Limited slip diff 987.2

[Slurms]

Hey All, 

Anyone retro fitted an LSD to a gen 2 987? I've heard there is a rare factory option for the LSD (which my car doesn't have) and as i'm doing a few more track days this year i'm thinking about getting one to improve the cars performance. 

[½cwt]

Quaife

[Bike Loon]

Rare factory option you say

[½cwt]

Factory build option 220 - Locking differential 40%

[edc]

There's quite a few different options but very rarely done here. Wavetrac, Gripper, Kaaz, Guard are a few others from memory. 

[Menoporsche]

33 minutes ago, Bike Loon said:

Rare factory option you say

Seriously?!!

You have more jam than an entire supermarket aisle…

[½cwt]

4 minutes ago, Menoporsche said:

Seriously?!!

You have more jam than an entire supermarket aisle…

Why do you think I registered my interest as soon (may be before) he got it!!!

[edc]

I've no experience of this but I've read the OE Porsche diffs are as good as dead after a good few miles on them. 

[½cwt]

3 hours ago, edc said:

I've no experience of this but I've read the OE Porsche diffs are as good as dead after a good few miles on them. 

And there are no service parts listed in the parts cat...  only whole gearboxes.

[Slurms]

5 hours ago, ½cwt said:

Quaife

I’ve heard good things about them from some of my friends who’ve tracked BMWs. Just hoping for a bit of real world feedback before I drop a load of cash on it. 
 

doing the front strut brace mod next week I hope.  My car appears to be one of the ones that has the turret mounts so that’s a cheaper upgrade. 

[edc]

1 minute ago, Slurms said:

I’ve heard good things about them from some of my friends who’ve tracked BMWs. Just hoping for a bit of real world feedback before I drop a load of cash on it. 
 

doing the front strut brace mod next week I hope.  My car appears to be one of the ones that has the turret mounts so that’s a cheaper upgrade. 

@map is one of the very few here who have done it. 

[map]

36 minutes ago, Slurms said:

I’ve heard good things about them from some of my friends who’ve tracked BMWs. Just hoping for a bit of real world feedback before I drop a load of cash on it. 

34 minutes ago, edc said:

@map is one of the very few here who have done it. 

Looked at both locking and torque biasing (TBD) differentials for my 986. Settled on the TBD variant following advice from Parr who looked after my car at the time.

Have done plenty of road miles (70k+) and lots of trackdays with it.

Am completely sold on the TBD for a daily driven track focused use case.

TBD’s are more progressive than Locking Diffs, they are a silent in operation and totally maintenance free.

The benefit on track compared to an open diff is very noticeable with higher corner speeds from entry right through to exit.

On road you do have the understeer you get with all locking diffs. In slippery conditions its very progressive nature find traction and stability that the open diff just won’t give you.

A locking diff is ultimately “better” on track - locks under deceleration (esp useful on rear engined cars) and retains the lock when one driven wheel is off the ground.

The TBD was used in the most bonkers FWD Hot Focus RS thingy.

A word of “warning” - you will sense marginally lower grip levels compared to your open diff - BUT you have far, far more control and I can assure you that a four wheel drift out of Paddock Hill bend under power is an amazing sensation. 

Edited April 24, 2023 by map

[Lennym1984]

I have a geared differential (which I think is the same as a TBD) on my race car (not a Porsche) and it's great. As Map says there are cons of this type of diff but even in race conditions (as in, running kerbs!) I haven't experienced anything untoward.

In comparison with the plated diff my friend has, the TBD is much quieter (silent) and feels like a lot less hassle (he is always having to mess with it). 

 

[Ninesomething]

There's a huge thread on I think rennlist from when the Quaife was first available for Caymans/Boxsters and everyone who got one was pretty chuffed. Those who tracked their cars reckoned they left PSM on but the light just never came on even during hard track use which says something. No-one thought that understeer was an issue which would be the thing that would put me off.

[phazed]

An interesting read.

