Add limited slip to base 991.2?
#46
Hey guys, after beating up my PS4S on a three-day weekend at Thunderhill, I got more camber (-2.7º front and -2.2º rear). The inside rear wheel on PS4S has gotten more skittish under hard throttle, so I'm putting on Cup 2s. I'm also thinking it's time to install an LSD. It's an interesting idea to use the rear axle gear to lower gear ratios. Has anyone done that with an LSD install on a 991.2?
Last edited by tosha; 10-21-2020 at 12:24 AM.
#47
Hey guys, after beating up my PS4S on a three-day weekend at Thunderhill, I got more camber (-2.7º front and -2.2º rear). The inside rear wheel on PS4S has gotten more skittish under hard throttle, so I'm putting on Cup 2s. I'm also thinking it's time to install an LSD. It's an interesting idea to use the rear axle gear to lower gear ratios. Has anyone done that with an LSD install on a 991.2?
#48
Not really... probably would have done the same to a T if I had gotten one. My base now has Tractive dampers, GT3-ish spring rates, my own DSC maps that make the suspension fun and comfortable in San Francisco, GT3-style sway bars, GT3 control arms for more camber, APR tune, TiAL turbo inlets, Girodisc brake rotors... This week I'm adding the LW carbon buckets and in a few weeks the GMG WEC roll bar will arrive (in an approximation of the exterior color, graphite blue). Probably would have taken me a lot longer to do these mods if I had gotten a T first. The suspension, tune, and brakes were urgently needed on a base, and so I went down the slippery slope
Last edited by tosha; 10-21-2020 at 06:25 PM.
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LWG (10-22-2020)
#50
I’m planning to do it in the next couple of weeks. My biggest concern is that TC/PSM is not calibrated for it, but I also suspect that’s unlikely because the T in MT has a mechanical diff and T with PDK doesn’t have a diff. I suspect it would be too much trouble for Porsche to parameterize this in the TC and PSM software, but who knows for sure.
#51
A shop told me that Porsche doesn’t sell the pinion gear you’d need so there’s no way to do this. Their alternative was to get an S transmission, which is pretty crazy. I agree that it would have been more prudent to get a GTS, but it’s a lesson learned...
#52
I’m planning to do it in the next couple of weeks. My biggest concern is that TC/PSM is not calibrated for it, but I also suspect that’s unlikely because the T in MT has a mechanical diff and T with PDK doesn’t have a diff. I suspect it would be too much trouble for Porsche to parameterize this in the TC and PSM software, but who knows for sure.
I would think APR would know if there's anything in the software. I doubt it since it's a mechanical diff. If it were an e-diff, it'd be a different story I'm sure.
If you could get ahold of a T manual transmission and swap it, that would be another option.
#54
#55
All the 7MT transmissions (at least housing) are the same and therefore there is a port/ cover to add LSD to a base transmission.
TC, torque vectoring and PSM use sensors elsewhere and not linked with transmission nor LSD for manual transmission so you should be ok without calibration.
guards is probably best LSD for the 991.
let us know how much labor is required and if subframe or transmission removal is required. The 7MT housing is big and not much room. Very curious.
TC, torque vectoring and PSM use sensors elsewhere and not linked with transmission nor LSD for manual transmission so you should be ok without calibration.
guards is probably best LSD for the 991.
let us know how much labor is required and if subframe or transmission removal is required. The 7MT housing is big and not much room. Very curious.
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rugu6869 (03-16-2021)
#56
What worries me is whether TC assumes that the wheels are independent and attempts to counteract specific fishtailing direction with one side at a time, and adding an LSD will affect that.
#57
Can't you just turn TC off? I've slid my car sideways a few times with the open diff without a problem.
#58
#59