinion, you should be able to get it covered under warranty. I think that essentially they look for folks to have aftermarket mods so that they don't have to put a fresh LSD in every car that comes through there and they have a way of at least weeding out some cases for warranty claim.
11-18-2015, 09:28 AM
#43
I agree...it will all come down to the dealer but if you do encounter one of the "difficult" type of dealers and you have aftermarket parts not related to the transmission maybe...and maybe...you could be bring up the Magnuson–Moss Act which states the dealer if fully responsible to prove, without a doubt, that the aftermarket part in question is directly related to the failure. Of course if you have headers and exhaust and a flash they could go the route that you are producing more power than what the LSD was designed for.....it's a PIA situation and one of the reasons you should do business with a solid, customer oriented dealer.
I used to have one of the original Honda S2000 (MY 2000), first batch out of the factory, and the OEM clutch was crap....a couple of track days and high-revs and it was gone. They would replace it under warranty but was able to negotiate using an aftermarket unit which I purchased and the dealer did the labor as a good will, even added a nice Toda Flywheel as part of the deal...of course another failure and I would had to take care of the whole thing.
I used to have one of the original Honda S2000 (MY 2000), first batch out of the factory, and the OEM clutch was crap....a couple of track days and high-revs and it was gone. They would replace it under warranty but was able to negotiate using an aftermarket unit which I purchased and the dealer did the labor as a good will, even added a nice Toda Flywheel as part of the deal...of course another failure and I would had to take care of the whole thing.
11-18-2015, 10:13 AM
#44
Rennlist Member
John, is the LSD diff visable when you bring it to a dealer?
My LSD was always in the stock housing so the dealer could not tell it was there.
Im going to need a diff regardless, put it on my list.
My LSD was always in the stock housing so the dealer could not tell it was there.
Im going to need a diff regardless, put it on my list.
11-18-2015, 12:05 PM
#45
Nordschleife Master
Hello,
I'm going to take a slightly different approach in how I look at this than has generally been expressed. It is the same position I take in the LSD Buster thread over in the 997 GT3 forum.
Porsche has put together a very nice car here. It is a fun car on track, as it should be. But, and this is a big but, it is a long way from being a racecar. DE usage has changed in recent years to the point where a lot of guys now show up and drive these cars almost, or just as hard as a racecar. This presents certain wear issues as well as reveals the limits of where the street car parts just aren't up to task on the track.
I do not hold the position that you will wear out the LSD in 5 or 10 or 20 track days. I hold the position that there are several other reasons why one who tracks their car heavily and regularly will want to consider replacing their LSD.
Porsche, when designing and equipping the car, takes the position that modern nannies can make the car both safer and feel like it is better performing. I say "feel" because the nannies make the average driver able to drive a sportscar more aggressively than they otherwise could. These cars make a punter feel like superman. And they are good enough that they do reward a truly good driver.
But the nannies come at a cost to performance and to wear and tear on the track. I jokingingly asked the price of a set of calipers because one place where the PTV is involved is braking. People who drive these cars really hard (like guys who have a set of track slicks or R compounds) will be activating the brake piece of PTV quite often on track and I have seen dozens of instances of cooked rear calipers. Not just rotor and pad wear but rotors that need replacement. It is one of many things the track is going to stress.
Ok, so you turn the system off to save the brakes. Now what happens? You've got an anemic little 22/27 LSD that doesn't have enough lock in it to stop inside tire spin on throttle. Now, you've increased your tire wear and your tire budget. And if you drive it hard enough and long enough, yes, you will eventually burn up the inside of the LSD. I've posted pictures of how hot and blue a 997 GT3 LSD gets inside in this situation. If you drive it like that long enough it will grenade the spider gears and blow the whole unit.
Warranty? Ha. You are tracking the car. If the dealership knows this or figures it out, you will be shown the door. And unlike the GT3, where Porsche sells replacement clutches and replacement LSDs, it is not a service part on a Cayman. You'll get a new gearbox, but don't expect it to be free. When the dealer can put in a $1000 clutch kit under warranty and send you on your way like with the GT3 it is one thing. When they are footing the billing on a whole gearbox? They are gonna tell you to get lost.
