After more than a decade of killing one piece cast discs, I've finally found some floating discs

teaser pic for now, until I can take some proper photos later....



They are not meant for a Coupe, but they fit without any modification to either the disc, carrier or hub / caliper - the only element that I have to resolve is that the centre bore of the disc is 60mm, but the Coupe hub is 59mm, so I need to come up with the equivalent of a 0.5mm thick "spigot ring". They are 4 x 100, but the bolt holes are 1mm bigger than the Coupe discs, so they fit without having to open up the holes. The only element that doesn't pan out is the small securing bolt, as the PCD is a little too far out.

I'm SO chuffed - I took an expensive punt on these, as most of the dimensions were the same as the Coupe, but a couple were different enough to have caused an issue - however, I've trial-fitted them to a hub with caliper and they are fine.

Just trying to see if I can get any more

I hope you find a way, they look good. My only concern would be how you're going to positively centre that disc with only a 1/2 mm thick spigot when there's a radius between the hub face/locating feature. Might be you need to go larger on the bell centre bore first.

I spoke with my friendly engineering workshop chappy this afternoon - he has also suggested that I should open out the disc centre bore and use a 5mm spigot to force a secure centring of the disc on the hub

On bigger machinery i have seen welds added to spigot's and the like,then machined out to the correct radius.
All though half a mm of weld may be risky?

I'm still working on this in my head......

The disc clearly has to be centred on the hub, otherwise it'll run un-true, vibrate and cause all sorts of problems.

However, unlike the wheel, the disc won't put any weight on the "spigot" - its purely there for positioning purposes - all the force of braking is rotational, not vertical. The wheel bolts will take the force of the braking (if indeed the braking force is even sufficient to cause any disc-slip between the wheel and the face of the hub - I rather doubt it)

So - I'm going to get a 185mm long strip of 0.5mm thick metal (stainless preferably) and coil it round the hub centre, then fit the disc over it. It should be a push fit, but it MUST be centred.

I'll then test thoroughly and see if the "spigot" stays put

You've been multiplying by pi, so you have... but don't forget it's another three and a bit millimetres circumference at the outside of the hole.

And some more photos....



LOTS of cooling capability...



Proper floating mountings...



Really can't wait to get them fitted and try them out

Aye - I twigged that, but I'd prefer there to be a small gap in the ring, rather than it being a perfect circumferential length - will allow for a bit of expansion due to heat

Abarth Punto Evo EsseEsse discs?

You have PM

I thought only the 695 carried floating discs as standard?

http://m.ebay.co.uk/itm/371229850896?_mwBanner=1

These??

A fair point, but I'm concerned that if you don't get an exact match you could effectively have a flat spot where the gap is. Shouldn't be a lot, though; don't forget that you will stretch the outside of the strip when you curve it.

Also, the hole will expand when the brakes are hot; with cast iron centres and stainless steel rings you'll have a similar expansion ratio difference as you have with piston rings/cylinder bore, and they get away with about ten thou.

What's the advantage of floating discs?

As I understand it, the advantage is that it allows the disc to effectively self centre, which reduces drag and allows the disc to go through its thermal cycle unimpeded. Helps reduce the risk of the disc warping. But I may well be waffling bull poop....

Nigel, I think you'll struggle to build the car with your solution. IMHO, not enough depth to the bell centre bore owing to the chamfer/radius interface you'll encounter at the hub face; I don't think it'd ever run true.

For my money I'd create a spigot that's an interference fit to the hub, then machine that assembly to a tight clearance fit for the bell. You'd need to measure the various radii to make sure the spigot starts life with sufficient diameter to transpose the radii. Then open open the bell to suit.

Pardon me for asking but would it not be easier to change the hubs?

Can't you have someone CNC a new center for the discs to sit on?

Personally I'd machine out the disc, including a key, and go and see your local wire erosion firm and get them to make some inserts. They work to 0.5 microns (usually) so I am sure they'd get an OE fit for you.

These are looking good Nigel shame I'm moving onto 330mm

Looks good Nigel!
Knight 7660: I got some response from Compbrake for split 330mm disc's before my Coupe was destroyed, just in case you're on the hunt!
Check them out, I asked for Alfa 147 GTA 330mm replacement discs with 98x4 holes so it would fit straight on. Lucky me I never got to pay!

