Stopping distance

Yes it was me, there are a few misconceptions though, the R53 calliper has exactly the same piston bore as the F and TF, the R56 calliper has the bigger bore but you need the smaller R53 calliper for this conversion. You may ask why bother swapping one 48mm bore calliper for another, its for two reasons, the first and most important is that the TF calliper was designed for 240mm discs, a 280mm disc doesn't fit into it properly let alone the 294mm disc of a Mini Cooper S. The R53 calliper was designed to fit a 276mm disc, a 294mm disc slots in perfectly and the edges of the pad don't overhang the disc. The second reason is that the brake pad is larger and will dissipate the heat quicker. The AP four pots aren't as effective as this setup either simply because of piston area, they are just 31.5mm in diameter. So pi x r2 is 15.75 x15.75 x pi = 779.3 sq mm but with four of them it totals 3117 sq mm. The R53 calliper is a 48mm bore so 24 x 24 x pi x2 = 3616 an increase of 14% but with a slightly smaller disc 294 versus 304 (3%) so the mechanical advantage is about 10%
You may have guessed by now that the brake disc that you need is a Mini R53, however there are two versions and you need the four hole not (obviously) the five hole one. Move the bolt holes 2mm inwards and some alloy spigot rings and you are almost there. I used some 10mm EN3b flat bar for the bracket and bought some stainless steel spacers from Ebay. I did have to grind a little from one hub mount due to it being cast on the generous side. Other than that it was a very simple job, no lathe or milling work and can probably be done for as little as £150, I paid £30 for a pair of callipers, then a rebuild kit, brake discs, steel bar, spacers and pads. I was helped out by selling my AP callipers for £200
For the rear I used MX5 276mm discs (bought with the left over money from the 4 pot AP's) again some AN3b bar, no spacers but a couple of washers. I had to open the centre bore by about one mm, easily done with a 60mm flap wheel in a fast spinning electric drill The standard TF rear callipers were actually designed for 260mm discs so a 16mm increase is nothing very much to consider. I actually bought new SAIC rear callipers but it failed the MOT because one was hardly working, I may experiment with MX5 NC callipers which may be a perfect alternative. I did read that the handbrake cable interferes with the subframe with large rear disc conversions but mine only gently touches when the suspension is at full droop. Although absolute braking performance is limited to the tyre grip nothing installs confidence as a rock solid pedal which is also helped by the servo brace and braided hoses which incidentally fit straight onto the R53 callipers.
If you are ever looking for something like these disc then Ebay is your friend, in this case I searched for "22mm vented brake disc" and the search came up with all the 22mm thick brake discs, Febi (the brand and Blueprint) is good because they normally list every dimension of their spare parts, so you can very quickly have a shortlist of what might fit, you can obviously do the same with diameter, centre bore etc
EDIT
I forgot to say that the only thing to do with the R53 disc apart from the hole moving is to get some spigot rings to convert the TF to Mini size disc bore.

That’s just brilliant, I’ve the R53 callipers being dropped off on Monday & my experimental discs will be delivered a little latter. They’ll be put on the “for future consideration “ shelf. The job list is long & the workers few so it might be a while until this lot bubbles to the top.
Thanks everyone.
M

Glad to be of help, my wife is now really enjoying the TF , the turn in on corners is now exceptional and as I have previously said the brakes are now crying out for more power. Fifteen inch wheels will fit over this combination although I haven't tried them nothing other than diameter has changed. Another possible calliper option (though expensive) are those from the FC and FD RX7, big pads, 22 or 24mm brake discs and much lighter than the AP callipers (over 1kg lighter). I have a set going onto my MGB. The problem with them is that the piston area falls between the common 48 and 54 mm callipers so if used on a TF you would definetly need the biggest (I think the 276mm or 280mm) would be OK) to balance out the braking.
It’s now 11.40 pm and we have just had a thirty minute drive in pouring rain , mostly backroads. Shame that the lights cannot keep up with the car, I will try some nightbreakers next.

