17 replies to this topic

[Rorf]

I have seen cases where the rear limiting valve ball bearing has been removed.

[Davebullock]

Hi everyone,

Thanks for all your replies.

The MOT man said that the DVLA online braking calculator (as he filled in the form) has to come back with a figure of 50% or better.

50% of what ... ...how do they calculate this 50% minimum?

Someone has told me that attempting to tighten rear wheel nuts against the footbrake you can still turn the wheels. 

So as Moke Spider commented earlier with 12" wheels (extra leverage) (and 3 Wheetabix) one may be able to rotate the wheels without a wheelnut spanner.

I don't want to start doing any mods that make the car dangerous as it stops pretty well at the moment!

Sigh....:-(

[carbon]

Is the 50% not for the total service brake? This is front and rear brake effort combined, you should check what figures you're getting for the front brakes.

 

Pretty sure 50% is the total retardation force divided by the vehicle test weight. So if you get 150kg on each front wheel and 50kg on each back wheel this is 400kg, and for a vehicle of 800kg test weight this would equal 50% brake efficiency.

 

Link to MOT brake efficiency table: http://www.motuk.com...manual/3-10.asp

 

Did it pass OK on the handbrake? In my experience you can't get much over 80kg at each rear before they lock up on the test rollers.