The donor used for the demonstrator was a base model year 2000 MK2 1.8.
Being a base model, the advantage with respect to the build, was that it did not have ABS, air con, central locking etc.making the stripping and fitting of the donor parts a little easier.
Several months previous to taking on the Replicar project, I had bought the MX-5 to use as a daily driver. It had only one owner from new, with a full comprehensive service history and new MOT. It also had a private plate and hard top (so was more expensive than the usual MOT failure type donor typically used. However, I recouped 2/3rds of its cost when it came to selling the parts not required - the hard-top fetching over £400 alone!)
Although the mechanicals were all in excellent condition and had proved themselves reliable over the preceding months, the body was beginning to suffer from the usual rot in the rear sills and front chassis legs - which is the reason I decided to use it as the donor.
Prior to starting the strip-down, all the body mounting nuts and bolts underneath the car were given a liberal dose of penetrating oil - as not only are they very tight but also very rusty from the years of being exposed to the elements. This would hopefully give the oil time to work whilst the strip-down takes place.
If you are intending to fully strip the rear hub assemblies to replace the wheel bearings etc; it is considered sensible practice to undo the extremely tight rear hub nuts at this stage - so as to take advantage of having the full weight of the car and handbrake to assist you.
However, having driven the car for several months, I knew there was absolutely nothing wrong with the bearings and therefore, in this case, there was no need to carry out this particular procedure.
To enable as much room and access as possible for the strip-down, the soft top roof and seats were removed first. Care had to be taken when removing all the trim and fastenings for the roof assembly, as many are hidden from view around the rear bulkhead and will prevent the roof being lifted away if missed.
The fuel tank access panels were then removed, along with the boot lid, rear lights and bumper etc. to expose the rear of the wiring loom. Any electrical connectors were labelled clearly first before disconnecting (- including any that are redundant) so as to aid identity when it comes to later re-installing the loom in the Replicar. The loom was then teased back through from the rear of the car into the cockpit area keeping as many connectors as possible still connected.
The centre console, carpet, doors and parts of the dash were then removed to further expose the wiring loom and allow access to it - especially that under the dash. Attention was then turned to the engine bay wiring, which again, was fully labelled before being disconnected and pulled carefully back through the bulkhead into the cockpit. Once freed from the dash panel, steering column etc. the entire loom could then be lifted from the vehicle and safely stored away in its own box.
Any remaining interior dash assemblies were removed along with the steering column and pedal box etc. so as to leave the interior completely stripped. The front bumper, lights, bonnet, front wings, radiator airbox, rear silencer and exhaust mount rubbers etc. were then removed so that the shell was ready to be parted from the power plant frame underneath. It was important to remember to remove the VIN plate and cut out the VIN stamped in the bulkhead itself. This was so as to remove the ID of the vehicle to enable the body to be simply disposed of as scrap metal and not declared as a scrapped vehicle (which would otherwise lead to complications when using the donor vehicle's details at the time of registration.)
The body mounting bolts and nuts, having now had a good long soak in the penetrating oil applied at the outset, were then cracked off using a breaker bar and deep six-sided sockets to help prevent them rounding off. The centre nut on each coilover top mount were also undone an initial turn or so before 10" long temporary struts made from steel tube were jammed in on each corner between the lower wishbone and subframe. These were there to take the weight of the engine/transmission/powertrain assembly and prevent it from collapsing to the floor when the body was to be lifted from it.The mounting bolts and coilover nuts were then fully undone and removed so that the body was free to be lifted.
An engine hoist was then manouvered into position from the side so that its hook hung above the transmission tunnel and a lifting chain attached across the transmission tunnel as described in the build guide.
With the addition of extra manpower to help balance and guide the body, the crane was then used to lift it up and away from the underlying power plant assembly. A local scrap metal merchant then collected and disposed of the body - freeing up valuable workspace in the shop.
Meantime, the fabricator had been busy tacking the chassis together in its jig. We decided it would be a good idea to trial fit the chassis to the power plant frame at this stage - just in case it needed any tweaking before being clamped back in the jig and fully welded together. I am pleased to report no tweaking was necessary - a testament to the skills of the fabricator and accuracy of the jig!
The stripping and reconditioning of the subframes and wishbones etc. could now begin.
