Rear Brake Upgrade 22v Discs update

[grash2]

I used the Corsa discs Brembo part number 09.8601.10,

which although it fits, it has some minor issues,
Tested, found minor issues, solvable but still not a 99% hassle free fit ,

issue a. the disc is 260mm, it sits just 1mm away from the caliper
issue b. due to the 260mm diameter, the pad sits 5mm below the end of the disc, leaving a rust trail
issue c. it is 24mm which my brake specialist swore that i needed 2mm washers to align the disc to the caliper, with the washers, again it is really close with the carrier, which i do not feel comfortable

here is a picture with the issues


i have then found a better replacement, that we fitted on a friends mk1

a better disc that i have found, and was fitted by a fellow mk1 owner in Greece
Fiat 500( and grande punto + other fiats) front rotor and corsa D, same part really, fiat is 4x98, which is not an issue, the stud goes in just fine

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Disc one
Brembo Part number, 09.5843.30
Brembo part Number 09.5843.34 Brembo link

its 257mm
60mm bore, needs a spigot ring to get it to 54mm bore
4x100
34.1 height from the mounting plate, sits in perfect position, no washer needed
22mm disc, perfect for the 22v caliper


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Disc 2

Brembo part Number 09.5843.11(painted)
Brembo part Number 09.5843.10 (unpainted) Brembo link

257mm
59mm bore needs a spigot ring to get it to 54mm bore
4x98 (but the 4x100 mk1 studs slide in fine) need confirmation as we did not use brembo, even if the 4x98 is a problem a 4x100 can be threaded
34.1 height from the mounting plate, sits in perfect position, no washer needed
22mm disc, perfect for the 22v caliper

[nik]

great info there.
nice to see another alternative.

[Gandalf]

The 09.5843.10 looks to be 257mm diameter, 59mm bore :)

[grash2]

thanks for the correction
both are 257. my bad writing 256, the only difference is the bore and the stub hole size and pattern, but many manufacturers have the same part number for both, ie remsa/ ebc etc,

also for some weird reason brembo sells one of those more expensive that the other, although its the same disc with different bolt and bore

[dimitriske30]

Also I have used ae86 front brake pads, they use bigger disc area but the calipers carriers needs a little bit trimming. After all of these, rear brakes acts perfect, much better braking than before, even if the disc is 6 mm smaller than the stock one.

[Tommytank]

Great info there. Found on Ebay and added to the watchlist!

[grash2]

Brembo part numbers updated, for easier ebay searches and links to brembo site with cross car makers references,
the same disc is fitted by many models and makers

I ll make an excel later this week with part numbers from major rotor manufacturers

[Mrskylighter]

It appears as though the Fiat 500/Opel Corsa 06+ disc to use is the D1398 or GD1398 if your wanting to use EBC branded stuff?

[Gandalf]

grash2,
I am FINALLY tackling this install, and since I have the Corsa discs already I will roll with them this time round. Going to a machine shop for the hub-centering rings tomorrow, and I may as well have the discs machined down for overall diameter too... it seems I could safely take the overall diameter down to probably 254mm since there is a full 5mm radial "extra" of disc on the outer edge? That's 10mm diameter (or 250mm total). 254mm total would leave a bit extra just in case. Why have the extra unsprung weight, no?

[Gandalf]

**UPDATE**
I fitted the Corsa discs, and confirmed it is absolutely necessary to use the 2mm spacers as indicated by grash2 and his mechanic.

Here is my original question, I'll leave it for the info, but the reasoning is irrelevant:
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I am looking at the Brembo diagrams for the Corsa disc, and I am curious as to why a 2mm washer is needed.

The Fiat disc 09 5843 30 is 34mm from mounting surface to back of disc, and 22mm thick. (This the same for the Corrado disc 09 6728 10, and the Lancia disc 09 5843 10). Now, looking at the Corsa disc 09 6801 10, it is 35mm from mounting surface to the back of the disc, and 24mm thick, which means 2mm extra thickness, of which it is placing 1mm towards the mounting bracket and 1mm towards the caliper, essentially splitting the difference, putting it exactly centered as compared to the other discs. Now, if we add a 2mm washer on the mounting bracket, we move the whole caliper outwards towards the disc by 2mm. This means that the caliper is now 3mm closer to the back surface of the disc and 1mm further away from the front surface of the disc. How does this improve the placement when compared to the other discs?

I can understand that if it is imperative to line up the back of the disc, flush at 34mm from mounting surface, that we would technically need to add a 1mm spacer between the HUB and the disc. And if it was imperative that we line up the front of the disc flush at 34mm from the mounting surface, that we would need a 1mm washer at the location you specified. And if it was imperative to "split the difference" of the extra thickness of the disc that we use no spacers at all because 1mm is forwards and 1mm is backwards... but I cannot wrap my head around why we would need a 2mm washer.

I hope I am being clear... can anybody help clarify what the objective is? And what is the most important aspect of the disc/caliper placement in this case?
Whew, my head hurts! lol