Part Two Of Daves Fiat 500 Restomod Projects | 18 Minute Read

Following on from the Moretti 750 in my previous post we have here what must be the ultimate Fiat 500 Restomod.  Built by the same man and nearing completion this year….. 2017 will mark 50 years after the Moretti…..but absolutely well worth the wait.

Sadly, the loss of institutionalised memory in the vehicle development side of the South African motor industry is a reality. Spawned originally from a series of local content programmes starting in earnest in the mid 60’s, the industry generated a first world technical activity on the tip of the African continent which at its peak could match any in the world and along with it creating a unique breed of engineers. We have come to see greater direct involvement by the big Brands in local manufacture and the flexibility given to local engineers tailoring vehicles to unique South African conditions has all but disappeared. Further, the engineering divisions in motor companies locally are shrinking and in some cases becoming tech post-boxes in the link between the mother ship and local suppliers. That’s not all bad though because vehicle design quality is reaching levels where special application engineering is, to a large extent, no longer required. That does not alter the fact that we have lost a portion of the industry and very special people the likes of which are unlikely to be seen again……that’s the downside.

The upside is what we are going to see in this posting…..many of the engineers schooled in the business of developing vehicles locally are still around and this story is the product of that engineering brilliance dosed with a dash of passion for creating something special.

Retirement in the strict sense of the word has not stopped Dave’s enthusiasm for continued involvement….. and after building his  retirement home overlooking the sea outside Port Elizabeth…. In his own words, “the garage was to be used for parking cars”….or that was the plan…. but was interrupted   “ I needed to swing that spanner arm”….proof that once an enthusiast, always an enthusiast…..but now with the additional spice of being a very competent and experienced motor engineer.

First Appearances can be misleading…looks like a stock Fiat 500 with alloy wheels….. but the sharp-eyed will spot a clue behind the spokes on that front wheel…..and that red roof…..read on.

The natural choice of vehicle for the project was an easy one for Dave and I remember visiting him a good few years ago and seeing this rather forlorn Fiat 500 body shell painted in Royal Blue stashed in the corner of the ‘garage’, soon to become a workshop. This, at the time, looked to me to be an ideal “rebel without a cause” project, with Dave threatening to install a monster power unit into the unsuspecting shell….. It took five years of planning, design and hard work to produce what the Italians would call an “Undici Cento” version of the Nuova 500….an 1100cc mini-monster which, strictly speaking should be named “SEN HYAKU” after it’s 1127cc Suzuki GSXR powertrain.

That Suzuki GSXR 1100 powertrain neatly installed in the stock engine compartment.

Bolting big engines into small cars has been the Hot Rodder’s standard mantra since the dawn of the car game… this was a little different though…and was about bolting a ‘small… but very angry’ engine into a tiny car…. as we all know, it has the same result. We need to stop the bus here because engine swaps can be done well…or…. very badly… and I guess as enthusiasts we have seen many of the latter, the good ones are less common but unquestionably remain etched in the memory

For me, the previous ‘number one’ slot in this regard was Basil van Rooyen’s conversion of a stock Firenza 2.5 Coupe into the first prototype Can Am in 1972…the key?…attention to detail. That job was done brilliantly and Hennie van der Linde had a major part in that detail which went a long way to convincing the GM engineers to arrive at proof of concept. (more on this story in future posts)….

It largely depends, therefore, on what the architect of the conversion really wants out of the task and in this particular story we cover a peach of a conversion which tics all the boxes…..

Dave’s latest conversion of the ‘500’ is a lot more than just an engine swap. That the task was accomplished in a residential garage is astounding because it encompasses a complete redesign of both front and rear suspensions and brake system in addition to the Engine and transmission installation….

Let’s start with that Engine.

After making the decision to go big or stay out of the garage on this one, Dave researched the bike world on the most appropriate mechanical package to use for a conversion and the numbers soon came back in favour of the Suzuki 1100 GSXR. The word is that the clutch arrangement on this unit is the most robust of the superbikes and in similar vein, the gearbox is also pretty tough and the engine has a reputation of being rock solid.  A suitable Engine/transmission was located in Cape Town if I remember rightly and work began.

