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Retro fit an LSD


andygo

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Has anyone got any experience of this?

 

Is it best to buy a gearbox with one in or buy a diff and fit it.

 

There doesn't seem to be much info on how they work. I assume its not a plate type diff and probably a Thorsen gear type. How 'tight' are they?

 

For example in my previous life as a rally driver, I had diffs that if you launched the car with one wheel on,say, a grass verge and the other driven wheel on the tarmac, 99% of the drive would go to the tarmac,(leaving rubber) where a free diff would merely spin the tyre on the grass with little forward motion.

 

Where does a Porsche Diff sit in that performance envelope?

 

Are they worth fitting as I am looking to hillclimb and sprint my 997.2 S?

 

Costs?

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I can't speak for the factory fit LSD but most of the online opinion on it is less than complimentary.

 

https://www.planet-9.com/threads/the-cayman-factory-lsd-dissected.44005/

 

I had a Wavetrac TBD fitted to my car and I am pleased with it, not that the car ever really struggled for traction with it's open diff but it does help on track, the other byproduct seems to be some of the slack removed from the drivetrain, throttle response feels better too.

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Thats a really illuminating article re the standard chocolate diffs.

 

Thanks for the 987s track car linky as well Rich!

 

 

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1 hour ago, Andyoz said:

Has anyone found that their LSD's introduced some understeer?


yes, when I changed from a Cayman S to an R, I thought it was very noticeable and irritated the hell out of me.  You can dial it out though, the main reason a lot of CR owners add spacers to the front and max the camber to liven the rear end up again.  
 

If you’re adding an aftermarket LSD though it will depend on which one you go for and how strong they are as to how much it will affect understeer.  

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The Wavetrac diff is a torque biasing diff and won't give any understeer issues as under deceleration they are not really locking. Certainly after fitting mine there was no difference in this respect. The factory diff being plated clutch type has a degree of lock hence car wanting to go straight on and inducing some understeer. 

 

More on the difference here: 

 

https://www.planet-9.com/threads/lsd-vs-tbd.15040/

 

The only other difference on the Wavetrac is it has an ability to lock when one wheel is off the ground unlike other TBD, not sure how relevant this really is on a road car though!

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18 hours ago, Andyoz said:

Has anyone found that their LSD's introduced some understeer?

 I found quite the opposite with the Quaife LSD. For hairpins like (Druids at Brands) and the 3 big ones at Snetterton, I find the car rotates so much better than standard diff and let's you put the power down earlier. But, a change in geometry may have also contributed to this. 

 

Can't comment on road driving understeer though, I don't drive fast on the road. 

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On 21/11/2020 at 00:58, Beanoir™ said:


yes, when I changed from a Cayman S to an R, I thought it was very noticeable and irritated the hell out of me.  You can dial it out though, the main reason a lot of CR owners add spacers to the front and max the camber to liven the rear end up again.  
 

If you’re adding an aftermarket LSD though it will depend on which one you go for and how strong they are as to how much it will affect understeer.  

 

Thanks for confirming, I've had a few telling me I'm imagining it but I do know how to drive.

Edited by Andyoz
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9 hours ago, Andyoz said:

 

Thanks for confirming, I've had a few telling me I'm imagining it but I do know how to drive.


No worries.  It does all depend on the LSD you have though, my experience extends only to the factory item. 
 

I’m actually toying with the idea of fitting an aftermarket item to my 996 so I’ll be interested in the outcome of this thread 

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