Ocar AC 'ACE'

Ocar AC 'ACE'

Postby wixwacing » Fri 02 Oct, 2009 2:17 pm

AC ‘ACE’
by Ocar



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There are few cars who could boast a descendant lineage as famous as AC and the model in particular which was the start of the line was a humble two litre sports car with an Italianesque barchetta styling, the AC Ace. Born from a desperation to update their ailing model range and another man’s desire to put into production a successful hand made sport car, the AC company eventually produced the car just in time for the 1953 London Motor show. From then on, this low volume aluminium bodied two seater achieved initial sales of 147 cars. A motor upgrade and some other body refinements ensured the car remained viable both in the UK and abroad. The car was also entered in Le Mans in the mid fifties and in 1959 it actually won its class. Interesting to note, Carroll Shelby was driving an Aston Martin in the same race, which he won.



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The Ocar kit



AC took a blow when the engine supplier ,Bristol Cars, went under and the supply dried up. A Ford 2.6 engine was substituted but was well under powered and not as tractable and AC was approaching a crisis in 1961 when Carroll Shelby approached their management with the idea of putting a big engine in this delicate car. Shelby had already approached several other sports car makers including Austin Healey but had been knocked back each time, so, in 1961 it was AC who started the process of upgrading their chassis and drive train to take the new Ford 221 c.i. V8.



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Eventually most of the old Ace dimensions and specifications were compromised, except one. Shelby wanted a fibre glass body like the Corvettes, but AC, who part owned the company who supplied aluminium to them, insisted on hand rolled bodies as part of the deal. After all, they were 27 kg lighter too! Shelby conceded and the car expanded in all directions. Eventually, the prototype was shipped to Shelby in America where the engine was soon to be upgraded to the Ford 260 c.i.


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Interesting to note that Shelby repainted the original prototype a different colour at each test outing to give others the impression he had gone into production! This is where the Ace story finishes. The new car was a world apart from the original and the two litre class it raced in. Once the AC Cobra went into production at Thames Ditton, the Ace was phased out and remaining Aces were eventually sold over the next couple of years.



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The Ocar model is a very good likeness to the Ace with its broad grin and stepped front valance. The scale is excellent too and I like the model because it fits in with the Italian cars of the era. No pumped out wheel arches, huge bonnet bulges and air scoops. No ten inch wide tyres and huge exhaust pipes bristling from underneath; and least of all, no massive chrome roll bars ensuring the driver retained his head and upper torso in a spill. Even the absence of front impact defences and the small overriders at the rear show this car was for the sports car enthusiast and not the SCM!!



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So what was it going to take to make this model something special to me. Well, I like to incorporate something new in all my scratchbuilds and this time , with a couple of front engined models behind me, I fancied building a cockpit with a full length driver figure! I decided against the soft option of a half tonneau and went for the full open cockpit! Mmmmmm!



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Lightening finished and thin spots filled!



The first task was to prepare the body for priming. All resin bodies come with a bit of work attached. Ocar have kept that to a minimum, and if you wanted to put an off the shelf chassis in it, you could buy one from John at Ocar. You could have the model up and running in a few days. This model was getting the Wixwacing PCB chassis, semi - wixle, front motor, prop shaft, detailed interior AND still be a good drive. So the body needed to come down from about 20 grams to as little as possible without compromising its strength too much!



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A ball ended tool was fitted to the dremel and I proceeded to take out all the surplus material. Holding the model up to a light source shows all the thick spots. These occur around the headlights and tail lights. The waste was ground away until I could see defined light patches from the inside. Being careful not to overdo it, I shaved one part, then another, checking all the time until I had a uniform light bleed through all parts of the model. This left me with a model weighing fourteen grams. I then set to work on the broad areas inside like the bonnet and boot lid, taking more off, bit by bit, weighing the model and trimming a little more.


