I am building a 3 wheel Morgan inspired car with front wheel drive using a Guzzi motor, Subaru gear box,front drive with 17inch 1934 ford Y wheels. To have the turning point of the tyres in the tread centre will require a 20 degree king pin angle. Because king pin angle increases self centering can I get away with a shallow camber angle, maybe 2 degrees, to offset the extreme king pin inclination. Any ideas greatly recieved. does three wheels lessen torque steer if the king pin point is inside centre of tyre?

Hello
I assume this is a twin A-arm wishbone configuration?

I feel 20d KPI is way to much, couldn't you reduce this and use 5 or 6d of castor.

I was hoping to use double A arms and would be easy to use my VW Golf front hub cariers. My think is that because of the very light weight the extreme KPI may be OK.

No, i'm not happy with this.... 20d KPI plus -2d camber (unknown castor) will not allow the SR to migrate correctly. In addition the declined KPI has less effect returning the steering if the car is so light.....

Need to know what intentions you have for the castor.

Sorry I did intend castor instead of camber. So my thoughts are; camber 0; castor 2 (this number easily variable) king pin inclination 20; This is because of wheel offset.Thank you very much for feedback.

You had me going there..... Is the camber and castor adjustable on your car?

I have only parts. The VW hub carrier with adaptor plate has the old style spoked ford Y wheels away from the bottom ball joint. If 20 degrees can not be used I will have to reivestigate other alternatives. The bottom ball joint may be able to be lowered and moved under the disc by changing it to a rose joint but will have to make some serious brackets to get it there. So if I can get away with 20 it would be much simpler.

If think this is a "suck it and see" situation.... Personally with 20d KPI i would want 6d castor and around 1d neg camber as a base. Whatever happens you cannot have zero camber because the camber migration of the inner wheel on a turn will lock positive and not return... Remember the KPI is longitudinally perpendicular so a low castor of 2d almost holds the KPI transversely during yaw.

Thank you once again, your thoughts are very appreciated. When you suggest the camber is critical will this mean that because it is a 3 wheeler I should have a high roll centre, about 12 inches and quite serious antiroll to prevent camber change or would camber change during weight transfer aid driving feel? One number that I will be sure of is the roll centre at the rear will be at ground level. What roll centre would you suggest for the front?

I couldn't begin to guess with your configuration..... I would suggest you keep the wishbones horizontal though.

Thank you for sharing your talent with me. You have given me a lot to go on. I will now suck it and see.

Sorry about that..... "suck it and see" is horrible terminology but on some builds residual errors in the build only come to light afterwards, however good the model looked.

My best advice is make the chassis as adjustable as possible, this should give you the option to change any errors.

I know what you mean. I have read a little bit about front wheel drive and most articles say that the centre of the tyre tread should be on the KPI line otherwise torque steer is inherant. But to get this requires the steep KPI. The old wheels that I am intending to use have little offset, but they are very good looking and classic. So I will 'suck it and see' because I think I am dabling with something not too common. Thanks once again for sharing your ideas and I will leave space for modification during my construction.

Ok mate..... best of luck with the build and if you can display a picture or two.