I suggest you do some research on Compbrake before buying - they don't have a very good reputation

Aha. Good riddance then..

A machine shop should be able to bore them out in a couple minutes and make you the spacer rings also. Another option is to build the gap with weld and machine it to desired bore.

I converted my hubs to 5 stud which involved machining the disks and hubs and a custom alloy spacer. Have not had a single problem yet

Any update on these Nigel?

Not yet....

I've sourced some 0.5mm stainless sheet, in order to make up a spacer - just need to work out how to cut it without distorting it - I guess a guillotine would be best

Thanks - good luck and look forward to hearing more.

Damn....

I wonder if 20vt front hub flanges come in different sizes....

When I trial-fitted one of the floating discs to a loose hub, it seemed to fit just fine (along with the Brembo caliper). However, then I came to fit the discs to my car on Saturday, the flange is very slightly too big for the disc centre - it'll need a bit of machining

The project continues....

Good luck Nigel.
A friend of mine in Italy has got Brembo Abarth EsseEsse floating discs.
They are expensive, but great!

Good work!

Was the hub hot on the car Nigel? Im just wondering why it would fit on a spare hub but not one on the car. Thermal expansion could be a reason if the car had been used.
Maybe heat the disc centre up too and see if it fits then, so long as both expand then youre safe.

On a 20VT? - If so, could you ask him to contact me to let me know what modifications were needed

It was nowhere near - hub flange was about 115mm, disc recess was about 110mm

It makes me think that some flanges (maybe aftermarket?) are smaller

I've asked Motormech and Eddie at AECars to measure some flanges for me - hopefully, there will be some versions that are smaller than OE

Oh blimey, 5mm is a lot to find. Odd how its gone from needing a spigot ring to losing 5mm. At least machining 5mm out of a hub lip or inner diameter of a disc is less complicated than fiddling with spigot rings.

Technically, it would still need a spigot ring, as the disc centre is 59mm against the hub centre boss of 58mm

However, if I can use the recess in the disc to locate against, I'll do away with the need for a sliver of spacer to take up the 0.5mm gap

TBH, I'll feel safer if I have to do it this way

Slightly off topic i know! but does this mean the Abarth esseesse alloys fit the Fiat Coupe not sure if the 500 or punto are different but does anybody know if either would fit and clear the brembos?
As im going to treat my self to some nice alloys if my house sale falls through!
Cheers

The Esseesse alloys are PCD 98mm, ET 35mm so it could be tight, but theoretically possible.

Be careful - Punto Abarth EsseEsse are 4x100 with 59mm centre bore. 500 Abarth EsseEsse are 4x98, but I don't know the centre bore

Confirmed - there must be more than one size of 20VT hub flange - the one on my Plus (original, I assume) is about 5mm bigger O/D than the loose 20VT hub I trial-fitted the discs against

Next plan is to buy a pair of new hubs and have them turned down to exactly the correct size to locate in the disc recess - the bonus is that this will negate the need to use the 0.5mm spacer in the disc centre

Sounds good keep the info coming (may need a set for the NA) Nigel good to see people still pushing forward on the tuning/parts front

Just keep in mind that you're reducing the land available to the threads to hold your wheel on, and you've no way of knowing if creating an interface where you plan will result in unwanted failure. I personally consider it a risky way of getting those disc on.

I don't think Nigel is reducing the flange thickness just the diameter so it will it inside the disc recess. So as for the threads there will be no change

The land is the area around the bolt hole,not so much the material thickness in this case. My concern is you could end up with crack propagation.

But as he has said he has found there are different sizes being sold the bigger one being on his plus they could be the originals compared to after market which maybe the smaller.

I guess we will find out shortly

Hopefully, it'd great if he finds a way. But what we don't know is if the two materials are exactly the same between the differing hubs. Perhaps Nigel's plus hubs just have a degree of grow out after all these years? One point I'm 100% on is that Fiat wouldn't have put any extra meat in unless they had to. Just my opinion, but I believe the hub diameter and disc interface is one of those things you shouldn't touch.

