997 LSD (Limited Slip Differentials) Explained
Every day is a school day, and in doing some research for this blog who knew that Limited Slip Differential (LSD) actually was the brainchild of none other than Ferdinand Porsche who commissioned ZF to engineer one for an Auto Union race car?! The LSD came about as the high-powered Auto Union’s would spin up their inside wheel at 100mph, pushing Ferdinand to produce a solution to maintain traction on these leviathans.
The basic premise of an LSD is that it limits the maximum difference in rotational speeds, between the drive shafts and then ‘locks’ to ensure they spin at the same rate. This gradual ‘locking’ allows more predictable handling up to and at the limit. Power can then be distributed evenly between the driven wheels under maximum acceleration when the diff is fully locked. A standard ‘open’ diff will allow the power to be sent up to 100% through one wheel, causing a lack of traction and unpredictable handling on or over the limit of adhesion. Still with me? We shall continue…
There are plenty of types of LSD that have been designed over the years, including the modern range of incredibly powerful Hypercars that run with super complex e-diffs. Porsche have used the traditional mechanical LSD’s as standard in their Motorsport products since the 1970s and offered it as a cost option on standard cars throughout. Weirdly an option that wasn’t often ticked. The 996 and 997 eras of Porsches 911 production had plenty of manual cars produced but sadly many without LSD’s.
We have been fitting upgraded mechanical LSD’s to 996 models for quite a while, and during that time we undertook a lot of research and development on the 997 range. We found that there was no 997 mechanical LSD aftermarket offering. So, as with many technical aspects of the 911, we decided to work on our own solution! We worked with an engineering specialist to produce an LSD that has adjustable ramp angles and clamping pressures, allowing our engineers to tailor the behaviour of the diff according to the owners driving style. The LSD’s are made in the UK to our specification with lifetime guarantees (excluding the consumable parts), the diffs are set up and installed by our in-house transmission engineer who has over 20 years of experience in setting up Porsche transmission. Needless to say, if you own a 997 and now understand the benefits of having an LSD, we can help.
We have LSD’s available for all manual transmission 996 and 997 models from 1999 through until 2012. Whilst Porsche GT products run a different design of mechanical LSD, these GT Porsches can also be converted to our LSD.
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Please call our technical director Ollie Preston on +44 (0)1296 663 824 or send us an enquiry online.