Since upgrading to the clear rear light kit that was originally supplied with my kit, I was concerned by the lack of illumination when hitting the brake pedal. A few friends were running a round third brake light, so followed suit and bought my own.
There is a bit of a debate on the lotus 7 club forum about fitting third brake lights, so though it would be a good idea to make a post of how I fitted mine, so others can follow (if necessary). Now for the disclaimer... This is just the way I thought was best for my requirements, and I'm not saying my way is the correct way, but the guide should help or give ideas to most third brake light installations.
There wasn't much to buy, but I've listed it below (with links):-
- FIA 51 LED Rain Light - £30 from Demon Tweeks
- High Level Brake Loom - £9 from Caterham Parts
- Some 2 core electrical cable
- Some various size and length heat shrink tubing
- Three packs of black Sugru
First part - installing the wiring loom
The first step is the remove the grommet on the inside of the offside rear wing. Once the grommet is removed, gently pull through the connector block (there is just enough slack) and remove the indicator connector block from the main loom by lifting the black clip with a flathead screwdriver as pictured below.
|Lift clip with a flathead screwdriver to remove indicator connector block from main loom|
|Connecting the high level brake light loom|
|Two core wire threaded up through boot seam|
|Two core wire coming out behind the boot carpet|
|Cable loom and two core wire joined, heat shrunk and cable tied into place|
|Two core cable and microphone wire heat shrunk and tie wrapped into place|
|Light connected with connector block|
|Rain light being tested - check out how bright it is|
A number of other Caterhams I've seen have this third light fitted to the roll bar, by way of a suitably sized rubber lined P clip. The P clip fits around the roll bar and is tightened with an M4 bolt which fits directly into the rear of the light.
As OCD as I always am, this wasn't quite elegant enough for my liking, so I looked into some other mounting solutions and the best idea I could come up with was to fit a u-bolt that was covered in rubber.
I contacted a number of U-bolt manufacturers, but none of them wanted to make a u-bolt in M3 size. The u-bolt needed to be M3 in size, as this is the correct size for the thread of the bolt to fit through the mounting eyes on the light.
Lee (my business partner) has a lathe and other gear for making things like this, so I popped over to his, cracked open a beer and let him get to work. (well not entirely, but it sounds good!)
|Tiger beer - whilst I was hard at work|
|Aluminium tube offered up to roll bar as a template for bespoke u-bolt|
|130mm brass tubing ready for machining.|
The brass was a little too thick for the M3 size required, so 15mm of each end was machined to 2.8mm in diameter.
|Brass rod being machined to 2.8mm diameter|
|.5 pitched M3 thread cut into brass rod, ready for bending|
|60mm u-bolt with black rubber tubing and M3 threads|
I trimmed a small amount of the profile off the rear of the light using a sharp scalpel to flatten it as much as possible before applying the sugru.
|Third brake light and sugru in packaging|
|Sugru packet opened|
Once moulded into shape on the rear of the light, I pressed the light up against the roll bar so the profile of the Sugru is indented with the roll bar shape for a good fit. It's not an extremely elegant solution, but it works extremely well as the Sugru is rubbery it creates a really good fit against the roll bar. The positive is that the Sugru is hidden when the light is fitted, so I've not real problem with the aesthetics of this solution.
|Third brake light with Sugru roll bar profile applied to rear|
|Caterham R500 with third brake light fitted|
|Caterham R500 with third brake light illuminated|