Possible Mini Brake Upgrade

[Rusty_McRusty]

Just been having a think about brake upgrades and saw that the Mini Cooper S Works uses a 294mm x 22mm disc. It's 10mm deeper than the stock 260mm disc but the G60 disc is around 6mm deeper and that's used a lot. The only dim that needs changing is, as ever, the centre bore (64.16mm).

Next, I also noticed that the E39 uses a 296mm x 22mm disc so the calipers for that will be suitable for the disc, not checked cylinder bore yet though.

Another option is a bracket for the OE caliper carrier.

Has anyone used the Cooper S Works disc for a brake upgrade before? A brief search hasn't thrown anything up but these things can get lost in a thread.

[GeoffBob]

Just been having a think about brake upgrades and saw that the Mini Cooper S Works uses a 294mm x 22mm disc. It's 10mm deeper than the stock 260mm disc but the G60 disc is around 6mm deeper and that's used a lot.

"Deeper" ? Not sure exactly what you mean but I suspect you are refering to the offset of the disc from the from the mounting face on the hub.

The G60 is just shy of touching the track-rod end. If the Cooper S disc is 10mm on top of that then the disc is guaranteed to collide.

[Rusty_McRusty]

Aye, more offset 10mm vs. 6mm.

Sounds like ~5mm spacer would be required between hub and disc.

[GeoffBob]

6mm offset on the G60's ?? Measured exactly where to where if I may ask.

[Rusty_McRusty]

Sorry, rushed that last post, as per the first post, I was referring to additional offset over and above the OE 260mm disc.

To be clear, offset for the 294mm Mini disc, taken off the Brembo technical drawing on their site, is 37.9mm +/- 0.1mm

The same site shows 27.9mm offset for OE 260mm disc and 34.0mm offset for the G60 disc, both with the same tolerance. I hope that clears things up.

[GeoffBob]

Ah, makes sense now. The G60 is indeed about 28mm if memory serves. I have G60's on my car with a 3mm spacer to pull the disc away from the hub, so I suspect you'll need a bit more than 5mm for the Mini discs. I have heard of others fitting them (the G60's) without the 3mm spacer, but then the disc is right on top of the track-rod end. I posted my front brakes up here if of any interest to you. Lots of other brake upgrades from other zoners around here too. KeriWMS products are very popular.

FYI, wouldn't a "mini brake upgrade" simply constitute painting the calipers?

[Rusty_McRusty]

LOL, yeah, the title was chosen for its ambiguity

Thanks for the link, I had a look at your Alcon setup, very nice. If I had the £... I been looking at Porsche 986 front or rear monoblocks as an option as they're well priced and take ~300mm disc but in 20 or 24mm. Found that Clio 182 discs are 24 thick x 280mm but that's for anther day.

I've seen a few brake threads and was thinking the options through, was just interested if anyone had touched on this disc as it offered a further few mm of leverage. The WMS kits look very good VFM, given that they're larger, lighter and 4 pot up and matched to the E30, spent a while reading the various threads on them the other day.

Taking your 3mm 'internal' spacer, adding in the 4mm extra to account for the offset from G60 to Mini (giving a 7mm spacer) and then taking off the ~2 mm due to a thinner mounting face, the wheel will move outwards ~5mm when compared to the OE discs.

[GeoffBob]

Taking your 3mm 'internal' spacer, adding in the 4mm extra to account for the offset from G60 to Mini (giving a 7mm spacer) and then taking off the ~2 mm due to a thinner mounting face, the wheel will move outwards ~5mm when compared to the OE discs.

Fair enough. Sounds like the mini disc is worth a try then. Not sure if you are looking secondhand but 4-pots off the Mazda RX7 are quite popular. Theo325, amoungst others, has a set of these on the front of his car iirc.

[Rusty_McRusty]

Yeah, it would have to be secondhand at the mo as the IS is my sensible daily transport ;) I've had the 996 425/6 monoblocks on the front of my S2 for over 4 years now, they stop rather well with some DS2500 pads in there, no fade on track, even with over 1.5 tons and plenty of abuse.

