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Discussion Starter #1
on my 87 Platinum. After the car is warmed up. I come to a stop but before I fully stop. Lets say the last 40' I start to push the clutch in and the brakes as usual. Then about the last 15' the car (man, try to type in a sound here) starts to vibrate like the clutch is dry or maybe the calipers are loose or the rear rotors are loose. Its like a dry chatter. can't tell if its the brakes or clutch. If you were to put a large disc with a 1/2 hole onto a rod with a 3/8 hole. It would spin good until it got to a certain speed and then it would chatter, vibrate, make a sound that i can't duplicate in type, lol.
If i let go of the clutch it goes away but it also means i let go of the brake too. I have no driveline vibration what so ever. Any ideas?
 

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im going to go with an exhuast hanger that has loosened and they can be tricky to find. also could be your driveshaft hitting your exhuast.
 

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As somebody who just got done with 4 trips to muffler shop to tweak new exhaust... you may have nailed it bc.

krazy, does it change pitch if you go hard left right?
 

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If you make a more hard stop, i.e. brake harder to a complete stop, does it go away? I would guess the rear brake pads are the source of the noise. I have had something similar in the past, but only after car is warm (been driven for 30-45min) or race car, and only during light braking, and only during the final feet of coming to a complete stop. I'm guessing the rear pads are vibrating as you are braking so light that only material clamping is applied to the fronts, and the rears get to a specific point where they vibrate but not enough to clamp them firmly against the rotors. You have the separting "springs" on the pads?
Jes
 

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new place to check is well is the header bolt to the cat can get loose and can rattle in all sorts of ways.
 

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Discussion Starter #7
If you make a more hard stop, i.e. brake harder to a complete stop, does it go away? I would guess the rear brake pads are the source of the noise. I have had something similar in the past, but only after car is warm (been driven for 30-45min) or race car, and only during light braking, and only during the final feet of coming to a complete stop. I'm guessing the rear pads are vibrating as you are braking so light that only material clamping is applied to the fronts, and the rears get to a specific point where they vibrate but not enough to clamp them firmly against the rotors. You have the separting "springs" on the pads?
Jes
Yes this is what it is like. Its difficult to explain but I think you explained it pretty well. as for your question. the answer is yes it goes away, but i can't be stopping that hard in regular traffic, I'd look silly. As i am i the last few feet of stopping, that whale bellowing chatter sound actually will remain even if i let off of the brake pedal and attempt to finish the stop with the clutch. Usually a good clutch dump at the last second cures it. But I also realize that that just means I am taking the stopping responsibility away from the rear brakes and temporarily giving it to the clutch. That being said the last few seconds I still have to use the brakes again and the bellowing chatter sound returns right up to the dead stop.
It is not the driveshaft, it is not related to the exhaust system, it is not a hanger, Its something in the brakes or clutch but my gut says brakes.
 

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If it is what I experienced it is definitely rear brake pads. Various manufacturers have this goo compound you can put on the back of pads. If it does it even with you being off the brake, then I wonder if you have rear brake pad clearance set correctly with the adjusters. Try back the pads off a tad.
Jes
 

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if its your pads shaking get them done immeditly before you need new calipers. the release valves will never come back if you let the pads go to far.
 

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This phenomenon is not related to pads being worn. There is likely nothing wrong with the pads.
Jes
 

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Discussion Starter #11
Jes I think were on the same page. Pads are very close to brand new. They are those Ferdo ones. My E brake started out low and now its high. Maybe I need to make sure my adjustments on both sides are still up to spec. in a mental visual I can invision the lets say outside pads pushing on the rotors and the inside pads doing almost nothing. I can see a "chatter" taking place from unequal pressures. Maybe I should mount my GoCam down there to catch this on film. Might be interesting unless the camera vibrates off the car and I run it over.
 

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I am not going to name names, but be careful with the camera down there: Someone among us once put a camera on the ground to capture the great exhaust note, but ended up running over the camera :eek: Collateral damage I suppose, serving a bigger, noble Alfa cause ;) Yeah, I would check clearances and set hand brake tension, but even if you can't get rid of it I wouldn't sweat over it, unless if the noise+virbration drives you insane.
Jes
 
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