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16" wheels

17" wheels

18" wheels

[chrisgixer]

First off, I'm not really interested in the usual "what's wrong with the standard brakes" reply. We all know that argument, it's been done to death. Apart from anything else the Mv8 project is GOING to need better brakes, it just is. And some members find the stock items lacking anyway.

So, any thoughts?

I know 2woody suggests ML discs and Audi S4(?) calipers.
Serek has Audi q7 options on callipers and discs, with smaller options too.
Ex Taxi Al has been looking at Monaro and Vxr8 stuff with possibly looking at Ap rotors in Alloy top hats.

Cost is a big one with Ap stuff although its top quality. But I can't help feel we could do better given their £1500 price tag.



I guess we could do with options for those with 16" 17" and 18" wheels, if interested.

On et30 18" irmscher sport stars there is a;
45mm gap from the calliper to the spokes.
60mm gap from the outer disc edge to the wheel.
35mm gap from the calliper to the wheel.


On first glance there appears to be several options from vehicles with a 112mm bolt pattern that fit with slight machining of the hub hole. Brackets will be needed to mount different callipers, and different callipers may well need different brake line fixings, so a good reason to fit braided hoses there.

After thought.
Weight. Bigger discs add a fair amount of weight to the un sprung side of the suspension. Might give wheel bearings and shocks a bit of grief?

Anyway, thoughts gentlemen please.

[chrisgixer]

Oh, and Kev mentioned piston area.


And what to do at the rear. Leave it be?

[Field Marshal Dr. Opti]

 The brakes fitted to the Lotus Carlton in 1990 were supposed to be excellent.

Twenty three years on I'm not sure how they would compare with a 'modern' setup.  

[Auto Addict]

You want one of these, sling it around a lamp post when you want to stop.

http://www.ebay.com/itm/Antique-Admiralty-large-ship-anchor-/221288045000

[Kevin Wood]

On the weight side, the disks are inevitably going to be heavier, but you can get some very light weight alloy calipers which might go some way to compensate.

But.. what is the problem we are trying to solve?

Do we know how the front and rear contribute to that problem? Equally?  or.. Is the front or rear end the weak link?

..and piston areas will of course be the main concern, second only to "will it physically fit?". You need to maintain the balance of the system. I'd only be willing to drive the car on the road if I could demonstrate some calculations or testing to show that the system has been competently designed in this respect.

[05omegav6]

On my Mot, the fronts were both 4.5 on the gauges, the rears 4.2...

...which ties in with the earlier thoughts on piston area

Opposing pistons a perhaps more mechanically efficient than sliding ones as well...

[chrisgixer]

Re piston area, are we not talking about a greater area to be taken up by fluid on a bigger caliper, but the travel of the pistons, and hence the fluid in the brake line to that corner of the car, being the same. So master cylinder would be unaffected.

What have I missed?

[martin42]

Try hispec motorsport,they can make custom discs to fit anything 

[P6UL K]

Try Hi-Spec motorsport,they can make custom discs to fit anything 

And their at the top of my road... http://www.hispecmotorsport.co.uk/ 

[cem_devecioglu]

there is a theoritical limit for the brakes.. and also tyres that you can use on omega ..  you have to install very wide big tyres that omega drive train may not be capable of .....

[05omegav6]

The ABS will manage the absolute stopping power, regardless of tyres, as its sole function is to prevent wheel lock

The four channel system on the newer cars ought to be upto the task of keeping all four brakes on an even keel, the three channel set up might be a bit less tolerant to an over braked rear end.

In order to keep things balanced, perhaps it will be necessary to use both front and rear calipers from the same donor and keep the disc diameters in proportion.

16" wheels are going to be quite restricted in size increases, 17"+ giving considerably more space to play with...

A starting point for the four pots would be late V6 vented discs/calipers all round, with better pads. For the six pots, larger diameter and greater thickness for heat tolerance along with larger calipers/pads.

Choice of disc and caliper is governed by the hub dimensions and the wheel dimensions, so it could be prudent to aim to keep either the inside face of the larger disc or its centre line in the same relative position as the originals in order to keep the caliper away from the inboard face of the wheels.

Another important point regarding disc/caliper choice is disc and pad thickness and availability

Regardless of choice of disc/caliper, there will be a certain amount of fabrication needed, either to fit the disc or to mount the caliper...

[Kevin Wood]

Don't forget the master cylinder. Some systems have different diameter MC bores for front and rear to balance the system. It's the ratio of master and slave cylinder area that translates force at the pedal to force acting on the brake pad. If you go to much bigger slave cylinders you will need to find a master cylinder that matches them.

[cem_devecioglu]

The ABS will manage the absolute stopping power, regardless of tyres, as its sole function is to prevent wheel lock

under certain conditions abs stops the car longer
 
a chain is as strong as its weakest part.. see Kevins post..

[Kevin Wood]

Yep, once ABS has kicked in you are in a compromise. A good driver could otherwise stop quicker using cadence braking. A bad driver would be sailing on into the ditch.

Best to get the system properly balanced before you consider ABS, so the ABS only has to function when both axles are at their limit of traction, IMHO.

[aaronjb]

Re piston area, are we not talking about a greater area to be taken up by fluid on a bigger caliper, but the travel of the pistons, and hence the fluid in the brake line to that corner of the car, being the same. So master cylinder would be unaffected.

What have I missed?

The ratio of the caliper piston area to the master cylinder piston area directly affects the force amplification and the relative travel (think of it like a lever ratio, I suppose..) of caliper piston vs. master cylinder piston.

But please don't ask me which way 'round it is as I can't remember  I know the relationship between force & travel is inverse, but that's all I can dredge up.