Car handling

[micdee]

Ok well I do not know how to describe my problem or feeling and therefore I can not search the forum about this.

the situation:

I ordered the adjustable upper control arms and lower control arms and a new set of the ARB links from 034 motorsport, because I noticed that the bushings of the upper control were very worn out.
I also had a new set of Goodyear F1 asymmetric 275/30 19 in the garage as the current conti's were almost worn to the minimum.
During MOT they found the rear right tire had a serious crack all around so I had to replace the tires sooner as expected, but almost immediate after this I got a problem with the thermostat.

All this happened about 4 weeks ago and I all that time I did not drive the car.
After I picked it up and have driven it for a while it felt to me that there was some sort of delay for the rear to react when I did some short zigzag turn on the highway.
later-on when I went into a long left curve, with a speed which is above the advised speed, but which was no problem with das Phantom before. This time it also felt like the rear of the beast came in the turn later.
After this kind of freaky situation, I checked the tire pressure and they were 2.4 and 2.5 bar. I set the pressure to 2.7 bar all around and drove the bent again it was a little better, but still not as I would expect a beast to take that turn.

Now I am wondering, what could cause this behavior:
- Is it because I have not driven das Phantom for 4 weeks that I am not accustomed to this behavior and have to get the feeling back (I really cant remember the car felt this way before in the same long left turn, although it is a tricky corner with a bump somewhere in the middle)
- Is it the combination of the new control arms kit with new/fresh bushings on the front, but old/worn suspension on the rear
- is this normal behavior for the GY F1 AS tire?

All your thoughts can be helpful and if there is a thread about similar behavior, please show me the link.

[Daveperc]

OK - not sure I understand fully what this post is about but...

I think the behaviour you are describing means that you have more understeer than previously - at least that's what I think you mean when you say the rear took a while to react.

You have replaced several front suspension bushes with newer (stiffer) components, and fitted new tyres. The effect of less compliant front suspension will be to increase understeer. The effect of replacing very worn rear tyres will be the same.

My suggestion would be to firstly make sure you are running the right pressures (2.7 sounds about right), and then make sure all the suspension geometry is properly aligned. If it is still understeering, then consider replacing the rear bushes or a stiffer ARB on the back (the Hotchkiss ones have two settings).

Hope that helps

Dave

[micdee]

Daveperc tnx for your thought:
It is also hard for me to describe my experience.
How I understand understeer is when the front wheels loose grip before the rear wheels do.
In my case I did not loose grip. Like I mentioned I did some S curves on a straight motorway and felt the same behavior like the rear reacts just a sec or so later.
Does anyone experienced that the Goodyear sidewall is (slightly) softer then the Conti's, which would also mean the car would "wiggle" a little more and maybe give the rear that tiny delayed reaction in a turn.

Hopefully this clarifies it a little more.

Been thinking about it more maybe I should describe it more as the roll of the car.

[Daveperc]

This reminds me a bit of the old joke:

Old lady to sailor: "Excuse me young man, which end of this boat goes first?"
Sailor: "With any luck Madam, both ends will go at the same time!"

You say the back didn't react for "a second or so" - that 10m or more at motorway speed!! I find that very strange, and in any case if the front is turning in, then the back will be doing something, or else the car is bending in the middle!

You mention increased roll - that would certainly be counter-intuitive if you have replaced bushes etc.

Are you on DRC or coilies? Failing DRC can result in odd wallowing behavious, as would a failing damper??

Dave

[Rupert]

I also had a new set of Goodyear F1 asymmetric 275/30 19 in the garage as the current conti's were almost worn to the minimum.

I think that is the source of your problem. You've gone from well worn tyres to new ones with a deep tread. I think it is the flex in the taller tread blocks you are feeling.
I had exactly the same issue before when I went from well-worn bridgestones on an impreza to new GY eagles... the handling went from "tight" to "wobbly" instantly, it was especially noticible on the motorway and it felt like the rear was lagging the front when sawing the steering wheel.

[micdee]

............... You say the back didn't react for "a second or so" - that 10m or more at motorway speed!! I find that very strange, and in any case if the front is turning in, then the back will be doing something, or else the car is bending in the middle!

Well the reaction was not at the same instant otherwise I would not have started this thread..
Maybe my ass is sensing per 1/1000 of sec, so in that case it might be 200/1000 of a sec later after I moved my steeringwheel.

You mention increased roll - that would certainly be counter-intuitive if you have replaced bushes etc.

Yeah well, I do not really know how to describe what I felt, or what the correct word is for what I felt. I apologize..

Are you on DRC or coilies? Failing DRC can result in odd wallowing behavious, as would a failing damper??

Dave

DRC is already replaced by KW 3v's. This was the first thing I have done on this car.