Speedometer Calibration

Now that the car is pretty much complete and ready for testing, I thought I had better calibrate my Smiths Speedometer.

I bought the Caerbont Automotive Instruments Smiths Electronic Speedo (200mph anti-clockwise).

To be able to calibrate the speedo, you need to follow the instructions very carefully. (Online Download)

The first piece of information requried is the rolling circumference of the rear tyre.  I stuck on a piece of masking tape onto the tyre and drew on a straight line.  I then placed masking tape on the floor with a similar straight line.  From the starting point of both lines touching, I rolled the tyre across the floor and when it went full circle, you guessed it, I placed another piece of masking tape down with another line.  Measured between the lines I got a measurement of 2087mm.  This is for the 275/40 R18 Michelin Pilot Super Sports.

Since my speedo is in MPH, the instructions request "Wheel revs per mile = 63360 divided by the distance travelled in inches".  

To convert from mm to inches you need to divide 2087 by 25.4.  This gives the answer in inches (82.16535433)

Therefore the Wheel revs per mile for my car is 63360 / 82.16535433 = 771.1279348 (give or take a few decimal points!)

We can now figure out the calibration number with the following calculation "Calibration number = (wheel revs per mile/km) x (diff ratio) x (number of magnets or bolts)"

The diff ratio for my Dana Spicer Hydratrak is 3.07:1

The VSS for the T56 Magnum has 17 pulses per revolution (That's what most people seem to confirm on the online forums!)

So, finally, the Calibration number sum of the speedo is:

771.1279348 x 3.07 x 17 = 40245.16692

The instructions state "the calibration number you have calculated should be rounded up to the nearest whole number" so my final Calibration Number is 40246.

To enter this data into the speedo itself,  as per the instructions:

"The calibration mode is selected by switching on the ignition while simultaneously pressing the trip reset button. The pointer will travel to full scale and return to zero. If the button is released before the pointer returns to zero, the manual setting procedure will be selected and the LCD (ODO.) will read ‘SET PPU’. If the button is released after the pointer returns to zero the ‘drive to set’ mode is selected and the LCD will show ‘DTS PPU.’  At this point, pressing the reset button momentarily will toggle between ‘SET PPU’ and DTS PPU’.  

Manually Inputting The PPU Number

Set the LCD to display ‘SET PPU’ as described above.  Press the reset button for 2-3 seconds, the LCD will show the calibration number currently set. Each digit within the calibration number will flash in turn for approximately 2 seconds. When a digit is flashing, each depression of the reset button will increment the digit by one. Once the last (right-most) digit has been set/reset, the whole number will flash. Press the reset button and the LCD will display ‘DONE.’ After 3 seconds the LCD will display ‘SET PPU,’ the setting is now complete. Switch off the ignition."

It is fairly easy to setup once you know all your figures - as long as you remember to press the reset button when all the digit flashes to ensure the number you have put in is stored...  When I double checked that I had put the correct number in, I found that the default number "008380" was still there.  I re-did it and remembered to press the reset button when all digits were flashing.  I have since re-checked, and my number has been stored.  I will test it properly once on the road compared against the sat nav.

Dashboard Completion

After completing the switches for the lights and fan, I thought it best to get the dashboard put together.

I had to fill in some of the holes with P40 which I had drilled in the fibreglass dashboard for the original layout using toggle switches.  I also decided to move the fan switch closer to the driver and hide the speedometer button behind the steering wheel shroud.

To help prevent the rotary switches from turning, and relying on the securing nut, I bonded on some angle aluminium at the correct angle.  There are some notches in the fibreglass, but I wasn't sure how this was going to all work with the padding and leather.

Once the switch locations had been decided, and also the key for the ignition (Far right hand side near the driver's door) I could tidy up the wiring.  I had left the factory wires at full length, in addition to the tails that came with the Smith's gauges.  This meant there were a lot of excess wires.

I had to extend the ignition wires since I had relocated the key far away, but mostly I needed to shorten everything else.  I kept the Smith's connectors, I spliced in the wires by soldering each one and applying heatshrink sleeving to each joint.  Once each unit had been completed, a larger piece of heatshrink was used and I hand wrote on this piece identifying what was what.

The fibreglass panel was then covered with 3mm thick Scrim foam - this has a material backing.  I fully glued this on using EvoStick.

Once the glue was fully dry, I cut out each opening using a craft knife.

A sneaky install to see how it was going to look

Then comes the leather.  This is a bit daunting to ensure you get the tension correct.  Rolling the leather out on the bench, we marked out the leather for where we would apply the EvoStick.  Timebond is best for this.  Only the back edge of the fibreglass panel is glued.  The leather is loose on the foam.  With the edges glued, the leather was stretched over the panel and parts were trimmed away to allow the leather to curve around.

