Technical Advice requested on Barchetta rear brake assembly to calipers

[LezLezLez65]

Hi and in advance, thanks for your input. I have a 1998 Barchetta and it failed its MOT (now on SORN) the rear brakes were found to pull unequally hence fail.
I am trying to disassemble the rear brake units and may possibly decide to replace some components. The handbrake cables seem to be fixed in length and position at caliper end. Can anyone advise how best to dismantle same? Is the nipple holder at caliper end fixed by a tapered bolt end? I don't wish to force something in error. Also can anyone sell me (Devon, UK) a replacement disk locator pin as I managed to shear one halfway down its bolt. Should the disks come off without force? Thanks in advance, Lez.

 

[Wiltshire Chris]

Hi, yes the handbrake cables are fixed in length but they will remove from the caliper end fairly easily

When I've taken the cables off and on've stuck a socket on the nut at the top of the picture and rotated it anti-clockwise effectively putting the hand brake on. That gives enough slack in the cable to use a pair of pliers to lift the nipple end out of the clip.

My disks came off with just a light tap with a rubber mallet from memory. I'm afraid I can't help with the bolt.

Good luck with it

 

[LeftyGreg]

I had exactly the same issue with mine last year, in balance of rear brakes when my car had been in storage for over 10 years

I replaced both of the calipers. Not really a difficult job, then bled the whole system to replace the old brake fluid and that got the thumbs up from the MOT centre

 

[LezLezLez65]

I had exactly the same issue with mine last year, in balance of rear brakes when my car had been in storage for over 10 years

I replaced both of the calipers. Not really a difficult job, then bled the whole system to replace the old brake fluid and that got the thumbs up from the MOT centre

Thanks Chris, thanks LeftyGreg, These comments have been helpful and reflect where I ended up yesterday with refurbishment.

One further question Chris, I found on YouTube a subscription group to a Barchetta fan ("PaulieCabs") who mentioned in one video the contoured piston in the rear calipers. He said (after buying a specialist brake rewind full tool set) that the piston can be screwed in but to keep on doing it as a lot of screwing was required. So far I have screwed mine in a little, but wonder how this piston works? If it is screwed well in, will the brake fluid pressure subsequently cause it to reseat back on the disk pad? Or is unscrewing a requirement? Are there screw threads on the inside surface of the piston cylinder? I might prefer not to disturb the piston if it looks OK from the outside but eventually it does need to press on the disk pad! The YouTube video did not mention unscrewing. Apart from that I have some surface rust to sand away on at least one disk. Wish me luck. Lez.

 

[Wiltshire Chris]

Or is unscrewing a requirement?

Not that I've ever had to do! I seem to remember that there are lugs on the back of the pads that engage in the profiles of the piston, if that's true then they wouldn't be able to wind/unwind when in use. I've just gone through the umpteen pictures I've taken during my work on my B and I can't find a relevant one. I wound mine in enough so that the fatter new pads would fit over the fat new disk which was a fair way in my case.

Have you read the guide https://www.fiatforum.com/guides/rear-brake-discs-pads-replacement.235/ ? If you haven't then the advice on being wary of the fluid spilling out of the reservoir when winding back is worth heeding.

I enjoy PaulieCabs' video as he's taken on many similar jobs to me so I've found them useful.

Good luck with it, I've learned a lot messing around with mine helped a lot by the more experienced hands on here.

 

[LeftyGreg]

For what they cost, I would replace the discs rather than clean up the old ones. I think they cost about £10 each from my memory

 

[pablopablo]

Pauliecabs had a problem with brake imbalance and after changing nearly everything to no avail the fault was eventually found to be with the brake power regulator. There wasn't enough pressure coming through the brake power regulator on one side (which was brand new!).

 

[Wiltshire Chris]

Pauliecabs had a problem with brake imbalance and after changing nearly everything to no avail the fault was eventually found to be with the brake power regulator. There wasn't enough pressure coming through the brake power regulator on one side (which was brand new!).

At the risk of hijacking the thread I got intrigued by this as I don't have the brake power regulators on my 1999 ABS car and, because I'd watched the video, was concerned I'd have an issue with them so was relieved they weren't there. As far as I can understand ePER they were dropped for cars with ABS as part of modification 2234 in March 1997 but retained on non-ABS cars. So if you've got ABS then you might not have to worry about the regulators.

 

[pablopablo]

At the risk of hijacking the thread I got intrigued by this as I don't have the brake power regulators on my 1999 ABS car and, because I'd watched the video, was concerned I'd have an issue with them so was relieved they weren't there. As far as I can understand ePER they were dropped for cars with ABS as part of modification 2234 in March 1997 but retained on non-ABS cars. So if you've got ABS then you might not have to worry about the regulators.
View attachment 405067

What do you have instead then? Is the brake pipe continuous or is there a section of brake pipe where the compensator power regulator is/was located?

 

[Wiltshire Chris]

They're continuous on mine.

Looking at the ABS models with compensator they have two pipes on each side
On the passenger side pipe 46734749 goes to the compensator and pipe 7735006 goes from the compensator. Change 2234 removes both of these pipes and replaces them both with a single pipe 46466570

 

[pablopablo]

They're continuous on mine.
View attachment 405210
View attachment 405211
Looking at the ABS models with compensator they have two pipes on each side
On the passenger side pipe 46734749 goes to the compensator and pipe 7735006 goes from the compensator. Change 2234 removes both of these pipes and replaces them both with a single pipe 46466570

Thanks for the info and pics!

 

[LeftyGreg]

Mine has the compensators (1995 model) but no idea how or if they work as they look bad!

I did clean them up a bit after this pic, but not much improvement