Lack of effort on rear brakes

[Damian6313]

I have a problem with the rear brakes on my Astra Sport hatch. When the car has no weight in the back end, the rear brakes don't appear to make any difference when slowing down.

The car hasn't been used for a few weeks as it has had a few minor problems elsewhere on it, as a result all the brake discs have surface rust on them. Yesterday I used the car pick some concrete slabs up for a friend. Whilst slowing down to cross a roundabout, it felt like my rear discs were missing as there was no braking effort at the rear end.

Today, with the front and rear of the car raised, I had a look underneath to see if there were any obvious problems. One thing I did find was the spring on the load proportioning valve was really loose. Even with weight in the back (car almost on bump stops!) The valve's spring is still relatively loose. On the valve, there is a securing bolt that secures the hook of the spring to the valve, which looks as if it can be adjusted, but I'm not sure.

The calipers are not seized, as these have been removed and fitted to another car, then refitted to my car. The discs and pads were recently replaced and covered less than 600 miles, so not done mega miles. Can anyone offer any help on this? All advice welcome.

Sorry for the essay

 

[kompo001]

Have the pads removed the surface rust from the disc's? If so, it would prove the rear brakes are at least working, if not working that well. The front brakes do most of the braking anyway, can't remember ever noticing my rear brakes working whilst braking, even in a full blown " where the fcuk did he come from" situation...........
Phil.

 

[Damian6313]

The front discs are spotless on the braking surface. The rear discs have hardly been touched, with the exception of approximately 2cm on the inner edge and centre of the disc surface on both sides. The route I took home was mainly down hill with loads of reasonably sharp turns, so plenty of brake action required.

I understand what you are saying about the front brakes do most of the braking effort. But during heavy braking, the rear end seems to be rather twitchy... It feels like the back end is trying to overtake the front end. Proper brown trouser moment

 

[MarkGSi]

I had this problem on one of the rear discs but i found the pad corroded to the calliper. Once i cleaned it all up the disc very quickly cleaned up. I'd ignore this though if you've had new pads recently. I think youre onto something with the load valve.

 

[Damian6313]

I had this problem on one of the rear discs but i found the pad corroded to the calliper. Once i cleaned it all up the disc very quickly cleaned up. I'd ignore this though if you've had new pads recently. I think youre onto something with the load valve.

Thanks for your reply Mark.

I am going to try new pads in there tomorrow. I am also going to clean the discs up with plenty of brake cleaner and emery paper, see if that makes any difference. If not, then I the only other thing I can thiink of is the load proportioning valve. Looking at it, there is a bolt that looks as though it enables adjustments to be made. Might have to give that a go if the above makes no difference.

When I put the new pads in last time, the calipers were cleaned out thoroughly, then I applied a fair bit of copper slip on the edges and back of the pads.

Thanks again for your reply buddy

 

[MarkGSi]

I put a fair bit of copper grease in too, mine hadn't been touched for years and were pretty manky. Odd that yours is affecting both sides?, must be the valve. I borrowed my dads vectra for a few days and the rears were making an audible scuffing noise under harder braking. After looking at his rear discs, they sound just like yours. I'm trying to get around to taking a look at his at some stage. Pity i wasnt doing it during the week, as i could have let you know if i found anything out there as may help you out.

 

[Damian6313]

I put a fair bit of copper grease in too, mine hadn't been touched for years and were pretty manky. Odd that yours is affecting both sides?, must be the valve. I borrowed my dads vectra for a few days and the rears were making an audible scuffing noise under harder braking. After looking at his rear discs, they sound just like yours. I'm trying to get around to taking a look at his at some stage. Pity i wasnt doing it during the week, as i could have let you know if i found anything out there as may help you out.

Good luck with it mate.

I'll let you know how I get on...... or if all else fails, my car will be a barbeque