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The ‘see through’ body




At this point I stopped reducing the four corners. These are going to be points of impact and I felt it best to leave them with a degree of strength, just in case! A final grind and a period spent smoothing the interior saw the model eventually weigh in at 12 grams!! Not bad! There aren’t many RTR’s that can boast that body weight!. The lightness of the body will help with the model’s corner stability as the C of G will be considerably lowered after ballast trimming. Not forgetting, there will be body posts to add, a cockpit and driver and several coats of paint. So, I expect the body weight to go up by six or seven grams again!



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Next up was the chassis. I have made more than several of these now and if I don’t know what I’m doing by now, then I never will. The trademark Wixwacing chassis is cut to size. The axle positions are marked on the copper and to ensure enough room for the cockpit, I mounted the motor as far forward as I dare! But not too far to require too much counterbalancing; and an NC1 by choice as they are such a fabulous motor for these mini classics!! Once the motor position was finalised by careful measurement, the chassis was cut to take it. After this the front and rear axle mounts were made (see tech section) and their locating holes carefully measured and drilled to ensure the wheels would be in the right spot. A feature of the axle mounts is the hole bored from underneath into the axle tube. This allows the axle to be lubed with a ‘train oiler’ without removing the body.



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The rear wheel arches on this model were a little unevenly spaced and I had to build up the rear edge of one side to reduce the excess gap. In hindsight I could probably have reduced it more, but things often look different before a coat of paint!! After the axle mounts came the slot guide hole. Because the model was to have a Semi -Wixle front end, I decided to mount the guide a little further back to reduce front wheel sideslip in corners. The rear axle was assembled with Ninco classic wheels and tyres and with the contrate in position, its hole was marked and later cut and filed.



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Chassis with upturned rear



On this model the rear underbody slopes upwards from the wheel arch centre backwards. A PCB chassis is inherently dead flat, to start with, but I have successfully modified this material to accommodate a sloping rear end. At the point where the up turn starts I marked a line with a square, then carefully sawed through the copper and probably two thirds of the circuit board with a razor saw. The rear was then persuaded up until it matched the body. I then cautiously part filled the slot I had created with superglue and bent the tail end up into position. Holding it in place for about a minute, I could eventually let go, and the tail stayed in place. As insurance, later, when I was soldering the other chassis parts in place, I soldered two thin angled plates over the join.



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The motor was kitted out with its prop shaft (the severed long end of an SCX rally (4WD) motor), and a Fly drive spring I have had for some while courtesy of Scalexworld. A Slot.it 9z pinion had been fitted to the shaft and an SCX 27 z contrate was fitted (this was later to be replaced by a Slot.it offset contrate). I also cut and fitted a short piece of 2.0 mm ID brass tube over the prop shaft. This was to help me secure the gear end of the shaft at the contrate. Once in place, the prop shaft offset was established and a brass spacer made to measure. It is important at this stage that the prop shaft and motor shaft are in line, even though they have the spring. If they aren’t, the drive train will generate a noisy vibration as power is pushed through the angle! Trust me!



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Mounting posts installed




With the chassis pretty much approaching completion, the body posts were manufactured. In this case it was three pieces of plastic tube telescoped inside each other along with a coat of liquid polystyrene cement. Once they had been dry for a couple of days I levelled one end of each in the drill and then tapped a PK screw thread carefully into this end (see article in tech section). The posts were screwed to the chassis which was then offered into the body. By taking careful measurements I was able to trim the posts and get the body and chassis to sit very well together with just the narrowest of gaps around the join. The contact area of the body where the posts were to rest was scored with a modellers knife and the body end of the posts too were scored. This was to give the super strength epoxy a better key than smooth plastic. The epoxy was worked into both scored surfaces and with a little extra on the ends of the posts, the chassis was lowered into place and left to cure for a couple of days.



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Once the body and chassis were mated, it was then time to fix the guide and ride heights. The axle tubes were set first to give the model its correct ‘stance’ and spot soldered. The height was rechecked and the tubes soldered to the PCB front and rear. After this, the braids were fitted to the guide and the guide installed in its tube and inserted in the chassis. This was then placed on a clear acrylic test block to help set up the optimum guide tube position. I had applied a couple of narrow layers of masking tape either side of the slot. This was to emulate raised plastic track conductor rails. If this isn’t allowed for, the front wheels will ride above the track on most plastic tracks. Being a Ninco sprung guide, hopefully there would also be enough spring tension to set the guide down on flush-conductor board track or recessed magnabraid.



