325mm discs on

[the Nefyn cat]

Like it says, the 325mm discs are on and looking fine. Only a few pictures as I'm sure you all know what discs look like. Did a bit of measuring first, the 330 calipers have 57mm pistons, the discs are 25mm thick, and sure enough amongst the various markings on the calipers there's 57/25 moulded in. Had a look at the Z3 calipers once I'd cleaned them up a bit and they're marked 56/22, the slightly bigger pistons don't seem to make any difference to the length of the pedal, if you know what I mean. The main difference seems to be that the steering feels slightly heavier, probably down to the bigger heavier discs. Anyway, shiny things...

Guess which is the new disc

Can't see the dirt-shield anymore

Fills up some empty space.

 

[Brian4]

I see you didn't change the calipers so the upgrade is purely visual as there will be no greater braking because you are using the same pads as before. You will just end up with the outer 12.5mm part of the disc not being used. Unless you can fit the calipers from a 330 onto the caliper mounting.

 

[Brian H]

I did the 330 upgrade to my car a while back, the increase in piston size did make a difference to the pedal feel for me, I had to pump the pedal once to get a solid feel, the upgrade lasted a day or so before I took it back off.

 

[gookah]

surely the difference in bigger discs is that the leverage is now greater, as the pads are now acting further away from the centre and the same effort produces more braking force

 

[t-tony]

surely the difference in bigger discs is that the leverage is now greater, as the pads are now acting further away from the centre and the same effort produces more braking force

I was having similar thoughts. I would like to get a car with both mods on and carry out a roller brake test just to see the difference, assuming there was one .

Tony.

 

[Brian4]

surely the difference in bigger discs is that the leverage is now greater, as the pads are now acting further away from the centre and the same effort produces more braking force

My reasoning is because the calipers and carriers haven't been changed the pads are acting in the same position as with the standard discs so the outer edge of the pad is still 300ish mm from the centre of the hub as before. If Nefyn has replaced the carriers then all will be ok.

 

[Jack Ratt]

If the ram area, ie, the piston area is the same as previous, the only way to increase braking efficiency is to increase the pressure acting on that ram area.

 

[Wilko58]

I'm confused on two points - surely if @the Nefyn cat has put bigger disks on he would have to put the calipers on as well otherwise the disks would not fit due to the original caliper distance from the hub and secondly if you have changed the calipers @the Nefyn cat are they 325 disks or 300 disks? I've just bought callipers from a 330i and was led to believe that they were for 300mm disks? Can you let me know before I buy the wrong ones! Thanks

 

[gookah]

If the ram area, ie, the piston area is the same as previous, the only way to increase braking efficiency is to increase the pressure acting on that ram area.

I am aware bigger pistons / more pistons will give more CSA for the pressure generated to act on. Pounds per square inch.... more inches =more pounds using the same pressure.
But that is not what I am talking about:
to fit the bigger discs he would have had to put new carriers on which take the callipers further outwards on the rotating diameter,

The further outwards on the diameter you go, the same braking force will give more stopping power.
try stopping a spinning wheel by grabbing the tyre or the driveshaft, see which is easier, the calliper is now doing the easier job

 

[the Nefyn cat]

They are indeed 330Ci calipers AND carriers, wouldn't fit the discs otherwise. The 330d caliper carriers are shorter to suit the smaller discs on the diesel, don't know why they bothered making them smaller, need to ask BMW that, and I for one can't be a55ed. I'm not a heavy brake user under normal circumstances, but up here there are some very fine twisty roads that need a certain amount of abuse every now and again. Too many tourists around at the moment too busy staring at maps/satnavs etc to look where they're going.
So this is mostly a cosmetic upgrade, was going to change the pads and discs anyway, and give the calipers a lick of paint to match the rears. Posted the pictures in case anyone else was considering doing it, easy job (apart from the little disc-locating screws, resorted to an angle-grinder in the end).
Cost around £200 altogether, wouldn't have been much cheaper to have kept the standard size bits, but sure does look good. Just my opinion, feel free to differ. But you're wrong.

 

[the Nefyn cat]

And should maybe have tucked this in with the above, but some may remember that I posted something a short while ago about changing the rear spring seats for thinner ones (10mm to 5mm). Finally got round to doing it yesterday and it's dropped the rear end by about 10mm. Not surprising, really, bearing in mind the layout of the rear suspension.

 

[Brian4]

@the Nefyn cat apologies for getting the wrong end of the stick but when you said using Z3 calipers I incorrectly thought you had changed just the discs.

