Calipers size

[AcyTom]

Hello!

I have on my bug 1303 disc all around. In front standard bug calipers (40 mm) disc 278 mm.
On rear I have golf 3 calipers (38 mm) disc cc. 220 mm. The bug brake OK but with big weight I must bush pedal a lot.
I thin that I do not get from rear all power because the front is blocked to fast. So I would like to put some better break in front. My idea is to put disc from corado G60, ventilated disc 280 mm. And calipers from polo or something size 48 mm.
Will be 48 mm calipers to much for front of my bug? My tires are 185/65/15.
Or it is better to put some 42 mm calipers?

Thanks a lot!

Tomica

[lazylongboarder]

[/QUOTE]
Will be 48 mm calipers to much for front of my bug?[/QUOTE]




.....No.

[volkdent]

Tough question. You may want to talk to Lanner at Vdubcustoms for info on brake stuff. Ricola might have some insight for you too.

Jason

[flat]

Changing from bug disks to the 280mm Corrado disks will not gain much. The brake torque is the mean pad radius (front center of rotation to the radial center of the pad) multiplied by the clamping force. So if you change from a 278 (stock bug) to a 280 rotor, we can assume that the pad radius will basically be the same, and assuming the same piston size on the caliper (means same clamping force), you don't gain much if anything in brake torque. Thicker ventilated disks provide more thermal mass and better cooling, hence less fade. If you use the 48mm calipers then your will increase the front torque significantly.

By increasing your front piston size, you will increase the clamping force. The campling force is the piston area multiplied by the line pressure. So if you assume the same line pressure (a function of master cylinder piston size and pedal force), then larger pistons will give more clamping force.

So, to increase your front to rear braking balance you have to either increase the rear brake torque, or decrease front torque.

To increase torque you can increase: rotor diameter, piston diameter, stickier pads. Vice-versa to decrease torque. Increasing your front rotor size and piston diameter will not help your cause.

Lanner

[AcyTom]

Hello!

I do not understand you mr. Lanner.

Increasing your front rotor size and piston diameter will not help your cause.

The rotor size will be the same this is OK. But if I change piston diameter of front calipers to 48 mm I will increase break power on front! ON your site you put much bigger calipers 54 mm.
So NOW my rear is 38 mm and front 40 mm. I think that I don't get everything from rear breaks. Because master cylinder first start to fulfill front calipers and then rear. So my front calipers are almost blocked and rear are not tightened as they should be! Increase of front I get better balance of front and rear!
Any I'm afraid of too soon blocking of front on panic braking!

What you think?

Tomica

[flat]

Let me step back a little. Your problem is that you have too much front brake and not enough rear, right? So you see how increasing the front caliper size will only increase the front bias.

The circuits in a dual master cylinder act in parallel, not series. They are both working together, at the same time. If you have a master cylinder issue, you can try a large master. Something like a 20.6mm.

In general, you want the front to lock up slightly before the rears, it's easier to control a car the understeers versus a tail-happy beast.

Lanner