CRex

Sorry for the thread resurrection.

Mike, has your opinion on the diff changed now that you've given it more street & track time? In choosing between yours and another LSD I'd value actual user experience more than anything else.

I'm outside the states currently and won't have the luxury of shipping my existing diff across the ocean for a rebuild. Will likely go for a whole diff purchase and have my local tech transplant the ring gear (and spider gear too?) onto the new diff.

FWIW my car is 70% street and 30% track and I'm leaning towards a lower preload (60lbs) and similar lockup values as yours.

mikymu

My setup will be perfect for your need. I have not notice any negative effects since I had my LSD rebuild. No noise or grind and excellent on the track as far as rear end stability on hard braking and acceleration out of a turn.

Make sure your mechanic know what they are doing. It's not a straight forward replacement and you need to shim and preload the aftermarket LSD to fit the case or it will cause $$$$$$$ damage. When I was looking for someone to install an aftermarket LSD in my RS, ALL the Porsche dealers in the SF area refuse to do it and they said they do not have the expertise. I finally located a former Porsche Motorsport mechanic that will shim and preload the after market LSD for $3K+ which includes transmission removal. That's why I chose to rebuild the existing OEM LSD and save myself the money and hassle of removing the transmission etc.

Carrera GT

Excellent post.

mikymu

Thanks

carrering

oh boy something else for me to do next winter when i can't drive the RS! thanks for the write up! I miss california winters.

CRex

Thanks this is good info. I'm cognizant of the potential disaster that awaits a poorly installed diff I'll report back as this project progresses.

NJ-GT

I missed this? Wow!

Miky this is amazing. It is seriously an easy job if you have the proper instructions.

My guess is that 50% or more of the 996 and 997 GT3, GT3 RS and GT2 have a worn out and useless LSD, and that 50% or more of the owners don't know it.

My 996 GT3 LSD was fried at just 2,000 miles with two track days only and a few autocrosses (8 laps per day autocrosses). I installed the 996 GT3 Cup unit, and problem solved.

It is great to rebuild the stock diff with new internals. I spoke with Paul Guard at large on this issue, as I was about going to do the same to my 997 GT3 RS, but sold the pumpkin.

Thanks

NVRANUF

After reading this I went out to the garage and did the "spin test".....
My wheel spun as freely as mikymu's initial video showed, and the car only has ~9800 street-only miles on it....
I wonder why this stock Porsche GT LSD wears out so easily....

again... excellent post all the way mikymu!!

GTgears

Where are you located? We've got dealers all over the world. I would be happy to give you a recommendation for an installer that will do the job correctly. I offer this to you whether or not you go with our product. I just want to see you get the work done right.

And the practical reality of it is any shop that is good enough to install an aftermarket LSD and get the ring gear set right is a shop that could also rebuild the LSD for you. I put rebuilding an LSD of a difficulty of about a 2 on a scale 5 with installing a complete differential a 4.5 or more.

my911rs

Great post!
My LSD on my '07 RS is open as well... I am going to try the warranty route before rebuilding with Guards.

RWK

I have a complete guard diff being installed in the RS aw we speak. They have proven very reliable for us, having run them for the last 2 yrs.

cfjan

Mikymu,

Excellent, thanks for the write-up!

A quick question for you: How did you get the car on the block like that? Did you have to jack up the car at the upright so you lift up the wheels while jacking? I'm trying to figure out what's the easiest / best way to do this just for standard maintenance.

Thanks!!

enthusiast

The spin test is not accurate. As stated in the article, the factory static load break away torque is very low. You can get a better estimate with the rear wheels off and using a proper range torque wrench but again the shop manual procedure to check this is with the LSD removed (bench test).

mikymu

Yeah, occasionally California winter is like an European summer.

Excellent, hope all goes well with your LSD rebuild

Any time Rad. These OEM LSD are pretty lame. They are pretty much dead after 1-2 track events

The OEM LSD come with a very low preload as indicated on my LSD (13.14 Nm or 9.6 lb-ft) and does not take much abuse before it's dead

I thought about the warrenty route too but they will just replace it with another OEM unit which will only delay proper rebuild by 1-2 track event. I heard the dealer will fight you tooth and nail about replacing the LSD.

This wood block method is pretty blue collar but works well. All you need to do is jack up each end of the car and stick one wood block at a time. Once all 4 corners have 1 wood block then you repeat the process for the second block. Lower the car the same way you stack the block - remove 1 block from each corner at a time. I love to have a lift in my garage but wife says no for now lol

This is a simple and easy way to measure the health of your LSD short of taking everything apart for a bench test. As you can see my busted LSD only had 2 lb-ft of preload left - that's 80% reduction of preload from the factory!

cfjan

Got it, thanks for the info.. one layer at a time... !!