Protrim
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| posted on 26/11/06 at 09:05 PM |
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How big brakes is necessary?
I am building a 250bhp XE Locost. Money is not the biggest issue since I am doing mostly "top of the shelf parts" and even if this extends
the building time I want it perfect.
The question is how big brakes do I need? Brakes is also weight which I will have on a minimum. I have a set of 285mm AP Racing ventilated brake discs
I was planned to run in front, but I am told that solid discs is enough both front and rear.
What do you reacon a 250bhp, 550kg Locost need? It must fit under a 15" wheel. It will be driven very hard on the track and I do not want brake
issues when the car is finished.
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Simon
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| posted on 26/11/06 at 09:42 PM |
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I've been using standard 1.8 Sierra discs and drums on my R V8 powered car.
However, I haven't given the car track time or driven it particularly hard on the road, so wouldn't know how much fade they'd
suffer.
I'm in the process of chucking on fuel injection, a pair of turbos, and a Jag rear end (yeah I know it's heavy etc etc!) but the discs on
that are huge, so I'm also going to remake the front wishbones etc, as I'll then be able to using Jag front uprights and dicss!
ATB
Simon
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flak monkey
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| posted on 26/11/06 at 09:45 PM |
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Solid, drilled and grooved discs with sport pads and a high spec 'racing' brake fluid will give you all you need IMO.
Sevens dont have the cooling problems with the front brakes that a normal road car has because they are open and get excellent air flow.
David
Sera
http://www.motosera.com
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chriscook
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| posted on 26/11/06 at 11:21 PM |
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Wouldn't bother with the drilled and grooved myself...
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craig1410
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| posted on 27/11/06 at 12:50 AM |
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I would use grooved but not drilled myself as the drill holes can often be the start point for cracks. The grooves help to disperse the surface gases
and keep feel more consistent. At least that is what I have read...
Also, there is less advantage in using drill holes when the discs are solid because there is always a pad on either side so you don't get the
same ventilation effect through the drill hole. You can pick pads to suit the usage.
HTH,
Craig.
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JB
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| posted on 27/11/06 at 05:05 PM |
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Brake SetUp
The biggest brakes you can fit will give the best braking because cooling will be less of an issue so you can run softer pads for better feel. Also
the larger the diameter the disc the less clamping force you will require so can run a bigger dia. bore master cylinder which will cut down on pedal
travel. This again is a good thing as it is easier to modulate pressure than movement. However the bigger the brakes the more the weight and
inertia.
However the most important aspect is to use quality parts, so this mean AP or Alcon, none of this drilled and cad plated disc crap. You have AP discs
so thats good. Calipers are also important. Again AP or Alcon. You will notice a difference over the other cheaper alloy calipers in pedal feel due to
caliper flex.
Cooling is also very important on any car if you want to optimise. On a vented disc duct air to the centre and seal the duct to the disc. On a solid
disc air needs ducting to both sides. Make the duct opening bigger than you think and you can always blank it off as required.
Now to to size. I do think that a 285mm dia vented disc (1" wide ??) is too much for your car. I ran Capri 2.8i vented discs with Mintex M1144
pads in Princess calipers on a 1000kg vehicle with full body work and no ducted cooling and never faded the pads or lost the brakes. I was doing
navigational scatters on very twisty roads that hammered the brakes. I often faded the dampers but never the brakes.
Solid discs will be fine at the rear and will probably be OK at the front. But if you want no hassle then fit the 285`s and have peace of mind. If
you are willing to experiment then certainly the biggest solid discs you can fit will be worth a try as those AP vented discs are heavy!
John
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roadboy
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| posted on 29/11/06 at 07:20 PM |
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I have used 285mm Mondeo vented discs with Lotus Elise 2 pot calipers ( AP Racing ) on home made radial mount brackets & they are brilliant with
normal road pads. The discs may be overkill but have absolutely no overheating problems even with heavy circuit use.
HTH
Ian
Jude Performance Services
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