seen various larger disc options with relocation brackets to fit standard calipers.

 

is it worth/beneficial to upgrade to larger front discs whilst retaining the standard calipers.

 

i was thinking something like 345mm drilled and grooved discs, but my aim is to improve braking force/ stopping power.

 

would be good to hear from people with bigger discs...... as they have experienced the change.

 

 

thanks in advance

It is an improvement as I had 324mm on my

First zed with smithys relocation brackets. There is no change in clamping force as it's the same caliper. You can also argue that less of the pad is on contact with the disk. This is certainly true. However it does give u a larger surface to dissipate heat so in theory would provide the breaking force for longer.

All the bigger discs really do with standard callipers is dissipate the heat better/faster, the callipers themselves are not actually that bad either, the car stops pretty well if you have decent discs and pads, the problem is the brake fade because of the small discs. So yes I would personally say keeping the standard callipers and uprating to bigger discs would be a positive step in braking, especially if you uprate your pads as well of course.

i fitted standard size grooved discs these i found helped breaking also

Personally I wouldn't go for them or all you end up with is this -

Yeah that photo isn't pretty, but it wouldn't affect performance, it'd just look ugly, lol. Obviously the ultimate solution is bigger discs + bigger callipers + better pads, but better pads and bigger discs with the grooved and drilled feature of course, would be a lot better than standard. I personally have done as Black Zed has done, I've got drilled and grooved, standard size discs all round, car stops on a 6 pence, but when it comes to track use I think they will heat up too quick to continue the performance :( Certainly had NO issues on the road though.

Yeah that photo isn't pretty, but it wouldn't affect performance, it'd just look ugly, lol. Obviously the ultimate solution is bigger discs + bigger callipers + better pads, but better pads and bigger discs with the grooved and drilled feature of course, would be a lot better than standard. I personally have done as Black Zed has done, I've got drilled and grooved, standard size discs all round, car stops on a 6 pence, but when it comes to track use I think they will heat up too quick to continue the performance :( Certainly had NO issues on the road though.

 

Yea that picture was on my Zed when I got it and I changed them for a set of standard sized drilled and grooved. I reckon theres no difference between the two (on the road that is) but as you say the track might be a different story :)

Never understood the whole drilled discs thing, you can clearly see the cracking around the holes in that photo there, do not want!

 

Larger discs will of course improve the braking, it's simple physics. Same force, larger distance from fulcrum = larger torque.

PerpetualZero what disc size are those in the picture mate. is that the db power kit?

PerpetualZero what disc size are those in the picture mate. is that the db power kit?

 

Sorry I couldn't actually tell you mate they were on it when I got the car and I never measured them.

When I took the pads off they were only half in contact with the disc, so all the hype about the braking force being more due to larger disc size etc. fails to take into account only half the pad is in contact with half the disc.

I'd assume that if you have the right size re-locating bracket for the calliper, you should see the entire pad touch the disc, but only part of it, either way, I reckon the braking power will be the same with a larger disc and standard calliper, as the physics involved, is forgetting that the pad is still small and so is the force that's pushing the pad onto the disc.

 

Of course as Clarkey says, it is further from the center of the rotation, so in theory, it will stop quicker. But then also in theory, you're now putting more strain on the standard calliper and pad, than you were with a standard size disc, so the discs will then heat up quicker, which should mean they'll die off sooner, but because they're bigger they'll dissipate heat quicker, so that won't happen, however your brake fluid probably will heat up, because you've not introduced any extra cooling for that, or a larger calliper to absorb it better and the small pad on the large disc, being further away from the center of the rotation, will now be generating more friction/heat, ergo, you might get the same braking force, or potentially even less if you boil the fluid, with larger discs but standard callipers, they just won't die off as quickly. Give or take miniscule amounts that could only be measured by a proper scientific test, or if you really knew enough about physics to know each value and work out the theory in full, you'd probably find the speed at which it braked, would be about the same, however you wouldn't heat up the disc as quickly.

 

Or, I could just be talking *****cks, lol.

Don't go for the drilled option they do crack and fracture

I reckon that has to depend on the manufacturer? I've had tonnes of cars with drilled discs and never had one crack yet. The only manufacturers I've had have been brembo, EBC and Black Diamond though.

withe larger discs you get a larger surface area to get rid of heat and also more leverage they do help

Ok used three sets one being brembo all have fractures on.... They are from my hillclimb cars though .....all the drilled ones have small fractures, grooved ones all ok, drilled and grooved have fractures going from hole to hole

I reckon that has to depend on the manufacturer? I've had tonnes of cars with drilled discs and never had one crack yet. The only manufacturers I've had have been brembo, EBC and Black Diamond though.

 

I bet you that if you examined the discs with crack detection dyes or X-rays etc, then every single one would have cracks !

Yeah no doubt, but I'd wager (Except I don't bet) that using those technologies, you'd find the same or similar results in not drilled discs too.

Yeah no doubt, but I'd wager (Except I don't bet) that using those technologies, you'd find the same or similar results in not drilled discs too.

 

Agreed, but you'll find a lot more on disks that have about 120 additional stress points built in !

While that makes sense, I've never had a set of drilled discs fail on me. I haven't tracked the Z, but I did quite heavily with the GTR and the Supra (The two most heavily modified cars I've owned) and never had any problems with the brakes on either.

we use a lot of genuine drilled discs on Mercedes - although we see very fine cracks on these Mercedes have stated that this is quite acceptable & there is no need for replacement if the rest of the disc is within normal wear limits

 

I have never seen a total failure from this very fine craking around the drilled holes & we get through a LOT of discs here!!! The discs are always below the wear limit & are replaced for this & not for any problems with fine cracking around the holes

 

:)

I know this is not scientific and it's only the exceptions not the norm you'll see here, but check Google images for cracked drilled discs.

i my self have had a cracked drilled/grooved disc ...

it was from inner to outer edge

will try and dig out the pic

 

found it

Ianl was talking bout this a while back im sure and said that even with the bigger disc they overheated witgin 5 laps, the brembo conversion is apprantly the way to go.

I know this is not scientific and it's only the exceptions not the norm you'll see here, but check Google images for cracked drilled discs.

 

perhaps Merc discs are just a lot better quality LOL! :D

indeedy

 

i had relocated stock calipers on skyline discs with a relocation bracket.

 

obviously with a bigger disc the curvature of the outer edge of the disc is different so will not match the pads, however mine was bad that lots of the pad didnt touch the disc.

 

it felt no better than my other zed with stock everything, in fact probably worse (but that could be the condition of the fluid or calipers)

 

at a track day at silverstone , breaking at the end of teh long straight on the 5th lap was like driving over rumblestrips. about an hour to cool the discs and i was good for another 5 laps

 

i've since replaced them with skyline calipers to match the discs and the initial bite is so much better, and track days have been ok, not been back to an open pit though so not sure how many laps it would do now.

 

i'm a firm believer that new brake fluid and stripping and freeing up the caliper mechanism will improve most zed brakes more so than changing disc size

 

see http://www.300zx.co.uk/forums/showthread.php?t=135955&highlight=brake+upgrade