LSD buster
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I'm REALLY conservative. I change my personal cars (WRX and '86 Carrera) every 5-6 track days. There's probably no harm in doing more events than that. For me that equates to once a year. If you're doing 12 track days a year, 1 or 2 changes a year is fine.
Former Vendor
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Part of that is likely the stock LSD. On the 997s we're seeing those diffs get smoking hot. I've had a couple through here that had this flakey coking of oil on the outside of the housing. A number of shops have been relating the same to me on what they are seeing on the customer cars. It's the friction and heat generated by the friction discs inside the LSD when they spin and don't lock the way they are supposed to. I would expect gearbox temps to go down with our internals in the LSD. You can probably get away with changing the gearbox on twice the interval you use for the engine oil.
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Yeah. I've had shops calling me trying to figure out why cars with 3000-5000 miles on them are spitting out gearbox oil that's black as night. It took a little time before we put two and two together, but I think that's the answer.
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Sorry, I guess I missed these questions the first time around. I often browse from my phone and sometimes if it kicks me to a new page, I never go back and look at the previous page, missing a post or two.
Anyway...
1. Gear driven torque biasing differentials do NOT offer lock up under braking. They are better than an open differential, but they are still inferior to a true clutch type LSD. While Audi loves to put torsens in their cars, the only vehicle Porsche has ever offered one on is the 968. I don't see it happening again in the future.
3. I think we covered this earlier in the thread but cars and their chassis have gotten so good on sports cars that they can do that. 90% of the population won't know the difference and the car is so good with all of it's electronic differentials and stability controls and gizmos that it lets people feel like superman when they are really just Jimmy Olsen. For someone who drives the car at the limit on the track and has some skills they will know the difference. But most people won't, and the limit and ragged edge is getting so far out there on these cars that the best performance doesn't seem to matter so much as that they deliver a car with really good performance. I blame Top Gear and magazine editors who don't really know how to drive a car.
Anyway...
1. Gear driven torque biasing differentials do NOT offer lock up under braking. They are better than an open differential, but they are still inferior to a true clutch type LSD. While Audi loves to put torsens in their cars, the only vehicle Porsche has ever offered one on is the 968. I don't see it happening again in the future.
3. I think we covered this earlier in the thread but cars and their chassis have gotten so good on sports cars that they can do that. 90% of the population won't know the difference and the car is so good with all of it's electronic differentials and stability controls and gizmos that it lets people feel like superman when they are really just Jimmy Olsen. For someone who drives the car at the limit on the track and has some skills they will know the difference. But most people won't, and the limit and ragged edge is getting so far out there on these cars that the best performance doesn't seem to matter so much as that they deliver a car with really good performance. I blame Top Gear and magazine editors who don't really know how to drive a car.
Regarding an open diff, in daily driving situations where the surface is uneven (driveway to street) or uneven adhesion, while you may not slip, the rate of acceleration offered by the wheel that isn't slipping does not increase. That can be very annoying.
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Regarding item #1, the owner of Virtuoso Performance, a well-known historic race car repair and prep shop explained to me that an open differential has better feel under braking for that very reason - that it's not locked. Comments on this?
Regarding an open diff, in daily driving situations where the surface is uneven (driveway to street) or uneven adhesion, while you may not slip, the rate of acceleration offered by the wheel that isn't slipping does not increase. That can be very annoying.
Regarding an open diff, in daily driving situations where the surface is uneven (driveway to street) or uneven adhesion, while you may not slip, the rate of acceleration offered by the wheel that isn't slipping does not increase. That can be very annoying.
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I don't see a single Porsche or 911 on the list of cars that Virtuoso has set up or prepped for racing. Take that FWIW. Regardless, I really have no interest in debating the effectiveness of an LSD. If they have convinced you that you don't need a working LSD in your car, don't spend the money on one. It's really that simple.
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Right. But they build and prep vintage open wheel racecars that are largely midengine. How does that relate to a 911 at all? It doesn't. It's like asking a Corvette builder what spring rates you should run on your 911 racecar. They may be an expert in their field, but it's not relevant to this application at all.
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I just switched to a 997 GT3 - I tried it at track 6 days and braking was better in my 997S. So had shop send diff to Guard this week to rebuild the stock diff to a 50/80, looking forward to trying it out next week.
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Was that your diff. I did for Dan Jacobs the other day? Good deal. Let me know how it works for you.
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Total BS with regards to a track driven 911, unless by "better feel" he means the back end wagging all over the place under heavy braking or spinning the inside wheel out of corners...
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After I track the car some strange noise comes from the rear,it only appears when the car ,transmission is hot.
I am starting to think it is the diff the car has only 1k.
The strange thing is that the noise has returned at the end of the last 2 trk days and in the mournings in normal street driving i don't hear anything.
I am starting to think it is the diff the car has only 1k.
The strange thing is that the noise has returned at the end of the last 2 trk days and in the mournings in normal street driving i don't hear anything.
Last edited by luiscarlos; Dec 13, 2010 at 07:27 PM.
Former Vendor
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Hello 6speeders,
I was just doing some year end cleaning and organizing and came across these:
It made me want to just stop for a minute and thank everyone how has sent us their LSDs for service, and especially Mike for starting this thread, which is both a great service to the Porsche community, and as you can see has been good for my business. This is only about 6 months worth since I did a clean up over the Summer. But it gives you an idea of how many people have upgraded their LSD, largely as a result of this thread.
So, thank you to all of you and have a safe and happy New Year. Enjoy these cars, and remember to keep it on the track.
Regards,
Matt
I was just doing some year end cleaning and organizing and came across these:
It made me want to just stop for a minute and thank everyone how has sent us their LSDs for service, and especially Mike for starting this thread, which is both a great service to the Porsche community, and as you can see has been good for my business. This is only about 6 months worth since I did a clean up over the Summer. But it gives you an idea of how many people have upgraded their LSD, largely as a result of this thread.
So, thank you to all of you and have a safe and happy New Year. Enjoy these cars, and remember to keep it on the track.
Regards,
Matt