Chuffer - your points are very sensible and logical and I'm sure most of us will totally agree with you. With regards to a vehicle that has been 'substantially modified' NOT being exempt from the annual MOT test and what 'Substantial' actually means..............without guidance from the DVLA I would say that a 'substantial modification' would relate to significant chassis and suspension changes - i.e 'live' rear-end with new fabricated trailing arms (Ford 9"). Replacement, custom aftermarket chassis or chassis from later Corvette 'marque'. Possibly aftermarket custom rear suspension (.e Sharkbite) or jag rear end.
Items like aftermarket brakes and suspension that still uses factory mounting points (Willwood/Baer/SSBC/etc etc) - modified or replacement engines from same manufacturer (i.e GM or generic aftermarket sources) will be unaffected as will transmissions choices (possibly not Lenco or similar that requires chassis modifications), turbo chargers and supercharger, although a 6/71 sticking out of the hood and obscuring vision will be a different matter I expect...........................
The DVLA lists modifications that do not count as 'substantial changes' and therefore allow MoT exemption....
1. changes are made to preserve a vehicle because the original type parts are no longer reasonably available
2. they are changes of a type which can be demonstrated to have been made when vehicles of the type were in production or within 10 years of the end of production
3.
axles and running gear have been changed to improve efficiency, safety or environmental performance
4. changes were made to vehicles that were previously used as commercial vehicles, and you can prove the changes were made when the vehicle was used commercially
Item 3 has occasioned plenty of debate among Classic Car Clubs. I own a 1963 Daimler SP250 Dart, the last of which were built in 1964. All these cars were originally fitted with cam and lever steering gear. This was heavy, even by the standards of the day, and without very regular maintenance and replacement, became imprecise (shades of the Corvette!). Perhaps more importantly, the steering box was the lowest point on the car and in the event of encountering a road hazard or accident, it could leave the driver sitting at the end of a six foot spear. A common modification has been to fit Rack and Pinion steering which is lightly weighted, more precise and obviates the impact hazard. Most of us consider this a modification that improves both safety and efficiency, and to date the DVLA has not queried exemption of cars with this modification.
If your 'Vette has been modified and the changes improves safety and/or efficiency, this may not automatically exclude it from MoT exemption.
