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Author Topic: Rear brakes JE  (Read 10967 times)
TheJoker
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« Reply #15 on: April 19, 2008, 07:22:59 pm »

I can twist the piston without any problems, but it doesn't seem to go any further in.  Sad
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Grand Espace 2.2 dCi 2001 Silver
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Dead: BMW K1200R
Martin Tyas
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Espace, because it's worth it!


« Reply #16 on: April 20, 2008, 12:24:59 am »

What's the actual status of the piston? Has it retracted at all or is it just in the same position as when you disassembled the caliper?... or has it retracted so far but not quite far enough for you to be able to insert the new pads?
I have known for the thickness of aftermarket pads to be a little too generous when fitted along with new disks so that they are too tight to insert without the judicious application of a file or sandpaper

What type / make of rewind tool are you using? It has to be able to not only rotate the piston but also apply pressure to it at the same time. The reason I ask is that there are some on the market that are little more than keys that locate in to the pistion head to rotate it but rely upon you trying to apply the sufficient pressure at the same time as rotating.

Any chance of any pix of the piston/caliper and the rewind tool?

Martin
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1968 Cessna 182L Skylane
1991 BMW 520i SE Auto
2002 Grand Espace 2.2dCi "The Race"
2003 Astra 1.8i Cabriolet "Edition 100"
2011 Insignia SRi VX-Line Red
2011 Honda VT1300CX Fury
TheJoker
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« Reply #17 on: April 20, 2008, 12:03:40 pm »

What's the actual status of the piston? Has it retracted at all or is it just in the same position as when you disassembled the caliper?... or has it retracted so far but not quite far enough for you to be able to insert the new pads?
I have known for the thickness of aftermarket pads to be a little too generous when fitted along with new disks so that they are too tight to insert without the judicious application of a file or sandpaper

What type / make of rewind tool are you using? It has to be able to not only rotate the piston but also apply pressure to it at the same time. The reason I ask is that there are some on the market that are little more than keys that locate in to the pistion head to rotate it but rely upon you trying to apply the sufficient pressure at the same time as rotating.

Any chance of any pix of the piston/caliper and the rewind tool?

Martin

I don't know exactly how far in the piston is, as the old pads were in quite good order (apart from not using the whole disk). I think I've pushed it in a bit, but there's about two millimeters or so too much thickness in the pads/disk to make the caliper not slide on.

The tool I have is a Draper one, like this:
http://www.thedrapershop.co.uk/draper-38-square-drive-brake-caliper-wind-back-cube34-p-3466.html
I had to remove two teeth on one of the sides to make it fit. I can apply quite  a bit of pressure by just squeeizing my ratchet handle, but obviously not any type of super-mechanical pressure.

The attached pic isn't really good as the only thing I was aiming to document with this pic is the Würth lubrication. But you can see the piston a bit.
Maybe I just have to grind down the pads a bit..?!
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
Martin Tyas
Sr. Member
****
Posts: 271


Espace, because it's worth it!


« Reply #18 on: April 20, 2008, 01:37:44 pm »

That's the tool that I was wondering if you might have. The rewind tools used in garages are like the one on the following page of the draper shop but are obviously much more expensive than the one you have.

http://www.thedrapershop.co.uk/draper-draper-expert-piece-brake-caliper-wind-back-tool-p-2324.html

and they are used as in the attached picture (not an Espace just a picture I "borrowed") and apply direct pressure at the same time as rotating the piston.

It's a while since I did mine so can't remember whether my pistons retracted further than in your photo.
I guess that you have 3 options.
1) try the caliper on the other side to see if the piston retracts any further with your existing tool
2) borrow or buy a wind back tool like I've shown to find out if the piston will in fact retract any further (pity we are not a bit closer... I'm up in Yorkshire... as you could have borrowed my wind back kit)
3) take a millimeter or so off the friction material of each pad

See what you mean about the exhaust paint.... is it also available in bright colours?  Wink Grin

BTW the pads are not in contact with anywhere near the full width of friction area available on the disks on the JE rear brakes so no need to worry about that.

Martin

« Last Edit: April 20, 2008, 09:48:13 pm by Martin Tyas » Logged

1968 Cessna 182L Skylane
1991 BMW 520i SE Auto
2002 Grand Espace 2.2dCi "The Race"
2003 Astra 1.8i Cabriolet "Edition 100"
2011 Insignia SRi VX-Line Red
2011 Honda VT1300CX Fury
TheJoker
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« Reply #19 on: April 20, 2008, 05:57:13 pm »

Martin, thanks very much for your insight and advice. Thanks to you I've now got new disks and pads on at the rear (front ones replaced about a year or so ago).
Sadly I wasn't even offered to buy one of those "proper" tools, so I simply got this one. I found a way to rewind the piston with this one, so I'll upload the pictures now. I don't know how many posts it'll take, but I'll start now (Might be interrupted by early dinner). Smiley

Thanks again! Smiley
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #20 on: April 20, 2008, 06:24:11 pm »

Painting the disks. Smiley I wanted to paint them to buy me some time on the rust as the old disks were quite rusty. Red... because I can. Also pics of the Würth brake lubrication. £1 + VAT from your local BMW dealer.
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
TheJoker
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« Reply #21 on: April 20, 2008, 06:25:38 pm »

More... Smiley
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #22 on: April 20, 2008, 06:30:19 pm »

This is what I started out with. It's not as bad as it looks, and I could probably have gotten away with a simple clean up of the disks and new pads. New disks does feel better, though. Smiley
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #23 on: April 20, 2008, 06:36:55 pm »

The biggest problem I had was, as you might have noticed, to wind back the brake pistons. The tool I have is a Draper cheap one, under £8. It didn't even fit. So I cut off two lugs on one of the sides that had 4. With that modification I was able to turn the piston, but not push it in. I tried several things, and I found that this double-screw-driver-set-up worked like a charm. I put the pad-holder on, then attached the sliding bolts to give me some leverage. The bottom screwdriver only keeps the sliding bolts from not sliding. The second screwdriver pushes the piston in, whilst I'm able to turn it clockwise. With about 1 turn or so, the piston is rewound. Easy when you know what to do.
Next pictures are:
- All off
- Disk on
- Pad holder on
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #24 on: April 20, 2008, 06:40:52 pm »

Continuing on the theme:
- Another angle (top)
- All lubed up and rewound. The Würth lube is a nice silver colour.  Cool
- Pads in place
- Caliper in place - Done, just need to put the wheel back on.
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #25 on: April 20, 2008, 06:51:58 pm »

Finally a few pics of the red disk peeping through the spokes.  Roll Eyes

And a few tips; A dremel with a rotary wire brush cleans the brake parts quite nicely, I wish I would have realised/remembered that a bit earlier. To jack the car up, I used a normal garage jack, and an axle stand. I put a piece of wood just in front of the rear wheel, and lifted as far forward as I could, and then I put the axle stand as close to the jack as possible. For additional stability I didn't remove the jack, but kept it slightly "pressurised"

Also, I was annoyed at not figuring out the rewind thing before I was doing the second side, so for the first side I sanded down the pads a bit, which now are a bit wonky and aren't gripping the whole disk. And they're also dragging a bit (which will wear off obviously). Hopefully it won't wear down the disk in a bad manner. Ah well, you live and learn.

Huge thanks to Martin for all the answers!  Cool Cool

Tomorrow the car goes in to look at why she's playing up, and hopefully the electrical problem too.  Roll Eyes
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Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
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