 

[Aaron MacQ]

Like it says, the 325mm discs are on and looking fine. Only a few pictures as I'm sure you all know what discs look like. Did a bit of measuring first, the 330 calipers have 57mm pistons, the discs are 25mm thick, and sure enough amongst the various markings on the calipers there's 57/25 moulded in. Had a look at the Z3 calipers once I'd cleaned them up a bit and they're marked 56/22, the slightly bigger pistons don't seem to make any difference to the length of the pedal, if you know what I mean. The main difference seems to be that the steering feels slightly heavier, probably down to the bigger heavier discs. Anyway, shiny things...

Guess which is the new disc

Can't see the dirt-shield anymore

Fills up some empty space.

Good job.
How you finding the brakes now as they bed in?
I did the 325mm upgrade a few weeks back, along with castor bushes, new tyres and suspension. I love them. Best braking power I've had in a car. Overkill for sure and alot of front bias, but awesome.

 

[Wilko58]

Good job.
How you finding the brakes now as they bed in?
I did the 325mm upgrade a few weeks back, along with castor bushes, new tyres and suspension. I love them. Best braking power I've had in a car. Overkill for sure and alot of front bias, but awesome.

I'm just about to do the same brake upgrade but out of interest what suspension did you fit?

 

[Aaron MacQ]

I'm just about to do the same brake upgrade but out of interest what suspension did you fit?

It goes against everything I would normally say, but I bought the cheapest 'branded' suspension I could find in the hope it would be relatively soft without being total crap (I had bought the Z for my dad - 65 years old) and that just happened to be the Apex budget coilovers from EuroCarParts. ECP part number 975114201.

When it arrived, there was no Apex branding on it anywhere but to be honest, it's fine. Quite comfortable and handles well on decent roads although if the car were for me, I'd have used KW's ST XT coilovers.

With the coilovers a 3mm spacer was required on the front wheels to clear the suspension bottom spring perch, but the only real issue I had with the brakes was getting the wheels balanced as there is only 1-2mm clearance between the caliper and the rim (OEM 17"). Had to move the weights about a few times to get the balance without fouling the brakes.

Anyway, it's a great upgrade. Oh, and I used Mtec disks (http://www.mtecbrakes.com/) which were good value and look fantastic.

 

[Wilko58]

Cheers. I've haven't decided on whether to stay standard ride height or lowered - it's on 18s so doesn't look too bad. I've bought Brembo disks and pads, don't know what they'll be like but carry a great name in brakes so can't be that bad.

 

[Dino D]

Good job.
How you finding the brakes now as they bed in?
I did the 325mm upgrade a few weeks back, along with castor bushes, new tyres and suspension. I love them. Best braking power I've had in a car. Overkill for sure and alot of front bias, but awesome.

What doe front bias feel like when driving? Does the rear get squirrely under braking?

 

[Aaron MacQ]

Hard to describe in words, but under normal driving, the bias doesn't matter one bit. Maybe in snow it would be an issue, but our Z won't see snow again.

When pushing on, you feel the front bite harder than before and the car pitch a little more than it would have before. In a straight line it won't matter but if trail braking into a fast corner I'd be more cautious about understeer due to the heavier frontend balance. It's not something that would bother me one bit but I'm used to front bias with big front brakes on all my cars.

 

[Dino D]

Hard to describe in words, but under normal driving, the bias doesn't matter one bit. Maybe in snow it would be an issue, but our Z won't see snow again.

When pushing on, you feel the front bite harder than before and the car pitch a little more than it would have before. In a straight line it won't matter but if trail braking into a fast corner I'd be more cautious about understeer due to the heavier frontend balance. It's not something that would bother me one bit but I'm used to front bias with big front brakes on all my cars.

So I guess it feels like it braking harder than usual (as it is I can feel the rear lighten if brake really hade).
Would it not make for oversteer as the front bites harder and the rear lightens as it pitches upward more?

 

[Aaron MacQ]

For any given pedal pressure, you are braking harder than before, but only at the front.

There's no more chance of the rear braking free than ever before as the rear isn't doing anything different. Infact for any given retardation, your now using less braking power at the back so it's possibly more stable at the rear.
Of course you can pretty much now stop as well as your tyres allow which may make the rear very light (and oversteery) but again, that's no different to pushing the pedal harder with standard brakes.
However with massive front brakes, the chance of front locking is higher, which is the potential cause of understeer when trail braking into a corner.

To summarise, to drive day to day, the balance is no better, or worse... Just different!

Just thinking tho, i did a load of stuff at the same time.
Castor bushes push the wheel forward improving braking stability and the fact they're polyurethane means there's no toe fluctuations under load and braided flexible brake lines help improve pedal feel.
Harder suspension keeps the car from pitching too much and the increased castor/camber provide more grip when turning.
All together tho, it's a brilliant setup.