The first order of business was the cooling package. There is a big difference between having an engine mounted in a motor bike right in the airstream and that same motor stashed in the back of a car. With the primary decision to use the GSXR powertrain for that overall robust reputation, there was also the bonus that this was not a purely air cooled motor. The engine is unique in the superbike world with a combination of both air and oil circulation to effect overall engine cooling. Dave figured that by ducting air to the substantial oil radiator mounted on the side of the engine it would keep things under control.  There was therefore no need for a front mounted water radiator as used on the Moretti.. An electric cooling fan supplies air to the system and also doubles as an air feed to the carbs. Initial ducting has been briefly tested using thermocouples to assess engine oil and cylinder head temps….. and so far so good.

The 1100 Suzuki engine showing the effective oil heat exchanger which cools the engine. 

Of course the magic of using a Bike engine/transmission as a unit is the compact nature of the assembly, with a single output chain drive cog ready to transfer power to the drive axle.

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Drive to the axle shaft runs through a Cushion device via two chains to reduce transmission shock loads

Drive from this output sprocket on the gearbox is by a sequential two chain set-up driving initially to an interim cushion hub, with the second chain driving from the hub to the sprocket on the axle differential shaft. Typical of the man, mechanical sympathy is in his blood and whilst conversions of this nature have been done with direct drive from the output sprocket to the diff shaft, Dave’s design minimises shift and drive shocks to the transmission and clutch.

Next we get to the subject of gearing and the choice of drive sprocket sizes. This particular engine is the 137Bhp version (that’s 117 Bhp more than a stock ‘500’) and given the size of the car, that power would result in a  top speed of over 200Km/h, something Dave is not interested in doing, so the gearing had been adjusted to a max speed of 171 Kmh at 9000Rpm or 190Kmh at the red line of 10 000Rpm. This Final set up being more of a balance between first gear gradeability and top gear noise levels than the desire to wring out absolute maximum speed.  Besides….once on full song, just imagine the sound of those close cogs rapidy playing with those engine strings.

Gear   Km/h per 1000 RPM  Km/h    –  

         1000              9 000         10 000

1         7.25                 65                   73

2        10.59               95                   106

3        13.83               124                 138

4        16.61                150                166

5        18.97                171                 190

That max speed in second gear bodes well for a 0-100 dash being completed in just two gears.

Initial shake-down tests have shown the gearing choice to be good. Whilst carefully trying the machine out recently, the superbike sounds of the engine and close ratio gears emanating from this machine make for  spine tingling stuff according to Dave.   The sequential gearbox is a gem, requiring a forward push for upshifts and rearward pull for downshifts.

Reverse gear: There is no reverse….but then again the car weighs in at around 550Kg and is physically tiny….so the lack of reverse is unlikely to be an issue.

Just for the record….. power to weight ratio of this 500 in ‘old speak’ is 8.9 lbs per Bhp, that is in the same ballpark as a Chevy Can Am and a little better than a BMW M2. So… if you let it all hang out, 0-100 is projected to be in around 4.9secs with a ¼ mile in the mid 13’s.  That’s the theory.

At this point you are probably saying to yourself  “that is all very well but how does one keep this screamer on the road and more important, slow the machine down..”……easy…..you have Dave.

As a development engineer specialising in suspensions, wheels, tyres and braking, my first recollection of the man doing his thing in his chosen field had to do with a severe wheel shake harmonic we were experiencing in the development 38/4100 Chevs of the early 70’s. This was the Opel Rekord/Commodore body shell fitted with the local Chevy straight six. The front end of the car was sensitive to a 15Hz frequency which, when provoked, set the front end jiving, resulting in a serious steering shake. Careful wheel balancing helped but the first harmonic of the wheel/tyre caused a vibration in sympathy with the front fender assemblies…. easily also induced by road input. With the vehicle launch drawing nearer drastic action was required.  The original ”final solution ” had been to attach a lateral ‘mini’ damper to the cylinder head and locate that on the inner wheel well in order to damp the lateral engine shake….this was expensive, looked terrible and induced a certain amount of noise into the cabin…..it was also something of a committee design at the time.

In one of the many Development stories I will be posting on the history of work conducted in engineering in the old days, this one took three to tango.  Dave is also something of a Noise and Vibration expert and in conjunction with the body engineers, worked out that the shake was caused by the front end moving forward of the bulkhead. Two corner stiffening box sections were introduced into inner wheel wells and “straddle” engine mounts designed to move the mounts off the engine X- member and onto the fender longitudinals.. These two mods stiffened up the front end and importantly changed the natural frequency …..80% of the problem solved…. for the rest it was up to the suspension group to suss out why perfectly balanced wheel assemblies still showed signs of imbalance.

