spikedjack
Member
Registered: 16th Oct 08
Location: wolverhampton/cannock
User status: Offline
|
Why in scientific terms is it better to use a larger disk set up for braking..
Ie using 308mm disks as aposed to 280mm disks...
same caliper and pad for arguments sake.
many thanks 
[Edited on 20-01-2010 by spikedjack]
|
purcell7
Member
Registered: 18th Dec 07
Location: Llangollen, Denbighshire
User status: Offline
|
Greater surface area in contact with the pad so more friction?
|
Root
Member
Registered: 28th Dec 08
User status: Offline
|
I can't give you it in science terms but I can explain in normal:
my guess is larger discs take larger brakes.
meaning with more friction and resistance, it stops the disc turning quicker.
|
spikedjack
Member
Registered: 16th Oct 08
Location: wolverhampton/cannock
User status: Offline
|
the surface area in contact with the pad at any one time would be the same if they use the same caliper and pad.
|
x14xe sport
Member
Registered: 27th Apr 09
User status: Offline
|
but having huge brakes doesnt mean you will stop better, at the end of the day your brakes are only as good as your tyres
|
Root
Member
Registered: 28th Dec 08
User status: Offline
|
quote:
Originally posted by spikedjack
the surface area in contact with the pad at any one time would be the same if they use the same caliper and pad.
yer it would, but if you use bigger brakes, then it's greater.
|
purcell7
Member
Registered: 18th Dec 07
Location: Llangollen, Denbighshire
User status: Offline
|
ye but generally a larger brake set up includes larger callipers and pads doesn't it?
|
spikedjack
Member
Registered: 16th Oct 08
Location: wolverhampton/cannock
User status: Offline
|
the 280mm and 308mm set up use the same caliper in vauxhall terms anyway...
|
Root
Member
Registered: 28th Dec 08
User status: Offline
|
quote:
Originally posted by spikedjack
the 280mm and 308mm set up use the same caliper in vauxhall terms anyway...
havn't you already answered your own question then? It won't unless you get bigger brakes
|
spikedjack
Member
Registered: 16th Oct 08
Location: wolverhampton/cannock
User status: Offline
|
so why would you want 308mm over 280mm brakes?
|
DAZ1985
Member
Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
User status: Offline
|
quote:
Originally posted by purcell7
Greater surface area in contact with the pad so more friction?
same pad though so not more friction
larger area to disperse heat better
like warming a larger area will take longer than a small area
negatives with bigger disc is its add unsprung weight
|
spikedjack
Member
Registered: 16th Oct 08
Location: wolverhampton/cannock
User status: Offline
|
i understand the unsprung mass, and rotational mass, but the only advantage is greater surface area to desperse heat?
|
DAZ1985
Member
Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
User status: Offline
|
quote:
Originally posted by spikedjack
so why would you want 308mm over 280mm brakes?
personally id go for the 280's
308's make pub talk imo
|
IvIarkgraham
Premium Member
Registered: 27th Mar 04
Location: Ellesmere Port, Cheshire
User status: Offline
|
308 and 284 use the same caliper but a different carrier
so a larger pad will be used
meaning a larger contact area
|
DAZ1985
Member
Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
User status: Offline
|
quote:
Originally posted by spikedjack
i understand the unsprung mass, and rotational mass, but the only advantage is greater surface area to desperse heat?
you need to double check its the same caliper for 280 and 308 discs
|
spikedjack
Member
Registered: 16th Oct 08
Location: wolverhampton/cannock
User status: Offline
|
i have 308mm, but im getting rid of them in place of four pots.
the argument was sparked elsewhere, and just wondered in braking terms only, if the 308mm brakes were actually better....
|
Nick-S
Member
Registered: 3rd Mar 04
Location: Leigh. Drives: RS Megane 230 F1 Team R26
User status: Offline
|
larger discs have more leaverage.
|
DAZ1985
Member
Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
User status: Offline
|
unless you get a slave to suit it would be worse
|
LeeM
Member
Registered: 26th Sep 05
Location: Liverpool
User status: Offline
|
the caliper is further from the centre of the axel as well. there some scientific way to describe it but the further out it is the less force needed to slow the disc down. so with the same force applied further out from the centre the quicker it'll stop
|
James_DT
Member
Registered: 9th Apr 04
Location: Cambridgeshire
User status: Offline
|
quote:
Originally posted by Root
quote:
Originally posted by spikedjack
the 280mm and 308mm set up use the same caliper in vauxhall terms anyway...
havn't you already answered your own question then? It won't unless you get bigger brakes
Yes it will.
The pads will be in contact with the disk further from the centre of the disk, which works in the same way as a lever with a longer handle, which amplifies the force.
|
DAZ1985
Member
Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
User status: Offline
|
another thing to consider maybe is if they fit under your wheels?
|
ed
Member
Registered: 10th Sep 03
User status: Offline
|
You get more braking power from a larger disk because you get more moment from a larger disk. It's the same reason why you can undo a rusted to fuck bolt with a great long breaker bar and not your little 1/4" socket wrench. Surface area doesn't come into it that much. More surface area will generate more heat, so there is an optimum amount which is dependant on the application.
|
stan_the_man
Member
Registered: 14th Feb 07
Location: Perth, Western Australia
User status: Offline
|
If you spin something round (Take a bicycle wheel for example) and try and stop it as close to the centre of the wheel as possible, its very hard. Try and stop it by touching the outside of the wheel, and its alot easier.
Relate this to the size of a brake disc and you will see why bigger is often better.
As already stated, larger brakes generally means larger pad surface area too, which also aids friction.
|
