One of the hardest and most time consuming things on this car has been sorting better brakes. The stock system is barely adequate for spirited driving with the factory performance, so tripling the horsepower certainly requires a suitable increase in stopping power also.
I have literally spent hours and hours combing through the internet, magazines, the DBA catalog and anywhere else I could find to figure out a way to get bigger brakes under this thing. Strangely enough nobody makes a big brake kit for a Morris 1100.
Years ago I bought a fancy Tarox big brake kit designed for a Mini from another member on here. Given the interchangeability of some mechanicals I had hoped it would work, but it was not to be. Those featured a 234mm disc and nice alloy mounting bells plus six pot alloy calipers. All lovely stuff, but when I would have to remake the mounting brackets and bells, only using half the kit hardly seemed worth it, and so they were on-sold.
The Metro turbo vented discs are the largest bolt on solution I could get at 213mm x 20mm. At one point I even looked at Austin princess brakes, which were 270mm diameter, as they seemed like they would also bolt on, however they were not vented and I doubt would fit inside any wheel I could make work.
The brakes I have fitted (Metro turbo vented discs with Renault Clio sliding single calipers) did pass the engineering brake test, but only just. And my engineer did recommend I fit a booster.
I improved them somewhat with some EBC greenstuff pads, but fitting a booster was always going to be a pain given the late mini split master cylinder braking system.
After much head scratching and poring over the DBA catalog, I settled on Ford Econovan brake discs as a possible option. They are 256mm diameter, 20mm wide and have a big enough hole in the middle to fit over the CV, and are basically flat like the motorsport style discs, just much cheaper. So with a suitable mounting bell made they looked like they just might work.
Econovan Disc
With those in my hand I fired up the CAD software and tried to see what sort of shaped I'd need. After many iterations I finally arrived at something I liked, I then 3d printed a model and took it out to the shed to verify my work.
Disc with Mockup bell
Econovan discs vs Metro Turbo
While initially I had hoped to reuse the Clio calipers by simply moving them outboard, it meant that the mounting holes clashed with the hub and just got problematic. However some rx7 4 pots came up cheap on market place so I figured I'd give them a shot. Their much wider bolt spacing made it physically possible to fit with an adapter.
3D printed caliper mount mockup number 5.
RX7 caliper on the larger disc
Mockups showed that the brake bell geometry was spot on, but I made a new design to use bolts and nuts instead of threaded holes at the disc mount. And I went thru 5 iterations for the caliper bracket to position it where I needed it while still allowing access to the grease nipples.
With the design sorted I uploaded the files to JLCPCB and sent them some money.
Final Brake Bell Design
RX7 Brake Caliper Mount
And so all this leads me to the shiny bits that arrived in the post today. They turned out awesome, now I just need to get some new bolts for all this and we can mount them up.
