Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing 1998 +8 Alignment Numbers

Sorry to be pedantic but when you say castor is the same as king pin inclination do you mean they set it to the same angle?

Caster is not the same thing as KPI

Caster is the angle of the kingpin when viewed from the side of the car. Ideally around 6 degrees on a Morgan

KPI is the angle of the kingpin when viewed from the front of the car, about 5 degrees, but because camber adjustment is made by changing the angle of kingpin it will be changed relative to the camber angle

Simon @ SiFab.co.uk

I took KPI = Caster as a typo. Should have been camber.

Thanks Simon, although the Caster is not right on 4 degrees - left 2.6 and right 3.4 the steering is returning to straight OK. But the camber is -0.1 degrees so I will change it 0 degrees or + a little bit. Toe in is 0.

Bill, you need to try and reset the caster to at least 4 degrees, 6 is better
Camber about 0.5 negative, no more
Toe needs to be a touch toe in say 1/8 “ (in American 😉)

Caster isn’t just about the steering returning to straight ahead
It also affects turn in, and camber gain/change as the steering is turned

Simon @ SiFab.co.uk

Simon...I’ve always been intrigued just how you alter the castor angle unless the body is off the chassis and you can remount it. Brute force?

You don’t need to remove the body to remount (or even replace) the front cross head

You don’t need much force to move anything on a Morgan chassis, although to correct the top kingpin lugs when resetting the camber you need to heat up the fittings or the can crack

It would help if the factory cross heads were square and true to start with
I’ve seen them up to 8mm out of true

The stub axles have similar variations so the scrub axis or offset can vary wildly side to side

(Scrub offset is the difference between the centre line of the tyre where it meets the ground and a theoretical line extended along the axis of the kingpin to the ground

Traditionally for light accurate steering the scrub should be minimised, however with wider tyres and more complicated modern suspension kinematics many manufacturers use scrub as another tool in the repertoire to improve handling)

Simon @ SiFab .co.uk

So to adjust castor, it is a matter of heating the tubes and applying some force?

To adjust camber on pre 2010/11 ish cars it’s necessary to heat and bend the top cross head forging
To adjust caster it’s better to move the entire cross frame rather than heat and tweak the tubes, but it can be done

Simon @ SiFab.co.uk

Thanks Simon, although the Caster is not right on 4 degrees - left 2.6 and right 3.4 the steering is returning to straight OK. But the camber is -0.1 degrees so I will change it 0 degrees or + a little bit. Toe in is 0. [/quote]

Bill, you need to try and reset the caster to at least 4 degrees, 6 is better
Camber about 0.5 negative, no more
Toe needs to be a touch toe in say 1/8 “ (in American 😉)

Caster isn’t just about the steering returning to straight ahead
It also affects turn in, and camber gain/change as the steering is turned

Simon @ SiFab.co.uk [/quote]

Thanks Simon - I was confused by the importance of Caster and was getting conflicting information from My Friends. Will get to work and resolve this.