A friend has reently purchased a first car for her daughter. The car came with a new MOT, yet the handbrake is only effective if yanked to the very limit of it's travel. It was identified as a problem to the dealer before purchase but their response is that it has an MOT so it must be ok.
Can anyone advise me of the standard applied by testers for handbrake efficiency?
Ta!
ND
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ND,
From what I remember, the parking brake efficiency is tested with the same roller tester as the 'service brake' (i.e. footbrake!) efficiency. A figure of >18% springs to mind (% of what, I'm not sure...).
In addition, the lever must not be near the end of its travel, and must not 'fly off' when given a thump from either direction.
As the owner of a venerable Citroen CX, this part of the MoT always causes consternation :-)
BTW, why is it still called an 'MoT' test, when the Ministry of Transport became the 'Vehicle Inspectorate' yonks ago?????!!
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ND
LHM is right. The handbrake must meet a minimum standard of 0.25g (I believe) retardation, and be equally balanced between the two wheels. Handbrake adjustment must also be correct, and the ratchet must be effective.
Regards
John S
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Thanks for this folks. I'm of the opinion that the lever is too close to the limit of it's travel at the point that the brake becomes effective.
As it's an Uno (known for rear adjuster problems) I think it's going to be back to the garage for a replacement cable. On them.
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ND
Before you change the cable, be sure the rear brakes have decent linings, and that they are properly adjusted (eg are the auto adjusters working correctly).
Then make sure you use the corrrect adjustment procedure for the handbrake. The last thing you want is to try to correct for faulty brakes with the handbrake, and perhaps end up with rubbing shoes and overheating brakes.
Regards
John S
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ND,
I was so close to asking "is it a Uno?" earlier. These are usually a stress at MOT time with regard to the rear brake/handbrake effort.
The auto adjuster device is rubbish.
Some reckon that reversing at speed then applying handbrake and footbrake hard together will get the shoes closest to the drums.
With the car you mention getting some useful effort near to the limit of handbrake lever travel then possibly cable replacement or adjustment could well help in this case.
MM
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Some reckon that reversing at speed then applying handbrake and footbrake hard together will get the shoes closest to the drums.
The mother of the 17 year old driver of this Uno is now undergoing cardiac massage having read that! She can just picture her daughter trying that one.
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...so to park on a hill the procedure is reverse flat out and lunge into the space all 4 wheels locked up and the handbrake on. Interesting!
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Just in case there was any doubt...
The method I described was from one of our MOT testers as a way of getting the Fiat auto-adjusters up as tight as possible on a marginal fail.
Of course he would never do it on the road...just in the confines of the workshop you understand.
;-)
MM
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MM,
So assuming it is the adjusters (and it probably is), what's the best answer? Passing the MOT isn't the concern (although I like the method you suggest) but having a safe car is.
ND
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OK seriously ND these Uno rear brakes can be a pain. It is possible to fit new rear drums, shoes, wheel cylinders and handbrake cables to find the rear brakes are still only just good enough.
In your case it does sound like the handbrake may be better if it is adjusted to give some bite at mid-position rather than near the travel limit.
Otherwise it is a case of getting the rear drums off and seeing which of the parts I've mentioned above are the most likely cause.
In a light car such as this the rear brakes are not designed to do much work so as long as it stops well from speed and will hold for a hill start then leave well alone.
MM
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Sadly it is failing to hold on a hill unless pulled on with both hands. Which means doing a hill start with both hands on the handbrake to release it.
Some head scratching and dismantling to be done.
Ta MM
ND
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ND, I've never had the pleasure(?) of owning, driving or working on a Uno. However, the old Triumph 2000 MkII had self-adjusting brakes with a reputation for handbrake problems similar to those that you have described and the popular cures have included a redesign & remanufacture of the backplates and levers by enthusiast owners. However, on my unmodified Triumph, a one-finger pull on the lever is enough to lock the back wheels.
In fact, the inefficiency problem with the Triumph handbrake is commonly due to sticky brake cylinder piston seals. The pistons don't quite return to the stops when the footbrake is released and this means that the handbrake mechanism is starting from the wrong point, i.e. handbrake efficiency relies very much on the brake shoes being fully retracted at the start.
I haven't explained this very well but I hope you can see what I'm getting at. The Uno system may be totally different but it might be worth checking that the shoes are fully retracting when the footbrake is released. On the Triumphs, the piston seals start to deteriorate after only 2 or 3 years and this causes the stickiness.
I think John S is right, that the MoT minimum for handbrake retardation is a lowly 0.25G (as in 'gravity'). I've an idea this hasn't changed since the MoT was introduced in October 1960 and so it ought to be easy to meet! In those days it was checked with a Tapley meter which was placed on the floor of the car and had a dial which showed the maximum retardation. For the footbrake, I think the figure was 0.5G ?
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Thanks for that Dizzy. I shall suggest they have a look and see how the adjusters work and play with the piston return if appropriate.
Ta!
ND
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