Stopping distance

The other day I had to do one of those emergency stops that rearrange your internal organs & in my case made my pacemaker work for it’s keep. The knob end who created the hiatus will still be completely obvious to the distress he caused me & others who had to take evasive action; there wasn’t just me unrolling expletives one after another.
If I’d been in the f I wouldn’t have been able to avoided trouble & this got me wondering all over again.
Brake improvements.
A few months ago one of you guys, I think it was MGB281 wrote a piece where he used R53 Mini Cooper front brake callipers on MX5 modified hubs & discs. This was interesting as the piston dimensions were in excess of our standards & that mixed with the larger diameter discs should create a superior system.
This has been a back burner though until I ended up with a pair of Mini Cooper callipers the upshot of which is a reassessment of the idea.
The big brake kits made by a number of companies are of course an option, as are the twin pot callipers but I want to retain my VVC wheels & I would find it interesting to try the Mini brakes.
I know the salient dimensions of the stock disc, what I want now is an equivalent disc with similar critical sizes other than a 280mm diameter & you won’t get that with our daft PCD. A 100mm PCD would have to be redrilled but that’s not a problem. So the question is would anyone recommend a disc type which would save me the fag of trawling through dozens of types spec’s & sizes?
Thanks in anticipation.
M

The thing that occurs to me is that if you have the ability to have extra holes drilled into a disc properly (from an engineering perspective regarding heating etc) could you not just have some of the 304mm discs from the 160 or special editions just machined down to 280mm?

My lathe won’t swing that diameter the throat being too small. If I had a big Harrison the picture would be different & so would the size of the workshop. Dividing the disc acutely I can do on my rotary table, although it is a little on the small side for a 280mm disc, I have successfully piloted this system on a scrap disc & the cooling whilst drilling is achieved by a crude but effective “suds system” made by my dad from an old oil can, dribble fed on to the workpiece.
Some might ask why not stump up & buy a system? Its the challenge which excites me; I didn’t need a miniature steam loco but my equipment & skills allowed me to build one (& start a second).
In comparison doing these modifications is small beer in comparison to other jobs, however as you quite correctly point out the same material care has to be considered in a small workshop as in a large engineering concern.
I’m blessed with this kit, being bequeathed it by my much more skilful dad, I’m just carrying on a tradition. And thanks for your comment.
M

Equipment limitations, I get you and while I understand your desire to come up with a solution yourself, I'm afraid I don't have any info about what may be a suitable disc. I can't even recall a place that might have a searchable index of that type of thing. If I was after computer stuff and looking for a graphics card that would fit a small case then a site like Skinflint.co.uk would be ideal but I checked and they haven't got anything about car brake discs.

Given the massive cost of kits by comparison, maybe a local engineering firm could still undertake the job I described at a fraction of the amount of a new setup?

Airportable wrote:

My lathe won’t swing that diameter the throat being too small. If I had a big Harrison the picture would be different & so would the size of the workshop. Dividing the disc acutely I can do on my rotary table, although it is a little on the small side for a 280mm disc, I have successfully piloted this system on a scrap disc & the cooling whilst drilling is achieved by a crude but effective “suds system” made by my dad from an old oil can, dribble fed on to the workpiece.
Some might ask why not stump up & buy a system? Its the challenge which excites me; I didn’t need a miniature steam loco but my equipment & skills allowed me to build one (& start a second).
In comparison doing these modifications is small beer in comparison to other jobs, however as you quite correctly point out the same material care has to be considered in a small workshop as in a large engineering concern.
I’m blessed with this kit, being bequeathed it by my much more skilful dad, I’m just carrying on a tradition. And thanks for your comment.
M

Just pop over and use my lathe!

