Rear Calipers under powered MOT fail help!

[darylfto]

Hi there, I need to pick your brains about a problem i'm having with my Mitsibushi FTO GPX Mivec (Manual Gearbox).

The Problem
Its failed its MOT because the rear brakes are not good enough on the footbrake or handbrake and excess travel in the handbrake. The MOT guy said both rear calipers were both under half the power that they should be on the footbrake. I don't know if this helps but he also mentioned that the front brakes were so good that it almost past the footbrake test anyway as it works on an overall percentage.

The car has disc brakes on the back. The pads look almost new, the disks look ok, I had put a different caliper on one side for the MOT and didn't see anything wrong with it when I put it on and i've had the otherside off and it seems fine too.

For the handbrake travel I tried adjusting the tension by setting it to where it was just slightly dragging on the rear brakes and then slackened it until it was just turning free. But the handbrake was still coming up way too high.

I would normally have suspected the calipers but its a bit of a coincedence when its happening to both sides and one has just been put on? So i'm a bit stumped, any idea what I can look at next?

[goz_83]

Air in the system when caliper was changed? If the foot brake feels a bit spongey, that's probably it, but one of the other guys may have a better answer.

[darylfto]

No I bled the brakes after doing the caliper, plus that would not effect both sides.

If it was a commercial van you would suspect the load balancing valve that alters the breaking bias front to back depending on how much weight was in the back. I don't suppose there is anything like that on an FTO?

[holio]

As far as i know the rear brakes work on a drum/disc aspect. Iv not gotten round to doing this on my fto yet but its needs to be done as the handbrake is horrendous.
The brake pedal works the calipers on the rear but the handbrake works the drum brake inside the disc.
The drum brakes are commonly forgotten/neglected so your pads might need replacing. (not caliper pads)
When you took off the rear discs what did you see?
Im not sure if the fto has disc and drum brakes on the rear but if it does it is more then likely why your car is failing.

[CJ]

As far as i know the rear brakes work on a drum/disc aspect....
...The drum brakes ....
...Im not sure if the fto has disc and drum brakes ....

@Holio, your comments are misleading, the FTO has rear disks on all models.

@darylfto,old / boiled hygroscopic fluid may be a cause although your fronts appear fine so perhaps not. As per goz, there may still be air in the lines, a full bleed @ all calipers should be taken in sequence to rule this out. Because its both slides, its unlikely to be an issue with both right and left handbrake cables but not beyond the realms of possibility.

[darylfto]

The MOT guy said that the Fronts were way better than they needed to be, which made me think it was some brake bias valve that was not working, you know putting more power to the front than the back, thus making the fronts overpowered and the rears underpowered.

But it looks like the FTO does not have anything like that or you guys would have said something.

I will try replacing the fluid using a speed bleeder and see if that sorts it. Whats the bleeding order on the FTO?

[CJ]

Whats the bleeding order on the FTO?

Info here:

http://fto-ireland.com/forum/phpBB2/vie ... php?p=6089

Play around with the tension on the cable as well, the handbrake on the FTO comes up quite a bit in comparison to other / newer cars but it shouldn't be anywhere near vertical.

[darylfto]

Surely all cars have a proportioning valve though? perhaps thats had it? What do you think?

[darylfto]

Checked Camskill and it does have a Proportioning valve:

http://www.camskill.co.uk/m3b0s8p68674/ ... _FTO_DE3A_

[darylfto]

Brake bleed order:

Near side rear
Offside front
Offside rear
Near side front

[goz_83]

Let us know if that sorts it, or if the valve is replaced.

[steelroe]

Brake proportioning valve is common failure on the FTO. Think this may very well be your problem.