My Lotus

I have just graduated as a mechanical Engineer from the University of the Witwatersrand in Johannesburg South Africa. This is an idea that was planted in my head whilst I was still at school. My Art Design teacher, John Scott, started building his...

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Tunnel Cover

Since the brake and fuel lines were in place the last bit left was the tunnel cover. I bought carbon vinyl wrap as this is the finish I wanted over the center of the tunnel. The wooden pieces were wrapped and then I used some leather to create a pouch under the handbrake lever. This is to prevent anything falling into the tunnel.

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Fuel & Brake Lines

A while back when welding in the suspension brackets I arced on the left brake line. Once can see the neat little hole left by the arc. 

At the same time I was inspecting the brake lines I saw that there was a fuel leak on the return line in the tunnel. Upon stripping out the brake lines I saw the following. 

The was all due to a cable tie chafing through the line. When I first installed the system, I didn’t put the flexible bundy tube in the rear of the car which meant the steel line was flexing and rubbing where the cable tie was. This in turn caused the fuel line to abrade through. After getting some 6mm connectors and hose clamps the bad section was cut out and replaced. 

So after measuring, cutting and flaring new lines I installed them.

The brake line was replaced and the T splitter bolted to the main central plate. I purchased two rubber bundy lines to give the lines room to move and prevent perishing in the future. 

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The next task on the fuel tank was to get the fuel sender in place and the gauge working. The gauge was never wired up as I had installed the sender before being able to calibrate it. The actual sender lever needed to be turned upside down as it was reading in reverse on the gauge. 

Once I had flipped it around I installed it into the tank and riveted in place. Due to the tank now being supported on rubber mounts an earth wire needed to be installed directly to the gauge. 

Now that the gauge was calibrated and in place the tank was installed. As seen below I stuck some EPDM foam under the mounts to give a better clamping surface.

The fuel lines were then linked up to the pump and the return line.

Fuel was added and the gauge was tested. 

Successful day all in all.

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Fuel Tank Complete

This will be a 3 part post due to three different tasks being done at the same time and in the same area. 

The brackets arrived from cutting and bending, and were made exactly as requested. This was a relief as there was a slight deviation when comparing the left and the right “strap” brackets. The top center plate also arrived with its brackets ready for me to get welding. 

I welded up the top mount plate first and foremost. Was pretty chuffed to see that my welding was still ok after not having welded for a very long time. 

Once welded and cooled, it was given a coat of engine black and then put aside to be installed with the fuel tank. 

The first step in installing the fuel tank was to clean the paint off the chassis tubes and get a good surface to weld on. Below is a pic about halfway through cleaning.

Once all the paint was off, the bracket was measured and centered I stitch welded in the lower main bracket

.Once it had a good coat of black spray paint, (didn’t want any bare metal), the fuel pump was installed. 

The top mount was then mounted in place using the old fuel tank mount bar.

 The plan as seen above is to make the place the central hub for the rear wiring and the main mount for the rear brake T split. The wiring was pulled through the plate and a rubber grommet installed. The fuel line and the pumps wiring was then tucked away nicely and cable tied in place. 

As you can see above there are rubber pieces which I glued under the fuel tank to give it support and to stop it slipping in the mount. 

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Fuel tank bracket design complete and heading for cutting and bending this week.

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Fuel Tank 2.0

The fuel tank arrived a couple days ago. I ordered it from Locost in Johannesburg, and at the price I paid I expected better craftsmanship.

I had to drill some material out of the fuel outlet tubes due to over penetration of the welds. I then gave it a once over with a scotchbrite pad to remove dirt and scratches. Below you can see it before the clean up and then after the scuffing with the pad.

I am now busy with a method to mount the tank. Since I can’t weld aluminium at home I need to find another way of securing it. So far I have modelled up the tank, lower tubes it will mount on, and the fuel pump. I have started with a preliminary bracket to hold both the tank and the pump as seen below.

This is still very much a work in progress but hopefully will be bent up soon.

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Problems

I have been driving around in the Seven lately and absolutely loving it!! The power is instantaneous and the motor just revs and revs, 8500rpm is a long way in such a small car. The suspension in the rear is a bit sticky. I never felt comfortable with the angle of the shocks and sent in some 4mm steel plate for laser cutting.

