Handbrake Issue

Horizon81

Coming back to this discussion of 'drum in disc' brakes, is there any link at all between the 2 braking systems? The footbrake operates the pads on the disc and the handbrake operates the drum in the disc, so are these 2 systems totally independent of each other?

bigjl

EdGasket wrote: »

The two systems are linked because they both move the brake shoes.

If it is as the OP suggest a drum in disc setup them the two systems are seperate.

The reason the car is movin is simply because the OP has taken their foot off the brake.

I had an Omega a few years ago and it would do the same thing if you left it in neutral, it would move a slightly before the handbrake "bit"

I never had it long enough to see if it would have passed the MOT as I bought it to tow a trailer.

bigjl

Horizon81 wrote: »

Coming back to this discussion of 'drum in disc' brakes, is there any link at all between the 2 braking systems? The footbrake operates the pads on the disc and the handbrake operates the drum in the disc, so are these 2 systems totally independent of each other?

Yes, completely independant.

Which is why you often see vehicles such as a Grand Cherokee with handbrake shoes in pieces but the brakes are perfect.

Drum in disc hand takes are one of the most neglected systems imho.

Sometimes meaning that they can seize up or the shoes themselves can break up locking a wheel.

People ignore what doesn't affect them day to day.

facade

Yes they are fully independent with that type of system.

The parking brake has to be mechanically applied, but can use the same pads as the hydraulic or air brakes, so some rear disc systems have an extra mechanism inside to push the pads out and hold them, whilst others have a small mechanical calliper as well as the hydraulic one.

The type in this post has a pair of shoes inside the hollow part of the disc that operate via a cable, whilst the hydraulic brake works a calliper.

Landrovers and Rangerovers for donkeys years used a mechanical drum brake on the rear propshaft, that worked perfectly well until it was replaced by eye wateringly expensive motors in the callipers to do the same job more expensively and less reliably.

AdrianC

Horizon81 wrote: »

Coming back to this discussion of 'drum in disc' brakes, is there any link at all between the 2 braking systems? The footbrake operates the pads on the disc and the handbrake operates the drum in the disc, so are these 2 systems totally independent of each other?

Yes, totally independent. Different friction material, completely different portion of the disk.

Only vehicle I've had with that setup was a Shogun.


Disk with footbrake caliper.


...and what's inside the disk.

Also, some clamping-the-disk handbrakes use separate pads to the main footbrake pads, although this isn't particularly common.

bigjl

facade wrote: »

Wheelbearing gone?
Disc calliper seized?

Something might be allowing the drum to move when you release the footbrake and stop clamping the disc.

I've only ever had one car with this set-up, a Vectra-B
IIRR, that used to roll back on hills if I did as you say, and needed an extra tug to stop it.
I could solve it with a superhuman snatch at the brake lever (but then I couldn't get the thing off again without an injury) but I generally just pulled the handbrake on and stuck it in P and let the transmission take up the slack. (Vauxhalls had a habit of the handbrake flying off anyway)

I was told that it could be an adjustment/balance issue, but I could never see how.

I half wondered if it was the rust in the drum holding the shoes off*, and grinding down as it starts to roll back, so I started giving the handbrake a few tugs when going along slowly to try and clean it, but I can't remember if it worked.


*(the drum brake doesn't do anything, and is never normally applied when moving, so there is nothing to scrape rust off the drum.)

If I remember correctly part of the service regime for some drum in disc systems was to actually drive a short distance with the handbrake applied slightly for just the reason you mention, to clean up the friction surfaces.

Can't remember where I read that though, I think it was when I had one of my Omegas.

AdrianC

bigjl wrote: »

If I remember correctly part of the service regime for some drum in disc systems was to actually drive a short distance with the handbrake applied slightly for just the reason you mention, to clean up the friction surfaces.

If it isn't part of the schedule, it's common sense.

gilbert_and_sullivan

Yes a sometimes neglected system but in my humble the best there is, fortunately its this system on all of ours cars and none of them present any problems.

Brake shoes only operate as parking brake shoes, nothing else, leaving the rear calipers to be nice simple sliding or fixed twin piston jobbies normally.

If you wanted to criticise the system at all it would be that the parking brake doesn't really lend itself to handbrake turns due to the shoes having quite a small surface area, but the benefits outweigh, these system don't need much maintenance, dismantle as often as you would to inspect clean and lube any normal rear drum brake.

Horizon81

I thought they were separate systems but there does seem to be some conflict with them.

If I just apply the handbrake when stationery it pulls up and grips fine. However sometimes - only when I've got my foot firmly on the footbrake - when I pull the handbrake up, it bites so far then loses a bit of tension - it's almost as if it's snapped but then you pull it more and it tensions up again. It only seems to do this when I've got the footbrake on, so I can't fathom out what's going on!!!

BeenThroughItAll

What car is it? The car doesn't have a hill-start assist does it? If it did, it might mean there's some clever additional mechanism at play.