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While all this was going on it was necessary to have other work under way while things cured and dried. In this instant it was going to be the cockpit! Using verniers I constructed the basic cockpit to fit inside the body. A simple small box which was a flush fit both sides and was long enough to tuck under the front and rear cockpit edges. I next cut the dash shape and profiled it to fit under the body. The box sides were trimmed to allow the chassis to fit flush and once final positions were determined, I fixed the basic box into the body with blue tack. The dash was then offered up and liquid cement was spotted on the ends.



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Seats before final fettling and painting



Other things to make were the seats. English sports car seats of the fifties were very basic. Usually leather or the then new ‘vinyl’ they were curved in a bucket shape and thinly padded. The trim was panelled and the edges piped to finish. I decided to make seats in the absence of a suitable substitute. This was done easily really! The backs were made from two bits of thin plastic which had been curved round a pin vice handle. The two pieces were then glued together and placed in a small hobby vice to retain the shape while they cured. The squabs were again thicker plastic pieces laminated together. The panels were carefully marked on the plastic and with the back of a modellers knife point I scored the detail into the plastic. The panels were then rounded and profiled with a hobby file and finished of with some fine (1200 grit) wet and dry glued to a narrow strip of brass.



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Now, if you think I’ve got plenty of time on my hands, you may be right!! Next up was the steering wheel. Not a skerrick or a sniff of a steering wheel anywhere in my bits box! It needed to be a three spoked alloy wheel with either a wooden rim or a black leather rim. I settled for the black leather and set about the task. Again the wheel is laminated. Once a reasonable diameter was settled on (governed mostly by the spread of the drivers arms), the parts were glued together and left to set. A couple of days later the outer circumference was marked using a hole gauge. The wheel was trimmed to its outer size and then the inner radius was measured and marked, again with a hole gauge.



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I then scraped away at the outer edge and achieved a smoothed radiused finish. The spokes were then marked out inside the inner radius and the waste material removed with some very small drills! When the gaps had been created and using a VERY sharp modelling knife, I profiled the inside wheel radius using shaving and scraping techniques! Finally, the spokes were thinned down and a centre boss (horn?) pad made and glued. The rear of the wheel had been drilled to 1/16” and the steering column ended up being mounted on some 1/16” brass tube. With everything in the cockpit being made I had the last item to do. This was the transmission tunnel. There was a very real need for this being a prop shaft model! The cockpit underside centre was marked and a centre section removed with the dremel. This was widened until it dropped onto the chassis with room to spare around the prop shaft. The now fully assembled chassis and cockpit popped into the body very nicely. Some plastic tubing was to be split down the middle and one half glued over the gap. Some larger diameter tubing became the collar at each end of the tunnel, just to finish it off neatly.



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Home made steering wheel and Patto's dash gauge decals




With the cockpit once again blue tacked in place, some final position adjustments were made. Once happy, I applied three or four strategic spots of superglue. This held all in place and after the chassis was removed again, I brushed epoxy all around the edge of the cockpit sealing it in place. Once this was dry, the chassis was offered up and any final trimming was carried out. Last thing to make was the windscreen,……Mmmmmmmm



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Now Ocar supply a perfectly respectable half driver’s tray and a windscreen. The windscreen though is purely that, and any form of track work might see it become an early casualty in the scheme of things. My solution was to make a screen with integral side screens. This allowed me to choose thicker clear material and to enhance its strength by having side screens brace it. This is something I did with the TR 59 Ferrari (this section) which has been raced and survived! The real car would have had slot in side screens which located in door tubes and would have either been secured by wingnuts or knurled, threaded knobs. These were mostly used when the soft top was on.

