I was hesitant to post this. Eighteen months ago I bought a 2004 MGTF 135 where the previous owner hadn't put oil in the engine. On the way back home with the TF on a trailer I also collected a low mileage VVC engine and gearbox. I bought it cheaply sight unseen and with well over £4000 of invoices over the previous four or five years it had to be a good buy, so much had been bodged I decided to strip it down and rebuild the subframes and suspension while doing the engine swap. The eleven spoke wheels had been very badly kerbed, the only good one was the spare wheel, likewise the AP callipers were in a dreadful state and I decided to sell them as well and let someone else restore them, but replace them with what. A chance conversation pointed me in the direction of Mini R53 front callipers' they have the same 48mm piston diameter as the TF's and were used with 294mm discs on the Cooper S. I was getting a good idea of where I was going and while looking for some new wheels found that the MX5 was 4x100 PCD and most of them are lightweight as well.EDIT
No wheel spacers are required if using standard MGF or TF wheels
Since I was replacing all the wheel bearings I had the hubs turned down to take the MX5 wheels and redrilled the hubs to a 4x100 PCD. Two R53 callipers off Ebay and two rebuild kits cost £79 The brackets are very simple just a piece of EN3b flat steel drilled to fit both the hubs and callipers and some 1/2" stainless steel spacers, various M12 bolts and it was finished. Today was actual fitting day and they went on a treat, I wouldn't have had the drilled brake discs but they were on a very special offer at the time.
What are the potential benefits? Well although the R53 calliper may seem to be another version of the TF one it has a big advantage in that the calliper fits the disc properly. The standard TF calliper does not fit onto a 280mm brake disc, it is too large to fit right in, with these there is no problem. Theorectically it will outperform the AP callipers with 304mm discs, the reason being the brake piston area. The AP callipers have a total piston area of 3117 square millimetres, for the R53 callipers the area is equivalent to 3620, an increase of more than 15% however the brake disc is almost 4% smaller in diameter. Given that a four pot calliper will be more effective than a single pot one the difference will be less than the theoretical 11%. The 13mm wheel spacers are needed to get the wheels centred, MG TF wheel offset is 28mm, the MX5 wheels are 40mm offset so the 13mm spacers get them within 1mm of where they should be.
It's difficult to calculate the true cost, The wheels, discs, pads, callipers, rebuild kits, nuts & bolts, paint, machining came to about £355. The sale of the wheels and AP callipers brought in exactly £200 minus Ebay fees so about £170. So for £180ish I have got the upgrade and four virtually brand new Toyo tyres which are worth over £200, so perhaps the upgrade was free.
