Serious Brake Vibration on 850

CamZH · Post by **CamZH** » 23 Apr 2012, 20:05

Hi Guys,
Had a quick search on my issue byt didnt find anything relevent.

I'm getting a very serious vibration when braking.
It only happens when coming to a stop, from say 15km/h to 0
60km/h to 15km/h is fine, but the last stopping is sometimes met with a very serious vibration.

It appears to be coming from the front left, it doesnt always happen, but seems to be getting more common.

I've recently replaced all the front suspension components and axels.
Brakes and rotors are around 20,000-30,000km old. but pads look to still have a bit of life in them.

Sometimes i can back off the brakes and re apply and the problem isnt there.

Any ideas ?

the car is a '96 854 R with 160,000km on the clock.

Post by **jblackburn** » 23 Apr 2012, 20:11

Sounds like the ABS kicking in.

Remove both front wheels. Behind the brake rotor, you'll see a little sensor. These have a 10mm bolt holding them in; remove the sensor and clean them up with some Simple Green, carb cleaner, or other good cleaning solution and an old toothbrush. Before you reinstall it, look down at the reluctance ring that the sensor contacts on the axle. Give those a good scrubbing down as well.

This will keep the ABS system from thinking that wheel is slipping anymore.

Post by **jblackburn** » 23 Apr 2012, 20:16

By the way, please don't use the Volvo jack. It will collapse or fall over and damage your car - or even worse - fall on you and kill you.

A good jack and jack stands, please!

CamZH · Post by **CamZH** » 23 Apr 2012, 20:24

Thanks for the quick response.

Don't worry I dont use the Volvo jack.
I'll give the ABS sensors a clean, when the vibration is happening i still have complete control and the car still slows down.
I didnt give the ABS sensor a clean when I changed all the other front end bits, but I'll do so today.

CamZH · Post by **CamZH** » 29 Oct 2012, 16:27

So this problem kinda went away for a while, but has reared its head again.
The ABS sensors have now been cleaned, I've tried running the car with the ABS pump fuse removed and its still there.

Just yesterday I've installed new brake pads in the front, the rears are low, but not metal on metal.
I've also recently installed some teflon shims in the rear too.

I didnt get the front disc cut when i replaced the pads, as I was hoping to see if these new (cheap) pads would solve the problem before I go out and get good pads all round.

Any more ideas ?

kcjones · Post by **kcjones** » 29 Oct 2012, 20:55

I believe you have brake shudder. I fought this same problem for months.

The best fix for me was Akebono pads and performance rotors. I tend to brake fairly aggresively sometimes, and my rotors kept warping. After buying drilled/slotted rotors, my junky old pads caused a bunch of vibration. Akebono pads have been impressive so far.

You probably don't need really high-end rotors unless you are a "spirited" driver, but personally I'd rather have one crack than warp and lose braking power.

SimLyons · Post by **SimLyons** » 29 Oct 2012, 21:06

I had same problems (many brands of rotors) and resolved the last few with taking my Zimmermans (or brand X rotors) in and shaving them down to perfectly flat.

14K miles and great results. Not a hint of wobble!

driesbabe · Post by **driesbabe** » 31 Oct 2012, 00:35

If the car feels like a earthquake is happening at +- 50hz, it's your brakes in the rear. If you have access to Vida then have a look for the bulletin on the rear brake vibration. You will need to replace the shims with a special replacment.

Regards
Andreas

CamZH · Post by **CamZH** » 31 Oct 2012, 02:08

driesbabe wrote:If the car feels like a earthquake is happening at +- 50hz, it's your brakes in the rear. If you have access to Vida then have a look for the bulletin on the rear brake vibration. You will need to replace the shims with a special replacment.

Regards
Andreas

Earthquake describes it well.
But its only intermittent, and seems to be less with the new pads in the front.

I dont know what Vida is, can you help me out with where to find the correct shims and other info.
I was looking at re-building all of the calipers shortly, so that might solve some of the problem.
Along with machining all discs and replacing all pads.

Post by **precopster** » 31 Oct 2012, 07:09

If you're going to go to all that trouble with an R I would be doing the 302mm front brake upgrade available through IPD volvo. It uses the original calipers and pads and the kit comes with larger brackets and discs; perfect for the more powerful cars.

Or you can just find out the bracket part number and order these separately, then use local discs to save on the freight.

A link to a write-up here: https://www.matthewsvolvosite.com/forums ... =1&t=38299