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brake vibration

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Matty Moo
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Year and Model: 850, 1996
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Re: brake vibration

Post by Matty Moo »

If you hear the mechanical grinding noise and feel the same noise through the pedal in the form of feedback then it's the abs system.
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http://www.midwest-abs.com
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1996 850 Platinum Wagon. ARD Green Tune, OBX.-Gone
1998 s70 ARD tune, EST exhaust, SE/R interior.
1999 s70 Plain Jane.
2000 s70 GLT
2014 Ram
2012 Jeep Wrangler Unlimited

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MrAl
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Post by MrAl »

Hi,

I had a similar problem in one back brake and had the rotors replaced and the sound went away.

There is a way to check the rotors for warping, by checking the runout. A dial indicator is mounted somewhere while the rotor is turned by hand, and the runout has to meet a certain spec. If it meets the spec then it is not considered warped, but if it does not meet the spec then it is considered warped. You might have to check for your model/year on the spec. I dont think it's too hard to do this but you have to remove the wheel and have a dial indicator with mounting arm.
I’ve been driving a Volvo long before anyone ever paid me to drive one.
That's probably because I've been driving one since 2015 and nobody has offered to pay me yet.
1998 v70, non turbo, FWD, base model, on the road from April 2nd, 2015 to July 26, 2023.

cynlim
Posts: 8
Joined: 4 January 2015
Year and Model: 850 1997
Location: Malaysia

Post by cynlim »

would the mechanical grinding noise sound like wooongwooongwooong? The abs code cannot be removed and I didn't see any blue colour on the rotors of all four wheels. I personally think its the abs system and I have asked the mechanic if I can remove the whole damn module from the car since its faulty and cost me an arm and a leg to repair. My last resort would be to skim the rotors in the rear since its still thick. What is ebrake? I'm sorry for probing cos I know next to nothing about the mechanics

Sommerfeldt
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Post by Sommerfeldt »

E-brake - emergency braky - your handbrake. :)

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2018 S90 T8 Inscription - glossy black with amber interior and dark as night rear windows.
[Gone] '96 855 T5 - R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
[Sold] '97 S70 T5
[Gone] '95 855 T5-R - one of the black ones... sadly stolen and wrecked.

cynlim
Posts: 8
Joined: 4 January 2015
Year and Model: 850 1997
Location: Malaysia

Post by cynlim »

for once I thought ebrake was electronic brake, and what the heck was that, lol!

For the latest update, I had three fuses related to the abs removed from the fusebox in the bonnet. The rattling is not so severe now. I'll test the car a few more days to see if it gets any better.

Thanks all for the feedback.

Matty Moo
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Post by Matty Moo »

cynlim wrote:would the mechanical grinding noise sound like wooongwooongwooong? The abs code cannot be removed and I didn't see any blue colour on the rotors of all four wheels. I personally think its the abs system and I have asked the mechanic if I can remove the whole damn module from the car since its faulty and cost me an arm and a leg to repair. My last resort would be to skim the rotors in the rear since its still thick. What is ebrake? I'm sorry for probing cos I know next to nothing about the mechanics
No. It makes a loud mechanical grinding noise with feedback through the pedal. What you're describing isn't it.
Image
http://www.midwest-abs.com
Simplycleanpowerwash.com

1996 850 Platinum Wagon. ARD Green Tune, OBX.-Gone
1998 s70 ARD tune, EST exhaust, SE/R interior.
1999 s70 Plain Jane.
2000 s70 GLT
2014 Ram
2012 Jeep Wrangler Unlimited

JNavas
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Post by JNavas »

MrAl wrote:There is a way to check the rotors for warping, by checking the runout. A dial indicator is mounted somewhere while the rotor is turned by hand, and the runout has to meet a certain spec. If it meets the spec then it is not considered warped, but if it does not meet the spec then it is considered warped. You might have to check for your model/year on the spec. I dont think it's too hard to do this but you have to remove the wheel and have a dial indicator with mounting arm.
Rotors do not "warp", a common misconception. What happens is uneven wear, usually caused by improper installation or improper turning. Proper rotor installation is critical.
Hope that helps,
John
2008 Volvo S60 2.5T (black with oak interior)

Sommerfeldt
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Post by Sommerfeldt »

JNavas wrote:Rotors do not "warp", a common misconception. What happens is uneven wear, usually caused by improper installation or improper turning. Proper rotor installation is critical.
I don't really see how this is relevant. "Warped rotors" is a common expression, and while it may be somewhat of a misnomer, most mechanics know that what people call warped rotors is caused by uneven adherent and abrasive friction. So it doesn't really matter, just like the fact that most people say that their brake rotors are steel, when they are, in fact, cast iron.

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2018 S90 T8 Inscription - glossy black with amber interior and dark as night rear windows.
[Gone] '96 855 T5 - R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
[Sold] '97 S70 T5
[Gone] '95 855 T5-R - one of the black ones... sadly stolen and wrecked.

JNavas
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Post by JNavas »

Sommerfeldt wrote:
JNavas wrote:Rotors do not "warp", a common misconception. What happens is uneven wear, usually caused by improper installation or improper turning. Proper rotor installation is critical.
I don't really see how this is relevant. "Warped rotors" is a common expression, and while it may be somewhat of a misnomer, most mechanics know that what people call warped rotors is caused by uneven adherent and abrasive friction. So it doesn't really matter, just like the fact that most people say that their brake rotors are steel, when they are, in fact, cast iron.
With respect, "warp" is more than a misnomer -- it's misleading.
What makes it relevant is that excessive runout is a common cause of brake vibration.
And rotor materials are not just cast iron -- better rotors are sophisticated alloys and other materials.
Hope that helps,
John
2008 Volvo S60 2.5T (black with oak interior)

Sommerfeldt
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Post by Sommerfeldt »

JNavas wrote:And rotor materials are not just cast iron -- better rotors are sophisticated alloys and other materials.
... and when was the last time you installed carbon-carbon or ceramic matrix on a Volvo? :roll: "Sophisticated alloys" and "other materials" aren't used that much in brake discs, buddy.

- S
2018 S90 T8 Inscription - glossy black with amber interior and dark as night rear windows.
[Gone] '96 855 T5 - R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
[Sold] '97 S70 T5
[Gone] '95 855 T5-R - one of the black ones... sadly stolen and wrecked.

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