A lot of people have asked me about MG TF Z, what it is under the skin, why I built it, and how it all came together. So here it is-


By Dave Dodd/Australia

I'd always rather regretted swapping my TF l250 (now owned by club member John Buxton) for Geoff Roud's Variant (23 ft keeler, not the car). Not that we didn't enjoy the boat. We owned it in fact for eight years, did trips as far afield as the Bay of Islands, and made many new friends through Richmond Yacht Club.

A lot of time and effort had been put into rebuilding the car. It had introduced me to the MG Car Club back in 1974, and we'd had a great deal of fun in it. I'd considered restoring another TF, but on checking, found that although there were suitable cars about, people seemed to think they were made of gold. They were asking what seemed at the time, to be astronomical prices, for what were really basket cases requiring rebuilding from the ground up. We didn't have too much of the folding stuff at that stage, and I was discussing the problem at morning tea one day with some of my colleagues at work. Now I'm not sure who it was that actually said, "Why don't you make one" but that was how it all started back in February 1980 or thereabouts.

Initially, there were three of us involved who were keen on the idea, and we spent a considerable amount of time, deciding just how we should go about it. Working where we were was a bonus, since it meant access to metal working equipment and machinery for making parts. Between us we had a considerable range of skills, and this would be a chance to exercise and improve these. Motor and gearbox etc. would come from a vehicle of about the same vintage and after much debate back and forth, we settled on an MG Magnette as the donor car. There were probably three main reasons for this.

1. It would contribute all of the major mechanical components, which would of course be genuine MG. These would include the later BMC B Series engine and gearbox, parts for which would be a lot easier to come by, than the original T Series units. Since we expected to produce a car of much the same weight as a standard TF, the 1488 cc engine would give comparable performance to a TF1500.

2. The track width of the Magnette was only one inch wider that the TF and we could accommodate this quite easily in a TF body. Although the wheelbase was longer, this would not present any major problems, since we had to build a chassis anyway.

3. There were quite a few Magnettes going rather cheaply at that time, and in fact the dearest one we purchased was only $450. We must have started a run on the market, because suddenly the price of Magnettes seemed to shoot upward to around $900 or $1000.

The first major area to be considered was the chassis, which would be the backbone of the car. We decided to use the complete Magnette front suspension arrangement, incorporating the front cross member into a fabricated chassis. This would provide, we hoped, a considerable improvement on the original TF suspension system. It incorporated a standard double wishbone and coil spring with telescopic dampers, as well as upper and lower tie bars back to the chassis. One problem to overcome was that the Magnette was around 4cwt (200kg) heavier all up than a TF. The engine in the Magnette is mounted partially over the cross member, and hence the whole system, and in particular the front suspension, would be considerably stiffer that the TF.

Knowing how my original car handled, and after having seen photos of it cornering at Bay Park, I'd always felt that the front suspension on the TF wasn't really stiff enough. Even so, the Magnette suspension would probably be too stiff, and certainly the ride height would need adjustment by resetting the front coils. It was quite easy to measure the weight distribution on each wheel by incorporating a simple pressure gauge into a small hydraulic jack, and the large tensile/compression tester at work made it very easy to check the spring rates of TF versus Magnette. After checking the geometry and relative forces involved in each arrangement, and after much cogitating, we decided to go for simply re-tempering and resetting the Magnette coils by lowering the free height. By cutting down the rear springs, which were conventional semi-elliptic to TF length, and removing the second full-length leaf, we obtained approximately the same stiffness in the rear as the original car. In operation, the suspension is certainly stiffer that the TF in the front end, with much less body roll on corners, although still providing a comfortable ride.

The design requirement for the chassis then, was to incorporate the Magnette front cross member into a steel ladder type framework, which duplicated the TF unit, providing the required mounting points for a conventional TF body. This was made from 4" x 2" x 0.1" steel purlin sections with cross members and scuttle support bar from 1.625" x 0.125" heavy wall tube. Body support brackets etc. were made up from 0.100" flat sheet. The real TF chassis section reduces over the rear axle and down to the rear spring hangers, but for ease of manufacture, we maintained the same section throughout. This was to cause some problems later on, but by February '81, we had a rolling chassis.

