Hello!

I have never posted a request on an internet forum in my life so let's see if I get any joy with this!

I have an 02 plate Multipla 1.9 jtd with rear disc brakes. The rear wheel bearings needed replacing so I set about doing it; no problems fairly straightforward. However, I noticed that the road wheel could barely be turned by hand and when removing the brake calipers that the pads were stupidly tight against the disc. The handbrake was off and the cables move freely! The sliding 'thingys!' are also free to move. This suggests to me that the mechanical bit of the handbrake inside the brake caliper may have a problem of not releasing properly, there is no reason to suspect that the pads themselves are the issue but it might be worth mentioning that new discs and pads were fitted two weeks ago by somebody else who did not bother to bring the wheel bearing to my attention despite the obvious fact that they do not rotate smoothly. Does anybody know how this system works / should work? Any tests I can do, remedies, repairs etc. The manual I have only shows drum braked versions. Do Fiat use this exact same arrangement on any other vehicles so that I could look in a different manual?
I hope I have filled this in correctly!!!!
You get the picture! Thanks for looking.
Michael

1. Check that whoever fitted the discs and pads wound the caliper pistons back in far enough.

2. The slider pins for the calipers may be worn/notched and not allowing the caliper to 'float' properly (is this what you mean by the 'sliding thingys'?). The easiest way to check this is look at both faces of the discs to see if the wear is even on both sides. As you've got brand new discs, it won't be very evident - have you still got the old discs?

I think BikeDoc on here has a Multi with rear discs. He may be able to give more detailed advice.

Michael Twiss said:

Hello!
... The sliding 'thingys!' are also free to move....

Click to expand...

Do you mean the lever-arms on the Calipers that the cables attach to, or the sliding Caliper pins?
If you unhook the Cable from the arm, the arm should spring back against the stop, and the wheel should spin freely.
If the Caliper is sliding freely on the pins, then you may have a 'sticky' piston.

The return spring for the mechanical mechanism is fairly puny, and coupled with the freezing/seizing cables syndrome, it's a surprise they ever work at all.
One of mine doesn't return properly, and no amount of WD40 or penetrating oil has cured it, I just don't use the handbrake any more, but I'll have to sort it out before the MOT in Oct...

Well thank you very much, this crazy virtual world does work!

The sliding pins on the calipers appear to be fine. Can I wind the pistons back in without getting a specialist tool? I made a tool to engage the piston notches but the pistons do not rotate. I think I need to push and turn at the same time but this has yet to produce a result. I also have noticed that since I posted the query that one of the rubber piston boots has a significant split in it which is not helpful. I rang FIAT but you cannot buy replacement boots. When I was younger car manufacturers would sell you even the smallest component separately! Does anyone know where I can get an exploded diagram or quality explanation of how this contraption works; I am really quite curious. Many thanks.
Michael

This may not help you much in the specific case of the rear calipers, as I think Fiats' general advice is to replace them with the drum set up, but for future reference:

Click 'ePER' atthe top of the page
Click 'Go!' (if the page loads - sometimes it gets a bit busy)
Click 'Spare Parts'
Click 'Fiat'
Enter you cars' VIN number in the box towards bottom right of page, then click the magnifying glass
Click 'Next' towards bottom right of page (just have a quick look to make sure it's describing your car correctly.

From there on in, any subsections you go to will refere specifically to your car and part numbers that aren't suitable are greyed out. The diagrams can also be useful. Note though that this only works for cars built before mid-2005ish and the prices shown are way out of date. As a rough rule of thumb, I've found that current (2012/2013) Fiat parts prices are about double what's shown.

Michael Twiss said:

...Can I wind the pistons back in without getting a specialist tool? I made a tool to engage the piston notches but the pistons do not rotate. I think I need to push and turn at the same time...

Click to expand...

That's correct, but they should turn fairly easily whether you're pushing or not.
I managed with just a pair of 'Swan-neck' pliers and a G-Clamp to start them off, then just the pliers.
Left piston winds in anti-clockwise, the right one clockwise.
Be sure to align the cut-outs in the piston face once they're fully bottomed (to match the pins on the pads), and you have to pump the piston out against the disc with the foot pedal (with the caliper fitted of course) before you connect the cable.
If you connect the cable first, the handbrake mechanism 'lags behind' the piston, and basically doesn't work at all.

More info/pics here...
https://www.fiatforum.com/multipla/220711-multipla-rear-brake-tips.html