Brake Lines Part 1

The routing of the brake lines is relatively straightforward.  The AK Build Manual shows the positioning of the pipe runs quite clearly and most other builders have had no problems with this layout and with fixing the pipes using P-clips or the plastic push-in type clips.

So clearly this is the way to go and it should all be simple, yes?

Well...

Clearly, for me, that would all be too simple...and I lay the blame squarely at the doors of the guys from Bad Obsession Motorsport (BOM).  I have been following their Project Binky build on YouTube for some time; there are several episodes charting their build of a Rally-spec Mini based on shoehorning the running gear from a Toyota Celica GT4 into the confines of the Mini.  These guys are evil geniuses when it comes to bespoke bracketry (of which their project required many) and when they imposed a "no P-clip" policy on the build and fabricated their own brake/fuel line clips, I started to get thinking.

The AK chassis is a thing of beauty.

 OK, maybe I'm getting carried away. but the chassis rails are all box section and fully sealed.  So why would I want to drill loads of holes into the chassis providing potential entry points for water and the risk of the dreaded metal rot?  I could inject Waxoyl into the box sections to mitigate this but surely it would be better to avoid the holes in the first place.

The BOM solution consisted of a steel plate, a couple of rivnuts and some 12mm thick nylon sheet; the resulting component can secure multiple pipes replacing several P-clips.  A CAD model of the basic concept is shown below.

Over-Engineered P-Clip Replacement Concept...

The steel plate, with the rivnuts welded in place, is welded to the chassis, the two halves of the nylon clamp are then placed over the rivnuts, bolted down and voila!  One pipe clamp with no drilling into the chassis rails.

After much mulling over this solution, I realised that I was probably being a bit anal about this.  On close inspection, there are already several holes drilled in the AK chassis for the body mounting bolts amongst other things.  I will also probably be unable to avoid drilling some holes for mounting the 3-way brake unions and eventually for mounting the fuel pump and filter.  Additionally welding the mounting tabs onto the chassis will involve removing some of the powder coat and having to try and recoat the patches, plus some welding into some tight spots between the chassis rails; which to be honest, sounds like a lot of faff (even for me).

(And actually by the time I have posted this I will have drilled a load of holes in the rear of the chassis for the fuel tank mounting...)

So maybe the answer is to bolt the clips to the chassis after all; in which case why not just use P-clips?  However, I still think the bespoke solution is quite neat and does have the advantage that I can use a single clip to hold multiple lines (including potentially the fuel lines) so that does reduce the number of holes that I will need to drill.

So with a slight modification, Version 2 of the P-Clip replacement concept was produced in CAD.

Version 2 - spot the difference!

The next step was to make a prototype based on the CAD concept.  The mounting plate was cut from a spare piece of 2mm sheet steel.  I drilled two 7mm diameter holes which were countersunk to accommodate two M5 rivnuts and allow the rivnuts to sit flush with the back of the plate.  A 5mm hole was drilled for the mounting bolt.

The clip body was made from two pieces 12mm thick Nylon-6 sheet cut 12mm wide.  The bottom piece had two 7mm diameter holes drilled to sit over the rivnuts and a 10mm counterbore 5mm deep to accommodate the head of the mounting bolt.  The top piece was drilled with two 5mm diameter holes with a 10mm counterbore 5mm deep to allow the heads of the fixing bolts to sit below the surface of the clip.

The final step was to hold the two pieces of the clip together and drill a 3/16 diameter hole and a 1/4 diameter hole (for brake and clutch pipe respectively) along the join line between the two halves.

All the components for the brake pipe clip...

M5 Rivnuts in place on mounting plate - large counterbore in bottom half of clip is for cap-head bolt

Bottom half of clip in place on mounting plate

Top half of clip in place - secured with M5 x 16 Cap-head bolts

Completed assembly - holes for 3/16 brake pipe and 1/4 clutch pipe

Rearview with M5 x 6 Cap-head bolt in place for securing to chassis

I'm pretty pleased with the prototype so now I just need to knock out a few more in various configurations depending on fixing location and pipes that need to be secured.

To be honest this is completely unnecessary and massively OTT compared to the perfectly adequate and usual methods of fixing brake pipes.  But it's another little way of putting my own stamp on this build.