those damned AP 2-piece front discs

[ed_crouch]

Has anyone recently obtained a new pair of discs for the Princess / 28*270mm monster AP 2-piece setup?

Mine are OK for now, buy I dont like the obsolescence of it all, and there's a small taper appearing on the disc surfaces. Not much - 0.1mm taper on top of 0.5mm flat wear on each surface, but it'll only get worse...

Options are:

-Stick with it
-Get some new discs made <<<<< where?
-put a Hispec billet4 conversion on it <<< looks good to me, but ~£750. Not that that's a ripoff or owt - it seems pretty good to me, but I'm only actually after discs...!

Has anyone got around this issue lately. I'd love to hear about it!!

I run 15" OZ splitties by the way, so I suspect the Tuscan brakes are out? Too big?

Thanks!

Ed.

[Number 7]

Not sure if the search function is working (is it ever?) but I have previously posted about my experience of sourcing these rotors. Last time about 5 years ago, BG Developments made a pair from AP blanks, with grooves. £250 +vat.

7.

[adam quantrill]

Try the "how to search" post above. I just used it and added a brakes secion to the FAQ articles.
I too have these discs and hope to have a replacement available if it's needed.

[ed_crouch]

Wow. Thanks fellas. £250+drat is a lot of money for discs...

Hispec may be the way to go... I think I'll hang on for now until the discs do actually need changing, then Hispec it...

Unless of course I redesign the front suspension to use Sierra bits, but I'd still need to find a 5-stud sierra-compatible hub with the right PCD...

[B-Reight]

ed_crouch said:

Wow. Thanks fellas. £250+drat is a lot of money for discs...

Hispec may be the way to go... I think I'll hang on for now until the discs do actually need changing, then Hispec it...

Unless of course I redesign the front suspension to use Sierra bits, but I'd still need to find a 5-stud sierra-compatible hub with the right PCD...

If you think £250+ vat is a lot, well they're now £314+Vat at BG developments when i rang a few months ago!

I looked into getting the discs made up in quantity from 2 or 3 manufacturers and the savings were no way near worth it. Maybe granada vented discs may fit, there is an article on the wedge pages about uprgrading the 350i brakes with AP 4pots and granny discs; http://www.tvrwedgepages.co.uk/maint_brakes_upgrad...

[Number 7]

Yeh, ok £300 odd plus vat is a lot, but we're talking proper AP rotors here, not mass-produced in the far east integral bell discs. I reckon they must be good for at least 30K miles on my car, including at least 1 trackday a year. I reckon that's reasonable value. Out of interest, are the Hi-spec's separate bells, and how much do the rotors cost - that's what you really need to compare with.

7.

[adam quantrill]

Does anyone know what the minimum thickness is on these discs - so I can tell when they need changing? Or do they usually crack first?

[ed_crouch]

Hmm, just looked up the price of production AP discs on BG developments shop... Hmmm.

Feeling a bit sick! Is this what competition discs cost?!? I thought 50 quid a pop from Audi was stiff!!!

Right. Perhaps I ought recon the princess calipers and do the discs as and when. Pistons and seals are available, so shouldnt be too much of a hassle.

[ed_crouch]

OK, another question - is there anything special about the eight bolts that secure the disc to the bell?

Are they high tensile? Mine are a little corroded and I'm tempted to replace, but I'd rather they didnt all shear off in unision when I hit the brakes so dont know what I have to replace with!

Any clues?

[adam quantrill]

ed_crouch said:

Feeling a bit sick! Is this what competition discs cost?!? I thought 50 quid a pop from Audi was stiff!!!

Yeah I think it's crazy, too, when you can buy a pair of rotors for 40-50 quid including the bell, these are a much simpler product, what are they made of, gold??

[stainless_steve]

ed_crouch said:

OK, another question - is there anything special about the eight bolts that secure the disc to the bell?

Are they high tensile

Any clues?

Yes there are high tensile 12.9
buy them here....
http://www.compbrake.co.uk/ROTORS/ROTORS_BELLS3.ht...

[ed_crouch]

Geeeeeniuss. Cheers fellas.

Still in slight shock. Whats the crack with just whanging a pair of granada discs on it? Where they truly ste?

[adam quantrill]

What's wrong with those powervane rotors - there's quite an extensive table, will one of them fit? At £100 each (give or take) they look like a much more reasonable proposition.

[ed_crouch]

Nah the only one in 5.5" BCD by 8 bolt fixing is 247mm diameter - too small... Shame, as I thought they might be an option. Wonder if its possible to have the bells drilled to match one of the other patterns?

[B-Reight]

adam quantrill said:

What's wrong with those powervane rotors - there's quite an extensive table, will one of them fit? At £100 each (give or take) they look like a much more reasonable proposition.

The wedge rotors are 270mm x 28mm x 179.7mm PCD which is a very odd size which handily no one on the planet seems to carry as stock line.


Ed, i'd take a punt at the granny discs and at 17 squid a pop, evenb if they are shoite you'll be able to go through several sets before you reach the cost of a single rotor!

[TVRleigh_BBWR]

The Granny ones don't fit.

[Number 7]

adam quantrill said:

Does anyone know what the minimum thickness is on these discs - so I can tell when they need changing? Or do they usually crack first?

When I checked on this with AP themselves a while back, I was told that maximum wear on the 28mm thick rotor was 1.2mm, i.e. minimu thickness 26.8mm

AP / BG Devs also supply the bolt kits.

7.

[B@man]

There is always the caprisport (www.caprisport.com) conversions using brembo callipers of Fiat coupe turbo with either 300 or 315mm disks.

At least the brembo callipers used in these conversions are designed for road use.

[TVRleigh_BBWR]

Problem is 300mm disc's will not fit under 15" wheels.
My AP Racing disc's are still 28mm and have done at least 15 hours of track time, so they maybe more expensive but will last longer than cheaper units.

[ed_crouch]

Bugger - mine are on their last legs in that case. 1.0mm on the inner edge, 1.2mm on the outer edge...!