Well folks, I have decided to take the plunge and modify my doors!
I have given some considerations to the issues raised so far in this thread. I think if I was to go with 100% originality, it would be very costly indeed. The hinges would need to be re-engineered together with the receiving hinge brackets on the doors. The rear door lock jam/frame would be a massive undertaking because on the original cars the structure was tubular but on the Mk 4's and Superblowers, it is a rectangular box section. I have therefore gone for what I consider to be a good compromise. I will log down what I have done in the following frames so if anyone in the future considered doing this, they could give see at least one method to consider for themselves.
First of all, I measured the length of the hinge 'strap' on my friend's lightweight. It was 2 1/2 inches in length.I therefore cut my hinge straps down to that length. At this same juncture, I cut away the side impact bar. The following image shows this work. I drilled and tapped a third securing hole on the remaining hinge strap and fitted countersunk bolts.
The following image shows the hole left in the door jam once the locating spigot of the original lock mechanism was removed. As you may be able to see it's not quite circular. I therefore used a reamer to make it perfectly circular with a diametre of 16mm. I then made the decision to fit the new locating spigot. The item has been shown earlier in this thread by REV. It is a tapered spigot which locates in the door lock, with an inch and a half 5/16th UNF threaded portion. I had a stainless steel 16mm bush made which fitted snugly in the reamed hole. The length of the bush was sufficient to fully but up against the rear of the rectangular box section frame. The bush was centrally drilled to received the 5/16th UNF portion. Using the bush then as a guide, I drilled a small hole through the hole in the bush, into the rear plate of the rectangular box section and tapped it witha 5/16 UNF thread. The locating spigot was then pushed through the bush, turned in the rear thread of the box section until tight. The whole assembly at this point was very firm and secure. To finish this area off, I placed a 5/16th UNF locknut on the exposed thread of the spigot which was visible in the wheel arch. Hope you follow!
I was then able to hang the actual lock onto the locating spigot in order to gauge to location for the mounting plate in the door.
I removed the rear lock mechanism from the door and most of the surrounding lock support framework. I retained some of the surrounding structure to ensure rigidity to the door, if it had have been all cut away the tubular door frame would be heavily weakened. As I completed this process the side impact bar was also taken away.
I then had the lock mounting plates fabricated with 3mm mild steel plate. It was bent to shape and to replicate that on my friends lightweight. Once it was fettled to ensure an exact fit to each door, it was welded into place.This was a tricky process because I was concerned the aluminium skin of the door would melt. To help reduce this risk, the outside of the door skin was placed onto a large cotton cloth and soaked in freezing cold water. Immediately after a small section of welding was done, it was also instantly quenched in water. It seemed to work as the outer skin is perfectly intact. The lock mechanism was attached to the locating spigot to ensure alignment was right for the support plate. As far as adjustment is concerned, there is none in the locating spigot, that is fixed and rigid. However there is lateral adjustment on the lock mechanism. I purposely made the mounting plate no quite as deep as it needed to be, so that if necessary I could pack washers between the lock and support plate. Additionally the lock is bolted to the plate by 4 slightly oversized hole allowing for a small amount of rotational flexibility to marry up against the spigot.
So there you have it. All that's left to do is repaint the door frames, carpet the inner door skins and have a leather pocket professionally trimmed and fitted.
For some reason Photobucket won't let me attach the final image. I will add another item to this thread with it on. Hope this has been of some value.
Gary