Am i being dumb here; if you reduce the size of that flange by 5mm then wont you need a 5mm spigot ring to locate the wheel central to the hub?

Or are you talking about reducing the hub face diameter by 5mm?

If so, what distance does it leave from the edge of the wheel bolts to hub outer diameter?

A picture would really help

OK - lets try to explain better - all measurements approximate for the purpose of illustration (although they're pretty close)

As you can see from the below photo, the alloy disc centre has a recess - this is the side that faces the hub. The size of this recess is about 125mm



When I trial-fitted the disc, the hub flange was about 120mm in diameter. This means that with a PCD of 98mm and a wheel bolt diameter of 12mm, there was about 5mm of metal between the outer edge of the bolt hole and the outer edge of the flange - lets say this is the left-hand hub flange from this very-hastily drawn diagram.



This meant that the smaller flange fitted within the recess in the disc (and in fact, moved around a little, due to the slightly larger centre bore - see below)

When I came to fit the disc to my own car, I found that I had the flange on the right of the above diagram, which was simply a larger diameter - approx 128mm

This means that it has a little more metal between the outer of the bolt hole and the edge of the flange AND it means it was marginally too big to fit in the recess of the disc.

OK - that was problem#1

Problem#2 was that the flange boss (the bit that the disc and wheel locate onto) of the Coupe flange is 58mm. The centre hole in my disc is 59mm. When I fitted the disc to my smaller-sized flange, the disc clearly moved around (by 0.5mm in any direction), as the disc hole wasn't locating on the flange boss.

The original proposal was to take up this 0.5mm gap with a "filler-ring" - I was actually going to use a feeler gauge, cut to the correct length and wrapped around the hub flange boss. The disc doesn't put any weight on the boss (unlike the wheel), so the "filler ring" would only have been there for the purpose of keeping the disc concentric with the hub flange.

My new proposal is to buy two new hubs (on order) and have them turned down by about 1.5mm (ie 3mm off the diameter) so that they locate perfectly in the disc recess. These machined hub flanges will still have more meat on them than the smaller flanges I used for the trial-fit. As the machined flanges will still have a 58mm boss, there will still be a 0.5mm gap between the disc and the boss (which won't matter, as the disc will be centred using its OD, instead its ID). The wheel will still fit perfectly, as it locates on the original flange boss.

Hope this makes sense, but I take Szkom's point about possible weakening, so I'll check the hubs after a short period of use.

Does the above make more sense now?

It does, thank you.

Cant you machine a radius off the edge of the hub Nigel or a stepped lip? No need to remove metal from the whole hub and potentially weaken them.
Looking at the picture of the disc, if the hub fits neatly inside then you'll have 0.5D of metal remaining on the hub, I wouldn't want to go much less than that.

Jimbo - yes, I'll probably specify a stepped lit to mate perfectly with the profile of the disc recess - the hub flange is quite a bit thicker than the disc recess, so I reckon I'll be able to leave some of the hub flange at its original OD

Nigel, I do hope you realise the centre bore for the hub is 58.1mm and not 58mm that you've mentioned a few times and that you're just being lazy and can't be bothered to type the .1 on the end

Nope - not being lazy - just mis-informed. Pretty sure I had read that it was 58mm (possibly read a thread where someone WAS being lazy and couldn't be bothered to type the .1 )

Either way, it looks like the centre bore sizing won't be an issue now

- back to Plan A....

The new hub flanges I've bought have arrived and they're the smaller OD version...

I'll be trialling the shim method of locating, using the new hubs - if it works, I'll get them fitted and see how they work on the road

If it doesn't work, I'll have to have my hubs removed and machined to fit the disc recess

UPDATE

The trial fit to the new hubs using the 0.5mm shim has worked exceptionally well....

Disc seated on the hub with the shim in situ - the shim is a very tight fit (had to tap it in with a small hammer and drift bar)



Hub with the loose shim



One bent and shaved feeler gauge



Proof that aftermarket hub flanges are smaller than OE - the OE hub wouldn't even fit in this recess



So - I have a couple of new wheel bearings on order and I'll have the new hubs fitted in the next few weeks

Note - I've noticed that the disc location holes line up perfectly - I wonder if these are 4x100 on the Coupe hub...