The other morning I noticed there was a dark stain under the rear diff. After careful inspection and checking, it wasn’t the diff at all.... Turns out the diff hit the fuel tank at some point and created a hairline crack, enough for fuel to leak. This was a big problem. So out came the fuel tank after much cursing. Below you can see the new shock mount plates on the tank.

After draining all the fuel I welded in the new shock mounts. This was helleva tedious as welding properly in such a confined space is not easy, Below you can see the old shock angle on the right and the new position mocked up on the left.

After most of the day,

The new mounts are solidly in place, using part of the old shock mounts as the second pickup. In the process of all of this I managed to arc on the brake line in the rear, this means I need to replace that hydraulic line and re-bleed the system.

For now, I am in search of a fuel tank...

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Aeroscreen Pt3

After letting the mold cure overnight I set to work releasing the plug. A little warm water squirted in between the two parts works wonders. The two separated with no hassles. A little bit of the plug stayed in the mold. This was due to the fact that the wood took on some water and softened hence allowing for the body putty to separate. The pieces did come out pretty easily and didn’t damage the mold.

Just as an extra precaution 800 grit water paper was used to give the mold a once over and remove any potential rough areas. When sanding gelcoat it goes matt in colour as seen below.

The mold was then waxed and buffed 6 times before applying a very thin layer of PVA mold release. The first screen was then laid up with 3 layers of CSM and some coremat. The reason for the coremat is to give the screen some additional strength in the event of debris striking it on the road.

The screen came out exceptionally smooth, so much so that no additional work had to be done to it. I just need to trim off the excess CSM and then wrap it in carbon fibre vinyl with some rubber edge trim.

Ill post those pics as soon as they are done.

Here are some positioning pics,

They  look a bit strange now but will wait to see what the carbon fiber does. If they are still too big then I will try something different. Right now the size is more so to get the driver and passenger out of the harsh air stream when driving.

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Aeroscreens Pt2

The laser cutting arrived from a work colleague who has a laser cutting machine at his house. He managed to cut it out of 6mm supawood. The 123D make program sliced up the CAD model and assembly was as easy as the program had made it out to be. After assembling and gluing the pieces to each other, automotive body filler was used to fill the gaps and start creating a smooth surface. There were 59 pieces in total.  

This process of applying filler and sanding was done 4 or five times with varying sandpaper coarseness. Once the surface was smooth to the touch 3 coats of MS primer were applied to build up the surface for a thorough sanding.

The plug was primed and sanded 4 times to achieve the required smoothness and prevent much finishing work being done to the mold itself. The devil is in the prep that is done. Taking time here will save you time in the long run.

Once the final sanding was done with 800 grit water paper, the plug was waxed with cobra floor polish and buffed to a shine. This was repeated 6 times. PVA mold release was then painted on very thinly as to avoid a water droplet effect on the gel coat. This dried in the sun and then a thick layer of gelcoat was applied so that there was enough to be sanded if need be.

The lay up of fibreglass consisted of 3 layers of CSM and a core mat section to give it some additional strength.

The daylight hours faded on me and this will be left to cure over night. Hopefully tomorrow yields good results.

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Aeroscreen Pt 1

During this past week I have been doing odds and ends and ticking off the little bits that need to be done. This included adding a vacuum hose from the ECU pressure sensor to the intake manifold so that it can be mapped on manifold pressure. I also replaced the reverse light switch on the gearbox and wired in the reverse lights. All the rear and front lights are operational now.  Over the course of this weekend I have been designing the aeroscreen that I want to use on the Seven. Here are some pics of the CAD model. 

It wont be carbon fibre, most probably fibreglass sprayed black or wrapped in carbon vinyl. 

Right now I have used 123D Make to slice up the model and will be sending those pieces for laser cutting to make a solid screen from which to pull a mold. 

Here are some pics of a paper template which I cut out for a size comparison. 

The plan is to bolt these down with M6 cap screws. I am busy seeing who can cut the dxf files for me at a good price so will update when there is more news. 

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Bonnet Fitted

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Bonnet Painting Pt3

Once the louvers had been completed the bonnet needed to be prepped for spraying. A specific primer called etch primer should be used on aluminium. This is due to aluminium having a hard oxide layer which prevents anything from sticking to it. I gave the bonnet a once over with 600 grit water paper and then laid down a decent coat of etch primer.

I left that for a week to make sure it had cured correctly and because the weekend was up haha.

This past weekend I gave the primer coat a once over with a 600 grit sandpaper, just getting any unevenness out. It was then rinsed off and made ready for paint.