Thank you both. If you were a little closer Cobber & I’d known you had a lathe that could swing a disc of that size (& other things that are of interest) you would be sick of the sight of me.
One problem with starting with an original disc of a 160 etc is the positioning of the grooves & drilling. In effect you would be pushing those closer to the periphery where there effectiveness would be reduced unless further work were to be carried out on the calliper position.
I don’t know many of the answers around this & before I start any development I have an amount of research to be done.
There are others jobs in the offing for me to do before the car goes back on the road, so there’s no rush. However once all the workshop jobs are complete the fitting will be little more than a full brake service.
Thanks again chaps.
M

Have you tried entering some numbers into the brembo website for disc size and see what comes back?
You might find a suitable disc from a standard car (or close enough to require little modification).

Thanks, I've the Brembo data downloaded on various computers + my phone & have been flitting back & forth for most of the afternoon whilst getting on with what I really should be concentrating on. I've been kidding myself that my wife hasn't noticed as she goes about her jobs, but she knows full well that I'm plotting. The calipers are off a mini cooper & it occurred to me that that disc might be something like & dam it it might just do. I've found a couple of bargain basement items to mess with, so ill report back, just in case anyone else is interested.
M

Airportable wrote:

Thank you both. If you were a little closer Cobber & I’d known you had a lathe that could swing a disc of that size (& other things that are of interest) you would be sick of the site of me.
One problem with starting with an original disc of a 160 etc is the positioning of the grooves & drilling. In effect you would be pushing those closer to the periphery where there effectiveness would be reduced unless further work were to be carried out on the calliper position.
I don’t know many of the answers around this & before I start any development I have an amount of research to be done.
There are others jobs in the offing for me to do before the car goes back on the road, so there’s no rush. However once all the workshop jobs are complete the fitting will be little more than a full brake service.
Thanks again chaps.
M

My lathe can do @ 350mm diameter without removing the bed gap and @ 500mm diameter with the bed gap removed. So I can tackle fairly big jobs with it, the only problem is it’s fairly brutal to use on small stuff and it’s too much trouble to try and hold pissy little workpieces in the big bastard, which is why I got a small lathe with only @ 80mm swing, for small delicate stuff.

I fitted the 4pot setup to my F and retained my hairpin 16s by using 6mm spacers.
Although I have to have the wheels statically balanced to avoid weights striking the callipers. I'm guessing a 10mm spacer would solve that issue too.

There is the dilemma of the engineer. If you are geared up to turn large items, such as locomotive wheels why worry about a lathe for small items & visa versa. It’s when you are bridging those gaps as I am now that the megalomania kicks in & you want a bigger lathe. Ok modifications to a brake disc isn’t exactly heavy engineering but in my workshop it’s outside the capacity of my kit.
I would regularly visit the Ffestiniog railway & take a tour of Boston Lodge works, there amongst wheel turning & large centre lathes was a Myford Super 7. I saw it being used a couple of instances & in both instances by an “old bloke” in a dust jacket & flat hat, just as I am now. It was covered when not in use & as cleaned as a whistle when finished with.
I digress (what’s new).
In comparison to Jupiter, South Australia is a close neighbour, but an inconvenient distance for my parochial outlook, which is why I’ll contact the local collage if I need to do anything outside my range.
Thanks Cobb’s, I would really like to meet you, we seem to speak the same / similar language; we would be arguing in no time at all.
M

Thanks David. If I could get MK1 VVC style wheels in 16” we wouldn’t now be having this conversation, I would simply have taken the four pots of my tf before it went & fitted my spare pair of bogos to make it stop in an orderly fashion. Obviously in retrospect I should have done that in any case but the road to hell is paved with good intentions.
As I mentioned earlier I have found a pair of discs that are reasonably close, requiring only stud holes being reworked & the centre diameter opening from 64mm to 66. This I can do on my mill, once it is set up, boring a couple of mm isn’t a problem.
Once the system is proven the pilot discs will find homes on the rear, whilst I’ll buy grooved & drilled for the front.
Don’t wait up for this, it could be ages before there’s another rush of inspirational blood, besides I’ve regassed spheres to fit & a fresh exhaust to go on, but it’s too bloody cold in the garage at the moment.
M