Along came the first car in SA to introduce radial force variation (RFV) matching on wheels and tyres ……the 38/4100 series, courtesy of Dave. What he and the team had found was that due to the large 14” rubber used on what was a relatively light body structure, the inherent sidewall stiffness variation in the rotating tyre assembly  had sufficient energy to induce a phenomenon akin to steering wheel shake. To cure this we had a real case of two wrongs making a right. Steel wheels have a natural characteristic in having a measurable high point on radial run out…it’s part of the process inherent in any steel wheel manufacture. Similarly, tyres have a characteristic as a result of the lap joint, which changes the sidewall stiffness ever so slightly as the tyre rotates. By fitting the tyre on the rim at specific ‘high’ and RFV points, the two cancelled out the energy transfer. No more vibes.

So we have a thinker and a problem solver here and as we go through the 500 Testarossa’s design pedigree you will see just how talented is this engineer.

Dave’s Italian leanings facilitated the next piece of magic….the decision on what type of rear suspension to use……. an Alfetta gave up an ‘A’ frame De Dion rear end complete with inboard discs and differential. The unit was cut, re-jigged and welded to cater for the narrower track width…. giving this baby a pretty sophisticated rear axle arrangement.

The Alfetta ‘A’ frame DeDion rear axle cut and reworked to fit the 500 wheel track

Alfetta inboard disc brake arrangement with differential in place mounted to De Dion rear end. Note the cooling fan supplying cool air via ducting to Engine compartment

We will get to springs in a moment but let’s have a look at the front end….. the Italians did not get this one….the Germans did. Front end is Golf 1 lower control arm and vented disc brake arrangement. Dave designed an upper ‘A’ arm to make the front end a twin arm design able to facilitate caster and camber adjustments. The upper arm bolts to fabricated brackets mounted on the inner fender wells and the rest of the assembly bolts to a beautifully crafted subframe.  Steering comes courtesy of the Italians again and a fascinating solution to the car being too narrow to accept a conventional rack and pinion steering box. The answer?….an  AlfaSud rack and pinion on which the steering arms locate in the middle of the rack  assembly, solving that problem and providing a simultaneous solution to controlling bump steer.

The subframe – designed to carry the front suspension lower control arms and  the AlfaSud Steering Box

Installed front end showing the long steering arm connecting to the AlfaSud steering box and the suspension pushrod running vertically through the A Arm

If at this point you are not scratching your head in amazement, the next step in this wonderful project will most definitely get your attention.

Now the springs…..both front and rear are horizontally mounted coil-over units driven by Formula one style pushrods…..connected via bell cranks…..to the de Dion rear end ….and lower control arms in the front suspension…..  Dave had to do some juggling of the spring rates to get the front/rear balance right but when he says it feels great, believe me it is.  The front assemblies hide under the hood and the rears inside the passenger cabin in place of the rear seat.

Brakes…when you consider that the brake package fitted to the ‘500’ Testarossa could stop a car having more than double the weight with ease, this combination only requires front/rear balance to be extremely effective. The choice of master cylinder was a difficult one and Dave’s calculations of caliper bore sizes ended at a single master cylinder sourced from a Ford Anglia as being the best match and fitted without a booster. Again the brakes feel sensational but may need final tweaking when serious testing begins.

VW Golf Vented Front discs

The fuel system. Feeding those carbs became a bit of a juggling act, there was no gravity feed to the engine as there would be with a motor bike and initial electric fuel pump pressure proved to be excessive. So a redesign of the fuel delivery system to approximate the pressure and delivery of the bike application was necessary, this needed a high volume, low pressure arrangement to prevent flooding. The standard ‘500’ fuel tank could not be used in its application under the bonnet and from the pics you can see the 26 litre aluminium version designed in its place to clear the coil-over units. Dave has also yet to evaluate the performance of the carburettors under high G cornering where the carbs remain roughly horizontal in the car application and where, in the bike fitment, the floats always see positive G-loading due to bike lean.

The bike carbs with ram tubes actually fit inside the stock engine compartment as shown but require a remote aircleaner and airbox arrangement which protrudes through a neatly contoured aperture in the engine cover. Again this looks somewhat menacing and makes a statement along with the exhaust system.

