MOT Failure - Foot brake 'efficiency'

[owenfackrell]

The oddest thing is the drum in a disc is not unusual, in fact our Qashqai also has them but use a normal hand brake lever to operate them. The difference in the amount of hold that gives is huge. To me the foot lever is where most of the problem lies. I have thought about experimenting with it to see f I can increase the mechanical advantage that it gives.

[Clan]

Originally Posted by owenfackrell

The oddest thing is the drum in a disc is not unusual, in fact our Qashqai also has them but use a normal hand brake lever to operate them. The difference in the amount of hold that gives is huge. To me the foot lever is where most of the problem lies. I have thought about experimenting with it to see f I can increase the mechanical advantage that it gives.

Volvo have used this parking brake virtually unchanged since 1966 with superb results until the XC90 got it, You might be right about the leverage , however a properly working one on the XC90 can lock the rear wheels on the second click ... new shoes need to be heated up and cooled down a few times before they give their best .

[Harley Dave]

In normal use, the parking brake shoes are never going to get hot so why should they need a couple of temperature cycles to operate properly?

Mine "passes" the MoT every year, and I use it every time I park up, but the MoT is done at my local indie, and he knows the issues with the system.

I probably get 6 - 7 clicks when I apply it and I have driven off with it on and not realised - that's how bad it is.

I don't see it as a safety issue as obv the gearbox is left in P; it's just a "feature" of the car.

Cheers

Dave

[spiralarms]

Originally Posted by owenfackrell

The oddest thing is the drum in a disc is not unusual, in fact our Qashqai also has them but use a normal hand brake lever to operate them. The difference in the amount of hold that gives is huge..

What I find odd about the drum brake, is that only one side expands. In my head I don't see how you get more than a small point of contact with the drum, given that it can only pivot about the H bar end.

I've tweaked the in drum adjusters and the one in the console. I've managed to get the foot peddle to 8 clicks (it looks like 11 clicks is the max travel of the foot peddle) and I can't stamp on it any further. I found what I think is a 14% gradient, but the car doesn't hold.

I'm going to pick up some new shoes from the local Volvo dealer tomorrow. If they don't do it, then I guess it will be new rotors too.

Though it seems there are two part numbers for the rear rotors, there's only one for the shoes, presumably they are suitable for both rotor numbers. I'll check with Volvo tomorrow.

The heating up and cooling down tip is a new one on me. Thanks Clan.

[Clan]

Originally Posted by Harley Dave

In normal use, the parking brake shoes are never going to get hot so why should they need a couple of temperature cycles to operate properly?

Mine "passes" the MoT every year, and I use it every time I park up, but the MoT is done at my local indie, and he knows the issues with the system.

I probably get 6 - 7 clicks when I apply it and I have driven off with it on and not realised - that's how bad it is.

I don't see it as a safety issue as obv the gearbox is left in P; it's just a "feature" of the car.

Cheers

Dave

Hi dave , im talking about when new volvo shoes are fitted they need a few hot heating cycles and re adjust to get the best out of them at first .
If you can get 7 clicks the cable needs adjusting , you should aim for a full parking brake 2 or 3 clicks .travel .

[Clan]

Originally Posted by spiralarms

What I find odd about the drum brake, is that only one side expands. In my head I don't see how you get more than a small point of contact with the drum, given that it can only pivot about the H bar end.

I've tweaked the in drum adjusters and the one in the console. I've managed to get the foot peddle to 8 clicks (it looks like 11 clicks is the max travel of the foot peddle) and I can't stamp on it any further. I found what I think is a 14% gradient, but the car doesn't hold.

I'm going to pick up some new shoes from the local Volvo dealer tomorrow. If they don't do it, then I guess it will be new rotors too.

Though it seems there are two part numbers for the rear rotors, there's only one for the shoes, presumably they are suitable for both rotor numbers. I'll check with Volvo tomorrow.

The heating up and cooling down tip is a new one on me. Thanks Clan.

no , both sides expand equally, the expander which the cable attaches to expands both shoes equally .
If you are talking 8 or 11 clicks your cable is WAY out of adjustment . the parking brake should be ON between 2 and 3 clicks and that should be the max travel .

[spiralarms]

Originally Posted by Clan

no , both sides expand equally, the expander which the cable attaches to expands both shoes equally .
If you are talking 8 or 11 clicks your cable is WAY out of adjustment . the parking brake should be ON between 2 and 3 clicks and that should be the max travel .

Sure I understand that both the top and bottom shoes move towards the drum at the side of the expander, I'm talking about the other side of the shoes, where the H bar is normally.

I've tried to doodle my explanation. The blue circle is supposed to represent the drum. The red dots are where the shoes are "fixed" they are a set distance apart, held there by the spring and the H bar. As the expander moves the other side of both shoes out towards the drum, to me it seems the shoes must pivot about the red dots, and so only the shoes only make a
small contact with drum at the yellow areas.

I could see that those yellow areas would increase in size, the closer the red dots are moved outwards towards the drum. Which is presumably the point of the replacing the H bar with the adjustable spacer.

Yes, I note those are not genuine Volvo shoes in there. I now have the proper ones, and tomorrow's job is to install them.

[Clan]

Originally Posted by spiralarms

Sure I understand that both the top and bottom shoes move towards the drum at the side of the expander, I'm talking about the other side of the shoes, where the H bar is normally.

I've tried to doodle my explanation. The blue circle is supposed to represent the drum. The red dots are where the shoes are "fixed" they are a set distance apart, held there by the spring and the H bar. As the expander moves the other side of both shoes out towards the drum, to me it seems the shoes must pivot about the red dots, and so only the shoes only make a
small contact with drum at the yellow areas.

I could see that those yellow areas would increase in size, the closer the red dots are moved outwards towards the drum. Which is presumably the point of the replacing the H bar with the adjustable spacer.

Yes, I note those are not genuine Volvo shoes in there. I now have the proper ones, and tomorrow's job is to install them.

Ahh but the H plate at the red end is fully floating it is not attached to anything . As the green end opens and presses the shoes to the drum the shoes shuffle sideways at the red end to jam themselves perfectly in the drum so the full contact area of the shoes is firmly pressed against the drum .

[amackenzie]

Originally Posted by Clan

If you are talking 8 or 11 clicks your cable is WAY out of adjustment . the parking brake should be ON between 2 and 3 clicks and that should be the max travel .

Mine used to take 10+ clicks to engage properly, so I have tightened the cable, following advice on here, by pulling apart the 2 sections of the mechanism in the image. The first time I did this it improved so it would only take about 5 clicks until it was fully on.

I then decided to tighten it further and now it engages fully between 2-3 clicks. However as in the image I am now concerned that I can see threads on the tightening mechanism - should I be worried about this or is it normal?

[Clan]

Originally Posted by amackenzie

Mine used to take 10+ clicks to engage properly, so I have tightened the cable, following advice on here, by pulling apart the 2 sections of the mechanism in the image. The first time I did this it improved so it would only take about 5 clicks until it was fully on.

I then decided to tighten it further and now it engages fully between 2-3 clicks. However as in the image I am now concerned that I can see threads on the tightening mechanism - should I be worried about this or is it normal?

you should be able to get a click or two extra from that but something is worn , what are the shoes like ?