850 Rear Brake Repair - AGAIN - Tips

PeteB · Post by **PeteB** » 06 Jul 2017, 09:59

Link to Volvo Brake Service manual: http://www.volvotips.com/index.php/850- ... ir-manual/
I repaired our 1996 850 rear brakes back in 2014 when it was making loud rumbling
noises. I started to write here that the caliper pistons were frozen, but actually the
pads were rusted frozen in the slide area so that only one side pressed on the rotor,
probably causing the rumbling sound.
Documented in this old thread:
viewtopic.php?f=1&t=65446
Summary here: viewtopic.php?f=1&t=65446&p=442588#p442335
We did the following at that time:
1. Rebuilt uncoated Cardone Calipers from FCP and new NAPA Premium rotors.
2. New cheap pads from NAPA, replaced about 20K miles later with NAPA Premium
3. Cheap Hardware kit from a local auto parts store, later replaced with Volvo hardware.
We ended up using the original Volvo pins with the cheap hardware kit since we
could not get the new pins supplied to seat. If I were doing this again and could
not get OEM/ATE hardware I'd just clean up the original hardware and reuse it.
4. People talk about the half shims between the pad and piston preventing the rumbling
but they were there in our application and did nothing to help the situation. The
latest version of the Cardone rebuilds have pistons where half of the face steps
down about 1/16" which I believe accomplishes the same thing as the shims with
older flat face pistons. Not sure about this but will try them without half shims.

WARNINGS:
1. Pins from most of the aftermarket hardware kits do not fit properly, the retaining
ring is too large as shown in detail here - see 6/14/14 safety update:
https://volvo850wagon.wordpress.com/category/brakes-2/
Note that he found that the Duralast brand hardware kit fits and looks exactly like
the ATE kit that I just bought in 2017 so it might be fine.
Picture showing incorrect pins vs. OEM: https://volvo850wagon.files.wordpress.c ... cn3336.jpg
2. Most of the aftermarket retainer hardware does not fit properly often touching the
caliper rather than the pads - use original ATE hardware that is now cheap at FCP
and fits properly.
3. The original Volvo pins will fall out if you do not tap them in with a punch below
the surface of the caliper. I know this from experience.

Now in 6/2017 the rebuilds are also frozen even though I have inspected, cleaned and
greased them about once a year. One side has excessive even wear on the pads with
only 1/3 left, the other side has one pad looking nearly new and the other with only
about 1/3 left. My theory is that the flex hoses are partially blocked so that the pads
drag for a long time after application causing them to overheat, rapidly rust, and fail.
I'll post pictures soon of the massive amount of rust on these calipers.

I was at FCP returning the front caliper cores and also showed them the frozen rear calipers
from 2014 which they replaced no questions asked! I even brought the OLD DOT 4
used brake fluid from 2014 which they also replaced for free!

PeteB · Post by **PeteB** » 06 Jul 2017, 10:37

Picture of the Cardone caliper installed in 2014 as it looks 6-2017:

: REAR-2014-RUST.jpg (281.28 KiB) Viewed 2770 times

Older, probably original Volvo caliper from 1996, note that the pad is seized into the
slide area due to the massive rust. Also note how much more rust there is on the side
that seized and dragged, probably due to higher temps:
Note that the lower shoe has uneven wear due to the half shim, this suggests that as
the shoe wears the half shim becomes less effective as some have noted on here.

: REAR-CALIPER-1996.png (875.91 KiB) Viewed 2769 times

The next picture shows a variety of "anti-rattle" hardware, first with the rivet is the
original from 1996, next is 2014 purchased from Volvo (about $40 with pins), next
is 2017 ATE OEM, and final was included with the 2017 Cardone calipers and does
not fit reliably. One just barely fit the other was too wide, the extra width is visible
by eye. I used the 2017 ATE OEM kit from FCP and it fit properly:

: CALIPER-OLD-2014-2017.JPG (148.29 KiB) Viewed 2716 times

2014 Volvo hardware test fitted to show the clearance of about 1/16" on each side:

: CALIPER-2014.JPG (200.94 KiB) Viewed 2715 times

Next pic shows new rebuilt Cardone with included hardware. It did not fit and I bent
it as can be seen to make it fit - still it is not right, so we bought new ATE OEM parts:

: CALIPER-NO-FIT.JPG (153.94 KiB) Viewed 2715 times

This is the other hardware included with the Cardone that DOES fit but with nearly
zero clearance:

: CALIPER-FIT.JPG (106.58 KiB) Viewed 2715 times

ATE OEM kit installed in both new/rebuilt calipers:

: CALIPER-2017.JPG (73.24 KiB) Viewed 2715 times

ATE OEM KIT, cheap at FCP, note the correct and too large pins below:

: 2017-KIT.jpg (69.58 KiB) Viewed 2715 times

Post by **scot850** » 06 Jul 2017, 10:54

Wow, and I thought we had it bad here with the spray salt on the roads. I normally paint the calipers, or buy coated re-manufactured units. Problem with uncoated units is if they are warranted for a year, you can't paint them or it voids the warranty!

I only use ATE or OE Volvo parts for all the reasons you mention for the service parts like the pins, retaining springs and parking brake hardware. For rotors I use coated rotors like some of the Zimmerman parts.

While in there, look and test the parking brake cables are not binding causing your rumbling issue or the shoes have delaminated.

Dragging brakes caused by failed internals of the flexible hoses is not un-common at this age. They are a real pain to do on a FWD car at the rear and are easiest done with a hoist if you can get access to one. I found it easiest to remove the whole pipe at the rear to the RH rear to replace the hose in the middle on top of the rear axle.

Neil.

PeteB · Post by **PeteB** » 06 Jul 2017, 16:34

I've said this before, I'm fairly certain that the rate of a chemical reaction doubles for
every 10 deg rise in temp, so hot dragging brakes rust a lot faster. The inside was no
where near as bad as the side shown there.

One parking brake shoe did delaminate and I replaced them with cheap Pro-parts
figuring it is just the parking brake.

I asked about upgrading the rears to the coated type from Cardone and the guy
suggested that I just paint the new replacements before we put them on, claiming that
they WOULD take them down the road as cores.
People at FCP really try to just help and be cooperative however they can.
When I brought the front cores in they had to have the boxes from the new ones which
I had to bring the next time that I was in town.

Post by **scot850** » 06 Jul 2017, 16:58

The guys at FCP are awesome and I keep going back. However, was looking at replacing the front springs/seats/4-C (adjustable) shocks on the 06 XC70 and they were nearly $200 more expensive than Tasca. Do love the lifetime warranty though!

I wish you luck! I have found the coated are not necessarily that much more expensive. The front one I have from Nu-geon was about $5 more at Napa than a regular (crap) uncoated re-build from another supplier.

Neil.

Post by **erikv11** » 06 Jul 2017, 17:12

Holy CRAP that is an obscene amount of rusting. Never come across anything that bad, even though my cars run on winter, midwest highways.

Post by **matthew1** » 06 Jul 2017, 17:15

I've seen less rust from metal bits from the ocean.

PeteB · Post by **PeteB** » 06 Jul 2017, 19:45

@scott850 FCP will price match.

Post by **abscate** » 06 Jul 2017, 19:56

That will not buff out.....

PeteB · Post by **PeteB** » 06 Jul 2017, 20:02

The only thing that we've not changed are the hoses, so I'll assume that it needs them.

I added a picture of the original Volvo caliper.