OTK Front Torsion Bar

FA Chassis
Front Torsion Bar

Today I messed a setup for sons race. He runs senior Tag Restricted Class.

Lately we have been running with the round torsion bar in front on dry tracks with good results.
Today it rained heavily and he normally drives excellent in the wet. I made all the necessary changes but this time I stayed with the round torsion bar. Normally it would have been flat horizontal bar. Note we always ran with a flat horizontal bar and never changed.
Reason toward round bar lately was for front grip.

So with that in mind I thought I would keep it in for the wet.

It failed miserably and made the kart hard to handle and hard to turn in. It made the rear very unstable.

Can someone explain why?

If the round bar gives grip then why wouldn’t you want that in the wet?

1 Like

Did you try both bars under the same conditions?

Which round bar was it? Silver, gold, or chrome?

The goal in the wet is the same as the dry, you want enough front grip to get the kart to turn in and jack weight but not too much that you overpower the rear, which is what it sounds like happened here. Kart was simply jacking too much and the rear wasn’t able to cope with the load.

The difference in the wet is the parameters of usable grip change, so the setup has to change to accommodate that. You have less ability to jack weight mechanically with the front end, so you need to add front grip to the kart, but you also have less rear grip available to cope with that added grip.

The game is the same, the goalposts just move.

How funny is it that just after reading your post, this popped up in my subscription list:

I think he nailed when he said it mostly affects the flex of the chassis. The chassis is a spring and with the bar at the front it will affect the front more directly, but the rear is affected indirectly. Assuming you have a fixed amount of total grip in the kart for any given set of conditions, moving the grip to the front takes away grip from the rear and vice versus. A stiffer bar will help the rear lift faster, but also set down faster as it prevents chassis flex from holding the wheel up longer. As to which one to use, that depends on your kart, your track, your driver and the conditions. Sounds like your driver was first used to the flat bar being run horizontal (soft front end) then after switching to the round bar the steering became more positive (stiff front end/more reactive) and was more comfortable with that set up. Throw that into wet conditions and maybe your driver did not change how they drive enough to account for the faster lift and drop of the inside rear. Basically in Fast / High grip corners = Fast up and down. Slow /Low grip corners = Slow up and down (Progressive Loading).

Unfortunately they ended up cancelling the event and we were unable to do that and see if that was the x factor.

Bar is Chrome. What your saying is making sense. From what I could see it was looking like the he was struggling with the front grip. In wet conditions he would normally turn aggressively and as the kart finds grip it would follow by turning. It surely looked like his actions were the same as he normally drives in the wet and the kart was flicking all over the place. Hence his exit speed was horrible.

So yeah, you were slightly stiffer on the front end than normal, so it would be expected that you could have too much front grip.

One thing to remember in the rain is that even if conditions seem similar, there can be a drastic difference in grip levels from one rainy day to another, or even one session to another. The track becomes much more unpredictable in the rain.

100 % correct

Thanks all for helping me clear up my f###up.

Hate it when a simple setup (which is my department) is the cause for a race result fail. Lesson learnt for next time.