map Posted February 16, 2023 Report Share Posted February 16, 2023 1 hour ago, daz05 said: The X73 rear ARB allows you to rotate the car under throttle. What is the physics/engineering behind this? How is the X73 ARB integrated with the car’s stability management electronics? Don’t have any e-stability on my aged 986 but I do have a locking diff and an adjustable ARB on the rear axle - am always keen to learn about chassis behaviour which is why I ask the question. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
ATM Posted February 16, 2023 Report Share Posted February 16, 2023 I recently fitted some Conti Premium Contact 6 and I think they are really good. Not an out and out performance tyre. I am not sure if available in the big 20 inch and 19 sizes for the 981. I know they are available in 19 inch sizes for the 987. Quote Link to comment Share on other sites More sharing options...
daz05 Posted February 16, 2023 Report Share Posted February 16, 2023 49 minutes ago, map said: What is the physics/engineering behind this? How is the X73 ARB integrated with the car’s stability management electronics? Don’t have any e-stability on my aged 986 but I do have a locking diff and an adjustable ARB on the rear axle - am always keen to learn about chassis behaviour which is why I ask the question. Thanks in advance. It's a slightly thicker and solid bar Vs the hollow one as fitted originally. Stiffening the rear relative to the front reduces understeer. Porsche has done the same with some models of the 718, using the stiffer x73 bar at the rear. They also added an additional bracing back there. The stability management software is not linked to fitment of the x73 package. There is adjustment in your geo to tweak to suit the revised set up. Quote Link to comment Share on other sites More sharing options...
ATM Posted February 16, 2023 Report Share Posted February 16, 2023 14 minutes ago, daz05 said: It's a slightly thicker and solid bar Vs the hollow one as fitted originally. Stiffening the rear relative to the front reduces understeer. Porsche has done the same with some models of the 718, using the stiffer x73 bar at the rear. They also added an additional bracing back there. The stability management software is not linked to fitment of the x73 package. There is adjustment in your geo to tweak to suit the revised set up. Are you sure that Porsche dont tweak the car maps for the full X73 setup? I know a lot of cars now apply brakes to one rear wheel to limit slip in place of a mechanical LSD. This is ESP right? Track work in a standard 981 can cook the rear brakes [or just one side] due to this. So it is possible that a factory specced Porsche with X73 could have different maps for stuff like this compared to a car without it. Quote Link to comment Share on other sites More sharing options...
Patt Posted February 16, 2023 Report Share Posted February 16, 2023 there was no s/w update when I had mine fitted. However there was a significant change to the geometry settings, and that also depended on what other options were fitted including PASM and/or Chrono package. 1 Quote Link to comment Share on other sites More sharing options...
daz05 Posted February 16, 2023 Report Share Posted February 16, 2023 @ATMthey would add it to the vehicle order as an official retrofit, but I don't think it changes the behaviour of the TC/stability system. Maybe someone who had it retrofitted will know for sure. Here we are discussing the arb only so they definitely don't have a setting for that! The GT4 has 3 ARB settings at the rear and you wouldn't code after each adjustment. Some 981s have the LSD with torque vectoring it was an option, cars with this fitted brake the rear and tracked tend to go through rear brakes much faster than than those without. My Golf R has it too. I know in PIWIS you can programme your pasm dampers to suit shorter springs I'm keen to lower mine another 10mm so would definitely code those to suit. Quote Link to comment Share on other sites More sharing options...
ATM Posted February 16, 2023 Report Share Posted February 16, 2023 11 minutes ago, daz05 said: Some 981s have the LSD with torque vectoring it was an option, cars with this fitted brake the rear and tracked tend to go through rear brakes much faster than than those without. I thought the standard cars cooked their rear brakes on track with novice drivers. I didn't realise it was only those with torque vectoring. Quote Link to comment Share on other sites More sharing options...
Patt Posted February 16, 2023 Report Share Posted February 16, 2023 My standard PSM certainly grabs rear brakes when it thinks it wants to cause an accident. Quote Link to comment Share on other sites More sharing options...
daz05 Posted February 16, 2023 Report Share Posted February 16, 2023 PTV is holding the rear brake on the inside wheel to help you enter and exit corners you can see why it's cooking brakes. Quote Link to comment Share on other sites More sharing options...
andygo Posted February 16, 2023 Report Share Posted February 16, 2023 4 hours ago, GTSMarky said: No I haven't had the geo set up as for the road it's fine and I've stopped car track days now. Had the rear trailing arm recall done late last year & I 'think' they check the geo of the car with that? They would have only set it to standard spec at the OPC. Quote Link to comment Share on other sites More sharing options...
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