Rotors & Bells

[Error404]

Baically the bell fractured seperating it from the disc! It was at CC one year.
If you look at the bell design there is a lip that fits inside the disc whereas AP use a flat flange.
If I can find them I will illustrate the difference along with some relevant measurements if that is of any use to the OP!

All relevant info is of use matey

James, I'll PM you

[twoqu]

Anyway here are some pics. Two different solutions to the same problem on, as it happens, two similar sized discs. The different pcd/diameter reflecting the different sized annulus. For the record, the flange on the Movit bell is 7.10mm and on the AP it is 9.25mm.
See how the Movit bell has a small lip that locates inside the disc. The different fixing hole sizes reflect that the Movit uses a bobbin whereas the AP uses nothing more fancy than a bolt!

[jade]

I was thing of using bells from this company with wilwood disks

http://www.rallydesign.co.uk/index.p...2noo03dra46457

[twoqu]

I was thing of using bells from this company with wilwood disks

http://www.rallydesign.co.uk/index.p...2noo03dra46457

Can't see which ones from the link. But its the same problem if you are using Porsche calipers. You will need to get the pad depth dimension of the friction material and compare it with the annulus of the disc. Don't forget that the bell itself will also decrease the available space for the pad on the disc.
As a guide you can compare the reverse side dimensions. If the pad will overhang that, it's not going to fit on the otherside with a bell.

[bluequattro]

I ve just spoken to a machinist who could make bells

[90quattrocoupe]

DBA makes an A8 bell rotor. Look at the PDF catalog.

http://www.dba.com.au/

Greg W.

[Mikes2]

Can't see which ones from the link. But its the same problem if you are using Porsche calipers. You will need to get the pad depth dimension of the friction material and compare it with the annulus of the disc. Don't forget that the bell itself will also decrease the available space for the pad on the disc.
As a guide you can compare the reverse side dimensions. If the pad will overhang that, it's not going to fit on the otherside with a bell.

I had this problem when first fitting Porsche calipers to my first S2 years ago.

I was trying to get two piece discs using the Porsche 968 CS pads and there was insufficient disc space for this pad using a 2 piece disc for a disc diameter of 305mm.

Even going with a 330mm disc, it only gives 12mm extra clearance over a 305mm. The pad size will determine which disc size you can run if you plan to keep the 996 calipers.

It was so long ago, I cannot even remember where I sourced the discs and bells but they weren't cheap at around £400 a set

[K Simmonds]

Here's my 20 year old Alcon 330mm X 30mm set up, the bells have faired very well with no serious corrosion, they are just a bit dirty in the pic's. So I'm guessing they used some pretty high grade alloy with an Anodised finish. Before being put back into use the fixing nut's on the rear are going to be replaced along with the Stainless Steel Allen bolts, the rotors are going to have a light skim. I'd like to know what grade of Stainless the bolts are, bet geunine Alcon replacements are dam expensive.

The hub mating face of the bell is 10mm thick.

The rotor to bell mating face is 7mm thick.

[europeanme]

what size wheels are you looking to fit them under??....

I am still undecided which route to go for my new calipers and have been looking into rotor and bell options/ideas.....

have you tried Bambridge?.....

[s2_wot]

Attached my design for:

Front disc (304 x 28) for 16" alloys with BMW brembo front calipers. This setup is lighter and more powerful than the 314mm porsche setup.

Rear disc (280 x 10) using the existing caliper on a larger diameter.

For me this is the best balance between brake effectiveness, rotational mass, un-suspended mass, cost, etc..

Details shown on the attached are unchecked & unverified. AP had no interest in making them for me on a one off basis which was fair enough given the size of the company. I'm interested in having bells manufactured if a good supplier is identified.

[S2TORNADO]

someone mentioned stainless allen bolts. i thought they weren't to be used for running gear and wheels etc because the tensile strength is too low.
you never see stainless used on any of those applications.

[4WheelDrifter]

I've had the same idea, Alex. It's working out way more expensive than just going for RS4/RS6/R8/Phaeton 8 pot brakes, but hopefully they will work well enough, and be a whole lot lighter. The goal has been to squeeze the largest brakes I can under my 17" Cups, which they do, just.

The main problem I found was my GT2 calipers and pads need a disk with a 68mm annulus, which is larger than any AP or Alcon rotor I could find, so Brembo was the only real option.
Thanks to a good friend I managed to source some 9.3kg 350x34mm Brembo disks, as I too wanted to get the best power to weight ratio. Brembo themselves were no help at all BTW.

As for bells, I also wanted some lightweight alloy items, and the offset based on original S2 disks. Now, if only I could find the design I did all those years ago. I also intend to use Ti fasteners, to save any galvanic reaction or corrosion problems.

I didn't get around to getting the bells made, as the project stalled, and it was bad enough watching my 999/S8 brakes sit there corroding.

For additional reference I have to hand a variety of brake options:
I have some AP Racing 330x28mm disks, which use a 8mm 6082 bell.
Also some Mov'it 'Big Black' 322x32mm disks, which use an alloy 10mm bell.
R32 334x32mm disks use an 8mm alloy bell.
And SGL/Porsche ceramic disks use a SS 7.3mm bell, but with lots of added chunkiness and weight. I didn't realise how light ceramic disks were until I separated the disk and rotor.

HTH

[Error404]

nothing is simple eh?
Is it possible to get custom pads made?

[4WheelDrifter]

Custom pads wouldn't solve the annulus problem, as the Porsche caliper's pad locating pegs would be the next issue.

[s2_wot]

Gents, just throwing these into the mix for you to consider.

http://www.ebay.co.uk/itm/BMW-E38-7-...item519f0ffa65

28mm disc, 40 & 44 mm pistons, 50mm high pad and they are cheap. Trailing orientation so no swapping pipes around etc. I can send or post a bracket sketch if you know the disc diameter.