Defender Handbrake - Better solutions?

Shouldn't think it'd be too difficult to fit a disc in place of the drum and say the rear caliper from a Mk3 granada on a bespoke bracket. Might even be able to adapt the landy cable to fit the granny caliper. my only thought against this idea is the possibility of drag playing havoc with propshaft u/j's, my 110 went through a spate of edible rear propshaft u/j's, finally cured by slackening off the handbrake drum adjuster 1 flat. There was only the slightest of drag as well! Badger.

On or around Tue, 16 Aug 2005 18:48:10 +0100, "Tom Gilmour" enlightened us thusly:

and you reckon that *wouldn't* get crudded up and stop working?

In theory, you could remove the drum and substitute a disc - all you need is a suitable disc to bolt onto the hub which the drum normally sits on - there are various calipers with cable operation, used as handbrakes on cars - citroen BX have 'em on the front wheels - it's a hydraulic caliper but also has a mechincal operation via a cable.

It would seem to me that a disc would be far more likely to be damaged, judging by the stone chips all over the lower half of the backing plate on my hand brake. A disc with the same braking area of the drum will be substantially larger in diameter and hence protrude lower and collect even more flying stones. JD

Wheel chocks :)

Na seriosly my handbrake was not in the best of condition until recently so reverse gear was as good as any solution

In message , Tom Gilmour writes

Believe it or not The drum is the better solution !

Disc brake handbrakes give there own share of problems on ordinary cars after a while, and that is without the conditions that a landrover has to endure.

In article , Marc Draper writes

Quite! Had them on an 89 VW Passat we kept for ages. Nice car in many respects but let down badly by some really poor quality materials/design, including the handbrake. Unless you do something very clever by way of a guard, it would be really vulnerable in that location. Ordinary disks are pretty well protected by the wheels, and don't rotate as fast either.

Don't go there!

Regards,

Simonm.

That, in all honesty, would be my gut feelings as well, however the question was asked so I answered it. Ok, purely from an engineering "can it be done" perspective. I think you could probably get away with a disc slightly smaller than the std drum, due to the torque multiplication of the diffs. After all, look how totally overpowered a std transmission brake is when working efficiently? Still the dirt ingress to deal with though, and possible drag. Badger.

An issue with disc brakes for parking is that if they get hot in normal driving (handbrake left slightly on?) they expand slightly. If the handbrake is applied whilst hot and then the disc contracts it shrinks away from the pad, losing clamping force, drums work the other way.

AJH

Discs do not expand significantly when hot (well, not in the direction of the pads, anyway). Expansion is proportional to the distance involved (normal to the pad/shoe) - with a drum, the distance is the diameter of the drum, but with a disc it is the thickness of the disc. this is one reason why discs are better for service brakes. But your expansion scenario is another reason why the drum may be better as a parking brake - if dragging, as it heats up and expands, the drum moves away from the shoes and will ease the amount of damage, at least slightly. where with the disc there would be no such effect.

As far as Brian's idea goes that you can get away with a smaller diameter disc than drum, I'm afraid that won't wash - the size is not dictated by the leverage, which is what he is talking about, but the swept area - which will have to be larger in diameter for a disc rather than a drum seeing that the inside radius of the swept area is limited by the speedo drive housing size, and the drum mounting flange on the transfer case output flange. Too little swept area will result in the brake being too easily overheated with typical misuse or emergency use, and will also wear too rapidly.

JD

In article , AJH writes

I wouldn't want to use a Landy handbrake whilst driving!

Regards,

Simonm.

On or around Thu, 18 Aug 2005 10:45:56 GMT, SpamTrapSeeSig enlightened us thusly:

very bad idea, it can result in broken things.

however, in a brake-failure-downhill scenario, I'd attempt to stop it with the handbrake, and risk the possiblity that it might not go again.

AIUI, half-shafts can fail.

Or driveshafts. And (not in a Landrover) I have seen the handbrake backing plate torn completely off the rear of the gearbox by applying a cardon shaft handbrake at speed!

That said I have used the handbrake to stop in a series II that suddenly decided that it didn't have brakes any longer - not a nice experience and it made some very interesting noises and shudders. And tore a gearbox mount apart.

Much less likely to have a half shaft fail on a full time four wheel drive than on a Series as the hand brake effectively works on all four wheels. In any case failures will occur when there is a lot of slack in the transmission AND the handbrake is applied abruptly. However, if you are travelling at any speed, are loaded and/or going down hill, the handbrake will be grossly overheated before you stop, and will, at the least, require major repairs. But in the case of brake failure or even the loss of one circuit, the use of (and damage to) the handbrake may well be the lesser evil. JD

On or around Fri, 19 Aug 2005 06:37:01 +1000, JD enlightened us thusly:

exactly. I've had a circuit failure in the disco, and that leaves you with not much braking. Also tried stopping it with no servo, which is pretty difficult. The 109" with it's non-servo drums stops a good deal better...

Thanks for the replies, a few issues i hadn't considered. Looking through Microcat, the handbrake actuating mechanism seems to be improved on the later Defenders (direct cable pull rather than the rod) and does away with the 3 pistons & rollers block unit which is the cause of the problem. might see if i can fit a 2nd hand one of those.

Tom

Opened this months Total Offroad and saw this:

Tom

Is it me, or there is nothing protecting the disk from whatever could happen to it?

Just wondering.

Fred

I thought the same as you Fred. It does look a tad 'exposed'. Having said that, it's smaller size would mean it is more tucked up out of the way behind the transfer box.

Stew

On or around Mon, 19 Sep 2005 12:46:44 +0100, Fred Labrosse enlightened us thusly:

well, apart from being behind the T-box and enclosed by chassis rails...

the existing drum brake protrudes below the T-box so can get hit on the ground, their disc being smaller doesn't.