Seagrams Posted June 2, 2009 Report Share Posted June 2, 2009 Ok so like the topic says, there is a terrible noise that happens intermittently when braking hard (it hasn't happened in a couple of days, but I have been moving and hard braking would put a lamp, desk drawer or picture frame through my dome piece or windshield). It's not the same sound as a worn out pad (been there) or warped rotors (there is no shimmy in the steering wheel) and I'm really hoping it's not ABS related (no codes at present). Ok so here goes, when I step on the brake pretty hard (maybe hard enough to engage ABS a bit) the WHOLE CAR shudders a bit and there is this awful, vibrating, buzzing, growly roar.... like a cross between a BZZZZZZZZZ and a GRWWWWRWAAHAAA... Like my phonetics? Could this be ABS? my pads were changed recently (akebonos i believe) and the rotors are all within spec in terms of thickness. Thoughts from the masses? I usually avoid trying to get help on the forums with noises to avoid describing them in text, but this sounds less than ideal and I would like any input please! Thanks!!! Link to comment Share on other sites More sharing options...
DonutsDemise Posted June 2, 2009 Report Share Posted June 2, 2009 at what point does the shuttering start? what situation are you braking in, like emergency braking on the highway due to a sudden back up from 70mph - 10mph or like stop and go traffic 25 mph - 0 mph? does the car pull to one side when this happens as if one of your front calipers lets go? when the abs kicks in, the car will shutter. dirty abs sensors could lead the abs unit to believe one or more wheels has locked up when really they are still rolling. if this were the case, when you hit about 5mph the sensors on affected wheels would read 0mph while clean sensors would read 5mph causing the abs to start pumping the brakes to avoid what it thinks is a locked wheel. what type of rotors are you running? you'll get loud cicada sounds if they are cross drilled, it's just the sound of the air moving through the holes and the pad moving over them. also, what are you running for your rear brakes? it could be vibrating back there if you don't have shims or the anti-squeal stuff is gone. Link to comment Share on other sites More sharing options...
Oreo931 Posted June 2, 2009 Report Share Posted June 2, 2009 Did you replace the shims? Link to comment Share on other sites More sharing options...
AverageVolvo Posted June 3, 2009 Report Share Posted June 3, 2009 As above mentioned Without Rear shims, will cause a nasty vibration Also possibly wheel bearing. Abs pump/module What is cars mileage Turbo or NA What year front noise or rear can you tell. Does it happen at high speed or low speed braking or both Link to comment Share on other sites More sharing options...
DennisG Posted June 3, 2009 Report Share Posted June 3, 2009 Have similar problem and replaced rear shims.Went away. ;) Link to comment Share on other sites More sharing options...
Seagrams Posted June 3, 2009 Author Report Share Posted June 3, 2009 It's not the vibration that really concerns me as it's not that pronounced, it's the sound. The situations it happens in (again i haven't heard it in a couple days as my car is packed with my life)aren't emergency braking situations, more like stopping from 40 mph a bit harder than you would normally, if that makes any sense. So i guess like halfway hard braking. It doesn't happen at low speed braking, or even high speed braking as long as the pedal isn't pressed too hard. The car as it says in my sig, is a 96 850R, stock rotors (no cross drilled)with 148K on the ticker. The sound def. sounds like it's coming from the rear. There is no pull to one side or the other... I guess what it kind of sounds like is when you go over those rumble strips like they have entering a school zone, but a bit higher pitched. Rear brakes are stock with akebono pads, not sure if the shim is there or not, I wouldn't imagine that it could fall out though. Can you check to see if it's there without taking the caliper off? I don't usually do my own brake work and acutally haven't ever had the rears apart, only the fronts. I'll have to check on the shims then (any advice there?) and empty my car and do some hard braking to really nail it down and give you guys some more information. Link to comment Share on other sites More sharing options...
Black Betty Posted June 4, 2009 Report Share Posted June 4, 2009 to check the shims you have to take the back apart. The good thing is theres no bracket for the back so its 2 bolts and the caliper and pads are off. When you go and check it out. check to make sure the dust boots are intact, and check to make sure the calipers are not seized. When you drive the car for a while are the wheels very hot? If a caliper is seized it will heat up the wheel signifcantly. To check if its seized simply use a C clamp or heavy duty vice grips and place a pad on the piston and try to compress the piston. Make sure before this you take the cap off the brake fluid resevoir. If you can move the piston its not seized. Link to comment Share on other sites More sharing options...
AverageVolvo Posted June 4, 2009 Report Share Posted June 4, 2009 Jack car up, pull rear wheels off, From back of caliper you can view pads, and should see a metal shim with a directional arrow, If you cannot see clearly , then there are two pins on each caliper that hold the pads in, , With a hammer and chissel, you can pop them out and inspect shims, There should be a soft shim attached to pad and a metal shim between caliper piston and the first shim which again rests against the pad. Check that everything is properly tightened, unfortunately mechanics make mistakes, especially non volvo mechanics. : ( Link to comment Share on other sites More sharing options...
volvoluvin Posted June 4, 2009 Report Share Posted June 4, 2009 I had this exact problem a couple weeks back...had the rotors machined and it went away nicely.. Link to comment Share on other sites More sharing options...
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