Technical 208mm Brake Disc Help

[Teal25]

Hi All,
I'm hoping someone can help me, I have a 1972 500 which has previously had a disc brake conversion.

I'm replacing the discs and pads at the moment, the pads are for the Cinquitento calipers but I can't find replacement discs anywhere.

They have a diameter of 208mm, and I don't think the caliper carrier will hold anything larger. All the 500 specific suppliers sell the 227mm discs for the conversion, but that's too big for my setup.

I'm hoping someone can point me in the right direction! Thanks

 

[the hobbler]

Hi All,
I'm hoping someone can help me, I have a 1972 500 which has previously had a disc brake conversion.

I'm replacing the discs and pads at the moment, the pads are for the Cinquitento calipers but I can't find replacement discs anywhere.

They have a diameter of 208mm, and I don't think the caliper carrier will hold anything larger. All the 500 specific suppliers sell the 227mm discs for the conversion, but that's too big for my setup.

I'm hoping someone can point me in the right direction! Thanks

I have a set of 'reduced' discs in my 'parts dept'----I will, measure them tomorrow for you. In all honesty, I am surprised that you are having to do a 'pad 'n disc' change----the 500 is so light on them, they seem to last for ever. If you can't get '208mm' discs, why not get a set off discs which are only a little bit bigger (on the diameter) and get them machined down---any competent machine-shop should be abe to do that very simple job for you.

 

[Teal25]

I have a set of 'reduced' discs in my 'parts dept'----I will, measure them tomorrow for you. In all honesty, I am surprised that you are having to do a 'pad 'n disc' change----the 500 is so light on them, they seem to last for ever. If you can't get '208mm' discs, why not get a set off discs which are only a little bit bigger (on the diameter) and get them machined down---any competent machine-shop should be abe to do that very simple job for you.

That explains why I can't find them anywhere! I'll get the new set I have machined down to the correct size. I wrongly assumed they were an off the shelf part.
I'm changing them as I had a seized caliper, so needed new a new caliper and pads anyway, thought I might as well do the lot.
Thank you for your help, hopefully I should be able to get it back on the road by the weekend.

 

[the hobbler]

That explains why I can't find them anywhere! I'll get the new set I have machined down to the correct size. I wrongly assumed they were an off the shelf part.
I'm changing them as I had a seized caliper, so needed new a new caliper and pads anyway, thought I might as well do the lot.
Thank you for your help, hopefully I should be able to get it back on the road by the weekend.

I have checked my 'reduced' discs---they are 210mm.

 

[Bigvtwin996]

well a long time ago I was looking at an alternative disk brake set up....
I don't like modern single sided callipers and looking at the setup they are probably too big for the weight of a 500...
Now some may say that you can never have too much breaking.....
I liked the look of the Brembo calliper used on the Ducati Paso 750... think it is the P2 108 but the cheapest I could get them was £120 each.. not bad for a nice alloy calliper

Well... that project like a few others was put on hold due to another business commitment...
I had assembled an aray of disks and stuff.... and had various ideas on how a reasopnable conversion could be made....
I have even aquired some cheaper oposing piston callipers.... that would also fit the purpose and are cheaper and potentially available off the shelf..
many people think Mini Callipers... simple fact Mini Callipers are too big... well not exactly.. I am led to believe that possibly the original 997 Cooper calipers were used by Fiat racers.. they were actually pretty useless, but they were infact bored out to take larger pistons.... but those callipers are rarer than hens teeth... (Yes I aquired a NOS one and it would be viable)

So if anyone is interested in picking up this project.. if they want to contact me I can let them know what is what.... and eve see about parting with my collection of bits....

 

[the hobbler]

well a long time ago I was looking at an alternative disk brake set up....
I don't like modern single sided callipers and looking at the setup they are probably too big for the weight of a 500...
Now some may say that you can never have too much breaking.....
I liked the look of the Brembo calliper used on the Ducati Paso 750... think it is the P2 108 but the cheapest I could get them was £120 each.. not bad for a nice alloy calliper

Well... that project like a few others was put on hold due to another business commitment...
I had assembled an aray of disks and stuff.... and had various ideas on how a reasopnable conversion could be made....
I have even aquired some cheaper oposing piston callipers.... that would also fit the purpose and are cheaper and potentially available off the shelf..
many people think Mini Callipers... simple fact Mini Callipers are too big... well not exactly.. I am led to believe that possibly the original 997 Cooper calipers were used by Fiat racers.. they were actually pretty useless, but they were infact bored out to take larger pistons.... but those callipers are rarer than hens teeth... (Yes I aquired a NOS one and it would be viable)

So if anyone is interested in picking up this project.. if they want to contact me I can let them know what is what.... and eve see about parting with my collection of bits....