The body was to follow the TF as closely as possible. This consisted of wooden frames mounted on an angle steel sub frame for support, with steel panels folded over the wooden formers. I was fortunate enough to have obtained an original TF scuttle some time in the past from Russell Ward, who had recovered it some years previously, from a car wrecked somewhere down near Turangi. It was rather badly bent, but recoverable, and to the purists I usually say, that I've actually rebuilt that particular car from the scuttle downward (with a few improvements on the way.) The wood frames were cut from patterns, using treated kauri, which was in turn, treated using Epiglass Evidure (two pot epoxy). I'd used this before in boats and it gave the wood a really hard dense and durable surface. Hopefully this would make it last a lot longer than the original ash framing, which in many cased ended up as a pile of sawdust, when the vehicle was dismantled. Obtaining patterns for these and the body panels was not difficult, with plenty of help from fellow MG Car Club members, who had their cars in various stages of restoration. Ernie Martin was of immense assistance here, and I'm extremely grateful to him for his help.

Making the panels was a long time consuming job. I'd already done a 4 term series of Vintage Restoration courses at Manukau Tech with the original car, and this was obviously worth repeating. These courses were, and still are excellent value, as those club members who completed the recent course early this year have discovered. Not only did they teach you the basic metal working techniques, but provided access to specialized machinery, such a rollers, wheeling machines, and folders etc. We had a further advantage, in that working for AIT gave us reduced tuition fees, and all up we spent around three years, working one night a week, to build up the body panels.

Although it looks difficult to construct, the radiator surround was not the most difficult part to make. The prize here would probably be shared equally between the doors and the rear quarter panels. These not only have curves from front to rear, but also slope inward and curve from top to bottom, with a tricky roll in the top section. One of the problems, which eventually confronted all TF owners with the mounting of the doors, was that the hinges were bolted through metal-wood-metal sandwiches. These tended to crush, due to the light gauge of metal used in the original section, and in order to prevent this happening, a 0.125" reinforcement was attached at the back of each section. In retrospect, it would have been even better to include captive nuts for the hinge bolts.

Two other modifications were made. The engine side panels were split along the line of the front wing, and the upper portions were then pinned along the join to the lowers, and held in place on their upper edges by Dzus fasteners. This was intended to allow greater access to the engine compartment for maintenance, and I've already been grateful that we did this. The second was to split the short upright panel behind the seats. This passes over the transmission tunnel, and is attached to the two box sections reinforcing the rear quarters, directly behind the doors. This was cut vertically and overlapped on both sides at the line of the sub frame, and means that it is much easier to remove and reassemble a rear quarter panel, if this is ever necessary. One further unplanned modification was needed to position the petrol tank at the correct relative height to the body. To do this, it was necessary to slightly recess the upper surface of the chassis rails below the tank. This was because of the non- tapered rear chassis section.

The petrol tank itself was rolled from one complete sheet with internal partitioning to provide baffles plus reinforcement. End caps were soldered in place, as was the drain and internal float from the Magnette and rather than a light, the sender drove a petrol gauge incorporated into a redesigned dash. One piece of luck at this stage was to locate a Wolseley filler cap, which apart from the letter "W" pressed into its stainless steel top cover, was identical to the TF unit. Some very precise panel beating and repolishing soon got rid of this.

Perhaps the last major change in the body was to make the front and rear wings from fiberglass rather than steel. The thinking here was that in the event of a shunt (heaven forbid), these would probably be the panels which would suffer most. I'd made up a steel front wing and it was an extremely long job, needing around 10 separate panels to be formed, joined, and beaten up, and even so, I wasn't overly happy with the end result.

We had fiberglass moulds made from original wings and then ran off sets for each car, (there were now only two of us involved) storing the moulds for possible future use.

I hadn't realized it at the time, but someone commented recently that the vehicle must be authentic, since it had the slightly different offsets from the radiator surround to the headlamp fairing of the original cars. Had I made steel guards, they would have been identical.

Anyone who has ever rebuilt a car will know how much room they take up when disassembled, and our garage and under house looked like Aladdin's cave or the hanging gardens of Babylon, with panels etc. stored in every available space. It stayed this way for some time, while we concentrated on fitting the mechanical components into the chassis with only minimal assembly to make sure that clearances etc. around the drive system were sufficient.