The Carburettor airbox

The exhaust system is just another work of art. Dave retrieved some of the original Suzuki bike muffler internals and grafted those into the design of the new stainless steel assembly…..and already the resulting sound is spectacular. Overall, the back end of the car looks purposeful, neat and carries a serious amount of intent. Reminds me of the days of 1300 Gordinis on the street.

David has exercised his creative licence at the business end of the machine. The three signature features being the airbox, that gorgeous exhaust system and finally the cooling slots, all signalling serious intent.

Two shots of the exhaust plumbing….. the RH pic shows the neat gear/chain protector and the rear drive axle

Engine cooling is as much about aiming cool air at the mechanicals as it is in getting rid of the hot air so as maximise air flow. The lower portion of the engine cover is a natural low pressure area hence the slots to evacuate hot air. The number plate will be mounted on spacers to keep those slots open.

The Aesthetics:

Firstly the stance of the car on the 175/50-13 Yokohamas was specifically intended to allow the wheel/tyre assemblies to fill the standard mildly flared wheel arches. So neat is the final execution that one would almost assume that the fenders have been doctored to look this way. Ride heights are adjustable front and rear and currently a little on the high side but that again is a signature of just how Dave goes about these things…given some driving once the car is completed, there will be a natural settling before final adjustment.

The Colour:

Again a tribute to the Brand and this time to Abarth racing colours. The grey back in the day being the cornerstone of works 850 and 1000 TC’s. The red roof tops it all and if ever the name Testarossa conjured up some magic, one would be hard pressed to find a more rewarding recipient for the name.

Interior:

The ‘bomber’ seats are a creation by Dave’s son, David Jnr, a design engineer specialising in prototype 3D body model drawings. A word on Dave Jnr….. he specialises in miraculously creating those 3D classic car drawings using only photographic information and known basic dimensions. His creations for specialist customers include a Maserati, an Osca, a MGA Special and an Alfa TZ …..scale drawings from which his customers make either aluminium or fibreglass replicas. His seats look fabulous in this application and are being fettled with inserts to help in the comfort department and positioned to take Dave’s lanky 6ft2 frame. (I recall us adjusting our original 500 seat positions in the 60’s by setting the seat runners to allow the front seats hard up against the rear seat, giving a true Italian Straight arm driving position.) In this case this is no longer a 2+2 but a dedicated two seat sports saloon, the rear seat taken up by that suspension hardware.

The seats are not the only contribution to the project by Dave jnr. Most of us in this classic car rebuild game have come across the dead-end street of badging. This is not so much the parts being completely unavailable but always extremely pricy and often, when accessible, found to be in bad condition…..the front FIAT grill and ‘chrome’ finish strips in this instance are in that category……Dave Jnr’s solution was to home-cast these out of aluminium….. both the grill and the mouldings.

More Interior:

Instrumentation is directly from the Suzuki Bike with Speedo and Tacho only… mounted on the steering column and the ignition switch on the dash…touches showing the ‘bikes DNA and  a minimalist  approach to switching and gauges…..just like the original 500.

The Suzuki Instruments in place on the column and the Ignition switch below the dash…. the original speedo aperture will be fitted with a neat closing panel

Now if we think that is all that David has talent to apply….think again…..the bonnet and front body panel were both produced from fibreglass moulds. The originals were too corroded for use and in the pic shown, give an idea of just how neatly these were made and fitted….a true perfectionist at work.

Having viewed the Fibreglass parts ‘in the flesh’ as it were, one cannot distinguish these from the originals

In Summary

We have taken a snapshot of this project nearing completion and testing and must say it provides mouth-watering anticipation of the final product. The car fulfils those two great achievements in producing a really special modern Restomod….Introducing absolutely top drawer ‘out of the box’ engineering without losing the original quaint vehicle aura. There are no super low profile tyres on exaggerated wheels we see so often on restomod classics, nor impractical lowered suspension, massive turbochargers or tacky body kits….this is special.

And it has those magnificent suicide doors.

That is about it for now. At this point the car is being tested carefully to ensure the integrity of the package with particular attention to engine/transmission cooling and optimising the final suspension & brake settings. Proper engineers tend to want to ensure that what has been done works properly before giving it the full beans…..

Knowing Dave it will be spectacular once he gives it the all clear……and better still, he has agreed to a video road test of the machine when that happens…..we wait with baited breath.