Massive Understeer At The Track, What To Do?

[xr_velocity]

4 pot Brembos with factory pads and rotors. QFM A1R pads on the stock rears with slotted rotors. I'll go with some better pads on the front when the Brembo ones wear out.

Does a pretty good job though, no fade with this setup so far.

[Smoke them tyres]

Hi XR,

Great stuff. Apologies for my tardy reply.....

"The car was only slightly more inclined to understeer, meaning when getting on the throttle mid corner it was more likely to push the front out than the rear"

Look forward to seeing what you think with the rear bar removed........as it should help the front some more and further transfer (diagonally) some dynamic weight to the rear. The initial push is saying to me that although close, slightly more weight needs to go to there.

Another great way to check that your set up is going the right way is to have someone observe it trackside at some mid corner bumps. If the body of the car is stable, and the suspension is moving, then the spring and damper rates are pretty close to what the car needs. Most people think team spotters for race cars are only looking at race position. The intelligent ones will have someone sensible looking at the behaviour of the car (and probably filming it as well also).

To see this in action in an extreme case, YouTube some clips for the Baja desert race in the US.

Edited 19/06/11 02:07 PM by Smoke them tyres

[xr_velocity]

Off to the track tomorrow minus rear sway bar to start the day off....will see how I go with it. Rain should hold off or so the weather man says.

Can't wait to wear out the Falkens so I can get some Nitto tyres! Just need more track days I suppose....damn things won't wear out, doesn't help I don't drive it much I suppose.

[xr_velocity]

Unfortunately I didn't get a chance to take the rear sway bar off, new baby takes all the time these days, but that's certainly nothing to complain about.

My best lap time last time out was 2:03.xxx, this time I was able to get a 2:00.464. That is not earth shatteringly quick, but three seconds a lap is definitely a huge improvement over my previous attempts with no changes made to the car. Thanks to the lower temps on Saturday I was also able to keep up it without the engine oil over heating so that helped in not needing to back off at any point in time over the 20 minute sessions, just a warm down lap and a quick trip to the servo after each session was enough to cool the car down. I couldn't crack under 2:00 minutes though, that was my goal. Became very frustrating in the third session when no matter how much harder I pushed I just couldn't get the times down. Tyres go too hot, so did the brakes.

I have ran two different types of QFM pads in the rear of the car with stock solid rotors that the BAs came with, both of them disintegrated down to nothing after the third session on those track days. Definitely the last time I ever run QFM pads, they may be OK for the street, but as far as track work goes they are garbage, they literally crumbled to pieces after getting too hot. This time I was using their A1R which is supposed to be their best pad. The stock front Brembo pads are still going...and they are the ones that take the full brunt of the > 1800kg car.

I definitely noticed that the understeer increased as the tyres got hotter, my faster laps in the first two sessions were always either lap two or three, with the next laps being 2 seconds slower usually. I could feel the front end understeer more as the laps went by....my fastest (2:00.464) lap came after the 6th lap in the third session...so if I had have had fresher tyres I probably would have cracj under 2 minutes. I got one more lap in after that one and the rear pads disintegrated and overheated the brakes as it was metal on metal...lost the brake pedal and had to back off completely. Session and day over! Am going to get a set of Ferodo pads now, hope that they don't crumble apart. But still 7 fast laps from 4 pot Brembos and stock rears is not a bad effort....especially since a lot of people rubbish the 4 pot Brembos, I find them pretty damn good and can only see them getting better with better pads and 5.1 fluid.

My ultimate move now is to get some semi slicks to help with the obvious short comings in the tyre. Also to get a camber kit to get more camber into the front of the car. Rear sway bar removal can be done next time I go out since I know know my bench mark of lap times, I will know if there is an improvement attributed to it. I also use Race Ace app on my phone while I am out there which logs G forces, speeds and alsdo maps it all out into Google Maps image of the race track so I can see my speeds and g forces around the track.

[xr_velocity]

Youtube clip taken by a Nissan Zed 350....that happened to have 350rwkw. He's chasing me down for a lap, you can see he can take the corners a lot tighter than me.

[Guest XR09]

Love your work.

Braking was the only place he had you. He caught a bit by mid in the slower stuff, but you gave him the fat ass all day haha brilliant.

That was one very stiff Z too.

[F6turbo]

I was out there on my bike on the 13th. Spoke to you for a bit, very close to sub 2 min now keep it up

[sexual harrassment panda]

so going by this thread - Maybe I should swap the rear bar for a stock one in the twisty bits?

confused as I love the feel of it with the stiifer rear bar

[xr_velocity]

so going by this thread - Maybe I should swap the rear bar for a stock one in the twisty bits?

confused as I love the feel of it with the stiifer rear bar

I wouldn't bother with a bigger rear sway bar, but I am no expert at the same time

It will give you the feeling that your car is flatter on the road around bends....but that doesn't mean you're able to go quicker. All cars need body roll to a degree to move the weight to where it is needed, in the case of the larger rear sway bar, the tendency to keep weight where it is will stop the weight of the car being planted onto that outside rear out of a bend and forcing it down into the road. Very much like a drag car in a straight line that lifts the front and puts all it's weight on the back wheels.

[sexual harrassment panda]

great explanation.

In the rear end my suspension is totally stock apart from the sway bar, while I love powerslides but I do know they aren't the quickest or safest way through a corner.