This then was major area number two. Fitting the engine and gearbox into the chassis. We had looked at this in preliminary detail and had been intrigued to note that the underside of the gearbox casting had a semi-circular recess just in front of the rear mounting point. When the units were fitted to the chassis, this recess lined up perfectly with the main cross tube carrying the gearbox support brackets. We couldn't help feeling that MG may have intended to put the B Series engine and gearbox to the TF at some stage.

Rather than using an engine mounting like the TF which required an engine steady box, two metallastic mounts were used set well apart on the front cross member. With substantial brackets bolted fairly high up on the engine front plate, the engine shows no signs of requiring a steady. (I was rather pleased about this later when fitting the carburetors and air intake to the engine, as there is minimal clearance for the front carburetor). The rear gearbox mounting is a single tube type metallastic unit as per the MGA/B arrangement, and once the rear axle and diff had been fitted, it was quite a simple job to get the drive shaft cut down to the correct length and balanced.

Garth Bagnall of Bagnall Motors did all of the work on the engine and gearbox. The 1488 cc Magnette engine was bored to 1622 cc to suit a set of MGA pistons and rods (which were polished and balanced). The original crankshaft showed up with a crack when tested, but I was fortunate enough to find another one, which had not been ground and was still standard. Garth had a 717-grind cam going relatively cheaply and we fitted an 1800 Morris Marina head, which has larger valves, and a better shaped combustion chamber than the Magnette head. The manifold and carburetors are standard MGB and Woolf Mufflers Ltd made up what is effectively a straight through exhaust system with B type muffler and resonator.

The gearbox was in reasonable shape. However, the lay shaft showed signs of wear and required replacement and a stronger design shaft with an extra set of needle bearings was fitted. This was a modification, which Garth had learned of from his Australian contacts and makes for far less bending of the shaft, and hence less wear. Apart from replacing bearing and seals and one synchromesh cone, this was all that was needed.

The net result of these engine mods was only apparent at some considerable time later. After the engine had been run in, we took the car out to Henderson, where it was dyno tuned putting out 80 BHP at 5000 rpm at the drive wheels, requiring only replacement of the carburetor needles and a modification to the distributor advance curve. My estimate for losses in the transmission is about 20%, so the estimate is around 100 BHP at the flywheel. With the increased power, I was concerned that the braking might not be adequate. However, the car all up weighs 900 kg or 17 1/2 cwt. This is nearly 3 3/4 cwt less than the Magnette which improves the braking effect from 6.32 square inches /cwt to 7.68 (or by approximately 21%).

Although the stopping power appears adequate, it requires quite a lot of pedal pressure, so the present plan is to fit a PBR VH44 remote booster unit into the brake line as the brake/clutch master cylinder was fitted into a floor mounted pedal box and there is not sufficient room for a combined master cylinder and booster. This will increase the braking pressure by a factor of almost 2.

The handbrake system for the Magnette required only minor modifications necessitating new cables and a modified linkage system. The only snag here is that unlike the fly off unit fitted to normal TF's it is a conventional ratchet unit needing the button taped up for handbrake turns.

As the Magnette radiator was not suitable, a new triple core unit was built up to suit the available space. Together with a 7 blade MGB fan and an overflow reservoir, cooling appears to be satisfactory although it does get a little warm idling in heavy traffic.

The other major mechanical component was the steering system. Whilst maintaining the original Magnette rack and pinion system, the change in both motor position and driving position required replacement of the original steering column with a new unit incorporating two universal joints. This allowed clearance past the distributor, and has provided a smooth and responsive steering action.

Having sorted out the basic mechanicals, the next step was to consider the electrics. It was quite easy to modify a standard TF wiring loom to incorporate the few extra components fitted such as key ignition, conventional wiper motor, high level stop light, reversing light, etc. I did however come unstuck slightly when finally connecting it all up. There are two connections for the wiper unit, which has an auto park function, which I managed to reverse. It worked fine when first turned on but on reaching the park position shorted directly to earth. The burning smell and smoke from the cable had me hurriedly killing the power. Fortunately I only had to replace the two wires although this meant undoing a portion of the loom. Curses!