I too looked at alternative brake calipers---at the time, for 12 in. wheels, they were often skimmed down calipers off a Punto, Cinquecento or Seicento. Nowadays you can buy specific calipers for fitting with 12in (or even 10in) wheels. I, like Peter, looked at the possibility of using calipers off a big motorbike, but as the discs on practically ALL bikes are only about 6mm thick, it was not possible to make then compatible with car discs, which are normally about 10-12mm thick. I looked at cars/small vans that had 12in wheels AND front discs---not as common as you would think that it would be. The only vehicle that I found that met this criteria was the "BEDFORD RASCAL" van. Maybe that is something that somebody would like to look into further.

 

[Bigvtwin996]

@the hobbler
It is possible to adapt any caliper to fit a wider disk.....
Austin Princess Calipers are a popular choice for Hot Mk1/2 Escorts using 4 Pot disks....
the Princess calipers are not wide enough!!!
but a simple spacer plate is used with 2 extra seals and the caliper is split and the spacer inserted with the seals....
this is a very common practice, and I believe a lot of race/rally cars use this technique...
With laser cutting or CNC milling it is relatively simple these days to produce the spacers....
I had a complete catalog of brake disks for almost every car produced, it gave their diameter and offset etc....
(I can't find that now... but probably still have it)

If you ever see a picture of a Real Abarth factory racer (from the 60s) the front hubs have 4 bolts similar to the rears...
I conclude (as do others) that there were used to hold the Brake disks.....

It could be (as I have done) a hub was spun down to remove teh friction surface this would provide the 190 pcd and then a disk is bolted to the rear and an adapter used to mount the calliper.. they may even have welded the caliper mounts to the bearing casing.....

The smallest disks I found are 178mm in diameter and 6mm thick....

but I take the view what Fiat probably used something that was available, hence the probability of the 997 Cooper caliper and bored out the cylinders.... and a disk that was bolted to the rear of the front hub...

 

[the hobbler]

@the hobbler
It is possible to adapt any caliper to fit a wider disk.....
Austin Princess Calipers are a popular choice for Hot Mk1/2 Escorts using 4 Pot disks....
the Princess calipers are not wide enough!!!
but a simple spacer plate is used with 2 extra seals and the caliper is split and the spacer inserted with the seals....
this is a very common practice, and I believe a lot of race/rally cars use this technique...
With laser cutting or CNC milling it is relatively simple these days to produce the spacers....
I had a complete catalog of brake disks for almost every car produced, it gave their diameter and offset etc....
(I can't find that now... but probably still have it)

If you ever see a picture of a Real Abarth factory racer (from the 60s) the front hubs have 4 bolts similar to the rears...
I conclude (as do others) that there were used to hold the Brake disks.....

It could be (as I have done) a hub was spun down to remove teh friction surface this would provide the 190 pcd and then a disk is bolted to the rear and an adapter used to mount the calliper.. they may even have welded the caliper mounts to the bearing casing.....

The smallest disks I found are 178mm in diameter and 6mm thick....

but I take the view what Fiat probably used something that was available, hence the probability of the 997 Cooper caliper and bored out the cylinders.... and a disk that was bolted to the rear of the front hub...

I agree, if you have the resources, just about anything can be adapted/changed, but at a cost. The reason for trying to find small "off the shelf" calipers to use on the 500 was to keep it simple AND inexpensive.
Just for the record, the 600 and all its Abarth variants have always used the standard (for the time) Fiat wheel-bolt spacing of 98pcd----among 'modern' cars, ONLY the 500 and Mk1 '126' used the 190pcd wheel bolt pattern

 

[Bigvtwin996]

I agree that off the shelf parts are always a better solution...
I have looked at the New "Abarth" disk conversions clearly a one off cast disk and I cannot find who makes the callipers so you are at the mercy of the manufacturer/supplier for replacements....

 

[the hobbler]

I agree that off the shelf parts are always a better solution...
I have looked at the New "Abarth" disk conversions clearly a one off cast disk and I cannot find who makes the callipers so you are at the mercy of the manufacturer/supplier for replacements....

That's the 3rd reason for trying to obtain "off the shelf" calipers---they will have been made by a major manufacturer, so spare parts will be available from either the manufacturer OR the vehicle maker (in this case, Vauxhall/Bedford) with a guarentee to back it up.