With the leather now in place, I could start cutting out for the indication lamps.

Then everything else was cut out - I cut multiple slivers for the gauges, I split a circle into 16 segments and cut the leather with a craft knife.  This made sure that it was flexible enough for the gauges to pass through.

Notice the small label I had made for the rear fog light

Piping glued on around the steering cloumn

In order to help hold the indication lamps from coming back out from the dash, I put flat rubber washers over them.  This adds some extra resistance to the lamp holder and keeps it in place.

Next is the leather cover for the steering wheel surround. The leather was rolled out and marked so I could see where to apply the EvoStick.  I lined it up so the joint is in the middle underneath - you can't see it once installed.

The leather needs to be trimmed around each of the stalk locations.  All in all a neat job, although the stainless cover is quite tight to go on!

I installed a small bracket underneath the dashboard above the transmission tunnel to house the connectors to the Lambda Sensor Controllers and also the CANEMS ECU.  Gender adaptors were bolted to the bracket, with the cables running from the bracket to each controller.  I thenn can use my RS-232 to USB adaptor to plug into which ever one I need.  

Looking more and more complete!

Dashboard Switches

I have been trying to think of how I would like my dashboard to look.  I prefer a minimilistic look, but also keen on the period feel of the car.

I was going to use the Lucas toggle switches, one for lights, one for the rear fog and then a rotary one for the heater blower.  I did toy on the idea of having a swith that I could use to run my fuel pumps to be able to prime the system.

I felt that there were too many switches going to be present so I scoured the internet for inspiration.  

I really like the look of the original rotary knobs in the AC Cobra and I found a place on eBay that sold one for lights and one for the fan.  I had a rotary fan swith so the first job was to get the new knob to fit the switch.  The knob is designed to fit 1/4" hex shafts, but the 3 speed fan switch I have is round with a flat cut in it.  The rubberised knob that came with the switch has a steel insert in it.  I removed this and proceeded to get it to fit in the new knob.

Using the Proxxon, I machined out the internal hex of the knob until the steel insert fitted neatly.  I used some araldite to help bond the insert in.

For the light switch, I had one rotary switch which has 2 positions, side lights and main beam.  The full beam is controlled from the stalks.  That means I will still need another switch for the fog light.

I scoured the internet to see if I could find a switch that was easily modifiable which had the fog light function built in.  I came across a Mercedes light switch (MER-LSWT-004) which has the very functionality I need and looked like it could be modified for my needs.

I set to and dismantled the unit to figure out what I needed.  This unit has a LED in the centre of the shaft, so that was the first thing to be removed.  Looking at the shaft, I thought it easier if I took the shaft from the other switch I had (brass), machined the correct size of hex on it and fit it to the new knob.  I then modified the aluminium piece of the Mercedes light switch to fit the newly machined brass shaft.  I fixed it in using 2x roll pins.

Once that was done, the switch felt a little stiff to operate (new knob is relatively small), so I machined out some of the Mercedes switch internals to soften the "clicks".  I machined a small piece of black nylon to fill in the gap of the shaft to the threaded boss.

The switch now worked very well, pulling the siwtch to get the rear fog light to come on.  Once you switch the headlights off, the switch automatically retracts causing the fog light to go off.  

Black Nylon Insert

The last thing to do now was to make mounting nuts which hold the switches onto the dashboard.  Both switches had horrid looking hexagonal nuts, and typically were a completely a different thread and size to the Lucas nuts.  So I had to make some.

I turned a piece of stainless steel and created 2x blank pieces.  I made them the same diamater so they would look the same, although different inner diameters.  I worked out that the thread of the fan switch was 7/16" x 28 and the light switch was 5/8" x 24.  I ordered taps from the internet and once arrived cut the threads in my newly created nuts.  I then cut grooves in the nuts and also created a tool for tightening / slackening them.  I polished the nuts with the polisher - All in all a good job.

This way I will only have 2 switches on the dashboard and will have a period look.

Dashboard

I have set out the standard GD dashboard layout which was pre-marked on the blank panel. I used a hole saw the neat size of the gauges, however the holes will need to be opened up later for the leather to fit in.

Even though the dasboard is uncovered, it makes the car look ever more complete.

I may alter the position of the switches, but this will be looked at later.

First Start

I temporarily hooked up all the gauges on the dashboard, and tried a first start.  She turned over but no signs of firing.

A phonecall to Dave at CANEMS soon had her fired up once he uploaded a basic map for the LS7.  She will get properly mapped once down beside him on the rolling road.

I realised that the thermostat wasn't opening, so I removed it from the housing and using a kettle I confirmed that it was very sticky.  New one on order!