Gav
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| posted on 9/2/06 at 10:12 AM |
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Is it worth upgrading to rear disks?
Last night i started fitting the rear hub plates.
Im gonna have to recondition the brakes anyway but it got me thinking is converting to rear disks worth it? with it being so light in the first place
will i need the extra stopping power? my intention is to do some hillclimbs/sprints when its finished so would brake cooling be a factor, also would a
disk setup be that much lighter?
Comments please.
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Bob C
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| posted on 9/2/06 at 10:16 AM |
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I believe the drum setup is significantly lighter than a standard disc setup.
There may be a couple of kgs in it!
Maybe someone with some bathroom scales & a lot of bits could confirm?
Bob
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Bluemoon
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| posted on 9/2/06 at 10:31 AM |
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Take a look at the thread:
http://www.locostbuilders.co.uk/viewthread.php?tid=36092
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Gav
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| posted on 9/2/06 at 10:44 AM |
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Looks like ill just recondition the rear drums for now then.
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ed_crouch
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| posted on 9/2/06 at 01:29 PM |
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There are 2 issues when designing brakes:
1. Amount of brake torque generated
2. Amount of energy to be absorbed in a maximum energy stop.
Brake torque is a function of brake system pressure, piston area, and coefficient of friction amongst others.
Energy absorbtion is all about converting the kinetic energy of the car into heat in the brakes. Kinetic energy = 0.5mv^2. Heat in the brakes =
mCpdT
i.e. theres 2 limiting factors:
Is the brake capable of locking the wheel?
In an emergence stop from the vehicle's top speed, will the heat generated in the brakes either cause the degradation of the materails contained
therein, or will it boil the fluid.
Drums generate loads of torque, but fall down on the heat criterion, since the surfaces on which the heat is generated are enclosed, and heat has to
conduct through the drums before it can escape, whereas discs are constantly in good airflow. BUT, discs generally are capable of less torque.
My guess is that structural limitations of brake calipers are the culprit.
Anyway, all of this means that you cant just say that discs are better. It really does depend on what you're using them for.
In the case of the 40ton trucks using drums: this is probably also to prevent accretion of mud and other crap on the brake surfaces: theyre enclosed!
I-iii-iii-iii-ts ME!
Hurrah.
www.wings-and-wheels.net
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Hellfire
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| posted on 9/2/06 at 05:33 PM |
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1 1/2 tonne brakes on a 1/2 tonne car drums are more than up for it.
If it's for aesthetics then yes... disk look far better IMO
You could always get some of those alloy drum cover disk lookalikes all the chav's use - they look lovely and very authentic 
I know I'd stick with what I'd got if I was you!
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Gav
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| posted on 9/2/06 at 07:51 PM |
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Yeah tbh it was more for looks than anything else 
Still ill keep it simple, stick with what ive got then ive got all the time in the world to change stuff after its on't road 
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Stu16v
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| posted on 9/2/06 at 07:54 PM |
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quote:
my intention is to do some hillclimbs/sprints when its finished so would brake cooling be a factor
I very much doubt that it would be a factor. I guess the average sprint or hillclimb lasts between 30secs to a minute - you wont worry the brakes at
all. And on most tracks, gravity will be helping to slow it down anyway!
Dont just build it.....make it!
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Browser
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| posted on 10/2/06 at 12:50 PM |
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And nearly all handbrake systems fitted to disc-braked rears are prone to ceasing to function sooner or later, whereas drums tend to be more reliable.
On a car as light as a seven/locost unless you need to go from 100mph to zero in twenty feet it ain't worth the aggro
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DarrenW
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| posted on 10/2/06 at 03:50 PM |
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i rebuilt a mk1 Golf gti a few years back. Spent a while converting to rear discs. Absolute waste of time. They hardly did any work anyway so the %
improvement was tiny. I wished i hadnt bothered. ZR has rear drums, they are massive anyway seeing as they are designed for a Sierra.
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