Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 4/4 road holding

I have a question to the experts:
In general, the my car tends to understeer slightly which is no problem. I love to drive mountain roads but have to notice certain limitations when pushing the car to the engine limits: The front axle starts to wobble when I drive tight curves with pressure. The engine would be strong enough for oversteer with spinning tires but the vehicle moves outward parallel because of the weak grip of the front. Is this typical handling of a 4/4 or is there a better way to stabilize the front axle or front tires?
(Different tire pressure and tire dimensions provided little positive influence on the road holding of the front end.)

Well, I'm no expert...The first thing I would have actually cited is the air pressure. I have 0.2 bar less air pressure in the front (with four identical 165/80/15 tyres), 1.8 in the front, 2.0 in the rear. My springs in the front are slightly harder than original spring, 140 pound springs, the dampers are set slightly harder than in the rear. Toe-in is (from memory) about 2.3 mm and what also makes a difference for better turn-in in my case is 1 degree of negative camber.

I have had new chrome kingpins since the spring. Only after fitting them did I notice very clearly how much the old kingpins had worn out. I have much better control regarding the steering movements.

Hannes

Most Morgans are set up from the factory with inherent understeer, you can overcome this with power oversteer (but the technique is perhaps best practised on quiet road and definitely not mountain hairpins where there can be big consequences from getting it wrong) If you manage to perfect this then you might want to try 4 wheel drifts , but again please practice in a safe place first. The 4/4 Sport is a lovely responsive car and you should be able to get it to "dance to your tune"

Regarding the front axle , I would first try to make sure that all the geometry is correct (caster, camber , toe-in etc) and that it is equal on both sides , you would be surprised just how many cars are not. (They are now built with a jig which has improved matters somewhat but I don't know the date when this changed. In the old days before the adjustable camber front end came in, we used to fit negative camber plates (only 1 or 2 Deg) which definitely encourages the rear end to step out. If you have the adjustable set up, try adjusting to get the maximum negative you can.

Secondly I would respectfully disagree with Heinz about tyre pressures and would go for higher pressures in the front than the rear, this encourages front end end grip and slightly lessens rear which will help promote oversteer.

I assume you already have brake reaction bars? If not fit them first, a cheap and easy mod before spending any further funds.

If all the above do not have the effect you are looking for, then start looking at some different shock absorbers, and possibly different springs.

The best person to advise on a good set up would be Cain at Wolfe Performance as he uses a car like yours for competition.

Andy,
I agree with everything in your eloquent post. Only with regard to tyre pressure, my experience is that a slightly lower tyre pressure at the front gives a little more grip at the front and therefore better steering/oversteer. But maybe I'm wrong.

Thx for your input. It is a confirmation for what I had in mind.
I do think the front geometry needs adjustment and springs and dampers require improvements.
Brake reaction bars were installed a long time ago.
The different tire pressure for front/rear is something I will play with.

On my racecar I would undoubtedly go up at the rear to reduce understeer .... not really road car applicable as the ends are assymetric with much taller and wider slick tyres at the back so there's more going on. There is a pressure sweet spot for each end that gives optimum grip .... going either up or down from that will, in theory, reduce the grip on that axle

I find the handling of my Morgan to be quite neutral (though I have yet to have it on a track) .... my logic would work slightly differently .... at 22psi all round the pressures are pretty low already ... the idea of lowering the fronts in order to improve the car's scratching potential means that we're not talking granny driving but drifting the car or leaning on the tyres really hard ... I would personally be uneasy dropping the car into a hairpin on the adhesion limit of modern rubber having dropped the fronts to where there's only 20psi stiffening the sidewalls or ,at extremes, holding the tyre on the rim ... should it come to it I'll raise the rears first.🙂

As Mog615 says, there are those who race their Morgans and their experience will count ... my Morgan ownership is quite new and, although I've been racing cars for decades there may be some 'Morgan Voodo' going on I know nowt of ... hopefully a racer (or preparation guru) will be along at a suitably speedy pace to help us out. 🙂

K

The drifting is not a problem. I can handle that. The wobbling of the front tires is the limiting factor.
I hope "wobbling" is the right description for the action of the front wheels (I'm not a native speaker)

Image, if I drive 1.8 bar at the front, that is 26 psi. 2 bar at the rear is 29 psi. This works very well with the T-Trac 2, even with the lightweight 4/4. It gives control and sufficient grip, even in the wet. In contrast, the sidewalls of the Conti tyre are like wood at this pressure and have no suspension comfort whatsoever, which is the case with the T-Trac 2.
Hannes, the wobble, if I understand it correctly, is not an imbalance but that the wheels wobble in the curves? Either someone has to tighten the bearings or the kingpins are gone. If there is bearing play, the wheel wobbles in all directions in the air with your hands, and if the kingpins are worn, it only wobbles when you turn the wheel to 12 o'clock and to 6 o'clock.

It's not the drifting ... it's the drifting on underinflated front tyres 😁..... I don't suppose the 'wobble' could be the rims moving in the tyres under duress due to low pressure??

K

Hannes, what tyre pressure do you use? My other assumption was that the whole wheel, starting from the rim and the hub, might have too much play, because of too much play of the bearings or worn our Kingpins.