V8V caliper pistons
Discussion
One of my calliper pistons has some corrosion on it. It still operates fine and I have no issues with it, but whilst it's off the car I would like to change the piston and seals as well.
I've spent a while searching, but can't seem to find replacement pistons and seals anywhere.
Anyone have any experience of this ?
Thanks in advance !
I've spent a while searching, but can't seem to find replacement pistons and seals anywhere.
Anyone have any experience of this ?
Thanks in advance !
Bit of an update - managed to find a very helpful chap called Dave at Frentech https://www.frentech-uk.co.uk/product_category/bra...
He can supply all pistons, seals etc necessary.
Turns out the original pistons are chrome covered aluminium and have a habit of corroding. The modern recommended replacement is anodised aluminium and the V8V rear calipers on my 2009 4.7 have 2 x 34mm and 2 x 36mm pistons.
Going to get a full set and do all pistons and seals on my rear calipers. Whilst the corrosion is currently on the outside face of the piston, if it were to corrode through and lift the chrome off the piston where it goes past the pressure seal, you would get loss of brake fluid and correspondingly pressure.
Another thing I wouldn't have spotted had I not decided to remove the rear subframe....
He can supply all pistons, seals etc necessary.
Turns out the original pistons are chrome covered aluminium and have a habit of corroding. The modern recommended replacement is anodised aluminium and the V8V rear calipers on my 2009 4.7 have 2 x 34mm and 2 x 36mm pistons.
Going to get a full set and do all pistons and seals on my rear calipers. Whilst the corrosion is currently on the outside face of the piston, if it were to corrode through and lift the chrome off the piston where it goes past the pressure seal, you would get loss of brake fluid and correspondingly pressure.
Another thing I wouldn't have spotted had I not decided to remove the rear subframe....
Edited by JonnyCJ on Friday 24th April 14:30
Edited by JonnyCJ on Friday 24th April 14:31
phumy said:
Jonny thats great hear that they can supply all of your pistons and seals for your car, i assume they would possibly also supply V12, if they are different.
Don’t see why not - drop them an email.You’ll need to know your piston sizes though.
Turns out the 34mm pistons they have are 1.5mm too long so I’ll need to get them turned down by someone with a lathe. Not an issue as there’s plenty of meat on the bottom of the piston and although I’ll lose the anodising it’ll be permanently covered with brake fluid so shouldn’t corrode.
Finally got round to finishing off my calipers now that lockdown is easing. My complete set of pistons and seals arrived from Frentech a while ago, but needed to get the 34mm pistons reduced in length by1.5mm.
Popped over to my local friendly engineering shop and they took the 4 pistons down on a lathe with soft jaws and didn’t want paying, so bunged the engineer a tenner for his trouble.
Took the old inner seals out with a pick and installed the new ones with some brake fluid to ease installation.
Popped the new pistons in, again lubricated with brake fluid. Make sure that the bleed nipples are undone and the pistons themselves are lubed up with brake fluid. Make sure they only go in half way before installing the dust seals.
Dust seals on next - again with a dab of brake fluid to ease installation. You'll note that the seals don't appear to sit flush to the caliper. This is because there's a slight taper on the face of the caliper, so not an issue.
Next up were the new pads - Porterfield R4-S. These have gone on with the original thin metal anti squeal shims and some Plastilbe between the shim and back of the pad to eliminate squeal.
Sliders and retaining spring installed with silicone grease to aid the pads sliding on the pins. Silicone grease has also been used on the caliper slider pads.
There’s actually 3 types of lubricant needed to assemble brake calipers and pads. Silicone grease for anything that slides, Plastilube or similar for noise reduction and red rubber grease for any rubber seals. Never use any petroleum based products (traditional grease, copper grease etc) on any areas where there are rubber seals. The petrol content makes the seals swell and perish.
The red rubber grease only really needs to be used on the handbrake caliper slider seals, these have a different construction to the normal calipers.
![](https://thumbsnap.com/sc/FYvcj5RV.jpg[/img]</a> <a href="https://thumbsnap.com/SfSik2iP" Target="_blank" rel="nofollow">[img]https://thumbsnap.com/sc/SfSik2iP.jpg)
Next step is installation of calipers and bleeding and then potentially onto the fronts if I’m feeling enthused...
Popped over to my local friendly engineering shop and they took the 4 pistons down on a lathe with soft jaws and didn’t want paying, so bunged the engineer a tenner for his trouble.
Took the old inner seals out with a pick and installed the new ones with some brake fluid to ease installation.
