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    • Guard Transmission claims to have a Porsche 991.2 LSD (Limited Slip Differential) upgrade

      If you opted for the base Carrera or even if you have a 2017 Carrera S, GTS, or T you might want to look into an LSD (limited slip differential) upgrade. The base cars of course do not have a limited slip from the factory meaning this is a major area that can be improved.


      You would think the high price of a 911 would guarantee you an LSD but Porsche sure knows how to squeeze those dollars out.

      Why is an LSD important? Here is a good summary:

      The vast majority of rear-wheel drive cars have an open differential. This means that the rear wheels can spin independently of each other. The easiest way to tell if you have an open differential is to jack up the car and spin one of the rear tires. If the other wheel spins in the opposite direction, you have an open differential. If it spins in the same direction, you have a limited slip differential, or LSD.

      An open differential always transfers an equal amount of power to both wheels. But if one wheel requires less power to turn than the other wheel, such as when one wheel is on dry pavement and the other on a muddy shoulder, it will take less power to turn the wheel in the mud than to turn the wheel on the pavement. The spinning wheel is getting the same amount of torque as the stationary one, but itís getting the majority of the engineís power because that wheel is easier to spin.

      The alternative is a limited slip differential. The LSD senses when one wheel is losing traction and, through a variety of methods, connects the two wheels together. It wonít allow one wheel to spin significantly faster than the other; limiting the slippage between them. This allows the engine to move the car forward, even if one wheel has less traction than the other.
      Porsche's solution for the Carrera is to brake the spinning wheel. Not exactly ideal although it works.

      For those who want a proper LSD Guard Transmission says they have one:

      Quote Originally Posted by Guard Transmission
      Thank you for your interest in our products. Yes, we have an LSD for your car. It's based on the PDK, and as such uses the same differential. Price is $3095 and it is in stock.

      Regards,

      Matt Monson
      Guard Transmission LLC
      970-669-7144
      Oddly the Guard Transmission website does not list the 991.2 under applications. There website also has broken links and their social media page has not been updated since 2013 so maybe they just aren't web people although it does not look professional.

      Either way, this is the only solution we know of for now until other options hit the market.

      This article was originally published in forum thread: Guard Transmission claims to have a Porsche 991.2 LSD (Limited Slip Differential) upgrade started by Sticky View original post
      Comments 9 Comments
      1. 93siro's Avatar
        93siro -
        Is the OEM LSD an E-Diff or something? If it’s purely mechanical and same ratio, would it be better to get a CS rear end swapped in?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 93siro Click here to enlarge
        Is the OEM LSD an E-Diff or something? If it’s purely mechanical and same ratio, would it be better to get a CS rear end swapped in?
        Good question. I'm trying to get clarification but I think it is mechanical and the same ratio.
      1. MT15's Avatar
        MT15 -
        T, S, and GTS MT cars have a mechanical lsd and brake actuated torque vectoring. Package ="ptv". S and GTS with Pdk get an electronic variable lsd with brake actuated torque vectoring. Package = ptv +. Above are standard equipment for these models. No lsd for T with pdk. C4 you can pay for ptv or ptv+ as an option but not c2.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by MT15 Click here to enlarge
        with Pdk get an electronic variable lsd with brake actuated torque vectoring.
        Ok so for a C2 there is nothing wrong with adding this LSD?
      1. 93siro's Avatar
        93siro -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Ok so for a C2 there is nothing wrong with adding this LSD?
        If C2 has torque vectoring by brake or even the brake based LSD like the McLaren, there is chance that this LSD will mess that up. If i were i would for someone else to be the sucker who will test it first.
      1. Xiao's Avatar
        Xiao -
        I‘m sure C2 has an open diff and also applies traction control that applies brake to the inner rear wheel going around corners, S and above PDK cars have computer controlled variable diff, some actual piece instead of an open diff + abs program. I remember there was a Japanese transaxcel brand did PDK mechanical LSDs for older models including 991.1, they are worm gear based but also optional for torque bias ratio by changing friction material. I doubt if there should be any different between 991.1 and 991.2 pdk box.

        As of interference, the abs based e-diff on C2 maybe, the decision is based on feedback from speed, tire spin difference, level of body corners, G, steering angle, throttle angle altotether, a mechanical lsd will do only good. For example if most of your trips have more right corner you won't end up wearing out your right brake pads when left pads still new.
      1. flsupraguy's Avatar
        flsupraguy -
        I thought the carrera4 came with lsd?
      1. MT15's Avatar
        MT15 -
        Ptv or ptv+ are options for the c4, not standard equipment.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Xiao Click here to enlarge
        I‘m sure C2 has an open diff and also applies traction control that applies brake to the inner rear wheel going around corners, S and above PDK cars have computer controlled variable diff, some actual piece instead of an open diff + abs program. I remember there was a Japanese transaxcel brand did PDK mechanical LSDs for older models including 991.1, they are worm gear based but also optional for torque bias ratio by changing friction material. I doubt if there should be any different between 991.1 and 991.2 pdk box.

        As of interference, the abs based e-diff on C2 maybe, the decision is based on feedback from speed, tire spin difference, level of body corners, G, steering angle, throttle angle altotether, a mechanical lsd will do only good. For example if most of your trips have more right corner you won't end up wearing out your right brake pads when left pads still new.
        Good explanation so who is going to try this LSD out for the base cars?