Here are some links I have found useful.

The best circuit race club in the world.
Pure gold for car modifiers in the UK
Tomcat motorsport
Demon tweeks
Mig welding explained plus a splendid forum.
All wheel drive club
MOT test regulations
Jaguar Enthusiast Club
Car data and specifications
Excellent descriptions of how things work
PPC forum, discussion on car tech


Ralph Hosier