Advice needed

[cris654321]

Hi All

Just bought a front brake upgrade for my mk1 mr2. The kit looks great. The discs however seem extremely heavy. They feel twice as heavy as the standard ones I took off and only 30mm bigger diameter.

Also there are about 7 stud holes init. I thought I was getting a bespoke mr2 kit but it looks like the discs will fit a wide variety of stuff and may have been designed for a much heavier car.

On top of this two of the stud holes are only about 2mm apart it doesn't look right especially for a supposed professional upgrade.

Is their anyway discs the same size could be lighter or is it just due to the size increase?

Will heavier discs improve or reduce the breaking effectiveness?

Should I complain?

[stevieturbo]

cris654321 said:

Hi All

Just bought a front brake upgrade for my mk1 mr2. The kit looks great. The discs however seem extremely heavy. They feel twice as heavy as the standard ones I took off and only 30mm bigger diameter.

Also there are about 7 stud holes init. I thought I was getting a bespoke mr2 kit but it looks like the discs will fit a wide variety of stuff and may have been designed for a much heavier car.

On top of this two of the stud holes are only about 2mm apart it doesn't look right especially for a supposed professional upgrade.

Is their anyway discs the same size could be lighter or is it just due to the size increase?

Will heavier discs improve or reduce the breaking effectiveness?

Should I complain?

The discs are probably from another car, no big deal. Whether there is any cause for complaint depends how crappy they look, and how much you paid....and of course what you expected to get in the first place.

And without knowing or seeing how the discs are constructed....no way to say if they could be lighter or not. Obviously as discs get bigger there will be more material so they will get heavier.

Unless you're going to pay for 2 piece alloy bells/discs, or try and lighten the discs yourself...not a lot you can do.

[paintman]

Don't suppose the ones you've taken off are vented & the new ones are solid?
Be an idea to speak with the supplier & see if you've been sent the right kit.

[phumy]

The extra holes that you speak of could be for securing screws, on other vehicles or even you own.

[Mr2Mike]

paintman said:

Don't suppose the ones you've taken off are vented & the new ones are solid?
Be an idea to speak with the supplier & see if you've been sent the right kit.

Solid discs are invariably lighter than vented ones of the same diameter IME.

phumy said:

The extra holes that you speak of could be for securing screws, on other vehicles or even you own.

Sounds very much like the discs have been re-drilled to suit a different number of studs or PCD, which is a fairly common way of fitting bigger brakes to a car. Having another hole close to one that is being used won't be a problem since the disc is clamped between the wheel and the hub.

Heavier discs will have a greater heat capacity (i.e. will require more energy to get to a given temperature) which is a good thing, but it also increases unsprung weight which is generally not desirable.

[cris654321]

The old ones and the new ones are both vented.

Thanks for the advice. By the sounds of it theres naff all wrong with them then. See the picture of discs below anyway.

[Mr2Mike]

They look fine. More weight is an unfortunate but inevitable side effect if fitting larger conventional discs.

As someone mentioned earlier, you can fit AP style competition brakes where the hub is a separate aluminium part to save weight. Expensive though, and they are still fairly heavy.

[SlimJim16v]

It looks like they've found discs of the correct dimensions, but had to drill new holes for the studs/bolts. It makes for a cheaper conversion.
The weight is something that comes with larger discs and helps with the heat, although will increase your unsprung weight which can't be helped.