KTM X-Bow GT4 | Setup Guide

Discussion in 'Car and Track Knowledge Base' started by Thomas Jansen, Apr 22, 2019.

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  1. Thomas Jansen

    Thomas Jansen Sector3 Developer Beta tester

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    [​IMG]
    The GT4 cars silently got a huge upgrade with the tire pressure update, this really made the KTM come alive in my opinion. It is an amazing car which really invites you to push harder and harder in every corner. What it lacks in straight line speed, it can definitely make up in the corners, but you need a setup that gives you the confidence to push.


     
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  2. Thomas Jansen

    Thomas Jansen Sector3 Developer Beta tester

    Joined:
    Apr 5, 2018
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    Bathurst

    Setup & Telemetry



    Tire Pressures
    As usual I tuned the tire pressures using the tire temperature telemetry. Ended up slightly lowering the front left pressure and increasing the rear right. This makes sense as Bathurst is a counterclockwise track, so the right side tires will do most of the work. So keep this in mind when taking the setup to clockwise tracks, a good starting point will be to simply swap the tire pressures on the left and right sides.

    Dampers
    Suspension velocity histograms were recently added to SecondMonitor, which really helps a lot in tuning the dampers to keep the tires on the road optimally. In most cases you want to equalise the bump and rebound speeds of the suspension as much as possible. On this car, the rebound speeds were quite a lot lower than the bump speeds, so I started lowering the rebound damping and increasing the bump damping, which made the feeling of the car better and better. The car was getting more predictable and stable over curbs and more responsive in corners, until I got to the limit of both of the settings! Ideally, I would have adjusted it a bit more, but the histograms were looking a lot better already anyway, so it would have likely not improved much more.

    Camber
    As there are quite a lot of high speed corners on Bathurst, I expected some extra camber could help in keeping the tires at the optimum angle in those sections. Increasing both sides by a few clicks definitely improved the grip on the mountain, which confirmed my expectation.

    Anti-Roll Bars & Springs
    Like most default setups, the balance was still quite on the safe side, so I played with a few different combinations of front springs and ARB values. Slightly lowering the front springs seemed to help to pitch the nose into corners, most likely because the ride height is quite high on the car, so letting the nose dive a bit more makes the floor a bit more effective. While the minimum value on the springs was definitely quick, it made the behaviour of the car quite twitchy in the downhill section, so I settled for one click lower than default and balanced the rest of the understeer out with the front ARB, going down quite a bit from default.

    Ride Height & Wing
    I thought I pretty much maximised the setup on this car, until I had a look at the ride height telemetry. This showed that the car was actually at about 7mm of reverse rake while on the track. This would most likely mean that the diffuser is not being used efficiently at all, so I tried increasing the rear ride height to maximum, 20mm up from default. This indeed increased the dynamic rake to about 13mm and increased the produced downforce by 5%! However, it also increased the drag quite significantly, costing about 2 tenths on both of the long straights. So I lowered the rear ride height again by 10mm, keeping the positive rake, but not too much. This worked exactly as I hoped, as it still gave a 3% downforce increase over default, but with a negligible drag increase. It also seemed to make the car much more predictable on power out of corners, which really confirmed that something was not right on default. The downforce increase shifted the balance quite a bit to the front, but as there was a bit of understeer before anyway this was perfect, so I did not feel the need to change the wing setting.
     
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