Front Wheel Bearing Replacement MGTF

If you do the maths you will understand, but briefly due to the combined surface area of the AP's pistons being smaller than the standard 48mm pistons they do not exert as much pressure on the pads. In fact the AP's need a 280mm disc to have the same performance as the standard 240mm discs. The upgraded 280mm discs give about 6% more braking effort than the AP's without the cost and effort of refurbishing corroded AP's. I actually went one stage further and fitted 294mm discs on the front. With that increased performance at the front you really do need the 280mm conversion on the rear whereas with the AP's you don't. What is surprising is that MG fitted such small discs for a car designed in the 1990's, the rear calipers were designed to work with 260mm discs and cope with 280mm's with no problems, however the 280mm's with the standard calipers do lead to a small amount of pad overhang. I overcame that by using Mini R56 calipers that were actually used the 294mm discs by BMW themselves.
EDIT
I have just read Ellisojo's last post, selling my AP's paid for the Mini Cooper calipers, the mini brake discs and the MX5 rear discs plus the steel, bolts, spacers, caliper rebuild kits and new pads all round. This also fits under 15" wheels. If I was doing it again I might go for RX7 four pots, they are about 10% more piston surface area and weigh about a kilo lighter than both the standard cast or AP calipers.

Thank you..that is a very interesting post.
My 15 inch wheels are limiting me but I am also getting the impression that the AP 4 pots aren't that drastically superior to warrant spending on 16 wheels and tyres.
Two questions.
1. Can you fit those 2 pot Mini callipers under 15 inch rims
2. Who makes the brackets to make the callipers fit
A really good reason to use Mini callipers and discs ifor me is being able to get competition pads. A better pad material is a Huge improvement in stopping power regardless of disc size
Thanks.

I made the brackets myself from ENB3 steel bar with stainless steel spacers from eBay which is why my setup cost so little. When I did this a couple of years ago I took some measurements and I was certain that 15” wheels would clear. I think the biggest clearance problem with the AP’s is with the spokes. I have gone with ATE ceramic pads which were the best performing pads in an ADAC test, far better than Brembo. Our TF is solely for road use, we drive over Exmoor quite a lot and you can test the handling and brakes up there now the tourists have gone home for the winter. 
I-also re drilled the hubs 4x100 so that both the mini and MX5 brake discs went straight on then chose to go with MX5 wheels due to the weight reduction. There are many ways to skin this cat

For a whole series of reasons I’ve ended up with the four pots but I’ve be 90% there with a system as per MGB281. I made all the bits, refurbished the Mini callipers & was all but ready to fit earlier this year but I elected to use the car, on the days it was suitable rather than fit the stuff.
Done well, they fit under 15” wheels & they look really neat, there are a few pictures of the job a fit back if you care to look. They’re sprayed in yellow, we’ll I had the paint & it would have been churlish not to use it.
I made a corresponding set for the rear using our standard callipers, they will be going on later.
M

The 60,000 dollar question is are you keeping them or selling them.
I won't ask for discount because of the yellow...

If your offering 60,000 dollars in definitely selling !
We might work something out.
But not tonight.
M

Thank you for your comment! You're right—upgrading pad material often provides significant improvements in stopping power without needing larger discs. To answer your questions:  

1. Yes, Mini 2-pot calipers can often fit under 15-inch rims, but it depends on the specific rim design and offset, so double-checking clearance is essential .  
2. Brackets for fitting Mini calipers are usually custom-made or sourced from specialized suppliers; some motorsport fabricators offer them, so it’s worth checking with racing or performance shops.  

Mini calipers with competition pads sound like a solid, cost-effective solution!

 

I urge caution on any brake modifications, your life and others are at risk if you get it wrong. Only do it if you understand the engineering aspects of the job, don’t get sucked in by “competition” pads, they often need warming up before they start to bite. Quality standard pads will be more than enough for everywhere except track days. We are very lucky in this country to be able to modify our cars, most owners in the EU and OZ are heavily restricted or need an engineer’s report. 

That is very good advice and needs to be noted.
Tried and tested bolt on upgrades are the way to go if mechanical and experience is limited.
Personally I am confident simply because every competition car I have built or helped build has had to have better brakes! 

 Not all bolt on goodies are equal. I have seen some examples which look like they have been designed & made by someone who has recently graduated from Airfix to Scalextric.
Conversely there are chaps like MGB281 who have produced systems which could easily be mistaken for a product from a competition specialist.
I can’t comment on soooper dooooper brake pads as I’ve never experienced the change from a respectable manufacturer, like Ferodo to some exotica.
A friend paid a fortune for some product made from materials from a distant galaxy & ran into a bus. Had he had bogo pads he would now have more hair & probably not the grey it is now.
I include a picture of my adapter plates; the unpainted one is for the rear callipers & still requires finessing, which in my workshop speak means another going over with a flat bastard file.
M
 

That's why I said"tried and tested" ..as recommended by this forum...ie. Mike Satur.
Those yellow callipers are quite fetching. You do good work even with a bastard file!

Thank you Airportable, my heads now too big to go through the doorway! Maths and Physics  (inherited from my mother) were my best subjects at school and I enjoy solving problems. I am always surprised to see five year old higher performance cars from the likes of BMW, Audi and Mercedes fitted with cheap Chinese tyres. If only they read how badly some of these tyres perform in the tyre tests conducted by Auto Express and ADAC they would spend a bit more on quality. The same with brake pads, ADAC tested ATE, VW, Brembo, Zimmerman and a cheap unbranded pad. The test include pad, wear, disc wear and repeated braking and a simulated mountain descent. What is surprising is that the two high performance brand’s failed to match the VW own brand pads or the ATE ones but the test equally revealed just how bad these particular unbranded ones were. 
One option for the rear on a TF would be MX5 NC calipers, same piston bore, the brake cable fits into the caliper bracket and only a small modification needs to be done to the actuation lever. They are designed for 276mm discs and have the bonus of being lighter weight. 
I know that this “upgrade “ isn’t needed but the challenge is there. I have an engine-less TF, I may yet experiment. 
It’s amazing how this thread has drifted from wheel bearings to brakes and now me adding tyres.