Front Ventilated Disk Upgrade Kit

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Hey Guys,

I have decided to offer a 240mm diameter ventilated disk brake kit. This is a bolt on kit using brand new rotors, with all parts supplied.

In summary, the rotor is virtually the same diameter as the standard solid rotor, except it is ventilated, which means it is thicker than the standard rotor. The caliper mounts in the same location, using the exact same method as standard, except due to the increase in thickness of the rotor, the caliper needs spacer plates inside the unit to increase the passage that the rotor spins through.

The ventilated rotor allows the heat absorbed by the brake componentry during braking, to be dissipated at a higher rate. This lowers component temperature, and increases the assembly's resistance to brake fade.

This type of upgrade would be ideal for weekend club sprints, rallys, etc, or for when a brake upgrade is specified by an auto engineer if an engine is installed that is heavier or has more horsepower than the original.

Due to the use of the standard caliper, a change in brake bias is not an issue. Brake balance therefore remains as good as factory.

The installation is literaly a bolt in job. Undo nut retaining wheel bearing, slide hub off, unbolt standard rotor, bolt on ventilated rotor, unbolt caliper, seperate two halves, install spacers, bolt everything back together and bleed brakes.

Kits consist of:

2 x 240mm diameter brand new ventilated disks - machined, drilled and tapped so bolts to standard gemini hub,
4 x laser cut caliper spacers - mount inside gemini caliper to allow fitment over ventilated disk, no modifications involved, simple bolt in procedure,
4 x genuine Holden rubber seals for spacers,
8 x longer high tensile (grade 8 & 10) bolts for calipers to allow for spacer thickness
fitting instructions provided, simple to follow.

Price is $280 per kit with brand new rotors only.

As I know some people will want to know, slotted rotors will be about $500 for a kit, and cross drilled and slotted will be around the $600-$650 mark. Obviously standard rotors are a lot cheaper.

If you want photos, or have any technical questions, let me know.

wight@giant.net.au

I was offering a 250mm diameter disk, but this requires at least a 4mm elongation of the mounting hole in the caliper to clear the bigger diameter rotor, when using a TX stub axle. I am not prepared to sell this kit without first doing an FEA stress analysis on the caliper in this condition. This may take a few months.

Ben Wight

ONLYA4 · petrol head Joined: 12 May 2003 Posts: 1114

Ben,

What power will these be suitable for? As in, if engineering says you need a brake upgrade, to what power will these pass?

Dunno if that makes any sence. Meh.

btw, you got mail.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

The braking requirements of a vehicle are determined by the weight of the vehicle, not the power. For engineers certificates in VIC, you need to conduct a test to verify braking performance if the weight of the vehicle has been increased by 10%.

I have not conducted the testing on these units, but I believe they would pass the performance requirements with the weight of a commodore v6 engine or small v8 over the front axle.

As a safety precaution, for a pre '77 model vehicle, state requirements also state that a brake test will also be needed if the vehicle undergoes an increase in either power or weight by 10%. If you simply increase the output of a gem engine for example, with the addition of a turbo, etc, then the weight of the vehicle is very similar to the weight of the unmodified vehicle, and it is likely that the standard brakes will pass any performance requirements.

For example, if you have a gemini engine outputting 500hp, then it is likely that the standard brakes will still meet the performance requirements, as the mass of the vehicle will only marginally increase.

However, in this situation, a set of ventilated front disks will probably only get 'warm', during such a test, i.e. pass easilly.

The same thing works in reverse too, if you have a 50hp, 2000kg boat engine in the gem, then even with monster brakes, you are still likely to fail a brake performance test due to the mass. Even though the amount of engine hp is less than the stanard gem engine.

I have seen some old requirements from other states such as NSW, where it simply states the installation of a more power or heavier engine will need a brake upgrade. I am not sure what the actual performance requirements are, but any engineer who is licenced to sign off vehicles will understand the benefit of a ventilated disk.

Ben

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

I'll do the FEA stuff, it will be a good chance to practice some stuff which I "should" have learned while studying. But Im guessing it will take a while to draw the mother fucker.
I had a feeling the caliper would sit a bit close in. When I was playing around with girling calipers, with the same sort of idea, I think I would have had to do the same thing, so instead I just went way oversize anyway.

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

Actually it wont be too hard at all, as the whole thing doesnt need to be done, but trying to simulate everything that happens with it might be a bit lengthy.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

You just need the two holes of the caliper, 10mm diameter, but elongated 4mm one way, the rest of the caliper can be a structure, square or whatever.

It will need a point loading representing the brake torque, at about the centre of the pistons. This loading would have to be calculated by picking a pretty big wheel diameter, and trying to stop the car from say 200km/h as fast as possible, whatever that torque works out to be. I will have to work it out. Probably using a vehicle mass of about 1100kg, as this would represent a v8, etc.

I dont get our FEA software at work for another month or so, and then I have to learn how to use it. So it will take me a while.

Ben

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

What are they gonna use?
We use strand 7...

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

I dont know what we will get as yet, its my job to decide. I have downloaded a demo of Strand7, I dont know how to use it so its a bit hard to put it through its paces.

I have a guy coming to demo solidworks next week.

I haven't used FEA since Uni, and even then, it was only for a few weeks on simple analysis, it was an early strand version.

TXcoupe · petrol head Joined: 05 Oct 2001 Posts: 1675

ben let me decide on what u want and if you would some one to trail them im more than happy to test them in real time on my racecar