Technical Rear brake fun

[Wiltshire Chris]

My 1999 Barchetta is now up on blocks in the garage for me to get some things sorted before the next attempt at the MOT.

First up was the ineffective handbrake. Its ineffectiveness was coupled with the fact it also didn't release particularly well.
Once I'd got the wheel off it was obvious from the grinding noise that the wheel wouldn't turn freely. With the handbrake off I could see that it wasn't springing back to its stop position.

I went to adjust the handbrake and, since it only goes up one click, suspect it has been tightened and tightened over the years to get it through the MOT. I've got new cables on order so just released the cables from the lever to give maximum slack. Still bit of a grinding sound when turning the wheel.

Since the discs had also an advisory against them I'd decided to change those out too. After much WD40 and resorting to stud extractors as the allen key sockets kept popping out I managed to get the studs out of the caliper. I was using the guide by Bumble which suggested a gentle tap would remove the caliper from the disc. Well, mine barely move and can't be persuaded off the disc, even with more than gentle tapping.

I wondered about using a big clamp to try and force the piston back in to the caliper but I believe that it's a screw type so I'm not sure if that will work.

Does anyone have any tips on what to try next? I'm a relatively novice mechanic but willing to learn. I suspect that even when I've got them off the calipers will need attention given how they are now.
Thanks
Chris

 

[arnietwo]

I dont think they are screw type. There is nothing inside that piston, only fluid pressure. So u could disconnect the brake hose, take off the disc and caliper and prise a screwdriver in there on a bench. Get them seperated somehow. You cant start to see what the problem is until you can get to the individual parts.

 

[Noideadave]

Mine were screw type on a 98. You can make a spanner from steel plate to do this or use waterpump pliers. What are the studs in the calipers??? When you change the hand break cables, tie some string to the cables inside the car and pull them through, then you can tie it to the new cables to pull them back or you will struggle. Keep the old cables, you might need a part off them as the new ones tend to be a bit too long. Changing discs and bearings are pretty straight forward. Good luck.

 

[Noideadave]

I modified the ends of the old cables and used them as spacers because they were too long.

 

[turining]

Screw in type - 1997

 

[Wiltshire Chris]

Thanks everybody. The studs are the ones holding the caliper to the trailing arm as shown here I'll look at them tomorrow to see if they're salvagable.

I took arnietoo's tip of disconnecting the brake pipe (I've got new ones to go on as they were an MOT failure due to corrosion) and I could then take the disc and caliper off together. I was then able to get enough leverage to get the caliper off the disc. The disc is pretty rusty so happy to ditch it for the new one. I'll take a look at the caliper in the morning when I can get it on the bench. I do have a caliper compressor that should work with the B so fingers crossed.

Thanks to Dave for the handbrake advice, I'll make sure I don't throw the old cables away and definitely pull a draw string through.
I'd like to try and tart up the metal protector plate as that has a ton of surface rust on it and I'd like to protect it but I'll see how I go tomorrow.
Thanks again

 

[arnietwo]

Thats great !! Yes, clean and paint everything before reassembly.

 

[gar074]

Pistons are screw-in on mine (98). The wind-in tool was only a few £. My rear brakes will be getting an overhaul when I've finished painting wretched window-frames , so I'll be following your thread with interest!

 

[Wiltshire Chris]

Don't envy you those window frames!
The job is progressing OK. I did buy a Laser 1314 caliper tool to get the pistons back in. So far I have new disks and pads in place and one handbrake cable.

The handbrake cables are being a bit of a sod as whoever put them in clamped them in very tightly to the supports and freeing them up has been a bit of a battle. As is dealing with the exhaust heat shield. I've managed so far by taking all the bolts of the heat shield out so I can wiggle it around rather than completely removing it.
The one that has come out is completely useless as the cable won't move in the sleeve at all so it definitely needed doing. The string tip to pull them back through to the cabin is pretty essential as is an assistant to apply gentle pulling from the cabin while yours truly pushed and aligned from underneath.
Hopefully I'll get the second cable in today then everything stops as I need to get a brake line made up as the MOT failure one is leaking.