Defender handbrake and mot test

[ianl1]

Today i watched my mot being done.

Being 4wd and only having one set of rollers they tested the brakes with a decelerometer (?) basically drove, braked, read the value off the gizmo

They then tested the handbrake in the same way. Now i was under the impression that being a transmision brake you were not ever meant to pull the handbrake when in motion at any speed. Luckily (?) my handbrake actually has no effect at all. I queried this procedure as potentially damaging, but they claim they are instructed to test 4x4 handbrakes by aplying them at 10mph.

Is this right? Is this bad? Will it damage it?

More importantly, once i fit my disc handbake conversion and take it for a retest will it rip the conversion off? will it trash the prop / gearbox/ transferbox/ etc? Or will it fire the tester through the windscreen?

[Tanuki]

Yes if they don't have a 4-wheel brake-roller, a decellerometer road-test is SOP for the MOT.

http://www.motuk.co.uk/manual_370.htm

(The alternative being a "gradient test"). You only need to score 16% efficiency.

They shouldn't do it at more than about 10MPH. The transmission-brake on my D90 is horribly snatchy and makes a bowel-loosening machine-gun-style rattle if applied while the vehicle is in motion. I like to think that this noise makes the MOT-tester think it's about to explode and so he passes it in order that he can run away!

[Eightpot]

They're obviously not meant to be used on the move, and I'd be mighty peed off if my MOT tester did that - if applied lightly it shouldn't do any harm, but what would be the point of applying it lightly?

My local tester had no idea how Land Rover handbrakes work and initially failed mine as the car was able to rock back and forth while the brake was applied - I had to explain to him how a transmission brake worked.

Don't assume your guy is any the wiser.

[Simon Smith]

Testing the wheel brakes on a single axle rig is perfectly fine as the speed is very low, however all the garages I've used have tested the handbrake by just trying to push the vehicle with it on. As far as I know it should never be applied while the vehicle is moving, no matter how slowly, it is a parking brake only.

[pat_pending]

No not just a parking brake. The law requires a scondary brake system that can be applied on the move in the event of failure of the primary system. Vehicles must reach a secondary brake efficiency of 16% for duel circuit systems because the brake must be capable of slowing the vehicle in the event of the primary system failing.

So yes, the transmission brake can be applied on the move, the law says it has to be able to.

With regard to testing, there's a specific method for testing in both rollers and decelerometer, the test ceases as soon as the minimum efficiency is reached.

As an MOT tester and Land Rover owner I offer this advice, go to a garage that's familiar with Land Rovers.

The test done properly will not cause damage unless there's already a problem but testers not familiar with transmission brakes can be unsympathetic.

[dirtydiesel]

I find the slope outside my testing bay the best way to check a transmission brake.

I often use the brake rollers as well to get a feel for how it is engaging and releasing.

[CwazyWabbit]

My local MOT station uses a single roller system that rotates the left and right wheels in opposite directions. This should prevent harm to the centre diff as it isn't moving the props at all. Obviously this only works for the main brakes and not the handbrake!

[mmgemini]

The way I understand the Defender brakes are.

Front brakes primary system

Rear brakes secondary system

Hand brake a park brake.

[pat_pending]

Duel circuit brake systems consist of two hydraulic circuits, they can be split front to rear, diagonal or like classic Range Rovers and Disco 1s, the rears and part of the fronts and then the remainder of the fronts. These are called the primary and secondary circuits.

However they are split and whatever they are called they are still part of the foot brake and remain the primary brake system and the hand brake is the secondary.

On older vehicles with single circuit foot brakes the hand brake must reach a higher level of efficiency, 25% as opposed to 16%.

This is because duel circuit brakes already have a built in safety factor.

Hope that makes sense.

[mmgemini]

Duel circuit brake systems consist of two hydraulic circuits, they can be split front to rear, diagonal or like classic Range Rovers and Disco 1s, the rears and part of the fronts and then the remainder of the fronts. These are called the primary and secondary circuits.

However they are split and whatever they are called they are still part of the foot brake and remain the primary brake system and the hand brake is the secondary.

On older vehicles with single circuit foot brakes the hand brake must reach a higher level of efficiency, 25% as opposed to 16%.

This is because duel circuit brakes already have a built in safety factor.

Hope that makes sense.

I don't agree......Although the system is a complete failure. Have you ever lost ALL the brakes on a Defender as I have.....If Land Rover call them primary and secondary circuits. Then that's what they are.

LOL

.

[Tanuki]

The way I understand the Defender brakes are.

Front brakes primary system

Rear brakes secondary system

Hand brake a park brake.

I'd disagree entirely: though a dual-circuit system the footbrake - having only a single device [the pedal] by which either or both circuits are applied - is the primary braking system.

The handbrake - operating independently of the hydraulics - is the secondary braking system..

I'm thinking back to my old Escort rally-car days where a "hydraulic handbrake" [operating on the rear wheels] was a popular fitment but would fail a MoT unless you were really close drinking-buddies with the tester concerned.

A "Park brake" is not recognised in any of the C&U/Type-approval documents I can find. OK, some automatic gearboxes have a "park" position on the lever which engages a pawl into a ratchet in the gearbox - but that definitely won't count as a secondary-brake because it won't engage if you try and activate it at speed.

[cluffy]

Last MOT I took my 90 tp the tester ripped the hand brale on at about 25 mph and twisted the propshaft so managed to get new props fitted and I had a rather red face! In my opinion a gradient test is more than adequate and when I did mots thats what I done as you would expect the truck to be treated as it were yourn own in a garage.

When it is used as a secondary system it is for emergencies when it could cause damge to components but will still stop you. I think the test is down to common sense of the tester really.

Just putting my input in

[mmgemini]

Remember the Ford Works Rally team not knowing that a handbrake had to be mechanical ???

I only used a bias pedal box on my rally cars.....NOT Ford though

[tecam]

Long time ago this post - but (long time ago as well) when I was in REME as an army mechanic it was quite common for squaddies to snap halfshafts by applying the handbrake before the Land Rover had stopped. It was a chargeable offence of neglect, misuse & damage for anyone doing it..........it was stressed it was to be used only as a parking brake.