The screen template was first made from card. This was trimmed up until it was a respectable fit on the body. It was then sellotaped to the clear material. The template was cut round and other details added were small lugs on the bottom edge of the screen that would eventually locate in carefully cut strategically placed slots in the body, one each end of the screen at the corners and one in the centre. There was another one each side in the centre of the sidescreens. Holes were carefully bored with a tiny drill and a pin vice. These holes were improved on with a sharp modellers knife until the screen slotted neatly into all locating slots. Before this I should mention that the windscreen/sidescreen join had been scored both sides with a modellers knife and a straight edge and carefully bent into the correct angle.



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Once again, while all this had been going on I had been preparing the body and a couple of minor pinholes were filled. Final body lines were sanded and filed. Headlight areas were cleaned and other stuff like the rear wheel arches were reprofiled. The body had its first coat of flat grey primer and the anomalies were repaired. A bit of body putty does amazing things. After each repair the primer was resprayed to confirm the rectification. Another item to be made was the grille. The model didn’t come with a grille which was a pity but it did come with some first class headlights and rims! Ten out of ten for those. They would be a lot harder to make than some old grille anyway!

Aaaaah!...... the grille, Mmmmmm another challenge. The original is a simple square section grille and the first task was to make the outer frame. The grille recess had been cleaned and trued and the grille was to be sort of constructed ‘on site’ so to speak. A strip of plastic card about four m.m. wide was trimmed off a sheet. This was dipped in very hot water (don’t try this at home kids!) until its pliability allowed me to bend and fit it into the recess without anything breaking! A spot of glue was dobbed on the ends and left for a day or two! With the rim still in place, some very fine strips were cut off the sheet using a straight edge and a sharp modellers knife. These were then glued one at a time into the rim until all the horizontal bars were in and equally spaced. Each bar was trimmed to length to fit its final resting spot.



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A couple of days later the vertical bars were cut and fitted in the same manner. These were located behind the horizontal strips and a dab of liquid poly glue on the tip of a modeller’s knife was spotted on to each touching crosspoint. Once again, after standing for a few days, the grille was removed from the model and the front carefully sanded to the same angle as the front of the model. Finally the grille bars, like other things, where scraped with a sharp modellers knife to put a radius on the front edges of the bars and any excess glue was carefully removed.



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The driver with his new smile! He doesn't know yet but he is to lose his feet and have both arms broken!!




Once again, while all this was going on, I tried the driver out in his new position. The passenger’s seat was painted and the drivers seat and driver needed to be set up at the right angle. I glued a small strip under the front edge of the seats to give them a more authentic tilted back appearance. Unfortunately in the name of space, the driver had to lose his feet! I hope he’s forgiven me! This was caused by the recess created to accommodate the end of the motor. His back and seat were scraped vigorously to get him into the right position and his final mod was to have his arms spread wider to accommodate the steering wheel. This was done by sawing into the back of his shoulders a bit more than half way with a razor saw. Super glue was then applied to the slit and the arms widened and wedged apart ‘til set. the remaining saw cut was filled and profiled before painting.

The last indignity for the driver was to give him a face. The driver is a Fly open faced helmet type. The face though has a scarf or some similar object round it concealing mouth detail. Again with not much else to do I carried out a facioplasty and whittled away until some features appeared. The nose had to have a good trim too and after fettling the rough edges it was my view that he was acceptable! Looking about me I could see it was time for some serious painting! It was time to reach for the spraygun!!!



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Body prep and painting was the same as it has been for a host of my models so I won’t bore you rigid with that. But I will say the body colour IS enamel! from a Tamiya spray can. I decanted the paint from the pressure pack into a spare jar and sprayed it on with my hobby gun! The cockpit and parts were brush painted before assembly and stuck in after drying. I had primed the driver grey and painted him flat white. I didn’t want a pristine driver so I let the grey show through slightly under his top coat, giving the impression of shadows in the folds of his overalls. The dash was brush coated with two coats of satin black enamel. The dash gauge decals were from a set of Vanwall decals I got from Patto’s years back and served the purpose nicely. The ‘Monza’ style filler cap came from the kit spares bin (probably an old Airfix one off something?)