Removing the wishbone pivot bolts proved 'challenging' to say the least -especially the rear outer lower wishbone (a common problem due to corrosion.) However, patience is the order of the day and using a combination of penetrating oil, heat, impact gun and long breaker bar, the bolts finally yielded and with further working back and forth, eventually loosened enough to be removed.
I decided that as some of the rubber bushes were showing signs of wear and having experienced the occasional creak or knock from the suspension whilst driving the donor, they would all be replaced with polyurethane bushes. Having done a lot of research, I settled upon fitting Super Pro bushes which although among the most expensive, were only a little dearer than OEM rubber. They are extremely well engineered and an accurate fit - meaning they will work correctly. Using a threaded bar with appropriate sized sockets (one slightly larger than the wishbone eye and the other slightly smaller than the outside dia. of the bush) the rubber bushes were drawn from the wishbones - which proved a long, labourious job as there are twenty two of them!
As I wasn't replacing the rear hub bearings, I disengaged the driveshafts from the diff and removed the driveshaft and hub carriers as complete assemblies (the brake calipers and discs having been removed previously.)
I also elected to keep the diff bolted to the Power plant frame's aluminium spine as I could see little to be gained from seperating them (apart from making it a little easier to clean and repaint the diff etc. - the bolts usually prove difficult to remove anyway) and ditto with the gearbox to spine mounting.
However, the engine and gearbox were seperated as I wanted to confirm that al the clutch components were indeed as new - as according to the service history, they had been replaced only a few months prior to my buying the donor. All was in order and it was also good to note that the catalytic convertor was a recent replacement too!
The GRP fabricator notified me that the body was ready to be popped from the moulds and would be available for collection in a day or two once the flashlines had been polished out. As the stripped subframes, wishbones and now fully welded chassis were ready for powder coating, they were loaded onto the trailer and despatched. The idea being that once done and collected, I could swing by the GRP shop on the way back and pick up the body - using the chassis to support the body on the trailer.
I have to say that I was really pleased with the quality of the work of both the body and powder coating - the wishbones etc. being unrecognisable from the rusty specimens they were previously.
Wishing to have a break from the constant cleaning and reconditioning of all the donor parts, I thought I'd do a little work on the body. As the new 7" headlight assemblies had just been delivered (if a MK1 donor is used, then the headlights from it can be fitted) I decided I would cut out the holes to enable the headlight bowls to mounted in their recesses on the body.
There are a couple of methods that can be employed to create the large hole required. One is to simply use a large core drill (160mm dia.) but that does mean there is little margin for error - so the centre has to be very accurately marked to ensure the headlamp bowl is mounted centrally (it is very easy to remove material - but very difficult to put it back!)
The other is the one I used - which, although is more labour intensive, means that any slight error in the initial marking out can be easily remedied during the drilling out process.
Firstly, the area was masked off and using the headlight's rubber mounting gasket as a template, the outline for the bowl marked out. The circumference of the hole was then chain-drilled using a 3mm drill before moving on to a step drill to remove most of the material around the circumference.
A hacksaw blade could then cut through the small 'bridges' between each of the holes created by the step drill. The rough edges of the large hole left were then smoothed back carefully with a powerfile until the final correct diameter hole was attained.
The headlamp fixing holes were then drilled and the whole method repeated for the other side. The headlamps were then temporarily placed in position just to give the car its 'face' before being removed and packed away safely until such time as required to be fitted permanently.
First job was to fit the polybushes to the wishbones (- a much easier job than the removal of the original rubber ones!) and replace the front lower ball joints with new. The upper ball joints only needed repacking with grease and fitting with new rubber dust covers.
Assembly of the subframes could then begin.
The rear subframe was assembled first before fitting it along with the freshly painted driveshafts to the diff using new rubber diff mounts. The diff, engine and gearbox had all previously been cleaned and freshly painted in an olive green to give them a 'period' look. The refurbed rear brake calipers and discs were then fitted along with new pads to complete the rear of the power plant frame.
Attention could then be given to the front:
Firstly, the refurbished steering rack was fitted to the front subframe. I was retaining the power steering capability due to the problem I have with my hands and thought it may also appeal to potential female customers or encourage wives/girlfriends to get involved in the building and driving of their partner's Replicar. To that end, I have added simple brackets to the chassis to mount the power steering fluid reservoir and these will also be included on all future customer chassis' (The customer can always de-power the rack if they prefer.)
