325mm Brake upgrade

ibasniper · Post by **ibasniper** » Mon Nov 11, 2019 12:00 pm

Hi Guys

Has anyone done the upgrade from 300mm dia to Si 325mm dia and really noticed a difference? I have some larger 330i calipers knocking around from an old car which could be refurbed, but if the difference is not worth noting i dont really want to waste my time and money on disc's and a change over etc

I currently have somewhat new 300mm xdrilled brembos on the front and always found them to be good for fast road ( under 70mph of coarse

) but there may be a chance of a track day sometime next year so do i swop them out for 325 mm, Or just a change the pads come track day?

The other attraction is, i'm guessing they look better ?

Mazza · Post by **Mazza** » Mon Nov 11, 2019 12:36 pm

Do it just for the hell of it! Or give them all to me so I can try it for you...

kis · Post by **kis** » Mon Nov 11, 2019 12:55 pm

It's all verrry subjective? What pads you used, what discs you used, flushing the fluid, brand new pads and discs... same brands? Or better?
I'd say there is improvement, but then I went from a old set of pads and discs and I was experiencing some binding to the front... That paired with new, bigger pads and discs and new fluid. If I were you? Keep what you've got for now, since they're brand new?

brillomaster · Post by **brillomaster** » Mon Nov 11, 2019 2:33 pm

personally, I'm happily tracking my car on the bog standard 300mm front discs... put a decent set of pads in and I can't see how they could really be improved.

i'f you've got money to burn, it'd be better spent on decent brake pads. or even better, decent tyres!

Kev · Post by **Kev** » Mon Nov 11, 2019 3:08 pm

I went 300 to 345mm big difference but so many other factors to take into account went to 4 pot calipers and Pagid pads at same time

ibasniper · Post by **ibasniper** » Mon Nov 11, 2019 3:46 pm

brillomaster wrote: ↑Mon Nov 11, 2019 2:33 pm personally, I'm happily tracking my car on the bog standard 300mm front discs... put a decent set of pads in and I can't see how they could really be improved.

i'f you've got money to burn, it'd be better spent on decent brake pads. or even better, decent tyres!

I certainly dont have money to burn, especially this side of crimbo, but your thoughts echo mine really. I may look at the 325mm setup after i try my first trackday...As you already appear to have done a trackday in a Z, whats your thoughts on tyres? i'm currently running Goodyear eagle F1's which have been very grippy on the road.

LittleZ4 · Post by **LittleZ4** » Mon Nov 11, 2019 4:53 pm

I personally believe there's a difference. I also upgraded to braided lines, flushed all the fluid and Went with drilled and grooved discs all round

brillomaster · Post by **brillomaster** » Mon Nov 11, 2019 5:00 pm

Well, ive only ever done trackdays in mismatched budget road tyres, or matching trackday tyres, so never matching decent road tyres, however... a set of trackday tyres were MILES better than road tyres in the dry, and still decent in the wet.

I use federal 595rsr cos theyre cheap, but grip so hard my face feels like its going to fall off!

As for brakes, main reason for bigger discs is to dissipate heat more effectively, so pads dont overheat and fade, or fluid boils. But decent pads and fluid withstand higher temps anyways, plus work out some cooling and keep stint lengths short and brakes dont get that hot anyways.

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