One other thing I will mention is the perception of wearing out the LSD that so many GT3 guys have. You get these guys who late in season one or in season two say they have started to feel rear end wiggle under braking that wasn't there before. Part of what a good LSD will do in a Porsche is settle the rear end coming in hard. These guys haven't suddenly worn out their LSD in most instances. What I believe is happening is that they have become better drivers. They have progressed their racecraft to the point where they are now threshold braking and find the limit where the wiggle exposes itself. They have become good enough drivers to exceed the capabilities of the street car part on the track and now need more to keep progressing.
I'm sure I forgot a few points and will raise some questions. I'll try to pop in a couple times today to answer if I don't get to busy at work.
Peter,
No, the dealer can't see that my LSD is inside your gearbox. The diff is totally encapsulated inside the gearbox housing and invisible.
Regards,
Matt
I'm going to take a slightly different approach in how I look at this than has generally been expressed. It is the same position I take in the LSD Buster thread over in the 997 GT3 forum.
Porsche has put together a very nice car here. It is a fun car on track, as it should be. But, and this is a big but, it is a long way from being a racecar. DE usage has changed in recent years to the point where a lot of guys now show up and drive these cars almost, or just as hard as a racecar. This presents certain wear issues as well as reveals the limits of where the street car parts just aren't up to task on the track.
I do not hold the position that you will wear out the LSD in 5 or 10 or 20 track days. I hold the position that there are several other reasons why one who tracks their car heavily and regularly will want to consider replacing their LSD.
Porsche, when designing and equipping the car, takes the position that modern nannies can make the car both safer and feel like it is better performing. I say "feel" because the nannies make the average driver able to drive a sportscar more aggressively than they otherwise could. These cars make a punter feel like superman. And they are good enough that they do reward a truly good driver.
But the nannies come at a cost to performance and to wear and tear on the track. I jokingingly asked the price of a set of calipers because one place where the PTV is involved is braking. People who drive these cars really hard (like guys who have a set of track slicks or R compounds) will be activating the brake piece of PTV quite often on track and I have seen dozens of instances of cooked rear calipers. Not just rotor and pad wear but rotors that need replacement. It is one of many things the track is going to stress.
Ok, so you turn the system off to save the brakes. Now what happens? You've got an anemic little 22/27 LSD that doesn't have enough lock in it to stop inside tire spin on throttle. Now, you've increased your tire wear and your tire budget. And if you drive it hard enough and long enough, yes, you will eventually burn up the inside of the LSD. I've posted pictures of how hot and blue a 997 GT3 LSD gets inside in this situation. If you drive it like that long enough it will grenade the spider gears and blow the whole unit.
Warranty? Ha. You are tracking the car. If the dealership knows this or figures it out, you will be shown the door. And unlike the GT3, where Porsche sells replacement clutches and replacement LSDs, it is not a service part on a Cayman. You'll get a new gearbox, but don't expect it to be free. When the dealer can put in a $1000 clutch kit under warranty and send you on your way like with the GT3 it is one thing. When they are footing the billing on a whole gearbox? They are gonna tell you to get lost.
One other thing I will mention is the perception of wearing out the LSD that so many GT3 guys have. You get these guys who late in season one or in season two say they have started to feel rear end wiggle under braking that wasn't there before. Part of what a good LSD will do in a Porsche is settle the rear end coming in hard. These guys haven't suddenly worn out their LSD in most instances. What I believe is happening is that they have become better drivers. They have progressed their racecraft to the point where they are now threshold braking and find the limit where the wiggle exposes itself. They have become good enough drivers to exceed the capabilities of the street car part on the track and now need more to keep progressing.
I'm sure I forgot a few points and will raise some questions. I'll try to pop in a couple times today to answer if I don't get to busy at work.
Peter,
No, the dealer can't see that my LSD is inside your gearbox. The diff is totally encapsulated inside the gearbox housing and invisible.
Regards,
Matt