Good work Nigel.

I wonder if you could do away with the feeler gauge if those disc locator holes are an exact match?

UPDATE

Turns out the location screw holes aren't in the right place, so I've reverted to the shim idea. TBH, the shim was so tight that I'm convinced its going to work, but I'll give it a thorough workout and then take the wheel off and see if the shim has moved at all. I have an option of fitting a slightly deeper shim that would be held in place by the wheel, as well as the disc

The car is at Motormech today and has had the new hubs fitted with new wheel bearings - the discs are on and looking V good - just got to fit some new pads, as the Ferodo DS2500 that were on there are looking a bit uneven

Now that the car is only used for 2,000 - 3,000 miles a year, I've splashed out on my favourite pad - the Pagid RS29 "Yellow" - this was the pad used by several LeMans endurance teams and which gave me the best brake setup I've ever experienced on a Coupe (along with DBA discs). It has been two or three years since I ran with the Pagids, so I'm looking forward to having a pad with great bite and amazing feedback

Any further update Nigel?

Yes - the discs are fitted. Matt at Motormech commented that the centring solution seemed to work well and that in his opinion, once the disc is clamped between the wheel and the hub, it won't move anyway.

I've also got some Pagid yellows going in, plus four new gearbox bearings, plus a camber change (down to -0.75) and finally, a re-fit of rear subframe polybushes

Hopefully, after all these tweaks, I should be back to the sharp but neutral handling I used to enjoy with my Sprinty, but has evaded me so far in the Moonie

A re fit with the poly bushes on the rear subframe? Are you just fitting new ones or was there something wrong with the old ones Nigel

Any photos of disc fitted?

My polybushes were the first time Paul had fitted any and the subframe twisted under the pressure of the press (which we didn't realise until after it was fitted). Paul now warms the bushes up before pressing in, and uses copious amounts of grease. We looked at extracting the old bushes from the twisted subframe, but it would have cost me more in labour than a new set of bushes cost



I have a photo on my phone - I will upload it later

Nigel, it's all ok?
We are waiting for photos

Coupe is still at Motormech, so I haven't been able to get any photos

The discs are on the car and looking great, but I'm still waiting for the gearbox bearings to be fitted, along with rear subframe bushes, a full geometry set-up and an aircon top-up and aux belts

Not looking forward to the bill......

Nigel, do you have any idea about the finale price of these discs?

The discs are available as a set (with rear discs and front pads) for about £330

I sold my rear discs and front pads to get some of the money back

If you're lucky enough to already have aftermarket hubs, you'll simply need the 0.5mm shim

If you have original hubs, you'll need to have them machined, or fit aftermarket hubs - either route will require new wheel bearings

Got my Coupe back today - floating discs fitted and seemingly working fine

I tried a few moderately hard stops on the way home and then took the wheels off to see if the spacing shims had moved - still where they were supposed to be, so I'll try a few monster stops to see if they can stand some proper abuse

First impressions are very good - the discs are silent (unlike the grooved MTecs that have just been taken off) and the feels seems to be better

Most importantly though, they look amazing....

They look spot on Nigel how's the braking difference have you had a change to put them through some testing yet?

Watching this with great interest

They look awesome!

Are these standard size just skimmed the older posts cant see any reference except 330mm but now i cant remember if standard is 305mm or 330mm??
just too early for me probably!

Standard size if I remember rightly. and yes to early my brains not fully working yet

Standard size - 305 x 28

They are the wrong pcd - 4 x 100 instead of 4 x 98, but because the bolt holes are bigger, they fit without having to open the holes

The only issues is the 59mm centre bore (against the Coupe's 58.1mm) - I have used a 0.5mm shim and it seems to work

If I could find Abarth 695 floating discs, I would have used them, as they are a perfect fit - 4x98, 305 x 28 and 58.1 centre bore

Yes i just went looking for some cannot find any now as im certain that partsworld had a load for fiat 500 for around £500 or perhaps it was for the punto and im thinking of 500 abarth alloys for £500

The abarth 500 brake kit is around £2000 but i think that includes the brembo calipers?

