Advanced Driving Hub

Been there, done that. Came back to my Xantia, which I had parked in a sloping car park at a Wealden beauty spot, to find it was not quite where I had left it. There was a note under the wiper and stones chocked in front of the front wheels. I concluded that the discs had contracted as they cooled and the pad's grip had diminished to allow the car to start moving. I was lucky that there were some public spirited individuals about who prevented a complete runaway.

The usual problem with a handbrake left on for too long is the pads and discs rusting or binding together. It can take quite a lot of power to force them off. My MGB GT managed to drag one rear wheel along the ground for some feet once before the brake freed off. Leave the handbrake off, leave it in gear, and use a chock if you're still paranoid (this applies on your private land, to be clear).

Mr Cholmondeley-Warner wrote:The usual problem with a handbrake left on for too long is the pads and discs rusting or binding together. It can take quite a lot of power to force them off. My MGB GT managed to drag one rear wheel along the ground for some feet once before the brake freed off. Leave the handbrake off, leave it in gear, and use a chock if you're still paranoid (this applies on your private land, to be clear).

Rear disc conversion? I thought they were drums, which will, when left for long periods, tend to seize on, as too with handbrake drums integrated into rear discbrakes.

Jonquirk wrote:Been there, done that. Came back to my Xantia, which I had parked in a sloping car park at a Wealden beauty spot, to find it was not quite where I had left it. There was a note under the wiper and stones chocked in front of the front wheels. I concluded that the discs had contracted as they cooled and the pad's grip had diminished to allow the car to start moving. I was lucky that there were some public spirited individuals about who prevented a complete runaway.

Tut tut, didn't do a cooling down lap?

WhoseGeneration wrote:

Jonquirk wrote:Been there, done that. Came back to my Xantia, which I had parked in a sloping car park at a Wealden beauty spot, to find it was not quite where I had left it. There was a note under the wiper and stones chocked in front of the front wheels. I concluded that the discs had contracted as they cooled and the pad's grip had diminished to allow the car to start moving. I was lucky that there were some public spirited individuals about who prevented a complete runaway.

Tut tut, didn't do a cooling down lap?

With three more choruses of "are we there yet" from the back row. Not likely.

WhoseGeneration wrote:

Mr Cholmondeley-Warner wrote:The usual problem with a handbrake left on for too long is the pads and discs rusting or binding together. It can take quite a lot of power to force them off. My MGB GT managed to drag one rear wheel along the ground for some feet once before the brake freed off. Leave the handbrake off, leave it in gear, and use a chock if you're still paranoid (this applies on your private land, to be clear).

Rear disc conversion? I thought they were drums, which will, when left for long periods, tend to seize on, as too with handbrake drums integrated into rear discbrakes.

No, just drums in this case. Bloody good drums they were too. Not unusual to lock the rear wheels with them. Crappy old tyres, of course

Mr Cholmondeley-Warner wrote:No, just drums in this case. Bloody good drums they were too. Not unusual to lock the rear wheels with them. Crappy old tyres, of course

Interesting fact that for a given size drum brakes are actually more powerful than discs, especially with leading shoes. However discs have better modulation, reliability, repeatability and less likely to be influence by external factors etc and hence favoured over drums

IcedKiwi wrote:

Mr Cholmondeley-Warner wrote:No, just drums in this case. Bloody good drums they were too. Not unusual to lock the rear wheels with them. Crappy old tyres, of course

Interesting fact that for a given size drum brakes are actually more powerful than discs, especially with leading shoes. However discs have better modulation, reliability, repeatability and less likely to be influence by external factors etc and hence favoured over drums

ISTR when I was autotesting, drums were preferred at the back as they worked better for handbrake turns

IcedKiwi wrote:

Mr Cholmondeley-Warner wrote:No, just drums in this case. Bloody good drums they were too. Not unusual to lock the rear wheels with them. Crappy old tyres, of course

Interesting fact that for a given size drum brakes are actually more powerful than discs, especially with leading shoes. However discs have better modulation, reliability, repeatability and less likely to be influence by external factors etc and hence favoured over drums

Is that so?

I've always been told that disc brakes are more powerful than drum brakes, and that's why they're preferred?

TheInsanity1234 wrote:

IcedKiwi wrote:

Mr Cholmondeley-Warner wrote:No, just drums in this case. Bloody good drums they were too. Not unusual to lock the rear wheels with them. Crappy old tyres, of course

Interesting fact that for a given size drum brakes are actually more powerful than discs, especially with leading shoes. However discs have better modulation, reliability, repeatability and less likely to be influence by external factors etc and hence favoured over drums

Is that so?

I've always been told that disc brakes are more powerful than drum brakes, and that's why they're preferred?

AIUI, a drum has a larger contact area, and therefor more friction is produced which should result in more power. But this results in more heat being produced, which has an adverse effect on braking, therefor, drums are less efficient except as hand brakes.

Nigel.