V70: Wheels/Brakes Different sized rear brake pistons??

[Vagabondrobb]

Hi all,

Ever since I replaced my rear O/S caliper and electronic parking brake 18 months ago, I’ve had endless problems. I’ve had to replace the unit again twice since, as the piston seal went, and the electronic motor failed (I think due to an ingress of brake fluid). Now I’ve got a warped disc and getting quite extreme wear only on the O/S. I had assumed the wear is from the disc warp, and ordered a new set of discs and pads. Interestingly, when picking the parts up from Euro car parts, the guy there cautioned me that Volvo state that the V70 can have one of three kinds of rear caliper - a non electronic, and two different electronic kinds - with each of the latter having different diameter pistons.

I guess if I have a wrong sized piston for the pad, this could explain the seal going, and all the other knock on issues etc.

Is anyone aware of there being different kinds of caliper?? Or had similar issues? I can’t seem to find any information regarding this.

I’ve got 2011 V70 2.0d (a fantastic car - I get 50 mpg on the highways)

Many thanks,

Robb

[The Edge]

Have you had this checked by someone who knows what they're doing? If not why not?

I'm sure you don't need telling that braking issues can be very dangerous.

I'd have thought that fitting an incorrect calliper would be impossible, they are quite deliberately different to prevent exactly that. It would seem that there is an issue somewhere and we cant see the car to help you. I did my rear brakes a couple of weeks back and Its hard to see how your can get it wrong, but mistakes can happen.

I'd start by making sure everything that should move can move freely and is lubricated - but you've most likely done that.

Get it checked

[apersson850]

AWD cars have ventilated discs, FWD cars solid ones. And then electric or not electric parking brake, and you have at least three options, if we assume mechanical parking brake is only delivered with solid discs.

[Vagabondrobb]

Thanks the reply. I pretty much do all the work on my cars, mainly because of where I live, and partly because I’ve always been interested in engines and mechanics and can’t help take them apart! But yes, in an ideal world, when it comes to a more complicated problem related to braking, it should go straight to a garage. Then again most problems are usually simple when you figure them out, so I’m trying to do that first.

I’m guessing the caliper itself isn’t different, but the piston, for whatever reason, is bigger or smaller. In which case you could fit the wrong pads - assuming the man from euro car parts was correct. It does seem unlikely - which is why I wanted to throw it out to the forum.

But yes I’ve checked everything is moving freely etc. I’m going to try and measure and compare each piston if I get a chance later today - that should clear things up!

[Kev0607]

Originally Posted by Vagabondrobb

Hi all,

Ever since I replaced my rear O/S caliper and electronic parking brake 18 months ago, I’ve had endless problems. I’ve had to replace the unit again twice since, as the piston seal went, and the electronic motor failed (I think due to an ingress of brake fluid). Now I’ve got a warped disc and getting quite extreme wear only on the O/S. I had assumed the wear is from the disc warp, and ordered a new set of discs and pads. Interestingly, when picking the parts up from Euro car parts, the guy there cautioned me that Volvo state that the V70 can have one of three kinds of rear caliper - a non electronic, and two different electronic kinds - with each of the latter having different diameter pistons.

I guess if I have a wrong sized piston for the pad, this could explain the seal going, and all the other knock on issues etc.

Is anyone aware of there being different kinds of caliper?? Or had similar issues? I can’t seem to find any information regarding this.

I’ve got 2011 V70 2.0d (a fantastic car - I get 50 mpg on the highways)

Many thanks,

Robb

Euro Car Parts... there's could be part of your problem.

I bought a brand new set of front Pagid brake discs from them for my S80. They were warped within a few months.

Buy genuine Volvo discs and pads, you won't have a problem with warping. They're built to last. Euro Car Parts sell nothing but junk in my experience. I will never buy brake parts from them again. Being honest, I'd be tempted to go to the dealer for the rear caliper too. The dealer will have the correct info as soon as you give them the reg. Euro car parts don't have a system like Volvo do, hence why it may be confusing.

What method are you using to retract the electronic parking module? You need a battery in reverse polarity or a scan tool to retract the parking brake back.

Does your car have solid or vented rear discs? Vented rear discs are thicker than solid ones, hence why there's different caliper options available due to the different thickness of the discs and the pistons are slightly larger for vented discs (only slight, maybe 3mm). If you establish which discs your car has on the rear (just look at them), then that will be a start.

All V70's of this era have an electronic parking brake. There is no non-electric rear caliper for this type of car... I'm afraid the parts man is mistaken there.

Edit...

I've just checked Euro Car Parts website. The rear left caliper has 3 options... 2 of them are for solid discs and 1 is for vented. All are for electronic parking brakes (despite what the parts man said).

Rear brake calipers for solid discs, although there's two options, are the same. One is cast iron and the other is aluminum. Dimensions of the piston are identical (38mm).

Rear brake calipers for vented discs have a piston size of 41mm (slightly larger). There's only one option available, so parts man shouldn't get that wrong.

It appears the parts man has just glanced at what was in front of him. Yes, there's 3 types of rear caliper available, but two of them (for solid discs) are identical in terms of piston size/dimensions (according to their site). Its just the material the calipers are made of that's different. We all make mistakes though, but clearly, he hasn't read the info available to him.

Find out what discs you have, take it from there.

[Vagabondrobb]

Thanks Kev - some good info there!

They are solid discs. So vented would not fit in a caliper meant for solid discs - that’s good to know. The only question is are there different pads for the vented vs solid discs/calipers? And could I have mismatched them. I think it’s highly unlikely, but…

Regarding resetting the parking brake - yes I reverse the polarity with a 12v battery.

Cheers,

Robb

[apersson850]

Originally Posted by Vagabondrobb

I’m guessing the caliper itself isn’t different...

Oh yes they are. The ventilated disc is significantly thicker than the solid one, so the caliper needs to have a wider gap to fit over the thicker disc plus the pads.

From what I know, AWD cars have ventilated discs, FWD solid. But it's easy to see.

[Simmy]

use the brakes international on line catalogue all info on most thing attaining to car braking systems its a great reference point even if you don't buy from them.

[Kev0607]

Originally Posted by Vagabondrobb

Thanks Kev - some good info there!

They are solid discs. So vented would not fit in a caliper meant for solid discs - that’s good to know. The only question is are there different pads for the vented vs solid discs/calipers? And could I have mismatched them. I think it’s highly unlikely, but…

Regarding resetting the parking brake - yes I reverse the polarity with a 12v battery.

Cheers,

Robb

Euro Car Parts list two types of rear pads - One is for vehicles with an electronic parking brake and the other is for vehicles that don't.

I'm not sure why they list rear pads for this era of car that say "without electronic parking brake" because every P3 chassis Volvo onwards has an electric handbrake. Manual ones were done away with years ago.

My understanding that there's only one type of rear pad for this car anyway (the ones that say "with electric handbrake" are the ones you want, if buying from Euro's).

Vented discs are thicker than solid discs, the calipers for vented discs are a different size compared to a car with solid discs... the pads are the same though (for the rear anyway).

[Vagabondrobb]

Well I’ve replaced the discs and pads with those provided by euro car parts - the wobbling at speed seems to have gone, and the O/S disc doesn’t seem to get any hotter than the N/S after a drive. Hopefully that’s solved the problem - a warped disc caused by either or both poor quality parts and the previous failed caliper/electronic brake. I will be sourcing some quality brake components when budget allows.

Thanks all for your input and help.

Cheers!