I have always had a deep liking for the MGB Sebring conversion. It really suits the MGB so well. Well, ok, I know it started as an MGC as a series of special aluminium bodied racers for the Sebring race, but it is by no means out of place on either model. It is rather a drastic and involved conversion to do properly though, and easy to make a dog's dinner of. Also, I have never seen any articles on the subject. After giving it much thought, I have decided to take the plunge while the car is under restoration and rebuild, in need of a respray etc. and while it is in bits, and to somehow make a really good job of it.
The conversion is based on the GRP wings kits which are available from various suppliers. The MGOC do kits, at a very cheap price, but I elected to spend more and have a Smith and Deakin kit, which hopefully would be better quality and would have better fit.
You are supposed to be able to fit the whole wings on the front, and use the rear wings as overlays over the original wings, according to the manufacturers. In practice, even the Smith and Deakin wings, although possibly of better quality (but my evidence for this is anecdotal) are still a diabolical fit, and using them in the way intended is just not viable. Many people have said to me that the only way to do it is to cut out the bulgy bits from the kit wings and bond them onto the original steel wings. Just what the hardship is in making wings that actually fit, I can't imagine. It can only be sloppiness and lack of professionalism that results in wings being the wrong curvature at the edges, too short etc. and apathy on the part of buyers that perpetuates it. In truth, they ought to mould and sell only the wing extensions, at a fraction of the cost, but of course, this would lose them lots of pennies.
Having bought the kit, I can only vouch for the approach of cutting out the extensions. It is abundantly obvious the first time you look at it, that it is the only way. The thing to do is to cut out the bulgy extensions so that the eventual blended edges will be made on the edge of the curve back to the original metal, and not beyond the curve in what is supposed to be flat surface. Trim the wings accordingly.
As it is my intention to use the extended arches properly and fit wide wheels and tyres, (otherwise why bother to fit them!) this means that the original arches need cutting out and re-forming. It means that The inner wheel arches have to be separated and the outer steel wing cut out in an arch.
I want to stress that this is only MY way of doing it. It isn't the only way, or necessarily the best way. I have for example, seen one which was done by flaring out the original steel wings by cutting them into vertical strips and these were all welded together before the grp overlay was applied. The outer half of the inner arch was extended in steel to meet the outer. This is obviously the strongest way of doing it, but my way is just easier for the average restorer.
This shows the extent of the cutting on the outside, which then is translated to match the height of the inner arch which will be split all round at the central joint.
And this is roughtly the piece cut out of the GRP wing to use the extension. I cut out a bit bigger for safety to start with. At this stage I sat back and thought about how the two would be married together and the inner arch extended to meet the new outer arch and then how these would be matched together. There are so many interfaces and these would have to be mechanically fixed and epoxied together in order to make for maximum rigidity and result in no movement between the steel and GRP which would cause cracking on the interface on the outside. Inside, the inner arch would have to be extended to meet the new outer flared arch, and this appeared to be complicated. I was adamant that this would have to be thought through before any cutting out took place, so as to be sure of a correct result first time. A second time would in any case result in a botch. I was also adamant that if I was going to cut these good wings, then something equally as good would have to be constructed.
It was then that I decided to consult an experienced restoration specialist, well versed in sympathetic re-construction of valuable vintage cars. Simon North, of www.simonnorth.co.uk came to see it and we pondered for a little while. It was he that came up with the clinching idea that turned the conversion from something which could be a potential botch up, to something which was really going to be an outstanding success and something really worthy of note. I then had the confidence to make a start on cutting out the wings.
The thing is that it was actually really simple. We were to cut out the original wing in the shape marked, then along the inner wing as described, and remove the lot as one piece. This is always what I had in mind, but the difference now is that the plan was to refit this piece by means of a steel band insert between the two inner wing halves and to effectively space out the outer arch to the position immediately behind the new GRP overlay. The GRP would then fit snugly over the top, flush with the original steel arch and be extremely solid. With this plan in mind, work started. The good thing about removing this section of wing is that it can be cleaned and rust treated at its rear while off the car, and thus, this section will be well protected against further deterioration on its inner surfaces. The same goes for the rest of the inside of the wings, which will be easily accessible from the outside.
