The task after routing the fuel lines under the floorpan was to do the same for the brake line and battery cables.
I measured the battery cable in the factory Starlet wiring loom and it looked to be 6AWG however because the Mini has a much longer cable run from the boot-mounted battery to the engine, I decided to use a the next gauge/size up (4AWG/4B&S) to prevent any voltage drop over the extra ~2 metres. I also decided to run both 12V AND ground cables to the engine bay. A separate ground cable may not have been necessary however it simply put my mind at ease when thinking about possible cable-to-body grounding issues.
I chose to run the battery cables in parallel with the rear brake lines so to clamp both the brake line and two battery cables I needed some more custom plastic clamps like I made for the fuel lines. Since the fuel lines were not flexible, I only used 3 clamps along the floorpan but I ended up making 6 clamps to hold the battery cables, spaced at ~250mm apart. Note that most of these photos were still taken when the shell was upside-down on the rotisserie.
From the last blog post about the fuel line clamps, I had a few people ask about how I made them so here's a quick run down...
Firstly I cut a small piece of 40x12x12mm HDPE plastic (from a sheet of 12mm thick HDPE) and marked the location of holes for two battery cables and one brake line. Note : The small screw in the photos is for leaning the clamp on, not part of the clamp
Whilst clamped in the drill press vice, the three holes were drilled.
Using my bandsaw, I opened up the holes so the cables and brake line would be a tight fit in the clamp.
I then cross-drilled a 5mm hole (for a M5 bolt) and countersunk it (using a 10mm end mill bit) to hide the bolt head.
The ends of the clamp block were sanded down to match the shape of the floorpan, which I matched by using a profile gauge.
A 5mm hole was drilled in the floorpan and a M5 nut welded to the inside of the cabin for securing the clamp.
Instead of routing the 12V cable through a hole/grommet in the boot floor (as per the original Mini setup), I chose to use a through-panel connector for the 12V cable. They are readily available at auto parts stores but I balked at spending almost $40 on one. As a bit of a challenge I chose to make one myself - for about $2 in materials. It was made from three simple pieces - with a custom machined bolt screwed through the middle of the (thread tapped) HDPE pieces.
The circular piece of the connector fits through a 25mm hole I drilled in the boot floor
I also made a custom gasket from 2mm rubber to seal the connector to the boot floor
For mounting the ground cable I machined a small steel boss with a 3/8" thread tapped in it, and welded it under the boot floor next to the hole/captive nuts for the above connector.
Photo taken from underneath the car :
The connector (and bolt for earth) fitted in the boot next to the battery box :
Because the cables are easily removed from these connectors on the boot floor, I didn't bother routing the battery cables up and over the subframe - between the boot floor & subframe, like the brake line and fuel lines. The cables run straight from the floorpan to the connectors with enough slack to stop them rubbing on the subframe, although I will cover them with some loom tube later. To visually differentiate 12V from ground cables, the ends of the cables have matching red/black heat shrink.
At the front of the car, I made another clamp to hold the battery cables and brake line away from the steering rack. As for the brake line it was planned to run from the master cylinder to the rear subframe as a two piece line to make it easier to fit/remove. I had already made both pieces - one piece from master brake cylinder to lower firewall; one piece from lower firewall to rear subrame. I only had to slip on some fittings, flare the line ends and screw the coupler in place to join the two pieces. The coupler and fittings were made installed near the base of the footwell, for no particular reason except that it was an easily accessible spot where line could be split without removing the front subframe.
Once the shell was the right way up and subframe was back in, I trimmed the cables to length and crimped on new cable ends connectors (with matching red/black heat shrink). I also machined a small adapter to allow the ground cable terminal to fit better against the round brace tube.
One last task was to make a short length of ground cable from the subframe to the body. The wiring loom and starter motor cable will be attached to the 12V terminal on the left.
Addendum : After fitting these battery cables I've since found out that by connecting the ground cable to the body in the boot AND to the body in the engine bay, it introduces a ground loop problem where electrical current has two paths of differing resistance (via battery cable & via car body shell). Ground loops can introduce unwanted electrical noise and/or sensor voltage errors. In light of this, I made a second through-panel connector for the ground cable near the battery box to isolate that cable-to-body connection.
The terminal on the ground cable under the boot will be cut and then using a butt connector, I'll extend it extended to run around the battery box to fit to the new connector. In the photo below the new connector is at the bottom of the photo.
