27mm master cylinders with SSVR Brembo brakes

[Skylarking]

I have done the calculations based on the info I can get when I was upgrading the brakes. AP info was a bit hard to get so it may not be the accurate figures. But the and brembo,pbr & mando caliper specs i'm confident.
Bottom line is that I have ran the brembo 6/4 pot combo on a 25 MC and it was signed off by the engineered
So I would say don't worry unless you plan to upgrading to a bigger kit being the AP 6 pot kit which would require more volume

View attachment 259147

That’s a nice bit of data you've presented

What would also be interesting is the BMC shaft travel for the given 0.5mm brake pad movement as that depends on the BMC diameter.. And from that we can work out the brake pedal movement we’d experience with Brembo‘s all around given a 25mm and 27mm BMC (assuming the pedal parts and thus the leverage are all the same across the range). Even better if the pedal movement and pedal pressure can be calculated (assuming no vacuum assistance).

(Don‘t know if there are differences in the vacuum booster between the vehicle variants or whether they are all one and the same…).

 

[Skylarking]

Certainly seems its a bloke thing to be worried over 2mm

Genuine question, wouldn't tires have a far greater influence overall on real world brake performance, such as stopping distance? (Ignoring things like brake fade, pedal travel etc) Still boggles my mind the amount of SSVR's and LSA HSV's I see rolling round that have the cheapest bargin basement tyres on them

bloke thing… made me laugh

I’d say tires make all the difference and the following may be of interest… and to me it highlights the stupidity of those massive brakes on powerful EV’s with max regenerative braking features…

 

[RevNev]

Certainly seems its a bloke thing to be worried over 2mm

Genuine question, wouldn't tires have a far greater influence overall on real world brake performance, such as stopping distance? (Ignoring things like brake fade, pedal travel etc) Still boggles my mind the amount of SSVR's and LSA HSV's that have the cheapest bargin basement tyres on them

Yes absolutely! The better the tyre grip, the more braking force can be used to pull the car up in a shorter distance before locking a wheel and activating the ABS. Factor in all the crap suspension mods that'll degrade the car's handling and cheap skating on tyres with strong horsepower, is a good cocktail to kill yourself or someone else particularly when the people who tend to do this can't drive either!

 

[RevNev]

What would also be interesting is the BMC shaft travel for the given 0.5mm brake pad movement as that depends on the BMC diameter.. And from that we can work out the brake pedal movement we’d experience with Brembo‘s all around given a 25mm and 27mm BMC (assuming the pedal parts and thus the leverage are all the same across the range). Even better if the pedal movement and pedal pressure can be calculated (assuming no vacuum assistance).

Without a booster to apply the same fluid pressure at the caliper, the smaller 25mm master cylinder will take less pedal (leg) pressure with greater pedal travel than the 27mm. With a booster and the need to apply more pedal pressure with the larger 27mm, pedal travel may not be much different. If it's noticeable, changing a 27mm to a 25mm should feel like the pads have more bite and effectively, the brakes should feel better.

On a non-boosted twin master cylinder balance bar system used in race cars, you could end up with a 1" on the rear to stop lock up and a 3/4" on the front or even smaller 5/8" perhaps. Excessive pedal travel is then adjusted by pedal ratio altering the pivot point to pushrod position. On our old VZ V8 Supercar that logs brake pressure, the typical pressure to the front calipers hard braking is about 800/900psi and you're pushing the pedal hard to achieve that. We haven't run the car since 2015 and I can't recall what the rear brake pressure was as the driver generally set the F/R brake bias on the seat of his pants.

 

[VT542]

Just checked my VF series 1 Redline ute with Brembos front only the BMC 27mm.

 

[vywgn]

Well if anyone wants a 27mm master I've got 1 available, as I'm removing the police/option spec brakes from my car atm

 

[Banjo79]

PM'd.

 

[NJD-1992]

Well if anyone wants a 27mm master I've got 1 available, as I'm removing the police/option spec brakes from my car atm

Any particular reason you're removing the police brakes?

 

[vywgn]

Any particular reason you're removing the police brakes?

Selling the car

 

[NJD-1992]

Selling the car

Oh wow! Wouldn't have expected that, another VF or onto something else?