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Cetane



Member Since: 27 Nov 2012
Location: Lancashire
Posts: 171

United Kingdom 2010 Defender 110 Puma 2.4 HT Galway Green
Brake Caliper Overhaul - Stainless Pistons
Today's job was to overhaul the rear calipers on my 2.4 110. Last time I changed my pads I spotted that the pistons were corroded so I treated myself to stainless pistons. I've already done the fronts, and off the back of that I decided to take some photos and do a write up. The process is pretty much identical irrespective if you're doing fronts or rears.

People seem to get scared to do DIY work on their brakes, but its not difficult, and as long as you are methodical its straight forward. I chose not to split the calipers as in my opinion it adds extra work. There was no need to replace the O-rings between the halves so why introduce an opportunity for error?

Here's the disclaimer bit... I've rebuilt these as I would do a set of race calipers. Ive never rebuilt a caliper with dust seals before, so just applied some logic. This is not the workshop manual way to do it. You work on your own brakes at your own risk.

Before you get started, go grab some disposable gloves. Brake fluid is rotten stuff. My preference is for Nitrile ones as they don't go baggy like Latex when exposed to solvents. Eye protection is an idea too.

For this I used:

£2 baking tray
Air compressor with a blow gun attachment.
Adjustable pliers
Hammer
Small flathead screwdriver (Think glasses adjusters)
Small "L" shape pick
G clamp
Brake cleaner
Genuine LR caliper seal kit
Genuine LR brake pads


To start....

As you can see on the picture below there is a lot of corrosion on the brake pistons. Quite why LR use these is beyond me. Because the pistons don't retract fully the pad wear is not even. Another intermittent symptom of this was squealing brakes when traveling down the motorway.


Click image to enlarge


If I had just replaced the pads again there would be a high likelihood of pushing the piston back so far that the corrosion would travel past the fluid seal and cause fluid loss. As you can imagine, this is much less than desirable!





Click image to enlarge


To start with remove the split pins that hold the pad retaining pins in place. Withdraw the pad pins and their springs. I keep these to one side until I replace them for new. With the retaining pins removed withdraw the pads from the caliper. Make a note of the orientation of the pads and the metal backplate as you remove it. As with the pins I keep hold of the pads until I break out the new ones. When doing front seals I use them to remove pistons. More on that later.

With the pads removed now is the time to give the calipers a clean. Copious amounts of brake clean, an old toothbrush and an airline are useful. I remove the surface crud to make handling the calipers a bit easier down the line.





Click image to enlarge


Now to remove the pistons. Simply use an airline down the inlet port to pop them out. When the first has popped out, then place it back in half way and use a G clamp to hold it in place. Apply some air pressure and the second one should come free.





Click image to enlarge


As you can see from the picture of the fronts, I use a pad to control how the pistons pop out. If you use 2 facing each other with one turned 90Deg you can control which caliper piston can move. Unfortunately I didn't think to take a photo of this. However, with some experimentation you should be able to find what works.

What if one piston is stuck? The answer depends on whether the piston is to be reused. My pistons were lunched so it didn't matter if I damaged them. The solution I found best was to grip the lip of the piston that was exposed with the adjustable pliers as hard as I could, then get someone else to tap the pliers to "persuade" the pistons out. I only had to get them to move about 1mm before the airline trick would work. I didn't fancy banging it out all the way.





Click image to enlarge


With the pistons out I set about removing the seals. The inner seal is the fluid seal. The outer is a dirt seal which is held in place by a retaining ring. The dirt seal and retaining ring should stay in the caliper. However, due to the corrosion some of mine popped out with the piston. To remove the seal I found it best to use the screwdriver as if I was trying to spin them. This leads to a small part becoming unseated. When this happened I then would use the pick to remove the seal. This method works for both seals. To remove the metal retainers simply flick them out with a screwdriver, taking care not to score the caliper as you do so.

With the seals removed, clean the up all the old fluid and make sure that the piston housings are free of debris. Again an airline and some brake cleaner is useful.





