Caster angle/ride height formula

[djmagee]

I have run 'Bertie' my 223 with a very low ride height for the past 16 years since i built him. I have finally decided to alter the caster angle to give my biceps a rest.
I may be wrong here but i seem to recall someone producing (and publishing via the mag) a formula for ride height, over degree of adjustment required (in mm) at the hub knuckle, in order to retain the manufacturers optimum caster. As all suspension arms should be the same dia this should be entirely feasible. I have long ago offloaded my back issues of Flat Out so i may well be dreaming. Anyone recall this or am i mistaken?
Kindest Rgds, David Magee

[howardjs]

Hi David,
Yes I have the same problem and hope to be fixing it soon. The angle at the moment on my car is about 22deg. and I'm still riding 25 to 30mm higher than I would like. The Haynes 2CV manual has it at 15deg. My proposed method will be to take out the king pin, support the arms with stands at the required ride height then put in a long sliding fit dummy king pin which reaches down to the floor. I can then measure the angle using a combination square. Subtract 15deg from this and I have the alteration angle. I will have to make up an adjustable welding jig to make sure the castor angle is maintained. All I need now is some time to do it..!!! Because of the 2CV swinging arm suspension the castor angle is constantly changing so, so long as both sides are the same the actual final angle doesn't need to be dead on.

What I could do with is a spare set of arms (just in case). If anyone out there has a set going cheap please let me know.
Regards Howard

[Eddie c]

Hi David
I found some information in the old forum that was helpful.
Regards,
Eddie

[Ken Hanna]

Something like this?
http://snail.s4.bizhat.com/viewtopic.ph ... orum=snail

About 5mm rotation on the suspension arm's surface is usually OK, unless you're aiming for '2CV racng club type' ground clearance of 40mm.

Ken

[david]

I have the info from the old hints and tips on altering the angle..I can email the pages -but have no idea how to add it here...maybe another to send to the moderator..

[JEP]

If my maths is right!

The standard front ride height for a 2CV is 195mm. and the caster angle is 15degrees.
For every 5mm. by which you lower the ride height from this standard you would need to correct the caster angle by 3/4degree to maintain the 15degree caster angle.
If you go too far with reducing the caster angle from the standard 15degrees you will loose the self-centering action of the steering.

Cautionary tale!
When driving an old Land Rover for the first time, my father turned left out of our drive, let go of the wheel as he pulled away expecting the steering to straighten and was very surprised to drive into the nearside bank of our lane. Good thing it was an old Land Rover!

John

[djmagee]

Thank you chaps for your assistance. All comments/advise greatfully recieved.
David Magee

[howardjs]

Hi, just been doing a bit of messing around on my CAD thought this may help.....

Sorry folks. tried to add the drawing in WORD, PDF and DXF but all "not allowed"

[howardjs]

Hi me again, if anyone would like this drawing of the 2CV front suspension castor angle just email me and I will send it.

hjsspecials@hotmail.co.uk

Regards
Howard

[howardjs]

Now I think I've managed to attach it as a jpeg not sure if it's clear enough

Howard

CASTOR ANGLE.jpg (76.03 KiB) Viewed 19110 times