A new wiring loom part 2 - Fuse holder and Relay Base

Main Aims 

- Improve reliability (existing wiring 79 years young)

- All circuits above negligible current operating via relays

- Minimise the current flowing through old switches in the dashboard

- Upgrade to modern head and spot lamps

- Reinstate Trafficators alongside new indicators

- Addition of hazard switch

- Addition of electric fan to cool engine

- Addition of electric fuel pump

- Provision of electric water pump

- Aux for USB sockets

- Additional interior light

- Upgrade from Dynamo to Alternator

- Replace starter solenoid

- Future proof with spare ways for fuses and relay

- Modern Thin wall copper cabling

- Modern fuse box and relay holder

There are many different fuse boxes available, some are pre-wired and others you build from scratch. I like the look of the MTA range of fuse boxes which are readily available in the UK. They offer a 16 way fuse holder, 4 way automotive relay base and a 7 way micro relay base. They are supplied complete completed with covers and come supplied with all the necessary connectors. They can also be connected together in any combination.

The initial draft required 1 x 16way fuse holder, 1 x 4way automotive relay and 1 x 7 way micro relay. The idea was micro relays for all the load switching and the 7 way base for the LED flasher relays.  Unfortunately the flasher relays are slightly too tall to fit with the lid so I ended up with 2 x 7 way relay base and remote mounting the flasher relays. 

I've used multiple suppliers for the re-wire including:

https://www.3waycomponents.co.uk/ - MTA Fuse Boxes

12 volt planet - Thin Wall Cable in a range of colours

Car Builder Solutions -  Wiring Accessories

https://www.3waycomponents.co.uk/ - MTA Fuse Boxes

Fuse Holder

Using a spreadsheet I listed all the circuits and divided them between the fuses based on power requirement. Some juggling required to observe the max current for 1mm or 2mm cable allowing for volt drop and heating due to bunching the cables together.  

Worth noting the numbers below are rounded up values with everything ON at the same time. In practice having measured the current with the car running the values are far lower. . 

Relays

The number is probably overkill but it does simplify the wiring and means the original switches on the dashboard and within the steering column only need to switch the current necessary to operate the relay coil. This massively reduces the load on the switches and they can happily operate for many more years. 

 
Fusebox prep

1st step was to add the feeds to the fuse holder. These are a combination of 1mm or 2mm wires. They will all need to be terminated at the supply side of the starter solenoid or battery. 

Sunbeam Talbot Ten - Adding 12v feeds to the fuse holder

The fuse holder and the relay terminals all use a similar type of crimp. 

Crimp connection to the fuse holder blade terminal

A new wiring loom Part 1 - Out with the old

From owning old cars electrical gremlins are the ones that let you down. The wiring on the Ten was original except the modifications to the head lamps, fitment of indicators and voltage regulator for a engine temperature gauge. For this, the loom was cut about and different wires added to suit. 

The build quality of the original loom is great. The loom is clipped to the chassis via brass nuts and bolts with steel p-clips. The cotton harness braiding is a delight and something you don't see now but at 79 years young an update is needed.

Sunbeam Talbot Ten Engine bay - old loom

Sunbeam Talbot Ten Engine bay - old fuse box &regulator, modern flasher relays

Sunbeam Talbot Ten Engine bay - reverse of old fuse box and regulator

Sunbeam Talbot Ten - original wiring to dashboard

Sunbeam Talbot Ten - original wiring to dashboard

Sunbeam Talbot Ten - Original Loom and cotton braid

Sunbeam Talbot Ten - Dashboard area

Sunbeam Talbot Ten - Original Loom with later additions

My main worry is the full current for the circuits run through the switches in the dashboard. I want to reduce this down to the bare minimum with the use of micro relays. For aesthetics I'm planning to refurbish the original fuse box in the engine bay and locate a new modern unit under the dashboard away from the elements. 

Paintwork restoration

Since purchasing the car I've been in regular contact with the son of a previous owner, it has been great to hear the stories of his late father owning the car and the changes he made during his ownership. His father put many hours into improving and polishing the paintwork. Sadly it was something that always let the car down and I'd assumed could only be corrected with a re-spray. 

My father-in-law came to stay over Christmas and was confident under the orange peel was decent paintwork lurking. The whole car was pretty much like the door below.

Started off with a mild cutting compound and a rotary polisher, overall not much of an improvement. It did confirm however the issue seemed to be the clear coat applied on top of the paint. We (FIL) then switched to 3000 grit wet and dry to cut back the top coat. I looked away at this point! 

Throughout the whole process no red paint was removed hence the assumption the issue was the top coat. 

Further machine polishing to remove the scratches from the wet & dry and the difference was stark. Paintwork has flecks and resembles metallic paint! 

At this point with one highly polished door there is no going back so we (FIL) proceeded to work over the whole car.

It has totally transformed the appearance of the car. 

Alternator Belt Sizing

 Bearing Boys have a helpful link to calculate the belt length by measuring the diameter and the centre distance. The centre distance is 440mm, crank pulley 126mm and alternator pulley 59mm. It suggests a pitch length of 1173mm.

The SPBX belt is designed to go around a smaller diameter pulley. I'll update once the belt arrives.