Click image to enlarge



Click image to enlarge


Now to install the seals.... There shouldn't be any confusion over the order they fit, but I've uploaded an excerpt from the WSM just in case.

First I coated the fluid seal in fresh brake fluid and pressed it into its groove making sure it was properly seated all the way round.





Click image to enlarge


Next I pressed into place the metal retaining ring. This can be tricky. Try to press it in as one, rather than doing one side then the other. I found using the old brake pad useful as a tool to press it in square. My stainless pistons came with an aftermarket seal overhaul kit. Out of interest I tried pressing in a metal ring. It was a nightmare as it wasn't quite the right size. My advice would be to use Gen parts, if only to make life easy.





Click image to enlarge


With the retaining ring in place it's time to fit the dirt seal. I found this very tricky. I installed it in much the same way as the fluid seal but the last bit was always a pain. I found I had to use the little screwdriver to move the seal around to remove the slack that bunches up just before you pop the last bit in. Again take care not to damage the seal.

With all the seals in place, take the opportunity to make sure everything is clean. At this stage I just used some fresh brake clean, a clean rag and an airline.





Click image to enlarge


With everything clean I took a new piston and coated it in fresh brake fluid. I also made sure the fluid seal had a fresh coat too. Making sure the piston was square I pushed it in. This can be a bit of a fight. It's best to do this bit by hand to make sure you don't damage the seals by forcing the piston in on the wonk.





Click image to enlarge


Click image to enlarge


Once the piston was comfortably past the fluid seal I used a G clamp to push the piston back. I had to keep swapping which side of the piston I was working on to keep it straight. I pushed the pistons back just so the chamfer on them was showing.





Click image to enlarge


At this point you can clean off the excess brake fluid and put them back on the LR to fit the new pads in situ. However, I decided to fit the pads on the bench as its easier. With the pistons fully back, there should be no issue slipping the caliper over the disc.




Hopefully that write up was of use to someone. If you feel like you want to give it a go, and have any questions then feel free to ask.

Cheers

Cetane

Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated Mr. Green
Post #521976 7th Apr 2016 7:13pm
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Retroanaconda



Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Scotland 
Nice work.

An alternative method for fitting the outer dust seal and seal retainers that I used was to fit the main fluid seal, then lubricate and insert the piston so there's about 1/2" still sticking out. Then place the dust seal into the metal retaining ring and slide the resulting assembly over the exposed section of the piston down to meet the caliper. Using a large flat washer with the G-clamp you can then push home the piston, seal and retainer nice and easy in one motion. Having the piston in place keeps it all square.

Genuine parts only for the seal kits, as you have suggested.
Post #521999 7th Apr 2016 7:52pm
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Fatboy Slim



Member Since: 04 Feb 2008
Location: Bridgend
Posts: 1006

Wales 
^^^^^^^ same as the way I do them works great.
Post #522007 7th Apr 2016 8:01pm
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Cetane



Member Since: 27 Nov 2012
Location: Lancashire
Posts: 171

United Kingdom 2010 Defender 110 Puma 2.4 HT Galway Green
Cheers for the tip. Will try it next time round.
Post #522013 7th Apr 2016 8:08pm
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YOLO110



Member Since: 14 Feb 2015
Location: Perth Oz and Stansted UK
Posts: 1641

Australia 
Thanks for the very comprehensive write up mate Thumbs Up YOLO... You Only Live Once...
Post #522075 7th Apr 2016 10:46pm
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17320

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
May I ask where you bought the stainless pistons, and are you satisfied with the quality of them?

Thanks!
Post #522255 8th Apr 2016 2:07pm
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Cetane



Member Since: 27 Nov 2012
Location: Lancashire
Posts: 171

United Kingdom 2010 Defender 110 Puma 2.4 HT Galway Green
I cant remember where I got them. I had always heard good things about Zeus ones but they don't seem to do them anymore. I bought these last year and its been one of those jobs I'd been putting off until I overhauled the axle. What I can tell you is that they were boxed as EAC. I remember buying them as a 110 kit. They seem to be machined well, but the poof will be when they've been run on the LR for a bit. I cant see me getting it back on the road for a while yet, as I'm going through the entire drivetrain from the clutch to wheel nuts.

