Why are cut and shuts illegal ?

[Dogbreath]

Yup, that pretty much echoes the experience of a lot of folk SVAing kit cars, you get differing advice from VOSA/DVLA depending on which droid you happen to speak to. Every local DVLA office appears to have different interpretations of the rules as well.

 

[BigglesPiP]

A cut and shut can be done properly, in fact I've seen a race car repaired by such means.

I think it's illegal due to the identity issues, and the potential for it to have been done poorly.

 

[fornowagain]

Unfortunately the HAZ (heat affected zone) around the weld is brittle! Not usualy a problem on bodywork, but a very important factor when welding structural components that are likely to suffer cyclic stress.

Very true, iirc in such instances preheat is applied and maintained to slow the cooling rate, allowing the formation of ferrite/pearlite grains instead of martensite. Not so easy with a big heat sink!