Date Created: Apr 10

So finally the front brakes have cried enough and so have I after getting them worked on every other 6 months so here is the upgrade. In short, rear caliper spaced out and hugging a Mazda RX8 front 323mm disc and the fronts, well they're a little special. Porsche 996 front monobloc 4 pot calipers gripping a Supra 325mm front disc! Bloody huge they are front and rear thank god for big wide wheels. The rear adaptors were bought through a Group Buy on IMOC the front calipers I sourced with the help of a lad on MR2.com called Karl aka scarecrow whose advice was never ending and always useful. So on with the story

Front brake upgrade

The front brake calipers beyond their useful working life and doing their best to kill the discs and pads which they succeeded with ease. The drivers front would cook the entire wheel to the point I worried the heat would break other items like the wheel or snap some studs which would be very bad.

I had looked into this upgrade a couple of years ago but never followed it up, in hindsight it would have saved a huge amount of time and effort not to mention money but you live and learn (eventually). After reading a thread on MR2.com I decided to take the plunge and Karl was invaluable in his advice, firstly by explaining the mechanics behind the braking system and the pitfalls of throwing on any old calipers and secondly providing me with details of where to get the calipers. The exchange rate had moved nicely back in the UK buyers favour so a pair of calipers from a crashed Carrera 996 were purchased and shipped over the pond. Once that was done I acquired a front passenger hub from a car that was heading to the scrappy and got some supra discs ordered. A machinist then made up the required brackets and supplied the caliper mounting bolts too. All I had to do was get the whole lot bolted together! I think Calum knows every bolt and dent in my car because of the amount of work he's done on it. Again, the mans a star!

Anyways, parts sourced were

• Porsche alloy 4 pot monobloc calipers from the 996 - 36mm leading with 40mm trailing pistons
• Toyota Supra Twin Turbo front 325mm discs, 30mm wide overall height 50mm centre bore of 62mm
• Caliper adaptor brackets - created by local machinist
• Hub to bracket mounting bolts - 4 of M12x60mm Grade 10.9 and locking nuts
• I chose Pagid OEM style brake pads sourced from a local Eurocarparts
• total weight gain per corner = 0.5kg - yep using std parts I gained zero point five kilograms per hub

The Porsche calipers are designed for a 315mm dia disc with a thickness of 28mm and while they'd easy take the 325mm dia the 30mm thickness of the supra discs did mean a bit of modifying. Nothing serious but the pad pins needed filing back by 1mm each to resort the original clearance. Doesn't seem like much but some forums where this conversion has been done on 30mm discs had found when the discs get hot they can expand enough to touch the pegs, no doubt made easier by the caliper itself expanding with the same heating action. It's not a chore to file them so it's not worth having to take the whole lot back off afterwards because you didn't file the pegs.

So we started as expected by removing the front drivers wheel (actually we did passenger side first but no pics taken lol) we got greeted with the front drivers disc which was looking very marked indeed. You can see multiple outlines of the pads where they've been cooked onto the disc surface, not good at all


so with the caliper carrier and disc removed the stone guard was eyed with suspicion then removed as the bigger Supra disc would not fit. Lucky for us the guard was pretty rotten, it pulled apart quite quickly to become a pile of rust on the workshop floor


which left us with the bare hub to work with


so first the caliper adaptor was fitted to the hub with some Grade 10.9 M12x60mm bolts, I think 65mm's would allow the locking nuts more purchase so when we strip it down for inspection we'll upgrade the bolts



A test fit of caliper and disc gave us this, note the supra disc fits straight on, mounting holes and centre bore perfect


That's about as good a brake coverage you'll get from a caliper / disc combination,as good as stock on a bigger disc. So after checking that we undid the hydraulics of the old caliper and found they pretty much bolted straight into the Porsche unit. My braided hoses are a little on the neat side so a bit of creative modding on the mounting bracket allowed a good fit however I'm sure it will vary from pipe set to pipe set. Below, see the difference in std to supra disc, not as much as you'd think but still useful enough


So how does it all look once the wheel is bolted on, does it even clear the caliper?


plenty of space for the spokes and the inside of the wheel rim itself

Rear brake upgrade

Now clearly upgrading the fronts and leaving the rears alone would not be the greatest idea in the world so in true fashion the rears were looked at too. Parts needed slighter easier

• Bracket kit for re-locating rear caliper - sourced from IMOC group buy contains all bolts brackets and hub spigot rings
• Mazda RX8 2005 front 323mm, 24 wide and 45mm total height - note these discs need the spigot ring as supplied in the bracket kit above
• clearly new pads are needed here as well - I stuck to good old OEM Toyota pads from er Toyota
• total weight gain per corner = 2.5kg - a little on the heavy side but that's std calipers plus a bigger disc. boo

Now that doesn't look too bad but these are the original discs as far as I can tell, I've never changed them so that's 15 years and 121k miles on them. The next picture tells the story, just look at the rust in the centre and how much the standard pads / caliper leave unswept on the disc. Sadly the upgrade will leave even more unswept but that's the drawbacks of using std calipers on bigger discs. Curse you Toyota for that stupid rear handbrake caliper!


Again the stone guard is in for a smacking as the Mazda Rx8 front 323mm will not fit with it in place. So after a bit of hammering and pulling and swearing, it's dead and on the floor though in much better nick than the front guards managed!




So on with the new rear bracket as sourced from IMOC BBK Adaptor Group Buy and we get this


and then with the carrier and disc in place looks like


smooth, very smooth. The pic below shows the black coloured spigot ring for the disc to centre it on the hub


and with the wheel fitted



These discs fill the wheel like the OEM stuff and actually makes the 17's look small.

Final shots