My experience from tracking my Boxster, is that with the limited power of even a 3.4, an LSD seems unnecessary.

I do quite a few Track Days but mainly in my front wheel drive car. This was always spinning the front wheel on corners, running 250 BHP at 1.2 tonnes. I then fitted a Wavetrac LSD. The difference is very noticeable. It pretty much completely stops inner wheel spin which is so noticeable and prevalent on front wheel drive cars. I switch off the traction and then just run the car flat out.

I’ve done quite a few Track Days in the Boxster although nowhere near as much as on my front wheel drive car. All Track Days with the Boxster have been in the dry and apart from the odd minor tail slide when exiting second-gear corners I have not noticed any downside of an open differential with only running 300 brake horsepower in these cars.  I am sure that if you could add a further 100 BHP, then an LSD would be desirable. 
My point is, I would certainly track the car with the open differential, unless you are very serious and you really want to spend a lot of money.

By the way, you do not notice any grabbing, or any downside with the Wavetrac.

It feels like standard now that I’m used to it, but when I first fitted it and did a bit of empty road testing, the pull from the front wheels around corners just seemed incredible!

A big thumbs up for Wavetrac if that’s the way you want to go.

[Ninesomething]

17 hours ago, phazed said:

An interesting read.

My experience from tracking my Boxster, is that with the limited power of even a 3.4, an LSD seems unnecessary.

I do quite a few Track Days but mainly in my front wheel drive car. This was always spinning the front wheel on corners, running 250 BHP at 1.2 tonnes. I then fitted a Wavetrac LSD. The difference is very noticeable. It pretty much completely stops inner wheel spin which is so noticeable and prevalent on front wheel drive cars. I switch off the traction and then just run the car flat out.

I’ve done quite a few Track Days in the Boxster although nowhere near as much as on my front wheel drive car. All Track Days with the Boxster have been in the dry and apart from the odd minor tail slide when exiting second-gear corners I have not noticed any downside of an open differential with only running 300 brake horsepower in these cars.  I am sure that if you could add a further 100 BHP, then an LSD would be desirable. 
My point is, I would certainly track the car with the open differential, unless you are very serious and you really want to spend a lot of money.

By the way, you do not notice any grabbing, or any downside with the Wavetrac.

It feels like standard now that I’m used to it, but when I first fitted it and did a bit of empty road testing, the pull from the front wheels around corners just seemed incredible!

A big thumbs up for Wavetrac if that’s the way you want to go.

Not wanting to sound like a smartarse (well - no more than usual...) but driving my 2.7 on twisty roads I could get fairly interesting slides going on until PSM poked it's nose in and in the S I get the PSM light flashing even more although I have PASM now which lets you hang it further out before it intervenes. I considered an LSD just because I wondered what the car could really do with the wheelspin reined in. 

That said since I got the DSC wheelspin is greatly reduced because of the suspension working properly. I'm still occasionally curious though. If one came up used for cheap I might just try it.

[edc]

1 hour ago, JonSta said:

Not wanting to sound like a smartarse (well - no more than usual...) but driving my 2.7 on twisty roads I could get fairly interesting slides going on until PSM poked it's nose in and in the S I get the PSM light flashing even more although I have PASM now which lets you hang it further out before it intervenes. I considered an LSD just because I wondered what the car could really do with the wheelspin reined in. 

That said since I got the DSC wheelspin is greatly reduced because of the suspension working properly. I'm still occasionally curious though. If one came up used for cheap I might just try it.

I think you'll be waiting a long time! The cost is in the fitting, the part itself is not that much comparatively. 

[phazed]

I am still of the opinion that an LSD or TBD is pointless for the road. In fact due to cameras etc I pretty much stick to speed limits, (unheard of in the past...).

Fun on track is addictive and anyone considering an LSD should try their car first before they splash out.

I didn't know when I fitted it that my Wavetrac in my Skoda is torque biasing...

 

One of my vids with a standard 3.4 apart from tyres and pads.