We did just under a hundred miles today over the Mendips on a run with the MGF Register, a nice run then a carvery lunch. I would highly recommend the ATE ceramic brake pads for the R53 callipers, ADAC tested them on a VW GTI against among others, VW own brand, Brembo and Zimmerman. The best performing pads were the ATE, very closely followed by VW's own then the Brembo's, this was a properly conducted test as are all those done by ADAC; https://www.adac.de/rund-ums-fahrzeug/reparatur-pflege-wartung/wartung-inspektion/bremsscheiben-bremsbelaege/

It’s interesting to compare the spread of prices for the ceramic pads, anything between £65 & £110. I haven’t done an exhaustive search across the range but there appears to be several part numbers for what initially look the same item.
Anyone who has been around cars for any length of time knows that two different numbers can pertain to a product which is indistinguishable from its mate & can be substituted one for one but one is a different colour batch & costs half as much again.
There are parts bin parts that reoccur across the BL / Austin / Rover / MG / Land Rover family which are absolutely interchangeable but have different part numbers & prices. Pattern part numbers might easily be dreamed up by faeries on LSD.
Anyway thanks again, all these pieces of information built into a fine picture, let’s hope the finished article looks like the picture.
M

One thought on the Osram Nightbreakers. Firstly it’s not easy to quantify the light output from different lamps, whether they are expensive or from the pound shop without proper tackle. What is a lumen if not a character of a kids TV program & has he / she have a pal, lux.
I have the Osram units & find them “satisfactory”, but against my daily drive they are lacking.
These are symptoms of rising expectations, had my Morris Traveler been fitted with Osrams I would have been king of the hill, but that was over fifty years ago.
I have a couple of circuits which jack the 12v up to as much as 36, so I’ve lashed up an 18v system, soak testing over several days & that’s where I run out of expertise in measurement.
Nether lamp failed, which is a plus & there was a perceived increase in light output but these were static tests.
Brighter = hotter = poorer reliability under dynamic conditions, however I will have a play with some spare lamps but that will be after the experiments with solid state switching on main beam. That won’t be any time soon.
M

If it makes the bulb run hotter you run the risk of the shitty plastic reflectors and the metalised surface deteriorating………the bloody things are inadequate as it is

Again you have proven how astute you are. It takes someone with the long view to notice the obvious, however those who are closer to the object are blinded by their problems proximity.
Or it takes a cantankerous old bugger in Australia to see what the cheapskates in the English Midlands missed first time around.
The probability of my fitting my “projected” 18v system is slim, it’s more from a technical standpoint. If I were to come across a pair of f headlamps I could we’ll give it a go & it would be switchable main beam / overdrive main.
It’s always good to have you comment Cobb’s.
M

I’m not saying don’t give it a whirl, but make sure you don’t bugger up your only pair of lights doing it. If you had a spare set laying about that might be sacrificial in the name of science then well.and good.

I had a look at the Nightbreakers and Cobber may be correct about heat output, they are rated at a maximum 73 watts but a nominal 60 watts. This may just be numbers because I think one relates to a 12 volts supply and the other to 13.2 volts, in which case the same would apply to any other bulb receiving the full 13.2 volts; https://www.osram.com/ecat/NIGHT%20BREAKER%20LASER-Halogen%20headlight%20lamps-Car%20lighting-Automotive/com/en/GPS01_3043435/ZMP_4057702/
I have not found anyone complaining about heat damage but owners very often don't notice a gradual deterioration in a lights performance.

The lamp units I have are in first rate condition & I certainly wouldn’t sacrifice those. If a pair trotted along at the price of a couple of beers I’d give it a run.
Certainly not under any other circumstances.
M

It’s interesting how many folk have no idea how ineffective their headlamp have become; until you get an MOT fail as this deterioration occurs at such an imperceptible rate.
How often do you see a vehicle approaching with defective lamps & you might see the same culprit over & over again with no change.
As the driver you don’t approach your car with the lamps on, you invariably turn them on at dusk then grumble like mad about how bad the illumination is.
Relatives of ours live deep in farming county where it becomes difficult to differentiate between road & field before & after milking, to such a degree that when returning home at night, the lights become useless after half a mile. It was this that prompted the headlamp washer system. Now I can drive a mile & a half.
M