[john]

Re: MOT handbrake test

Originally posted by dave_H:
[qb]Compared with some posts this is a bit low level, however.......
[/qb][/b]

Dave_H - it is not a problem at all - all questions are valuable as we can all learn from the answers given. I'm sure you'll have a few responses very soon

 

[murphwiz]

Originally posted by dave_H:
[qb]In real life the handbrake is in effect, a parking brake, so why is it necessary  to test  the handbrake in way that would only be used in the unlikely event that the entire multi circuit hydraulic braking system had failed? [/qb][/b]

Because if your hydraulic brake should fail.....

 

[mark e]

Indeed, the handbrake is often referred to as the "emergency brake"...

 

[dave_H]

Thanks for your responses, but... .. when I owned a 99LEA some time back the handbrake was classified as a parking brake only as it operated on a separate set of small break shoes on the rear axle. So it would appear that Saab now consider the multi circuit system requires that other last option.

 

[murphwiz]

You will find most cars now use a set of shoes that operate on the inner 'drum' surface of the rear disc...

edit>
The minimum std for the 'hand'brake is 16% of total braking force, and 25% on single hydraulic circuit systems.

 

[SteveN]

When I MOT'd the 900 2 years back the tester commented the handbrake wouldn't hold the car but "they rarely do on front wheel handbrake cars". He passed it & I went home to adjust my rear wheel fitted handbrake

 

[wrighar]

When I MOT'd the 900 2 years back the tester commented the handbrake wouldn't hold the car but "they rarely do on front wheel handbrake cars". He passed it & I went home to adjust my rear wheel fitted handbrake  [/b]

Strange, because 2 years ago my '84 turbo failed with a 0% handbrake reading amoung other things.

I fixed the other bits and it passed with flying colours. No adjustment to the handbrake at all.

Me thinks he tested the rears....

Andrew

 

[9000CS23T]

The handbrake technically doesn't need to be able to stop the car, but as Leon says must have a braking force minimum of 16% of the vehicle weight. This isn't a great deal, but obviously better than nothing if your brakes fail. 16% will do little more than hold the vehicle on an incline most of the time.

 

[ms08]

must have a braking force minimum of 16% of the vehicle weight[/b]

Yeah - presumably much more than that and you give it a hard tug then you see the back end passing you by as you pirouette down the road.

 

[Toby Mack]

Yeah - presumably much more than that and you give it a hard tug then you see the back end passing you by as you pirouette down the road.  [/b]

I know that was tongue in cheek but I did a bit of handbrake turn practice on an icy carpark early this year.
I was suprised how stable the saab is with the rear wheels locked. About the only way to induce a spin was to get the car turning before applying the handbrake. Otherwise it just dragged the rear around after the front. I did find that after a bit of practice I could do donuts indefinitely just by applying the handbrake, getting it on opposite lock and controlling everything on the throttle. Lots of fun