Floating Discs - Advice Appreciated

[GFraser]

Hi all,

I'm looking at big brake upgrade options for later this year, but I'm concerned that they seem to not just cost a lot up front, but also cost a lot in consumable items and potentially be a bit high maintenance. This is all pretty new to me, so a bit of advice would be much appreciated.

My question is regarding floating discs (i.e. separate bells and rotors), as pretty much all the brake kits seem to use these. When the time comes to replace the rotors is this a job a typical garage can do or is it one for a specialist? I'm not very mechanically minded, and don't really have time to spend doing stuff like that sadly, so what do you guys do when it's time to replace rotors?

[GroundEffect]

My car has floating front discs. You just change the whole thing....

[GFraser]

Sounds much easier! Do new bells add much to the cost of replacement rotors?

[Ikemi]

Eh? Surely you just change the disc ... It's bolted onto the bell and removeable. I'm pretty sure I can swap my AP's without new bells!

[GFraser]

That's kind of what I'm asking really. With the fancy floating discs it looks as though the rotors are the consumable part which fit on to the bells. If this is the case, is replacing the rotor a faff or pretty straight forward? With a young family etc I don't have much time for stuff like that, more's the pity! Also, as a daily driver, if discs/rotors need replacing I just need to be able to get them done quickly. Are floating discs, therefore, a bit high maintenance for my needs?

Thanks for the replies so far.

[kambites]

Ikemi said:

Eh? Surely you just change the disc ... It's bolted onto the bell and removeable. I'm pretty sure I can swap my AP's without new bells!

The rotor just bolts onto the bell, usually with a load of little hex key type bolts. Generally speaking the process is something like:

Remove brake pads
Unbolt one end of the calliper and swing it back
Remove the grub-screw locating the bell onto the hub
Remove the whole disc assembly from the hub
Unbolt the disc from the bell
bolt new disc onto the bell
Push back the brake pistons (since the new discs will be thicker than the old ones)
Reassemble everything.

As long as nothing is horribly stuck, you're probably looking at maybe 20 minutes per corner with no special tools.


I don't really see why having separate rotors and bells is any higher maintenance than having them combines, the rotor will still wear out as the same rate, the only difference is that you don't have to buy a new bell and the bell can be made of a lighter material than the rotor (aluminium for the bell and steel for the rotor is probably most common).

Edited by kambites on Friday 13th January 09:26

[thebraketester]

As above. Fairly straightforward. I would always use new hardware. You'll need a low range torque wrench to make sure you tighten them to spec

[mackie1]

Surely it depends on type? Separate ali bell bolted to iron disc != floating. Floating discs generally sit on an arrangement of pins (like BMW M or AMG) or are attached via flexible straps:

Pins:



Straps:


If your choice is like either of those then I'd imagine you'd replace the whole thing.

Exception might be these which only allow lateral movement but look to be bolted together:

[kambites]

True, I assumed he was just referring to replaceable rotors since he said "most brake kits use it". Whilst I'm aware they exist, I've never actually used a set of floating discs, I'm not really sure what they offer over floating callipers (which are far simpler/cheaper)?

[thebraketester]

Strap drive rotors are swappable. (Like the AP ones)

I know of no disadvantage of running 2 piece disc on a road car, other than cost.

[kambites]

thebraketester said:

I know of no disadvantage of running 2 piece disc on a road car, other than cost.

Two piece setups, no.

Floating ones, I'm not sure about, I suppose a floating disc is more likely to stick than a floating calliper.

[thebraketester]

kambites said:

thebraketester said:

I know of no disadvantage of running 2 piece disc on a road car, other than cost.

Two piece setups, no.

Floating ones, I'm not sure about, I suppose a floating disc is more likely to stick than a floating calliper.

I still don't see an issue. I've been using 2 piece floating discs on my car for 2.5 years. No issues, apart from initial cost.

[GFraser]

Thanks guys. The discs in the kit I am looking at appear to be attached with small bolts. Perhaps the maintenance side shouldn't put me off after all.



I'm looking to upgrade the power to about 300bhp this year with a Mountune upgrade. For fast road use and the odd track day do you think a kit like this is overkill? I am just concerned that when improving the suspension and with so much extra power that the standard brakes won't be up to the job.

[kambites]

Yes those are not floating, just separate bells and rotors.

[GFraser]

My mistake. I'm new to this!

[thebraketester]

They could be float in the disc . Can't see the rear.

AP do 2 types. Float in the disc and float in the caliper

[kambites]

thebraketester said:

I still don't see an issue. I've been using 2 piece floating discs on my car for 2.5 years. No issues, apart from initial cost.

So what is the advantage in a floating disc over a fixed one with floating callipers?

[kambites]

thebraketester said:

They could be float in the disc . Can't see the rear.

I can't see how that disc can possibly move relative to the bell?

ETA: Oh I suppose the picture might well have been taken with the bell settled fully down onto the disc so you can't see the float bar thingies.

[thebraketester]

kambites said:

thebraketester said:

I still don't see an issue. I've been using 2 piece floating discs on my car for 2.5 years. No issues, apart from initial cost.

So what is the advantage in a floating disc over a fixed one with floating callipers?

Most of the applications where a floating type disc is used, the calipers are fixed.

Floating Allows better radial expansion for one.

[thebraketester]

Float in the disc.