replacing brake discs

[Simon J]

>Why would the swept area be irrelevant, however?
>
>If we're dealing with wear rates, a greater swept area would
>give more pad-to-disc contact and thus greater retardation for
>a given clamping force - you'd also get better heat
>dissipation which would also help improve the braking,
>especially in trackday situations.

This is just basic physics. The braking torque is a function of clamping force (not pressure), coefficient of friction of the pads, and effective radius of the disc. The area of the pad makes no difference at all, (except that a larger pad will dissipate heat more quickly than a small one). Don't forget, for a given clamping force, the larger the pad, the lower the pressure with which it is applied to the brake disc, and vice versa. It seems to defy logic, I know, but that's physics for you!

Simon J

[don kalmar union]

To correct an earlier attempt to muddy the water here.

I had understood that this thread concerned the braking characteristics of the 850 and S70, old shape V70 and C70.

A previous post has sung the praises of a new shape V70 fitted with non standard Brembo plain discs and Ferodo DS2500 pads and its competant performance on a circuit. You can get more than adequate results from a standard vehicle on track...certainly to compare with most other standard road cars.

That is not a good example as Volvo have produced a far more adequate standard braking system in their new shape cars.


Don.Norchi.

www.kalmar-union.com

TME software for serious Volvo Tuning.

[Simon J]

Don,

You mentioned earlier the cost of the DS2500 pads for the AP kit - how much currently are replacement discs?

Thanks,

Simon J

[pyaap]

Hi Adam,

Which version of Redstuff pads do you refer to as there have been several? There is a page on this in the Sept issue of Circuit Driver and the Redstuff is reported as an alternative to DS2500 and Mintex M1155. Also a review I read on the net:

http://www.subiegal.com/sgracing/new...mic_review.htm

I'm not sure if the comparison of a P2 V70 here is a fair one against the classic S/V70 or 850 (which was the initial question posed) because the P2 brakes are very much better as standard.

I think this subject of brakes is very heavily dependent on driving style. I've come across some T5 owners who report to have never experienced brake fade and yet, after a very short period of 'spirited' driving in the cars, I've had the brakes go. Conversely, I know of another T5 owner who runs Police Spec brakes and is still consistently setting his brakes on fire!

Hi Ashok,

>Which version of Redstuff pads do you refer to as there have
>been several?

I don't remember now, but they were on my 850R and were the worst pads I have ever tried. Not just my findings either.

>
>I'm not sure if the comparison of a P2 V70 here is a fair one
>against the classic S/V70 or 850 (which was the initial
>question posed) because the P2 brakes are very much better as
>standard.

Very true, however the point I was making was that there is no need to upgrade phase 1 stuff to AP kits when you can do the whole thing at much better value by getting the 302 mm discs and Ferodo pads.

>
>I think this subject of brakes is very heavily dependent on
>driving style.

Yes, I agree. And again I refer to public road use where the Ferodo DS2500 pads on a 302mm disc is also more than adequate. If you are setting this combination of brakes on fire, perhaps it may be worth consider altering the driving style slightly!! :)

Adam.

[pyaap]

Hi Adam,

Thanks for your reply. I would agree that the first generation Redstuff pad left a lot to be desired. I was sent a set of Redstuff Ceramic ones to replace those and I must say that they do stand up to the test a lot better; hence I wouldn't be so quick to write them off completely. Ultimately, I've tried the Redstuff, Mintex C-tech and Tarox fast road pads and they've all given up eventually, even on the road. Unfortunately, the DS2500 is not available for my application; I have driven a car with them on but did not get the chance to really put them to the test. The 'best' pads I've driven with are Pagid Blues but those were on a car which had some fancy brake cooling so it would be an unfair comparison.

All these uprated combinations do offer some improvement for sure, but I think its marginal and we need to be a little cautious about using prodigious comparison to high end race equipment like AP Racing brakes; its a step closer to what AP Racing brakes can do but still some way from what they are actually capable of. Yes, the APs are expensive but you can expect them to cope with extreme punishment (which is still possible on the road) and stock replacements will simply not be able to take the same kind of repeated pounding. Anyone who lives near the "round-a-bout capital of the world" (a.k.a. Swindon) will know what I mean! :-)

[pyaap]

Whilst we're on the topic of brakes, why bother with an AP Racing kit when we can all have 'Brembo callipers' in a matter of minutes? Group buy anyone? ;-)



http://www.volvoclub.org.uk/dc/user_files/1221.jpg

[Simon J]

Wonderful!!!!!!! Put me down for a set}(

[IC]

Ashok, looks like they have all makes of caliper covered, lol :+

Hi Ashok,

>All these uprated combinations do offer some improvement for
>sure, but I think its marginal and we need to be a little
>cautious about using prodigious comparison to high end race
>equipment like AP Racing brakes;

If I take my 850R as an example, I always had the 280 mm discs. When fitted with the Ferodo pads, the braking was completely transformed and the car never suffered fade even when driven hard. Perhaps I never drove them hard enough. ;) But the difference over stock was more than marginal - it was huge. Not only was stopping power greatly improved, but also the number of high speed stops you could do without brake fade.

Adam.