MGF and TF 294mm brake upgrade

After my last post where I couldn't figure out that I had put the gearbox cable bracket on the wrong way around :roll: 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.
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.
EDIT
NO SPACERS ARE REQUIRED IF YOU ARE USING STANDARD MGF OR TF WHEELS

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.

That's a really ingenious upgrade. Would it be practical to do the calliper conversion without changing the wheels ? If so would there be sufficient clearance for 15" rims or would it dictate the need for 16", same as for the AP 4 pot callipers ?

Notanumber wrote:

That's a really ingenious upgrade. Would it be practical to do the calliper conversion without changing the wheels ? If so would there be sufficient clearance for 15" rims or would it dictate the need for 16", same as for the AP 4 pot callipers ?

Because i only have 16" wheels I am not sure about clearance for 15" wheels but I do know they need an internal wheel diameter of 344mm. The disc radius is 147mm plus 25mm for the calliper, double that is 344mm. If they will just go in then you might gain 5mm by grinding of the two ridges on the outside of the callipers, however that might (or not) affect the strength of the bridge. The beauty is that it is entirely doable at hone apart from the spigot rings, the mounting bosses on the R53 callipers are widely spaced and clear the TF hub easily. The brackets were made from EN3b flat bar which has very precise measurements and it drills and shapes nicely. I only used a pillar drill, a small angle grinder with flap discs to do the shaping and a set of digital callipers for the measurements. At the rear I used MX5 276mm discs and did the same. Since I had machined the hubs the MX5 discs slipped straight on.

For the benefit of my fellow countrymen……… wheel spacers are illegal here in Oz, so that knackered that sketch!

Cobber wrote:

For the benefit of my fellow countrymen……… wheel spacers are illegal here in Oz, so that knackered that sketch!

HP
That’s not the case, if you read again you will see that the spacers are only there because I am using 40mm offset wheels, if I was using MGTF wheels then no spacers are required. Due to selling my TF wheels I nothing to do a test fit with to establish if the wheel spokes clear.

It doesn’t matter if it is legal in other jurisdictions, it won’t pass a RWC here in Oz
Good engineering and safety have nothing to do with it, some government turds who’s sum total ofautomotive engineering expertise could be written on a postage stamp with a broad felt tip pen decided against it and that is that.
It varies from state to state, I’m in Victoria which is probably one of the most lenient states as far as the regulations go, West Australia for instance is much worse.
There are some things,in fact a great many, that they would never notice but spacers would be too obvious.

So you can tangle with a funnel web spider, swim in crock infested water & mix it with big whites, all of which will shorten your life to a considerable degree but you can’t widen the track of your car by using spacers! Just in case? Just in case of what!

Cobber, with the greatest of respect you have misread again, the 294mm brake disc conversion that I have described above does not need wheel spacers if you are using standard MGF or TF wheels which have an offset of 28mm I am using MX5 wheels that have an offset of 40mm. Using a 13mm wheel spacer reduces the 40mm to 27mm which is almost identical to the standard 28mm MG offset. I will edit my original posting to reflect this.

It’s the spacer they will object to not the offset

Airportable wrote:

So you can tangle with a funnel web spider, swim in crock infested water & mix it with big whites, all of which will shorten your life to a considerable degree but you can’t widen the track of your car by using spacers! Just in case? Just in case of what!

I think that you may have miss understood the purpose of the wheel spacers, the MX5 wheels are a 40mm offset, without the spacers they would have reduced the track by 12mm each side, using the 13mm spacers brings back to 1mm wider each side. To make it absolutely clear if you use standard MGF or TF wheels no spacers are required.

Cobber wrote:

It’s the spacer they will object to not the offset

Cobber, you still have not got the point you do not need spacers with this setup if you are using standard wheels, I chose for my own reasons (mainly because they are 3kgs each lighter than the eleven spoke MGTF wheels) to use the MX5 wheels which do need a spacer. MGF and TF owners can do this mod in OZ because it does not need wheel spacers to work.

I understand your sentiment, you take away with one hand & you return with the other, using the spacer to return the track to within the odd mm. I also understand what Cobber is saying with regards to the regulations in Australia & my comment was intended to highlight the eccentricities our legislators foist on us. I suppose you would be able wander off, ill prepared into the outback with little more than a shrug but have the temerity to stick a half inch spacer to increase the track on your truck & every blue light in the area will be after you. Daft I call it!