The clutch and flywheel assembly was then refitted to the engine before it was re-united with the gearbox. Using the hoist to suspend the engine, the front subframe was offered up to it and secured using the engine mounts. The remainder of the front suspension components were added and the temporary struts once again fitted before lowering to the ground as a once again complete power plant frame.
Next on the agenda was to lay a large sheet of 1.5mm thick aluminium on the floor and sit the chassis on it to enable the accurate marking out of the outlines of the floor panels and chassis members within them.The floor panels were then cut out using air shears and using the marked outlines of the chassis as a guide, 3mm pilot holes drilled at approx. 100mm centres along all fixing points.
Templates were then used to mark and cut out the transmission tunnel and front bulkhead panels from the same 1.5mm thick aluminium sheeting. The tunnel and panels were then folded into their final shape using a press brake folder. These were also marked and drilled using the same method as for the floor - then trial fitted to ensure correct alignment with the chassis and each other. However, they would not be permanently fitted until a little later in the build.
The chassis was then flipped over so that the chassis floor was uppermost and the floor panels clamped in place before drilling 5mm dia. holes through the pre-drilled pilot holes into the chassis members themselves. Having then removed the floor panels to vacuum away any swarf etc, a bead of light grey Tiger seal PU adhesive was applied to all floor chassis members before the panels were again positioned in place. Large head 4.8mm dia. x 12mm long blind rivets were then pushed through each of the pre-drilled holes to ensure correct alignment of the floor panels and chassis. A pneumatic rivet gun was finally used on the rivets to permanently fix the floor panels in place.
The last job to be done before mounting the chassis on the subframes, was to consider how the front to rear brake and fuel lines would be run from in the transmission tunnel and what method of fixing to use. As there would be three lines (fuel supply and return plus a brake pipe) I didnt want to use individual P-clips for each line as it would look too cluttered and messy.
Rather than buy new (and expensive) 3-way clips, I realised that as I would be doing away with the carbon canister and associated pipework, I could modify and re-use the original 4-way retaining clips from the donor's fuel/brake lines. The original evap line from the fuel tank to carbon canister was covered in a plastic sheath which, conveniently, made it almost the same overall diameter as the 8mm fuel lines. Hence its redundant position on the outside of the clip could be used to move one of the fuel lines from the centre and its vacant position used for a mounting hole to affix the clip to the chassis.
To that end, the rusty mounting brackets were removed from the back of each clip and the clip backs smoothed flat on the belt sander. A 4mm fixing hole was then drilled through the clips in the position as described above. The clips were then offered up to the chassis in the appropriate positions along the inside of the transmission tunnel and using the pre-drilled holes as a guide to mark their centres, 3.5mm holes were drilled into the chassis itself. Stainless steel self tapping screws were then used to mount the clips.
Finally,the chassis was mounted on top of the subframes using high tensile (10.9 grade) button head set screws and nyloc nuts.
The rear subframe brace was then shortened, re-profiled and the cut ends re-flattened. They were drilled so that the brace could be attached to the tabs on the bottom rear of the chassis (again, using high tensile fasteners) - thus further stiffening the rear subframe/chassis assembly.
Moving on, the driverside lower aluminium bulkhead/footwell panel was permanently fixed in place using the same method as the floor panels (except using standard 4mm rivets.)
Next to be installed were the steering column and pedal box assembly. Initially,this all has to be loosely mounted before being gradually tightened - ensuring all the while that the lower column isn't binding where it passes through the bulkhead and rubber shroud. The rubber shroud is fixed in position by modifying and folding its original steel mounting ring so that it fits the profile of the bulkhead. Holes are then drilled through the bulkhead to align with the ring's mounting tabs and screws used to secure.
An aluminium sandwich plate was then made using an off-cut from the floor panels and a non-setting mastic sealing tape (such as used on caravan windows etc.) applied to the back of it to form a watertight seal between the clutch master cylinder and bulkhead.The brake servo and master cylinder was next to be installed and a square hole formed in the bulkhead to accept the accelerator cable's retaining clip.
To complete the rolling chassis, the donor's freshly repainted coilovers were re-assembled using a coil spring compressor. These were installed along with the anti-roll bars and new drop links. Work could then begin on making and fitting new kunifer copper brake lines.