This was the impetus needed to get going; to have a plan, even if it needed modifying as we went along. Now, having cut the wing out of one side, it can be seen in new light. I am no longer sure that what we planned is the best thing. I am now in favour of making up a band of 2mm aluminium, seven inches wide, which will curve along the inner wing, to extend this all the way out to the new extension, without using the cut out piece, this not being quite so good metalwork wise as it might be, and not fitting quite as snugly as it might have been thought to do. This band of aluminium will be trimmed along the outer edge to meet the shape of the new arch extension, and bonded to it. The best way of doing this is yet to be discovered as we write. Cut out piece. 12th July 2009New aluminium arch seven inches wide, curved to meet inner arch and measured out with offsets to the grp overlay, marked out below. The arch is trimmed to about threequarters of an inch of the marked out line and bent over as a fixing flange onto the overlay. Bent into the curve along the top and outwards away from the arch at each lower end where the arch is close to the edge of the opening.Arch with final trim having a trial fitting. Only a few fixings in place. Eventually fixings will be at two inch spacings.
19th July 2009While all this was going on, thoughts were turned to how the arches would be fixed and lots of time was spent doing other things while trying to find something suitable. It is obviously of paramount importance that a mechanical fix of absolute maximum integrity would be needed in order that the joints would not crack out over time. Simon suggested that it should first of all be mechanically fixed using screws and nuts, countersunk into the grp, and then the whole would also have to be epoxied into place additionally.
A search ensued to identify the best sort of epoxy to use to stick the arches on. 3M products apparently make some of the best available, but these proved hard to find, and there are so many different ones that it was not at all clear which would be best.
I subsequently found "West System" products, and these came with ringing endorsements from Simon North, who had used it previously for all sorts of things.
This is marketed by Wessex Resins and sold by Marine Scene in Cardiff amongst others. It is a marine epoxy which can be used with lots of different additives for various uses. This is the base resin and hardener. 5 litres of resin and 1 litre of hardener, although they are officially mixed by weight rather than volume. Wessex Resins have a comprehensive website which includes a fully detailed user manual which is really worthwhile. All this clinched it.
4th September 2009.
For fixing the arches, "high density" filler was used, which is supposed to promote high adhesion. Glass strands were also added in the mix, for tensile strength and gap filling properties. The mix is made up to a very thick consistency so as not to run off. It is a bit like cold thick porridge.16th September 2009The instructions say to "wet" the surfaces to be bonded with neat mix before blending in the fillers. The neat mix is almost colourless and is like syrup.Slapping on the full mix. It was still a bit thin and is sagging, but it worked okay.After bolting the arch in place, which was very messy as the screws and nuts had to be put in through the wet glue and nuts put on the end with very sticky fingers. the excess glue was spread out and below is the result after curing and initial sanding. As can be seen, not much more filler is required over this.2nd October 2009Slapping on a layer of filler, below, which will even up the indents and the curvature generally. This is Dinitrol Aluminium loaded filler which seems to be very good stuff. Screws and nuts were installed at about two inch intervals, and these have to be filled over.After a layer of filler, Simon North came up and put the finishing touches to the curvature with a selection of body tools and lots of experience. I wasn't going to be happy to finish it myself as besides taking longer, I am not going to spoil this job by putting up with something less than perfect when a couple of days with a professional would put the edge on it. Below, it is shown almost finished but with some ground out holes where some screw heads were a bit proud. These will be filled and sanded again until perfectly flush finish to the exact curvature is obtained.17th October 2009Looking towards the front end, it was time to try the front wings for fit again. Initial trials showed that the wings were, as expected, a diabolical fit as we have already seen before. I was determined to use the full front wings firstly as preserving my as new steel wings would be a good idea, both for value and for future possible refitment, and also to see what it would actually take to make them fit and look half decent.The first impression was like this,below. Awful.21st September 2009
After some jiggery pokery, the door shut line was made parallel, although it was about half an inch wide! The stepped trim line is still pointing downhill however, and will have to be made up level with epoxy. This is only on the near side as the off side one is level okay.