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The door mirror was from the spares box too along with the interior mirror. The rear overriders and number plate come with the kit. The light rims and rear bumpers are pewter and the number plate is anodised plastic. The beautiful front lamps and rims were a delight to fit. The lenses had the sprue remnants trimmed off and the mounting spot and back of the lenses were painted bright silver. The lenses pop through the rims and into the body and I spot glued the lenses from behind. I also put the merest of epoxy spots on the pewter rims just to consolidate them on the body.



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The body previously had a top coat of clear acrylic. The decals were then applied and left to cure for a couple of days. Another thicker coat of acrylic was applied and again left to dry hard. Rear lamps had a coat of silver and once well dry I applied some acrylic ‘clear’ red to the lens area, leaving the silver to show round the edge. And to finish off, another layer of clear on the rear lights and number plate. So what have I missed ? Mmmm…………..? Ah yes, the windscreen!



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Windscreen template



This is probably the most fiddly bit! I wanted to glue the screens in with Super strength Epoxy, but this takes a day to cure. Once applied it can take a couple of hours just to thicken. The screen had plenty of spring in it and it wasn’t going to sit around waiting for the glue to dry, and I was loathed to tape or use fixings of any sort on the fresh acrylic clear as it would pick up marks easily in the first few weeks of life! Mmmmm??? But the solution was fairly simple. I decided to fix the front edge first and not the whole screen in one go. Some epoxy was mixed and using a fine artists brush I painted a thin but healthy bead along the back edge of the screen mounting strip. Now, remembering there are three tabs on the front screen and three slots in the body, I placed some superglue down the tab slots in the body, once again with the tip of a pointed hobby knife.


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With a decisive and much rehearsed movement, I slotted the screen into its front holes and sat frozen like a stunned wombat for almost an eternity, hoping the superglue was working. I finally released the screen and sure enough it was fast in place!!. Yet again having left it a day to cure, I then applied epoxy to the top inside of the drivers tray and once again, with superglue down the locating slots, I held the sidescreens in place one at a time ‘til they were secure. This was also left for yet another day to cure.



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The completed model with calculated ballast in situ




This was pretty much the closing stages for the model and something I had been looking forward to for some time. With the screen in place and all the other little bits glued and painted, the model was done. The chassis had been run alone several times and was ready to go. The last measure would to be to run it against its peers, and hopefully that wasn’t to be too far away. How does the model stack up against the more conventional models? Well………..


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The AC Ace and its stable mate the Ferrari TR59


Needless to say I am over the moon with this model. I have excelled my own expectations once again and I consider I have ended up with a beautiful model. I did side step some conventions like colour and decal placing. The model is supposed to be of the 1959 Le Mans class winner. That car, if I’m correct, was red and the decals were mounted on the doors and not the front guards. Top marks to Ocar for yet another nice model and I look forward doing the other two I have in the queue. I haven’t run the model finished and ballasted yet but it has done some serious laps in unpainted form and I was very pleased with it. I will Endeavour to post an update on the finished model and eventually, its progress in competition, this is why it was made!


If you feel inspired by this model, pop along to World Classic's Ocar page and do yourself a favour



Ocar Models at World Classics
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When I'm not racing slotcars,
I'm out in the back yard, burning food!!

When I win, it's because of my talent, not my car or my controller!
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wixwacing
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Re: Ocar AC 'ACE'

Postby wixwacing » Sat 17 Oct, 2009 10:57 pm

I took the Ace for a serious run at the Red teams home track on Friday. It went well but was dogged by a high frequency chattering noise and slow acceleration?????

Further investigation today showed the tail shaft I used had a bend in the pinion end and was trying to throw the rear axle side to side at several hundsred times a minute!! After replacing the shaft the model has become as quiet as any. Stay tuned for further road tests.
Image

When I'm not racing slotcars,
I'm out in the back yard, burning food!!

When I win, it's because of my talent, not my car or my controller!
User avatar
wixwacing
Marshal!!!
 
Posts: 1906
Joined: Thu 10 Jul, 2008 8:22 pm


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