Now because the paint has been standing for quite some time, it has become a bit thick. I tried to rectify this by thinning it out with thinners, which seemed to do the trick. I then laid the colour coat on.

In the pics you can see what they call tiger striping. Now this could be due to a few things, heat, speed, flow rate, spraying motion etc. Personally I think it looks cool. It is only this pronounced in direct sunlight.

I then secured the bonnet clips back on. I had done the alignment and positioning of them prior to the painting of the bonnet.

I will post the pics of it fitted when I have some more time this week.

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Bonnet Forming Pt2

Once the bonnet had been cut and bent, see previous post, it was time to put the louvers in. The main reason for this is due to the heat the engine generates. The walls of the driver and passenger compartment are thin and thus the least amount of heat should be trapped in the engine compartment. It also helps aid in engine temperature management when sitting in traffic etc. 

I went over to John’s place for him to show me how his louver tool worked and to try it out on a test piece of aluminum myself. Below is the result. I took this while positioning the louvers for the best look. 

Once the position was decided upon, the cut lines needed to be measured and marked. 

The distance between each louver is dependant on the tool. Once I had each one marked out, a thin blade angle grinding disc was used to cut the edge that would be formed. 

The tool works in a similar way to a pair of scissors. You split it and then place the material in between in the correct position. One then takes a hammer and gives it 3 good wallops and then repeats for each one. 

Here it is complete, 

Now because the louvers landed up quite close to the end of the bonnet, some deformation of the sheet occurred. Better seen below. 

I dont have a sheet metal shrinker so this will just have to stay. Hopefully the paint job will hide it a bit. All in all a good outcome. 

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Back on Track

So this blog has been quiet for some time, especially after the progress I was making at the beginning of the year.  The reason for this is my new job! I have been employed as a Design Engineer for a company manufacturing Military Vehicles and it is awesome!!

I just haven't had much time to myself with getting life in order and hence no time for the build either. The following post is a catch up post of all the odds and ends I have done here and there.

Between everything I also suffered a major laptop crash and lost a lot of pics and files, thus I will try show you as best I can in the following posts to come how I did things. 

First up I added a few extra mounting points to the nosecone to give it a more rigid fix to the chassis. It is now secured with four M6 bolts, into riv-nuts and with body washers to help distribute the load better into the fiberglass. 

A big issue I found was the fuel line. The guy who sold me the fuel line actually sold me water hose, hence it perished and leaked fuel everywhere. This I managed to fix but due to the laptop debacle have no pics. Basically I got a bigger section of hose and sleeved the inlet pipe onto the fuel pump inlet pipe.

I managed to get the indicators working through the use of this little guy and a crash course in flasher unit wiring haha. 

I also found that the spring I used to keep the brake pedal in place had popped out. I half expected it to happen as it was a temporary installation. I have now made a proper mounting and it works like a charm. 

Now there have been issues with the motor mis firing and back firing. I spent a few weeks eliminating problems and landed up finding the coil is faulty. I approached toyota for a new one and the cost was R1600.00 which is bonkers! I then went to our local spares shop and got one for R200.00. The only hitch was that I needed to make an adapter for my plug lead. This I did by turning up some copper bar and bridging the gap. 

Works like an absolute charm! I have completed the bonnet and a few other things which I will post shortly.

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Nose and Bonnet complete!! 

Just need to get some bonnet clips during the week.

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Bonnet

Once the nosecone was fitted and in position the bonnet was the last big piece of the puzzle. 

As mentioned before I had just enough aluminum to make this out of...it came down to millimeters!! Luckily it worked. 

First up was to get a template, which came from an old roll of tracing paper I had lying around. 

The template was then laid out on the aluminium and cut out.

The exhaust port was then measured and carefully cut.

The sheet was then placed on the car and measured up to get the rough bends. Once the rough bend lines were marked it was over to the bending machine...

Then the lip for the edges of the bonnet needed to be bent.

I had some rubber trim to be laid on the scuttle lip to aid in preventing vibration and to seal the engine bay. It was however a bit too thick, out came the vegetable peeler and it was shaved down. 

Once the back end lined up properly the front was marked out for cutting. 

After much filing and measuring and cutting and more filing over the course of a day and a half the bonnet was completed. I will post up the finished result in a photo set in the next post. 

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Nosecone fitted using M6 riv-nuts on the top chassis members.

Getting there