The bottom fit is awful on the nearside one too. The offside one is almost acceptable, but on this side it sticks out and the flange is too low. This is to be cut off and rejoined with epoxy.The next two show the wing to scuttle connection. The provided angle is far too short. This was made up with epoxy and a steel bracket provided for the rear connection, epoxied in place. Extending the downstand with epoxy seems to have worked very well and the joint is very strong.26th September 2009After much fitting work, this is the best it gets. Not too good really, and some shaping in filler will be needed to make the scuttle and wing flush. That door shut line also needs sorting out. This will be done in epoxy. 26th September 2009Filler strip tee section courtesy of B&Q's tiling department. This will provide an original looking bead. The original section is shown to the right. To use, the edge was ground off over the full length, the start of which can be seen on the long piece. The bends were easily formed by heating with a heat gun while bending with ones fingers. It sets in shape nicely.14th October 2009This was epoxied in place and then filled to profile with Dinitrol filler.17th October 2009The door gap was made up in epoxy. In this picture, the profile of the door is transferred over to the wing, which is a bit flat in the middle section and will need profiling in filler. Simon migged up the trim holes while he was there.Looking at the front of the car. the grille would not fit with the wings in place and the bonnet side gap parallel and still too wide. The sides of the wing gap had to be opened out considerably. Below is a wodge of epoxy applied behind the cut out, so this can be opened out. virtually all of this had to be removed to make the grille fit.26th September 2009See, the bonnet gap is still too wide although parallel. This will need to be sorted out with filler strip.26th September 2009Filler strip applied with epoxy. This will now need filling to fair off properly and blend in. The bonnet gap is now much improved.26th October 2009The swage line which was miles away from matching the door, has been made up and reprofiled in epoxy. This will now be filled over and faired off,Rebonded bottom flange of the front wing, refitted after trimming, as the original fit was impossible.The front arches were left with a thin sharp edge and this looked unfinished. It was decided to trim this up with a bead. The bead used was the same B&Q tiling trim as used on the wing tops, and is seen in the picture below, both clamped in place for the epoxy to go off, and a separate strip below partially cut.
20th October 2009Preparing the underside of the rear valance for the fitting of the Sebring item. The holes are the fixing holes for the new Sebring valance.
6th December 2009
Set screws and nuts fitted to valance, below. These are fitted through the drilled holes and nuts further applied inside. A nut's thickness of epoxy fills the gap and bonds the valance in place.Epoxied in place, now, it can be seen that there is some more profiling to be done in filler. The curve down the rear is also rather "M" shaped, and so has to be filled out from the joint line to the tangents on each curve above and below.The outer edge of the valance just after fixing in place. Not a bad fit on this side.After much filling and sanding in quite a few layers, the result is very pleasing, below. The width of the necessary filling can be seen, in order to attain the correct curved profile.
1st January 2010General prepping of the whole of the rear of the car is progressing at the same time, seeing as this naturally follows on from the body conversion. Rubbing down by hand is underway, with block and 60 grit AlO2 paper. All prepping of the body is done by hand as described. The old layers of paint are blocked back to where metal starts to show through in places, and where only the original initial layers of paint remain.
In this way, most of the imperfections in the metal; the bumps and dips, are highlighted and mostly rubbed out level already, without further work to level the new primer, so reducing the work which will be necessary to flatten the filler properly and to rub off the guide coat later on. If you take it back to metal all over, firstly it is unnecessary where there is good underlying paint, and secondly all this levelling work has to be done with layers of applied primer. The emerging patterning in the layers and patches of metal which show through shows how many imperfections there are in the base metal panels. I found that doing the sanding with a flat electric sander is actually no quicker than doing it by hand, and there is less control, more dust and lots of noise. Doing it by hand is rather satisfying. Back around the front end again and the swage line is seen in almost finished state after realigning with epoxy and a good few layers build up in filler to profile it. At the bottom, the cill has been reprofiled to meet the bottom of the wing. This actually gives the cill a better line than it previously had, and gives the wing a virtually perfect fit. The gap line is also nearly complete, having been reprofiled in epoxy and filler. The bottom wing flange is still waiting to be trimmed off to the right depth though.Basking in the sun on New Year's Day 2010, in the new polycarbonate shelter, during work to the bonnet shut gaps.And again on the 2nd January, the bonnet shut gaps are now looking almost presentable.January proceeded in a leisurely fashion, not doing a lot until it was decided that the only major piece of prepping yet to be done was the door shuts and so it was time to take the doors off, seeing as now the line and profile of the wings was set.The doors are held on with pozidrive headed countersunk screws which are very tight. Some came out but others had to have a hex headed set screw welded to the head to get them to turn. They were very tight.
16th January 2010Some came out like this.And some shanks twisted and broke off without gettting very far. This was inspite of soaking in WD40. Heating is difficult too as you can't head the threaded block they screw into at all, only the screw, which is the wrong way round. The remaining shanks had to be drilled out with firstly a small pilot and then increasing diameter drills, as shown in progress below.One other thing
needing doing was to fix the aluminium brackets to the front wings
where they bolt onto the side of the front apron. No method of fixing
was provided on the moulded wings, and so these had to be made
separately. They were fixed with lots of epoxy with glass
reinforcement. Holes were drilled in the brackets for the epoxy to
connect through and provide more strength.6th February 2010