HTH

Cetane

PS Just had a quick Google.... Possibly these?
http://www.shop4autoparts.net/Defender/Bra...f-110.html
Post #522262 8th Apr 2016 2:30pm
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termohe



Member Since: 23 Jul 2012
Location: De Pinte
Posts: 15

Belgium 2004 Defender 90 Td5 HT Alpine White
I just split them, makes life a lot easier.

Bought the pistons from Paddock with oem sealings
Post #522277 8th Apr 2016 5:16pm
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 4554

17H8764L - BRAKE CALIPER INTERNAL SEALS RRC you will need there seal if you split them, not included in most rebuild kits Exclamation 6 QTY for both front and rear split rebuilds
Post #522319 8th Apr 2016 7:21pm
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Merlin



Member Since: 30 Oct 2010
Location: Newmarket
Posts: 981

United Kingdom 
I used stainless steel pistons from Zeus:

http://www.zeus.uk.com/index.php

About £107 posted, last year.

Merlin
Post #522478 9th Apr 2016 12:46pm
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Justtellme



Member Since: 23 Nov 2015
Location: Ottawa
Posts: 310

Canada 2003 Defender 110 Td5 SW Oslo Blue
dorsetsmith wrote:
17H8764L - BRAKE CALIPER INTERNAL SEALS RRC you will need there seal if you split them, not included in most rebuild kits Exclamation 6 QTY for both front and rear split rebuilds


Is this part number good for front and rear calipers? Including later front calipers for td5 / puma?

Thanks
Patrick
Post #941059 5th Feb 2022 12:21am
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The Zee



Member Since: 26 May 2019
Location: Salisbury
Posts: 289

United Kingdom 2014 Defender 110 Puma 2.2 USW Indus Silver
Great write up. Thumbs Up

As a Defender newbie and not that mechanically savie, I admit I had somebody do the refurbishment for me, using a set of lightly used take off calipers (both F&R) together a strip, blast and paint, but provided Zeus Engineering pistons. Zaid-M
www.DefencePhotos.com
2014 Defender 110 Utility, 2.2 Puma, Indus Silver
Not just transport more like a religion
Post #941191 5th Feb 2022 9:45pm
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blackrock



Member Since: 01 May 2022
Location: Hampshire
Posts: 57

United Kingdom 2012 Defender 110 Puma 2.2 SW Firenze Red
What I've done on other vehicles in the past is buy a new caliper and pop that on when one needs refurbishment, then refurb at your leisure until the one you just put on needs doing and then keep swapping. It's not the cheapest way, but it gets you back up and running quicker and allows you to take your time when working on a caliper.

There are also tools that can help when trying to remove a stuck piston, or indeed just remove a piston when you don't have air:

&t=347s

You can also pump the pistons out with fluid if you have a pump available, such as when working on a motorbike where you can take the master cylinder onto the bench, or use the vehicle brake system to pump a piston out.

Andrew
Post #992269 11th May 2023 5:14pm
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MK



Member Since: 28 Aug 2008
Location: Santiago
Posts: 2408

Chile 2007 Defender 110 Puma 2.4 SW Chawton White
dorsetsmith wrote:
17H8764L - BRAKE CALIPER INTERNAL SEALS RRC you will need there seal if you split them, not included in most rebuild kits Exclamation 6 QTY for both front and rear split rebuilds


So do these seals apply to let´s say Puma calipers? Puma 110" SW

.............................................................
Earth first. Other planets later
Post #1010277 6th Oct 2023 11:13am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17320

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
The last pistons I removed I ended up splitting the caliper, then drilling and tapping a hole in the centre of the piston and using a jackscrew to force the piston out. Surprisingly the bores were fine, but not the pistons (even disregarding the large threaded hole in the middle).
Post #1010309 6th Oct 2023 3:32pm
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