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Car vibrating when braking... ABS?

dawg

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G'day. I notice it when reversing out of my driveway, and braking soft/medium while slowing down to a stop. The whole car vibrates and makes a low grrrr sound. I am thinkin it may be something to do with the ABS brakes. It is a v6 auto. Although i dont think it does it when driving at speeds,forwards. And it wont do it if i brake very softly when reversing.

Just wondering if anyone has had this before and has any ideas of how to fix it?
Cheers,
Dan
 

Patti2912

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Hey mate.
Shuddering when braking can be a large number of things.
Does it shudder when taking off (more so when fast) as well?
A few things that i know can cause it, if its shuddering on light braking, id suggest it could be warped rotors, possibly get these checked, if it is then have your rotors skimmed and get new pads.
Unless your rotors are just slightly warped, you may be able to feel your brake pedal pulsating whilst its shuddering, this is a pretty clear indication that thats the problem.
Also try replacing your spark plugs, leads and coils. I had a big problem with shuddering during take offs and replacing these things fixed it up perfectly.
Getting these things looked at/replaced is probably the first thing id do as its my understanding that they're the more common causes when dealing with shuddering during taking off and braking.
If its making a 'grumbling' kind of sound, then it could possibly be your wheel bearings as well, but that would be the case if the wheels were shuddering pretty much all the time.
If you are feeling the shudder more in the steering wheel, my suggestion is that its something to do with the front calipers/rotors/bearings, or if its mainly in the pedals then id be looking at the rear.
Can be a pain trying to eliminate the problem but id say take it to a mechanics with these things in mind and a few hundred dollars later you should be smiling.
Hope this helps bud.
 

hako

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Probably badly worn brake pads - either front or rear. It won't be ABS as you need to be above a certain speed plus the ABS light will come on and you'll feel the pedal vibrating. The grrr sound can come from a pebble stuck in the brake caliper but my bet would simply be worn pads.
 

VR_Acclaim

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heres a mind twist for you my vs and vr both done this after replacing bearing rotors and pads it was an engine mount
 

Patti2912

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heres a mind twist for you my vs and vr both done this after replacing bearing rotors and pads it was an engine mount
Engine mounts aye?
At least they are easy to check.
Put the car in reverse, get a friend to brake hard and slowly rev up and down, then put it in drive and do the same whilst you look at the engine,
If the sides lift then its your mounts.
I've never had to replace my engine mounts but im pretty sure your idle will be a mess if they need replacing.
 

Brett_jjj

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The V6 engine mounts tend to collapse before actually breaking.I have seen a few broken ones though,I had a lot of trouble with noises, and also a bad vibration in my VS about midway along the car,near the middle,a few people tried to tell me it was normal for a VS,pfff,yeah,right..I replaced the rear control arm bushes,the engine mounts and uni joints etc and trans mount and no more vibration or noise.The engine sat about an inch higher in the engine bay.I couldnt believe how far it had dropped.I think the vibration was from the engine sitting to low, and this was misaligning the drivtrain components and causing the vibration and noise.
 

dawg

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Cheers for the comments. Its fine when driving around at any speeds. it's only happened in reverse (so going pretty slow)
I have replaced the front rotors 18 months ago, as they were warped and shaking the car and steering wheel when braking. New rotors + pads fixed that one. This current issue didnt come about straight after that so i dont think there is any connection there.
Its makes the grumbling noise, but its the whole car that vibrates not just the steering wheel. But I can feel it through the pedal more than anything.
An engine mount or gearbox mount could be a possibility, will check this out tomorrow.
I've also noticed that every now and then randomly, the brake pedal gets really hard/stiff.... as if you were to pump the brakes a few times with the car off, it gets real firm. It sometimes does this on random occasions... thought this may be the power steering pump on its way out?

Thanks fellas
 

hako

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You may have a caliper piston sticking or a problem with the master cylinder to cause the hard/stiff brake pedal. It should have nothing to do with the PS pump. I'd get it seen to pretty soon as brakes are you last card....lose them and you are in big trouble....and you are getting the warning signs now. If you are prepared to check it out yourself then you should get hold of a Gregorys workshop manual as guidance and go from there. If unsure of exactly how and why brakes work/perform/fail then I'd say take it to a brake shop. Please don't take chances with brakes.
 

Cheap6

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^ yep. The guide pins that the caliper slides on can also wear and stick. It helps to remove them, clean the old grease off both the pin and the guide bore - which can get dry and hard - and relube with something like Copa-Slip or Never Sieze. Sometimes you can get away with rotating the pins in the guides, especially for the upper ones as most people undo the lower one to replace pads and it gets rotated anyway.

Worn wheel bearings can do funny things to brake feel too but they have to be pretty bad.
 

RainArcher

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I seem to be having the same problem. I just had a pbr brake kit put on and both the engine mounts were snapped and have been replaced but now on some turns it shudders (doesn't matter what speed it will happen randomly). Any ideas?
 
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