1996 850 Strong Vibration During Braking

PeteB · Post by **PeteB** » 24 Aug 2014, 19:29

My son's new/used 850 has started having very strong vibration with a sort of droning noise in the rear on braking. I've read of where it this happens on the 850 after the brakes are hot, and more so at low speed. This is all the time and gets progressively worse with increased speed.
We were fairly certain that it was the rotors and thought we'd start from the front, even though I thought more of the sound came from the rear.

We used Napa Premium rotors which I understand are from Raybestos and seem to be decent from my research and speaking to their tech people and also Napa Premium Semi-metallic pads. My son says that it is significantly better but the issue is clearly not solved. We plan to do the rear next but I'm looking for any tips that might help.

I read that there are shims to replace and we plan to do this just to avoid any other problems and in the hope that it will fix the vibration.

We will inspect things in the rear but is there anything else in particular to look for?

One concern about the new front rotors is that they were not tight on the hub. They sat flush and square but the hole was about 1/64" too big and there was slight play - is this something to worry about? I certainly don't like it since I seem to remember most fitting snug with no play at all.

Post by **dosbricks** » 24 Aug 2014, 21:09

Here is an excellent DIY (with many photos) by an MVS member who blogs his repairs. It should cover all your questions.

http://volvo850wagon.wordpress.com/cate ... rake-pads/

Post by **jreed** » 25 Aug 2014, 05:05

+1 on above recommendation... this is a good blog and I look forward to reading new posts!

My experience with vibrating rear brakes was solved by adding stainless steel shims between the pads and caliper. I used OEM Volvo pads, ATE rotors and got the stainless steel shims from FCP.

Post by **dosbricks** » 25 Aug 2014, 13:00

+1 on above. I also use Volvo pads and the stainless shims on the rear.

Some members have reported no squeal and low dust from Mintex red box pads made in England, but I was unable to find a US supplier that stocked the rear pads. Fcp has the fronts and I am trying out a set on the S70. I only have about 800 mi. on them, but so far they seem to stop well and produce less dust.

PeteB · Post by **PeteB** » 25 Aug 2014, 16:18

Thanks, that blog really does answer all my questions.
I did read about the brakes before starting this but I didn't notice any
particular brand favorites so I just went with what I usually use - we'll see how
this turns out. Prices have been very good so far but I'm starting to think I
should have used OEM brake pads, or a lower dust type.
Anyone tried ceramic type pads?

I ordered the NAPA Premium rotors and pads for the rear, and the shims from
FCP. I've actually never dealt with FCP, and I was in a restaurant with wifi
looking up parts when finishing the FCP order it offered, pick up in Milford
CT. I was having lunch in Milford, lol! Went to the location and Wow, it is
the corporate headquarters and quite the fancy building ... looks like something
from a movie. I ordered right at the front desk and was standing outside the
President/Founders door! The CEOs office was right next to it.

I looked into Raybestos about 6 months ago since I kept seeing posts on other
forums saying that their "professional" rotors were quite good. The more
recent posts were mixed with many saying that fabrication moved to China
and the quality went way down. I called their tech support and the fellow
seemed quite knowledgeable, claiming that they had some problems since
they did not have a good source for steel there until they bought their own
foundry there. They own and operate that foundry and he says they are
getting very high quality steel. I asked if he was sure that the NAPA Premiums
were their parts and he said that HE actually trained the NAPA sales people,
so yes absolutely they are their parts. NAPA Premium = Raybestos Professional:
http://www.raybestosbrakes.com/magnolia ... otors.html

Post by **dosbricks** » 25 Aug 2014, 17:38

No doubt if you need Volvo parts in a hurry, it certainly would be convenient to be on your lunch hour in Milford, CT!

Post by **shaker_chi** » 25 Aug 2014, 19:08

When you do the rear rotors remember you have to adjust the emergency/parking brake. If not, when you pull off the rotor you will pull the brake drums with it (don't ask me how I know!!!). The adjustment is done via the little hole and you have to line it up with the adjuster. Do a search on here or google it, It's been a while since I did it. Good luck.

Post by **jblackburn** » 26 Aug 2014, 10:14

Anyone tried ceramic type pads?

I have used Akebono ceramics on 2 cars now, and Wagner ceramics on another and have been very pleased with all of them. Minimal dust, no noise except first stop on a rainy day, and good bite at all times.

PeteB · Post by **PeteB** » 27 Aug 2014, 08:43

Thanks very much for the additional tips. I'll probably go ceramic next time since I already
have the parts now.

I picked up the NAPA premium rear brake pads and they have shims included and
installed. They snap on and seem to have some glue there also. I bought the factory
improved shims so should I remove the sort of integral shims and use these or
return the pads and get some alternatives? I'm inclined to return them since I don't
want this vibration coming back.
Edit: Looked again at the blog and his also look to have the integral and factory upgrade,
extra shim so perhaps I'm okay with these?

Post by **dosbricks** » 27 Aug 2014, 14:13

Many pads now have a built-in shim, but they have a limited life span. On my last set of Volvo OE pads on the 850, the organic shims had worn through and the squeal was horrible. I replaced with the same pads but added the additional stainless steel "L" shims. On the S70, I had become aware of and installed the SS shims, and they kept the brakes quiet throughout the life of the Volvo OE pads.