Brake disc's

[Mr Tank]

Hi

I know this is a well asked question, but here goes!

Just put the 4.5 cerbie back on the road after the winter.
It sailed through it's MOT but yesterday I started to get brake judger.
My set up is original and I know you can,t get new disc. I like to keep my cars as original as poiss what option's are there bearing that in mind?

Andy

[Steve_T]

You can get AP 330x28 rotors and use a 4mm thick spacer for the caliper and keep the original bells if that's what you have. It's about twice the price of the later 1 piece discs though! Definitely keep the bells.

[Gazzab]

Check 'drag bushes' before you start changing discs.

[Gazzab]

Steve_T said:

You can get AP 330x28 rotors and use a 4mm thick spacer for the caliper and keep the original bells if that's what you have. It's about twice the price of the later 1 piece discs though! Definitely keep the bells.

Steve - do you know where the spacers can be sourced from?
I want to upgrade my cerb to bells and separate rotors (I have some bells, just need the rotors and spacers).

[Steve_T]

It's a 4mm thick piece of plate with two holes in (centres are 152mm apart). The caliper itself sits on two pads about the size of a thumb print, so just get someone to make them up for you.

[JensenA]

Think twice before doing it - Using the bigger discs the caliper will catch the outside circumference edge of the disc. Hence the need for spacers. This pushes the caliper outwards, so it clears the disc. What this does though, is reduce the amount of pad to disc contact as the top part of the pad does not come into contact with the disc. You'll have lighter discs due to the alloy bells, but possibly less stopping power.

[mikethebike1127]

Gazzab said:

Check 'drag bushes' before you start changing discs.

100% agree......I just changed mine (£15 each for the poly ones) when I still had judder after a brake rebuild and disc skim....what a transformation and it only takes 20mins a side.

[skidoo]

mikethebike1127 said:

100% agree......I just changed mine (£15 each for the poly ones) when I still had judder after a brake rebuild and disc skim....what a transformation and it only takes 20mins a side.

+1

[BCA]

We have the larger disks fitted to our Cerb, I know you prefer OE, but they look the business under RL7s. Our T350C brakes look tiny in comparison, it doesnt appear to brake as well either - they're not bad, its just Cerbera brakes are awesome.

[Basil Brush]

JensenA said:

Think twice before doing it - Using the bigger discs the caliper will catch the outside circumference edge of the disc. Hence the need for spacers. This pushes the caliper outwards, so it clears the disc. What this does though, is reduce the amount of pad to disc contact as the top part of the pad does not come into contact with the disc. You'll have lighter discs due to the alloy bells, but possibly less stopping power.

?? That doesn't seem to make sense?

[Gazzab]

Makes sense to me :-) :-(

[jammy_basturd]

Basil Brush said:

JensenA said:

Think twice before doing it - Using the bigger discs the caliper will catch the outside circumference edge of the disc. Hence the need for spacers. This pushes the caliper outwards, so it clears the disc. What this does though, is reduce the amount of pad to disc contact as the top part of the pad does not come into contact with the disc. You'll have lighter discs due to the alloy bells, but possibly less stopping power.

?? That doesn't seem to make sense?

The middle bit of the top of the pad is off the edge of the disc therefore doesn't come into contact with the disc. Slightly less contact = less friction = less braking.

Having said that, wouldn't this slight decrease in drag not be (at least partially) be counteracted by the increased leverage afforded by moving the caliper further out?

[Basil Brush]

But if the disc radius increase is the same as the spacer (322 to 330 discs therefore 4mm radius increase) the outer edge of the pad should be in the same relative position as before. What am I missing?

[MackemPete]

It makes sense in a common sense sort of way... but isnt friction = frictional coefficient x Mass (or in this case pressure from caliper pistons)

So *in theory* even if you had half the size pads they would still exert the same friction on the disk at the same pressure as the larger pads. Obviously the smaller area wouldnt be great as it would lead to more heat in the pads etc. Overlapping the edge of the disk might cause some funny noises when the pads start to wear around the disk, dont know it might not?

[jammy_basturd]

Basil Brush said:

But if the disc radius increase is the same as the spacer (322 to 330 discs therefore 4mm radius increase) the outer edge of the pad should be in the same relative position as before. What am I missing?

The outer circumference of the pad is smaller than the outer circumference of the disc, therefore the middle of the pad is off the disc and the corners of the pad are on.

OP: Stick a straight rule across your disc. If the disc isn't too worn just get them skimmed.

[jonbarrett]

Another one for drag link bushes. Spent a year trying to solve my brake judder. It was the bushes.

[Basil Brush]

jammy_basturd said:

Basil Brush said:

But if the disc radius increase is the same as the spacer (322 to 330 discs therefore 4mm radius increase) the outer edge of the pad should be in the same relative position as before. What am I missing?

The outer circumference of the pad is smaller than the outer circumference of the disc, therefore the middle of the pad is off the disc and the corners of the pad are on.

Must be a Cerbera thing? I've got the 4.5 calliper/322 disc setup on my Tuscan and the outside edge of the pad lines up with the disc. I still don't see how adding spacers of the same size as the increase in disc radius makes the situation worse but fair enough.

[Mr Cerbera]

Mr Tank said:

Hi

I know this is a well asked question, but here goes!

Just put the 4.5 cerbie back on the road after the winter.
It sailed through it's MOT but yesterday I started to get brake judger.
My set up is original and I know you can,t get new disc. I like to keep my cars as original as poiss what option's are there bearing that in mind?

Andy

When I did mine last year a very helpful bloke at AP said that they did a 322mm vented disc and that Powers Performance (ex TVR Power) could fit.

Have heard that Carbone Lorraine are the pads to stop you but will eat discs.

You pays and you takes..... but if you are on original kit then the first two things you want to do are fit steel-braided felxible hoses and bleed with 5.1.

Improves feel and reduces fade.

p.s. Borrow some thighs from Herr Scwarzenegger

---

ETA
Just re-ead your comment and see that you want to stay orig. in which case the one-piece bell and disc from Powers Performance are the closest you'll get. They also supply a non-squeaky pad set.

Edited by Mr Cerbera on Monday 18th June 21:56

Edited by Mr Cerbera on Tuesday 2nd October 19:19

[purpleliability]

Are the original bells an 8 mounting bolt design? Ie are there 8 bolts to attach the rotor to the bell?

Is this what the 330x28mm disc mentioned above is?

Thanks!

[Gray_101]

Gazzab said:

Check 'drag bushes' before you start changing discs.

I agree ... Change your drag link bushes first.. Cause when they fail it feels the exact same as warped disc s