The instrument panel copied the TF one in many respects although I wanted to incorporate a voltmeter and petrol gauge. I found a complete set of Smiths instruments (apart from an ammeter) from a Triumph 2.5 PI which were suitable, although it was necessary to change the electric tachometer from 6 to 4 cylinders and to recalibrate the speedometer to allow for the change in gear ratios and tyre size. The ammeter to match the rest of the instruments came from an early Jaguar. I'd made provision for, and fitted a sender unit into the sump to measure oil temperature, but so far have not incorporated a gauge to check this. Light switches, horn and indicators switches all duplicated the TF. The only real problem was to incorporate a petrol tank sender unit into the mounting arrangement on the tank. This was done with an adaptor plate which caused difficulties in sealing, as it is permanently subject to fluid pressure in the tank, being mounted low down on the front side of the tank, rather than through the top as per the usual set up. I tried a number of different sealing compounds but seepage caused paint problems around the unit, until finally using a neoprene packer and Loctite Master Gasket, which overcame the problem.

The next stage of fitting the body was a bit like doing a complex jigsaw. You know that all the bits fit together, but you have to use the correct sequence and not only that, but get the alignment right so that bits not yet fitted will be correctly positioned. This in some cases meant minor modifications, but on the whole it went together remarkably easily. The first part of the exercise, which is critical to the fit of the rest of the panels, is the main body tub. This is mounted in three places effectively - front, rear and just behind the doors. There is a "hinge" point between the front and rear quarter panels here, and by judicious packing and adjustment it is possible to get the doors to position correctly in their openings. This can be modified slightly by packing under the hinges where necessary. The doors themselves incorporate an adjusting diagonal brace, which allows alignment in the vertical plane, and providing the hinge holes are drilled in the correct position, allows for a neatly fitted door.

The TF door hinges are normally painted the same color as the car, but I'd decided to plate them, as the paint always seems to chip off. Plating was a hassle however, as initially the electroplaters simply plated them in an assembled condition. This of course left unplated areas when they were opened and closed. Upon pointing this out, they rather ungraciously agreed to plate them unassembled, following which of course, it was impossible to reassemble them due to lack of clearance for the pins. At this point I decided to fit stainless steel pins rather than extend the argument.

Although many parts are available from overseas sources, they are in most cases highly expensive and for this reason many of the body fittings were cast locally using existing parts for patterns. Our friendly foundry man did these in phosphor bronze, which is certainly harder and stronger than brass. This meant however a great deal of time spent in cleaning up and polishing these prior to machining where necessary, and subsequent plating. This was OK, since one thing we had was plenty of time, and so items such as taillight plinths, windscreen supporting brackets, side screen wing nuts, tank strap supports and badges were done this way. Other hardware such as door locks and striker plates were bought in from Moss Motors Ltd, as were the bumpers, over riders and sidelights. One item, which was (and still is) unavailable, was the windscreen frame extrusions, and short of having a special die made to extrude these, we were faced with fabricating similar sections from standard alloy extrusions. These were glued and screwed together, and when completed were metal polished and clear powder coated. This has not proved ideal, as the metal has oxidized in places where the glass fitters chipped the powder coating.

The glass of course has to conform to NZ transport regulations. Although there should be a convex curve across the top of the screen, this has not happened so one further area of improvement is to obtain (somehow) a set of proper extrusions and redo the screen (Does anyone out there have or know of a source?)

The upholstery and trimming is always an enjoyable area. There is the feeling that this is the last job to do prior to completion of the vehicle. The seats are modified Triumph Toledo and it was quite an easy matter to make up a suitable mounting to provide fore and aft adjustment. Trim panels are made in the usual way, using sheet ply or heavy upholstery tarred panel/card material which is then covered in vinyl.

The beading used plastic tubing of the correct diameter and matching tape was readily available. Probably the most difficult parts were the door panel sections which my wife Stephanie sewed up, incorporating the usual pockets, and which required about five hands to fit successfully to the ply panels.

One main body panel still to be completed was the gearbox cover. The gearbox and clutch were modified to use a side entry gear lever with an MGB slave cylinder rather than the original Magnette top mounted lever system. This made the cover a relatively easy job to do in fiberglass, requiring only a cutout for the gear lever and mounting holes to be drilled. Incidentally, the gear lever was shortened and bent backwards slightly to obtain the best position when changing gear.