Correct

I can get the 500 695 floating discs for £500 + VAT (£600) which is still a decent price for a low-volume two piece disc setup

Have you put these in water to see if they really do float or is it just hype?


They look great Nigel, good job.

So a direct bolt on set of floating discs is £500 + VAT?

How much of an improvement will this make to cooling do you think Nigel?

If you can find them, yes

The only issue may be the diameter of your hub flange - OE appears to be wrong, but aftermarket seems to be capable of taking the floating disc

Too early to tell about performance, but the initial feel is very encouraging (although that's always the case when you fit new stuff like brakes or tyres - the new stuff feels like a big improvement)

Thanks Nigel,

Get out on the road and test them I'll be up for a pair if they help the cooling and brake feel

Been out today and given the brakes a decent hammering (repeated big stops to bed in the Pagid yellow pads) - the spacing shim has stayed put (although I'm going to modify the design a bit) and the feel is much improved over the previous brakes (MTec and Ferodo DS2500)

I have a feeling that once the wheel is bolted on, the disc simply cannot move, so the spacing shim is more of a locating device, rather than taking any kind of load

Overall, I'm very pleased with them, although because of having to change the hubs (and thus the bearings), the cost wasn't as attractive as it first looked

Its definitely worth having your wheels off and measuring your hub flanges - if they are the smaller aftermarket size, these discs will be a pretty cheap, but highly desirable upgrade

Nigel, is there any possibility to make a group buy for the complete set?
Spacer and discs?

I'll have a look into it, but I think there may be a supply issue - I don't think there are very many sets of discs around

If the absolute correct size are for the 695 I guess it will be a while before they are available, the car is very new to the market and probably only sold in very limited numbers so won't be much about - there isn't even a brochure available for the car yet!

Not so rare.
Only expensive

http://m.ebay.it/itm/301404210180?_mwBanner=1

Another update.....

I got lucky and found a set of worn-out discs from a 500 Abarth 695

I paid £40 for both discs and I've had a chance to try them on a Coupe hub - perfect fit - 4x98 and 59.1mm centre bore (edit - not 58.1 - see below)



So, I'm now looking for aftermarket brake rotors - I've found a place that will make them up from Brembo blanks - just got to give them the dimensions and negotiate a price

While I'm talking to them, I'll probably look into the cost of having disc centres made as well

Great news for my own brakes, but not good for general availability, as worn-out 695 brakes are hardly commonplace...

So what's going on with the set you have fitted Nigel

Nothing - they are behaving perfectly (other than the drilled holes are almost full of dust now...), but I always knew that the Punto Abarth discs were only a 99% perfect solution, so I'm continuing to explore the options - TBH, I could easily fit the existing rotors to my 695 hubs and I'd be fully sorted, but I want to see if I can find a solution for everyone else too

BTW - I also found out that the standard Coupe disc has a 59.1mm centre bore (not 58.1mm)

This is because the hub flange has a 0.5mm step to locate the disc, and then a 58.1 diameter for the wheel

Nigel if i remember correctly the new disc has a 59mm centre bore?

Does this mean they are a straight fit and there is no need for the shim??

No - Punto Abarth discs are 4x100 and 60.1mm centre bore, so still need the shim

Abarth 500 discs are 4x100 and 59.1mm centre bore and fit without the shim

My earlier posts were incorrect - we all know that Coupe wheels are 58.1 centre bore, but I hadn't twigged that there's a step in the hub and the discs have a 1mm larger centre bore

I guess the simplest way to look at it is that Punto discs are 1mm too big (as well as the wrong PCD) and 500 discs are exactly right

AP have some nice "J hook" rotors, 304x28mm. For about 250$. Just don't know will it fit to the center plate.

Nigel, does that mean that the discs off the 695 fit on the original Coupe hubs, or are you meaning the aftermarket ones? Great news if they fit the original hubs (except maybe for my bank account!).

Just thinking about it - cost is probably pretty high, but would this kit be a bolt on upgrade - http://www.abarthcars.co.uk/Site/uk/ABARTH_BREMBO_BRAKING_SYSTEM_KIT

Could be a great way to get better brakes if so.