Popped the new pistons in, again lubricated with brake fluid. Make sure that the bleed nipples are undone and the pistons themselves are lubed up with brake fluid. Make sure they only go in half way before installing the dust seals.
Dust seals on next - again with a dab of brake fluid to ease installation. You'll note that the seals don't appear to sit flush to the caliper. This is because there's a slight taper on the face of the caliper, so not an issue.
Next up were the new pads - Porterfield R4-S. These have gone on with the original thin metal anti squeal shims and some Plastilbe between the shim and back of the pad to eliminate squeal.
Sliders and retaining spring installed with silicone grease to aid the pads sliding on the pins. Silicone grease has also been used on the caliper slider pads.
There’s actually 3 types of lubricant needed to assemble brake calipers and pads. Silicone grease for anything that slides, Plastilube or similar for noise reduction and red rubber grease for any rubber seals. Never use any petroleum based products (traditional grease, copper grease etc) on any areas where there are rubber seals. The petrol content makes the seals swell and perish.
The red rubber grease only really needs to be used on the handbrake caliper slider seals, these have a different construction to the normal calipers.
Next step is installation of calipers and bleeding and then potentially onto the fronts if I’m feeling enthused...
Edited by JonnyCJ on Monday 8th June 08:32
I remember in the old days when there used to be a bustling office environment, I was ordering over the phone to a motor parts factor during a quiet lunchtime and asked in a loud clear voice for 'a large tub of red rubber grease' which did raise a few eyebrows...
To be clear it is still very much in use for automotive rubber-related functions only.
To be clear it is still very much in use for automotive rubber-related functions only.
Calipers installed and part way through brake bleeding. Always make sure your nipples are pointing upwards !
The calipers can be installed with the nipples pointing down, however, if you do that you’ll never get a firm pedal as the air will rise to the top of the internal lines on the caliper and the nipples will be at the bottom.
The calipers can be installed with the nipples pointing down, however, if you do that you’ll never get a firm pedal as the air will rise to the top of the internal lines on the caliper and the nipples will be at the bottom.
Brakes bled and all well with no weeping at any of the unions after refitting the calipers.
Whilst the old brake fluid that came out looked pretty much brand new, I took the opportunity to drain the clutch fluid as well. That was slightly more discoloured.
Pretty much exactly 2 litres of Motul DOT5.1 used.
Incidentally, I replaced the rear wear sensor indicators. Got these for £16 delivered and I have to say, the quality is as good as OEM. Comparing them against each other I couldn't see a difference. https://www.ebay.co.uk/itm/For-Aston-Martin-V8-Van...
Plugged them in and the "rear brake pads low" light went off, which had been on when I'd removed the old pads and sensors. The system looks like it's pretty much a continuity signal. Break the continuity by the wire being worn away and the warning light comes on. Hardly rocket science and for the price I'm extremely comfortable fitting these.
Whilst the old brake fluid that came out looked pretty much brand new, I took the opportunity to drain the clutch fluid as well. That was slightly more discoloured.
Pretty much exactly 2 litres of Motul DOT5.1 used.
Incidentally, I replaced the rear wear sensor indicators. Got these for £16 delivered and I have to say, the quality is as good as OEM. Comparing them against each other I couldn't see a difference. https://www.ebay.co.uk/itm/For-Aston-Martin-V8-Van...
Plugged them in and the "rear brake pads low" light went off, which had been on when I'd removed the old pads and sensors. The system looks like it's pretty much a continuity signal. Break the continuity by the wire being worn away and the warning light comes on. Hardly rocket science and for the price I'm extremely comfortable fitting these.
Edited by JonnyCJ on Monday 8th June 15:33
JonnyCJ said:
Brakes bled and all well with no weeping at any of the unions after refitting the calipers.
Whilst the old brake fluid that came out looked pretty much brand new, I took the opportunity to drain the clutch fluid as well. That was slightly more discoloured.
Pretty much exactly 2 litres of Motul DOT5.1 used.
Incidentally, I replaced the rear wear sensor indicators. Got these for £16 delivered and I have to say, the quality is as good as OEM. Comapring them against each other I couldn't see a difference. https://www.ebay.co.uk/itm/For-Aston-Martin-V8-Van...
Plugged them in and the "rear brake pads low" light went off, which had been on when I'd removed the old pads and sensors. The system looks like it's pretty much a continuity signal. Break the continuity by the wire being worn away and the warning light comes on. Hardly rocket science and for the price I'm extremely comfortable fitting these.
Good to know about the sensors. I managed to keep the OEM ones when I replaced my pads, caught them just before the sensors would touch the discs.Whilst the old brake fluid that came out looked pretty much brand new, I took the opportunity to drain the clutch fluid as well. That was slightly more discoloured.