The hood and carpets were one area that was left to the experts. The hood frames and bows had already been made up. The bows were quite a tricky job being rolled from tube and then curved and flattened at the ends. The frames are also difficult, having to concertina properly when folding the hood down, but having an original to copy made this a lot easier to get right. The underlay and carpets were really well done but the hood and tonneau cover were disappointing in some aspects. The hood appears to

have shrunk since it was fitted and I suspect this is because of the way in which it was cut from the material. Unfortunately I didn't have a tonneau, which could be copied, and the method of shaping the rear section was not very well done. Another job to attend to in the future!

One last area, which I haven't covered yet, is the painting. The paint used was a 76 General Motors Carnation Red in ordinary 93 spraying enamel with appropriate primer/surface undercoat. It's interesting, that the same color in a synthetic gives quite a different shade. The enamel was chosen since I was going to do it myself, and our yard looked like a mad washer woman’s, with bits of car hanging from lines strung between the garage and the trees. It should also be easier to repair/repaint sections following any dings (who, me??). One problem, which became apparent, is that all panels should be painted as positioned in their usual orientation on the car, as they seem to show up with slight variations in color tone when repositioned on the vehicle. I should also have given the front guards a few more coats, but had got to the point where I needed to get the car mobile for its LVV certification. One of these days I'll get round to it, but it's very difficult to pull it off the road again.

The April 1995 MaG contained quite a useful article about registration of vehicles and requirements for VIN's (Vehicle Identification Numbers). One category it didn't really cover however was that for LVV's (Low Volume Vehicles) which includes one offs such as mine. Fortunately, in 1991 I'd gone to a car show in Auckland's Greenlane, where the Sports Car Club of New Zealand had a display with quite a lot of information on the requirements for certification. They have spent considerable time and effort working alongside the road transport people on this area, obviously figuring that this was the best way to have input into the final regulations. If you are considering building a special or even modifying an existing vehicle you should talk to them (or some other authorized body) as a first priority. Briefly, you will need to submit plans with relevant engineering calculations for approval, they will carry out a series of inspections as manufacture/assembly progresses, with a final check and road test on completion prior to issuing a VIN and identification plate for the vehicle. At this stage you can obtain a VIC (Vehicle Inspection Certificate) and WOF (Warrant of Fitness) at the local garage followed finally be registration. There is of course a cost involved in obtaining a VIN, and to some degree this will depend on the complexity of your proposal. Vehicles that incorporate matching parts (i.e. all componentry from one donor vehicle) are more easily certified than those, which are a mix of components.

Insurance was interesting with conventional companies uninterested. A policy was eventually arranged through the Car Club insurance scheme run by Garry Mooney Ltd for an agreed sum under their limited mileage option.

Would I do it all again? The answer on reflection is probably no despite a surprising number of requests for this.

What did it cost? Having done the exercise over approximately 12 years it didn't seem like I'd spent a lot of money and all up the cost was below NZ$10,000. However, if you conservatively estimated only a couple of hours per week over this time, the labor cost still comes out at over NZ$20,000.

Would I sell it? I don't think so, even though everything has its price. After all that time and effort, it would be extremely difficult to part with. Besides, my kids would probably kill me.

Why is it registered MGTFZ? Simple really, it's basically a Z type Magnette that looks like a TF.
The Magnette used to built the TFZ was in a very rusty condition and it was on it's way to the wreckers. Mechanically, it was also in a verybad shape and I had to rebuild almost all the major components, as well as suspension, steering etc.
I have retained the chassis no. on the ar, on the TF identification plate, as the car number. It was KA BB 23 29847.

When am I going to stop rabbiting on? Right now - hope you enjoyed the article.



Capacity 1622 cc

No of cylinders 4

Bore and stroke 76.2 x 89

Valve gear OHV, pushrods

Compression ratio 8.9 to 1

Camshaft 717 grind

BHP 80 HP @ 5000 rpm (at rear wheels)

Carburetors Twin SU HS4 Semi downdraft

Exhaust Free flow twin pipe from MGB manifold, muffler and resonator


Clutch Borg and Beck 8" dia single dry plate diaphragm spring type

Gearbox Four speed synchromesh on 2nd, 3rd and top

central floor change

Overall ratios Top 4.55, 3rd 6.252, 2nd 10.074, 1st 16.562

Reverse 21.658

Final drive Hypoid bevel 4.55 to 1


Steel ladder type


Front Independent coil spring and wishbones

Telescopic dampers with upper and lower tie bars

Rear Semi-elliptic leaf spring

Telescopic dampers

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