I've seen those RX7 brakes mentioned on here and another post I looked at on a Mazda MX5 forum (came up when searchuing for 294mm discs), cheers for the name.

[Rusty_McRusty]

92-96 Mazda uses a 294mmx22mm thick disc

Shame that the offset on it is 60mm.

Might have to source some calipers and have a look.

[Theo]

WMS brakes on the front of mine. Proven product with no messing about with wheel spacers and longer wheel bolts etc.

I seem to remember reading that the RX7 calipers are far from ideal - can't remember why though.

[GeoffBob]

WMS brakes on the front of mine. Proven product with no messing about with wheel spacers and longer wheel bolts etc.

Theo, did you have RX7 4-pots on the front at any point in the past or has my dementia progressed? Apologies if I goto it wrong. I know that I interacted with someone at some time who had RX7's on the front ?? ??

[Theo]

I think you've been in the sun too long Geoff!

I've had my WMS calipers for years now (as an aside, they have no dust seals and are still in perfect working order) so you're definitely getting me mixed up with someone else.

Easily done though, must be plenty of other people like me pestering you for help.

[keri-WMS]

I've got a couple of points that might help:

- The main problem with the RX7 calipers is they are too wide, and don't fit inside the 15" BBS even if you grind the "Mazda" raised part off.
- The G60 disc does indeed fit straight on the hub (and is the one used in the 4P025 WMS kit), but Geoff is right that it's TIGHT. To date though, no-one I know of has had the disc touch the balljoint...
- The mini disc doesn't have a huge amount going for it to be brutally honest, while it is 4x100 and only needs 2mm taking out of the bore once you add the 4/5mm spacer it will probably not locate concentrically on the hub any more, and even if you did you have both added longer wheel bolts/studs and altered the car's track at the front.

Please don't think I'm being negative, but we searched through 1,200 disc specs to find our 298.5x24mm one, then bought in about ten likely candidates (ditching the 9 runners up, expensive R&D!) to find the best one "in the flesh", and the resulting disc is as close to the balljoint as possible (like the G60 one) and is a straight fit.

Be daft to spend all the time and money twice when we already did it! The only downside might be that you need a fairly shallow pad to suit the disc, see photo (260mm left, G60 280mm centre, WMS 298.5x24 right):

[billgatese30]

Keri, just out of curiosity, how far away was the G60 disc from the track rod end?

As you say, it is one of the biggest considerations when it comes to disc choice, if not the biggest, as a wheel can be changed, the track rod position is fixed

[Rusty_McRusty]

Thanks, worth asking for sure.

Out of curiosity, did you do a 4 pot to OE disc setup?

[keri-WMS]

Keri, just out of curiosity, how far away was the G60 disc from the track rod end?

As you say, it is one of the biggest considerations when it comes to disc choice, if not the biggest, as a wheel can be changed, the track rod position is fixed

"very"! 2mm-ish off the top of my head?

But the disc is used so often (not just by us) without problems that the range of tolerances on the ball joint outer body must be ok.

I wouldn't normally have chosen a disc this close if it wasn't for the fact that the E30 community were happily using it already!!!

Due to the G60's 5mm mounting flange we could also have opted for Geoff's approach of fitting the 2mm spacer (to get back 7mm like E30 OEM) under the disc instead of on top - but every 1mm closer you get away with the disc being to the balljoint is 1mm less wheel spacer a diffecult wheel might need. Every mm really does count!

Thanks, worth asking for sure.

Out of curiosity, did you do a 4 pot to OE disc setup?

No problem, hope the info is some use...

Re the 260mm / 4 pot option, we did indeed create a single pair of prototype brackets, but the caliper "at 260mm" starts to rub the 15" BBS where the 280mm version clears, so there was little point I thought!

