Would the XJS be Safer and less likely to 'Spin' if there was a bit more weight inside the Boot/Trunk.

As the unfortunate mishap to one of our members, has certainly got me taking Corners a lot more slowly than maybe I've done at other times in the past.

 

The only times I've really had any problems with the back end breaking loose has been on wet roads. Even then, it was more because of my heavy right foot, than it was a light rear end.


The right set of tires is really can make a huge difference for those of us who live and drive our XJS in areas that get a lot of rain. I was stationed at MacDill Air Force Base, in Tampa (the same general area that villain is in), so I know its one of the rainier areas in the US. You could just about set your watch to the 3PM storms that roll ashore nearly every day. My advice is to use the reviews on sites like www.tirerack.com when choosing your tires. I always pay close attention to the wet performance category when selecting a set of tires for my XJS.

 

NOPE.

 

Cheers JagZilla

I am still going to take it a lot more easy, as that 'Mishap' was a real 'Wake up Call'

 

NEVER EVER let anyone else drive your cars. Has worked for me for many years. If they must drive your car, (kids learning to drive etc. ) buy a cheap beater car that you don't care that much about.
That really works out much cheaper if your pride and joy gets totaled in the long run

Simples......

 

Nope, as well!


It is/was the "tail heavy" cars that get "loose" in a tight fast turn.
Tail goes out...


Nose heavy cars are judged to be safer for most. They "push", that is
the nose tends to lag in the direction change.


So, the engineers recognizing that "push" is easier to control than "loose" for average drivers, they build them with "push".


Messing with balance best left to the pros. Race drivers and mechanics.


Carl

 

'Tis the limited slip differential that plays a big role in these types of spin outs.

Rounding a corner, low traction surface, too much power applied.....

With a standard diff the inside tire will spin madly but the other three tires maintain traction and the car remains pointed in the desired direction.

With a limited slip diff both rear tires break traction. You know the rest

Cheers
DD

 

You don't need a heavier trunk
You need a lighter foot

 

Best example: a Porsche 911 will happily whip and slap if you are too hard on the throttle in a corner... You can't have anymore weight there other than an engine. Heaviest part of the car.

Best is an understeering car. You can achieve that by fitting a thicker anti roll bar at the rear or better, if none fitted, fit one. Don't touch the front one.

 

I haven't found XJS to be particularly tail happy, I.e prone to over steer.

Havings said that, many drivers used to modern cars with esp systems that will selectively brake a single wheel to correct oversteer and understeer have lost or never gained an understanding of how to drive in slippy road conditions.
Good tyres , well maintained including tyre pressure then gentle on the brakes, throttle and steering.
Commiserate with owner and his partner, but that accident unless vehicle found to be defective wasn't caused by design problems, simply driver error.
Recommend advanced driver training as appropriate remedy.

 

The first order of business would be front and rear
tracking. Toe for North American readers.

The XJS suspension is closely related to the X308
suspension where I developed this opinion.

Excessive toe-in or any toe-out in the rear can make
the vehicle very unstable in slippery conditions.

In general, toe-out, front or rear is a disaster for most
drivers on the stree. The sole exception is the front of
FWD vehicles where called for by the manufacturer.

The full reasons for this are detailed in a post in the
X308 section after a member lost control in snow.

I currently run with the rear toe just inside zero, equal
on both sides and the car is very stable in slippery conditions
now.

 

Ummm ... no.

The opposite is true.

A rear bar will increase or introduce a tendency
to oversteer.

That is why the difference between a base suspension and
a sport suspension on most RWD vehicles usually includes
the addition of a rear anti-roll bar. Example, the Sport and
XJR versions of the X300 and X308 have a rear anti-roll bar
while the base model does not.

 

Plums,
The XJS rear toe is not adjustable, and unless something is bent/bearing utterly worn out, there can be no toe out. The radius arm geometry creates some more toe in at the rear as the outer wheel gets loaded in a corner, a designed-in safety feature of the axle.
I agree with your basic point though about rear toe out being bad news for the street driver. Front toe out, not so much. Owing to a cockup in the Haynes manual, I had my car on slight toe out for years, and it was absolutely fine!
Greg

 

Hmm, that then must only apply to a FWD car then. After upgrading the ASB on my C30 I had a higher tendency to understeer. As I removed it the old bugger would oversteer really quickly.

 

Which bar did you remove, front or rear?

If you removed or reduced the FRONT bar, then
yes it will understeer less/oversteer more. That
would be expected.

The characteristics of how a anti-roll bar affects
a chassis is the same for both FWD and RWD.

Maybe you typed that last paragraph in the previous
post in haste and got it backwards or I am not
reading right?

 

As is mine. Due to me not including the effect of non-parallelism between
the laser and the laser mount.

Drives fine, not so great on the tires.

A small amount of toe-out on the front aids in turn in
and is fine as long as the driver is on top of things.

Apparently hobbyists who autocross their street vehicles
often run toe-out on the street to avoid changing it before
and after every event. But they know how their vehicles
behave. Not so much for the owner who buys a vehicle
off the showroom floor and just jumps in.

 

I agree


I disagree

Not that advanced driver training is a bad thing, mind you. It's just that "gentle on the brakes, throttle, and steering" is a basic, fundamental thing when driving an unfamiliar car....or driving *any* car on a low traction surface. No advance training needed to avoid this type of accident. Just common sense.

I'm not trying to disparage the driver in this mishap. I've had a few cars get away from me in my time....either from sheer stupidity, or from having a bit more enthusiasm than skill, or not being familiar with the car I was driving at the moment. Or all three at once

That was a long time ago. That's how I learned.

Cheers
DD

 

look it was like that for our Jag when the tires were worn out slip and slide.... new tires and all the sudden all sorts of sticky... no slip and slide....

 

I think this idea is entertained during winter on the snow, when extra weight would push snow around and make rear wheels more likely to contact the road. I doubt it will help when cornering in general.

I haven't driven my XJS on wet road yet... but it scares me a bit because in the rain ABS on my XJ8 is kicking-in very often(and I am having fun with it!)... what am I going to do without ABS on XJS? I will forget that it's not there...

 

The theory was putting weight over the drive wheels gives better traction in snow/ice conditions. That's why FWD cars are generally so much better in winter than RWD.

As a general rule though, adding weight is not a good thing to increase stability, since in corners it just increases the loads on the tires. Which corners better: A Lotus or a Rolls Royce? Which weighs more?