The issue with the hub flange diameters remains

The OE Coupe disc has a 151mm recess for the hub flange, the 500 Abarth disc has a 123.1mm recess - see the two technical drawings below

Standard Coupe disc



500 Abarth floating disc



I didn't measure the OE flange on my car, but I estimate it was about 128mm - just a little too big for the floating discs recess

So - if you have the smaller hub flange, the floating discs will fit, but if you have OE flanges, you'll need to have them replaced with aftermarket flanges (which involves replacing the wheel bearings as well)

PS - note on the technical drawings - the floating discs are 1.8KG per disc lighter than standard - given the money some of us spend on lighter wheels, this is a very significant saving of un-sprung weight

Ok so do you need different calipers to fit these?

As you can get a big brake kit including discs, callipers, pads, hoses and fitting kit (for a 500 of course) for £1000 which seems reasonable value and better value for money than £550 for just the discs

+ vat of course

^^^ that is the kit I was referring too in post above^^

You can fit these discs and use the OE Brembo calipers - no mods necessary

I also thought about the Abarth 500 brembo kit in order to get the bigger calipers - wasn't sure whether they would fit the OE Coupe mountings

Thread resurrection

Looks like we have another brave Coupe owner about to fit some floating discs from the Fiat 500 595/695

I'll let him own up when he's ready, but there's a chance that we can get the discs for rather less cost than was previously the case

watch this space...

Look forward to this I’m going to be doing this but may have to be realistic and wait till After Christmas Depending on what deals are around!
Cheapest I saw them was about £400 plus postage but cannot find the link now as I’m having major issues with my win 10 pc constantly crashing
I did put the part no in google and it came up with some bargains but they were listed off an evo Mitsubishi so most likely wrong
Keep us posted!

We have found that the price is extremely volatile - the price today is about £50 more than it was mid-week (from the same supplier!)

It appears timing is everything.....

I might just pounce on one or two pairs if I see them cheaply enough

Knowing how cheap you got them before Nigel, how cheap is cheap enough?
as i would like to say get me some too!

If the prices stay around what they are currently im waiting till after christmas, but if there is a mega deal I will have some now
I am about to get my alloys refurbed this month, tomorrow actually but i will see how i feel when i wake up in the morning might put it off just in case a deal comes along!

Appreciate you taking the reins on this Nigel and appreciate any updates too!

I'm very tempted for when I next need discs but mine is still on its original hubs so the job gets bigger!

Nigel hes not the only one recently to take the plunge i have a set sitting in the boot of the the LE awaiting fitting

198 euros inc. delivery EACH
but only deliver to Germany damn!

That's around £350 a pair

I think that's a reasonable price if you are going to Germany or know somebody there

The prices are highly volatile - I've seen them at about £340 in the last few days, but they are now at nearly £400 again

Spotted this kit in the Demon Tweeks catalogue yesterday and wondered if it could be used on the Coupe - https://www.demon-tweeks.co.uk/motorsport/brake-kits/wilwood-big-brake-kits

Need to select Fiat 500 from the drop down list.

Mounting points for the calipers are likely to be quite different, although there's no reason why the discs shouldn't fit

A bit of a thread resurrection, but...
Using the Autodoc app on my phone, they're now at £152.19 each, so a little over £300 (free shipping)

(Online they're £154.28 each, so over £8 more for a pair)

The cheapest I have ever seen...

Hi Dave, do you have a link either on here or via pm, as I would like a pair

Cheers Rich

https://www.autodoc.co.uk/spares-search?keyword=09.B085.13

But a little cheaper if you download and register with the phone app

Ok they are definitely the ones that fit? Did you order any?
Cheers

Going via abarth 595 they didn’t list them but straight to them with your lunk

These are what I bought and fitted straight on to my Porto 20vt, but paid around £350 quite some time ago

Remember that the discs may not fit if you have the original hub flange - the flange doesn't fit in the recess of the floating disc

If you've replaced your front wheel bearings, the chances are you'll have aftermarket flanges which are smaller in diameter than OE and will fit easily in the disc recess

I remember that issue you had Nigel but I still have the original hubs, and the floating discs fitted straight on, no problem?!

Well I have ordered so will see what happens
Thanks for the heads up Dave

Cheers