TTurbine

I just did the classic LSD test on my GT2 with one wheel jacked up and the other on the ground and there was little or no resistance turning the wheel

I looked around the forum and i guess the answer is installing a Gaurds LSD, now I need advice on what locking ratios should i choose , i track my car 12 times a year.. and it has a RS tuning 600hp kit... I need something that wont affect the car in a negative way , since i do alot of VMax runs and commuting also

I know nothing about LSDs Shall i just do a lsd rebuild ? or should i get a brand new gaurds GT2 LSD ? will a 40/60 locking ratio do good? I think the stock is 30/70?

Also in our region there is no Porsche race car expertise so i want something that will be a simple bolt on job without any hassle..

Please advice me

rodjac

It also only took three track days to toast the LSD on my 997 GT2. I installed the Guards 40/60 LSD and have been very happy. I now have a lot of track days on it and it is as good as new whenever I test it. I think the 40/60 would best for you needs, but you should talk to Guard directly and get their input. I think any shop with a little Porsche experience should be able to do the job. Do a search, there is a detailed post on how to do the install.

Z06

You can install upgraded clutch packs...call BMC&G, Brian Copans. He does the North America Porsche Motorsports transmissions.

I have them but have not needed them yet.... maybe 10 track days also with the 600 RS kit.

Crazy Canuck

I should check mine.

996FLT6

A guard 50/80 is pretty civil on the street but more geared towards track. 80/80 is pretty civil as well since I go to/fro to the track but scary in the rain ESP standing water- it'll want to lock up as soon as it senses slipping. For your purposes 40/60 would do very well. Mike

85Gold

I went with the OSgiken LSD on the 996GT2 and have been very pleased with the performance.

Peter

mikymu

Yeah, I felt the same way when I found out the sad state of my lousy OEM LSD. I agree that you need at least 50/80 ramp set up and high break away torque since GT2 is more powerful than GT3. Matt at GT gear has seen 996 Cup car with preload of 126 ft-lbs and 140 ft-lbs on some of his turbo customers because they don't like to see any wheel spin under hard acceleration. You can certainly discuss your specific need and spec with Matt via e-mail: gtgears@yahoo.com

The cheapest and easiest way to fix your LSD is to use the OEM unit and rebuild the inner. You will need to have the transmission removed to properly shim and preload LSD if you go with after market route

NJ-GT

my 996 GT3 LSD had a 95 ft/lb preload in the LSD (2003 GT3 Cup LSD). It was a 40/60 great for street, autoX, rain, shine, track, etc.

TTurbine

The only concern with the 50/80 setup is that it might cause understeer and agressive locking under hard braking and acceleration compared to the 40/60 ? correct me if im wrong?

mikymu

I did not have any above mentioned problems with my 50/80 ramps and it's not that much different compare with 40/60. Best to e-mail Matt at GT gears for exact answer

TTurbine

Just emailed Matt , Thanks for the help

Will keep you guys updated

Moe

mikymu

Sounds great Moe. Hope it will be a simple fix

Mike

10 GT3

First, the proper check is to jack up both sides and spin 1 wheel forward with the transmission in neutral. For a clutch or cone type diff, the other wheel should spin the same direction. The stock diff doesn't have a high torque ratio, only transferring 28% on acceleration and 40% on deceleration. Based on the test you tried it does not mean the diff is toast.

GTgears

This!

TTurbine,
Does your car spin an inside wheel on corner exit? Does your tail wag when you brake hard from 100mph+ to try and get speed down before entering a slow corner? These are the on track things you will generally experience if you diff. is shot.

The old spin test is pretty much out the window on the new generation of street differentials. Porsche has gone to low, or in the case of the Cayman, a no preload design. If you want to aggressively by hand spin a wheel using the old "spin test" methodology you might be able to feel some resistance if you can shock load the thing hard enough by hand to get it to start to lock. But it's still not really going to tell you much.

Here's the bottom line, as is being laid out in the FAQ thread that was posted recently: The crappy brass friction discs they are using don't have a very high coefficient of friction. They don't lock very well or very hard even when they are brand new. Preload or no reload isn't really a question given the use of those discs. Some guys are putting more preload into the diffs and getting them to "work" longer but that still doesn't change the ramp angles.

That's issue number 2. As mentioned above, Porsche made the new locking percentages very low at 28/40. This is compared to the 40/60 that was on the 996 GT3. But even in the 996, the GT2 got the less aggressive ramps. If you want more lock out of your diff. you're going to want to change the ramps. There's really no way around that.

If they haven't "worn out" already, the brass discs in your car will "wear out" soon. I put those in quotes because when they come out they show very little wear. That's because they don't bite hard enough. So, even though they come out looking brand new, they aren't doing their job. You can keep your stock ramps if you want a more forgiving car, or you can change them to something with more bite. Regardless, I encourage you to get rid of the stock brass discs and definitely install a friction disc with more bite.

Regards,

Matt Monson

roberga

for me this was more disappointing than the sun roof. After putting the guard 40/60 diff in my 997 GT3 I was happy with the change. TC never on and with the LWFW and the exhaust it is a better car for me. THe good from the 996 and the better in the 997.