Vibration when brakes applied

GerryB · #1 (**permalink**) 04-09-2005, 11:57 PM

Hi,
My 1984 Afetta sedan has been basically laid up for nearly 12 months and I re-registered it last week. I've noticed that, when I brake, there's a noise which sounds just like going over closely spaced corrugations on the road. I assumed it was rust on the rotors but that isn't the case. I also suspected a warped rotor but, having checked them, they're all fine and none of the calipers are loose etc. One other thing that has me thinking is that I suspected that there was an engine vibration which was apparent at about 1500 to 2000 rpm that wasn't there before - if I rev the car whilst stationary. I've started to wonder now if it could be the rear donut (the noise / vibration seems to come from the rear). My theory was / is that, whilst braking, the rear axle tries to rotate (by inertia I mean) and, in doing so, if the donut was damaged, would accentuate any noise / vibration by placing a strain on the coupling. It does seem as if the noise is about twice road speed. I haven't been under the car to check yet but I wondered if anyone agreed with this as a possibility ? Any suggestions (as always) welcomed !!

muhraka · #2 (**permalink**) 04-10-2005, 05:38 AM

try checking the gear box mounts as well

**papajam** · #3 (**permalink**) 04-10-2005, 06:00 AM

Does the nature of the vibration change if you brake while in neutral or with the engine switched off? Also, if braking with just the handbrake is the vibration still there?

GerryB · #4 (**permalink**) 04-10-2005, 01:29 PM

Hi
Yes, still there in neutral but I'm not sure it's quite as bad.
Good point about if it does it with the enguine off and coasting - haven't tried that yet - I will today !

alfetta77 · #5 (**permalink**) 04-13-2005, 05:46 AM

Hello Gerry,

Try looking at the condition of the centre bearing and also the rubber donuts. If they are fine check the condition of the bearings in the clutch housing, but I'll do this last as it involves taking the clutch housing out.

Hope this get you thinking

Regards,

Julian

GerryB · #6 (**permalink**) 04-16-2005, 01:52 AM

Hi again

Thanks for the suggestions - much appreciated.
An update is that I did, in fact, try coasting, engine off etc and the vibration is still there. I'm assuming, by this being the case, that it has to be brake related (?). I've examined the front discs and found the offside rotor has strange 'patches' on the surface in a couple of places - almost like faults in the metal - except I suspect they may have been caused by the pads staying on the disc whilst the car was laid up for the past 12 months, only moving a couple of times and not being driven as such. What threw me was that it seemed, even to a passenger, that the noise was coming from the rear but the rear rotors are perfect, although getting to a stage of needing replacement due to thickness wear. I suppose, pain as it is, I'll only confirm my suspicions by changing the front rotors. Not sure about the centre bearing but I could check it just in case, wheel bearings are all fine, although a couple need adjusting. I really do appreciate the interest, response and time taken by you guys in responding with suggestions, again, my thanks.

**papajam** · #7 (**permalink**) 04-16-2005, 03:51 AM

Yes, since the vibration is still there when the engine is switched off, the drivetrain has been eliminated and points to the brakes as the source of the vibration. But before shelling out for new front rotors, try braking using only the handbrake. If the vibration is there, the problem is in the rear; if no vibration, it's the front.