garry.hingley wrote:

Hi,

has anybody fitted a battery isolation switch to a 2.4 Puma. What with all the thefts of Defenders I was thinking of isolating the battery to provide another level of security.
I have also heard that a hydraulic shut off valve can be installed between the clutch master and slave cylinders so the vehicle cannot be driven. Has anybody else heard of this?

Regards
Garry

blackwolf wrote:

You'll need to figure out how to deal with the alarm and BBUS with battery disconnection.

It is entirely legal to fit an hydraulic lock to the clutch, no problems at all with this. The name Mechlock comes to mind (Google with different similar spellings if need be). It is believed to be illegal to fit to the brake lines because of the risk of the vehicle becoming immobilised in a dangerous place, e.g., the middle of a level crossing.

blackwolf wrote:

The hydraulic locks are in effect lockable one way valves, i.e., when unlocked fluid can flow either way, when locked fluid flows one way only.

On the clutch you'd fit the device so that when locked the clutch pedal can be depressed to throw the clutch out, but the clutch will then stay out, so no drive. It doesn't stop someone towing the vehicle away, of course, or simply cutting the hydraulic line between the slave cylinder and the lock and driving without using the clutch.

If fitted to a brake line, the device would allow the brakes to be applied but then they wouldn't release, effectively immobilising the vehicle. Again, releasing the fluid would release the brakes, but the vehicle would essentially become undrivable with no brakes. It could still be towed away.

In either scenario the real defence is that the villains would probably not know of the device before finding out that the vehicle was not drivable, and would therefore not have come prepared to tow or disable the device.

The legality of fitting a device to the brake line is interesting, since I have never been able to establish why everyone thinks it is illegal and have never found any specific legislation making it so. I think that the case may actually be that a device so fitted would be unable to gain type approval, and therefore no manufacturer sanctions this. (If anyone knows specifically what legislation if any actually makes it illegal, please say). The 'dangers' are pretty apparent, namely that the vehicle becomes immobilised in lane 3 of a busy motorway, half-way across a level-crossing in front of a train, etc. Realistically this is very unlikely, since if the vehicle is stolen it will probably end up being abandoned immobilied at the first junction or hill, i.e., in a predictable place. I would have no hesitation personally in fitting a device to a brake line.

Back in the 1980s my father had a Granada which was fitted with a lock on the brake line by the supplying main dealer, with no issues. This device impressed me so much that when I rebuilt my S1 86" in the 90s, I fitted a lock on the brake circuit since it is really the only effective security on a ragtop. It is actually very useful in other ways, for example you can apply all four wheel brakes and get out of the vehicle when winching.