Pretty much exactly 2 litres of Motul DOT5.1 used.
Incidentally, I replaced the rear wear sensor indicators. Got these for £16 delivered and I have to say, the quality is as good as OEM. Comapring them against each other I couldn't see a difference. https://www.ebay.co.uk/itm/For-Aston-Martin-V8-Van...
Plugged them in and the "rear brake pads low" light went off, which had been on when I'd removed the old pads and sensors. The system looks like it's pretty much a continuity signal. Break the continuity by the wire being worn away and the warning light comes on. Hardly rocket science and for the price I'm extremely comfortable fitting these.
And onto the fronts...
As I thought the fronts caliper pistons are corroded to a similar level to the rears.
Thoroughly cleaned the calipers to remove 9 years of ingrained brake dust before tackling the pistons. To clean them I used old brake fluid and a micro fibre cloth. It’s a messy and time consuming job, but no way around it and looks great once cleaned up.
The trickiest part is getting the dust seals off. The trick here is a sharp screwdriver, tapped into the edge of the seal with a hammer to give you something to grip. I put some paper between the screwdriver and caliper to prevent damage whilst levering off the seal.
The pistons came out with specialist piston removal tool - £18 or so on eBay. You can use a couple of screwdrivers to lever them out, but are liable to damage the paint unless the shafts are protected with electrical tape or similar.
|https://thumbsnap.com/VRGmdiHh[/url][url]
Finally, I touched up the various stone chips and spanner nicks with some red paint and left to dry.
Frentech look like they’ve come up trumps again on new pistons and seals and I’ll post up pics when installing. Hopefully they will be listing a full caliper rebuild kit on eBay soon, so watch this space.
Caliper rebuilds from specialist rebuild companies can cost £500+ and you have to send them away, so hopefully this will save people a lot of time and money.
As I thought the fronts caliper pistons are corroded to a similar level to the rears.
Thoroughly cleaned the calipers to remove 9 years of ingrained brake dust before tackling the pistons. To clean them I used old brake fluid and a micro fibre cloth. It’s a messy and time consuming job, but no way around it and looks great once cleaned up.
The trickiest part is getting the dust seals off. The trick here is a sharp screwdriver, tapped into the edge of the seal with a hammer to give you something to grip. I put some paper between the screwdriver and caliper to prevent damage whilst levering off the seal.
The pistons came out with specialist piston removal tool - £18 or so on eBay. You can use a couple of screwdrivers to lever them out, but are liable to damage the paint unless the shafts are protected with electrical tape or similar.
|https://thumbsnap.com/VRGmdiHh[/url][url]Finally, I touched up the various stone chips and spanner nicks with some red paint and left to dry.
Frentech look like they’ve come up trumps again on new pistons and seals and I’ll post up pics when installing. Hopefully they will be listing a full caliper rebuild kit on eBay soon, so watch this space.
Caliper rebuilds from specialist rebuild companies can cost £500+ and you have to send them away, so hopefully this will save people a lot of time and money.
Edited by JonnyCJ on Thursday 11th June 21:46
Robotron-2084 said:
Good thread, I'm pretty handy on DIY type stuff but never stripped/refurbed a set of calipers so it was a good read. 
It’s easy ! Trick is to convince yourself you can do it and then go for it. Make sure you have bleed nipple dust caps to cover the brake lines once disconnected. Worst case scenario is you end up with lots of brake fluid on the floor and have to top up and bleed the system with a bit more fluid.One way of getting sticky pistons out is to only remove one brake pad while the caliper is fully attached on the car. Have the glamorous assistant press the brake pedal slowly. Once the pistons have come out a good way - not all the way obviously! - push a screwdriver in and hold them there. Then remove the other pad and repeat. All 4 pistons should be quite a way out and easier to remove.
This works with pistons that are almost seized in.
Nice write up.
This works with pistons that are almost seized in.
Nice write up.
Yes a really useful write up and excellent pics, thanks Johnny!
Compressed air is good for piston-popping if the calliper off the vehicle, a cheap compressor has been a regular if infrequent friend, having rebuilt a fair few fiddly motorcycle callipers over the years... Beware they do 'pop' when they go and important to restrain those pistons that are already freely moving!
Compressed air is good for piston-popping if the calliper off the vehicle, a cheap compressor has been a regular if infrequent friend, having rebuilt a fair few fiddly motorcycle callipers over the years... Beware they do 'pop' when they go and important to restrain those pistons that are already freely moving!
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