I measured the battery cable in the factory Starlet wiring loom and it looked to be 6AWG however because the Mini has a much longer cable run from the boot-mounted battery to the engine, I decided to use a the next gauge/size up (4AWG/4B&S) to prevent any voltage drop over the extra ~2 metres. I also decided to run both 12V AND ground cables to the engine bay. A separate ground cable may not have been necessary however it simply put my mind at ease when thinking about possible cable-to-body grounding issues.
I chose to run the battery cables in parallel with the rear brake lines so to clamp both the brake line and two battery cables I needed some more custom plastic clamps like I made for the fuel lines. Since the fuel lines were not flexible, I only used 3 clamps along the floorpan but I ended up making 6 clamps to hold the battery cables, spaced at ~250mm apart. Note that most of these photos were still taken when the shell was upside-down on the rotisserie.
From the last blog post about the fuel line clamps, I had a few people ask about how I made them so here's a quick run down...
Firstly I cut a small piece of 40x12x12mm HDPE plastic (from a sheet of 12mm thick HDPE) and marked the location of holes for two battery cables and one brake line. Note : The small screw in the photos is for leaning the clamp on, not part of the clamp
Whilst clamped in the drill press vice, the three holes were drilled.
Using my bandsaw, I opened up the holes so the cables and brake line would be a tight fit in the clamp.
I then cross-drilled a 5mm hole (for a M5 bolt) and countersunk it (using a 10mm end mill bit) to hide the bolt head.
The ends of the clamp block were sanded down to match the shape of the floorpan, which I matched by using a profile gauge.
A 5mm hole was drilled in the floorpan and a M5 nut welded to the inside of the cabin for securing the clamp.
Instead of routing the 12V cable through a hole/grommet in the boot floor (as per the original Mini setup), I chose to use a through-panel connector for the 12V cable. They are readily available at auto parts stores but I balked at spending almost $40 on one. As a bit of a challenge I chose to make one myself - for about $2 in materials. It was made from three simple pieces - with a custom machined bolt screwed through the middle of the (thread tapped) HDPE pieces.
The circular piece of the connector fits through a 25mm hole I drilled in the boot floor
I also made a custom gasket from 2mm rubber to seal the connector to the boot floor
For mounting the ground cable I machined a small steel boss with a 3/8" thread tapped in it, and welded it under the boot floor next to the hole/captive nuts for the above connector.
Photo taken from underneath the car :
The connector (and bolt for earth) fitted in the boot next to the battery box :
Because the cables are easily removed from these connectors on the boot floor, I didn't bother routing the battery cables up and over the subframe - between the boot floor & subframe, like the brake line and fuel lines. The cables run straight from the floorpan to the connectors with enough slack to stop them rubbing on the subframe, although I will cover them with some loom tube later. To visually differentiate 12V from ground cables, the ends of the cables have matching red/black heat shrink.
At the front of the car, I made another clamp to hold the battery cables and brake line away from the steering rack. As for the brake line it was planned to run from the master cylinder to the rear subframe as a two piece line to make it easier to fit/remove. I had already made both pieces - one piece from master brake cylinder to lower firewall; one piece from lower firewall to rear subrame. I only had to slip on some fittings, flare the line ends and screw the coupler in place to join the two pieces. The coupler and fittings were made installed near the base of the footwell, for no particular reason except that it was an easily accessible spot where line could be split without removing the front subframe.
Once the shell was the right way up and subframe was back in, I trimmed the cables to length and crimped on new cable ends connectors (with matching red/black heat shrink). I also machined a small adapter to allow the ground cable terminal to fit better against the round brace tube.
One last task was to make a short length of ground cable from the subframe to the body. The wiring loom and starter motor cable will be attached to the 12V terminal on the left.
Addendum : After fitting these battery cables I've since found out that by connecting the ground cable to the body in the boot AND to the body in the engine bay, it introduces a ground loop problem where electrical current has two paths of differing resistance (via battery cable & via car body shell). Ground loops can introduce unwanted electrical noise and/or sensor voltage errors. In light of this, I made a second through-panel connector for the ground cable near the battery box to isolate that cable-to-body connection.
The terminal on the ground cable under the boot will be cut and then using a butt connector, I'll extend it extended to run around the battery box to fit to the new connector. In the photo below the new connector is at the bottom of the photo.
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