So there is a single 260mm setup available (we won't bother running a batch), but no-one wants it so far. Makes for a very dusty pair of brackets!

[Rusty_McRusty]

OK, cheers, remembered reading about them in one of your previous posts...

[BadDave]

Keri.

I can supply details of a 302x28mm disc which clears the TRE by approx 3mm should you require it.

[billgatese30]

Keri, just out of curiosity, how far away was the G60 disc from the track rod end?

As you say, it is one of the biggest considerations when it comes to disc choice, if not the biggest, as a wheel can be changed, the track rod position is fixed

"very"! 2mm-ish off the top of my head?

But the disc is used so often (not just by us) without problems that the range of tolerances on the ball joint outer body must be ok.

I wouldn't normally have chosen a disc this close if it wasn't for the fact that the E30 community were happily using it already!!!

Due to the G60's 5mm mounting flange we could also have opted for Geoff's approach of fitting the 2mm spacer (to get back 7mm like E30 OEM) under the disc instead of on top - but every 1mm closer you get away with the disc being to the balljoint is 1mm less wheel spacer a diffecult wheel might need. Every mm really does count!

Yep, mm's make the difference.

I can remember trying to find 300~320mm discs for the front of the S50 (before it went tire wall bound) and had the same problem finding a disc with the correct depth (cue lots and lots of templates printed onto card )

I can always remember meaning to ask you the question, but never got round to it before it became irrelevant

[GeoffBob]

I think you've been in the sun too long Geoff!

'Couldn't have put it better myself Theo

Geoff is right that it's TIGHT. To date though, no-one I know of has had the disc touch the balljoint...

Mine did. Not the balljoint itself but the rubber boot. Wouldn't have done for long though

[keri-WMS]

Dave, cheers for the offer, but at 28mm it gives 4mm less wheel clearance than the 24mm thick one we picked - most 16's seem to be pretty tight as it is!

Chris, did you ever get to the bottom of that little escapade?

Geoff, you're a statistical anomaly, I always suspected it! Interesting though, I wonder if the specs of the balljoint or wheel bearing or G60 disc are a bit different in your neck of the woods? Or even the rubber boot?

[UweM3]

I run 300x25 MERC disk on the M3 strut and they sit very close (1mmto the rubber boot) to the ball joint with no issues so far.

[billgatese30]

Chris, did you ever get to the bottom of that little escapade?

Not 100%. I'm still 95% that it was a master cylinder issue, but until I retrieve the car from the unit and get some work done on it I can't be sure.

My house move should be going through in the next few weeks (if the damn solicitor decides to pull his finger out) so for once I should have all my Brilliant red, 2 door, H reg E30's all on the same driveway at the same time to work on them (all 3 of them)

[GeoffBob]

Geoff, you're a statistical anomaly, I always suspected it! Interesting though, I wonder if the specs of the balljoint or wheel bearing or G60 disc are a bit different in your neck of the woods? Or even the rubber boot?

Quite simply, the rubber boot was perished. With a new boot fitted it sat ~ 2mm from the disc. I didn't fancy the idea of the heat from the disc slowly melting away the new boot, or the fact that the boot would inevitably touch once it too had perished, so I fitted a spacer between the hub and the inside face of the disc.

Oh, and lest I forget, the big advantage to fitting the spacer is that the 45' chamfer (that is required in order that the disc mate correctly with the hub, can now be machined onto the inside lip of the spacer. Saves having to machine the chamfer onto the centrebore of the disc everytime. Of course the cenrebore of the disc still has to be opened up everytime.

[keri-WMS]

Well good luck with the move Chris, and let us know if you do find the culprit!

Geoff, I can totally see where you're coming from - this is one rare case where I followed the masses! I wonder if the rubber boots you get are different to the ones we see here, doesn't seem very likely though. You're right about the straight bore being cheaper, but then you need to do the same chamfer on the spacer initially, and as I get the discs done in batches anyway the chamfer doesn't cost much extra.