Slapping Noise when brakes applied

dallasite21 · October 30th, 2009, 11:41 AM

I have a 1971 Cutlass, and I am having a problem when I hit my brakes. This only occurs when I am going faster than say 40mph and I hit the brakes hard. I feel a knocking that vibrates up through the shifter and I hear the knocking noise like somoeone is knocking on your door really fast and the tempo slows as the car slows. I almost feel like it would be my emergency brake pulling tight for what ever reason, but I dont know... Anyone else ever have this problem?

joe_padavano · October 30th, 2009, 01:08 PM

Quote:

Originally Posted by dallasite21

I have a 1971 Cutlass, and I am having a problem when I hit my brakes. This only occurs when I am going faster than say 40mph and I hit the brakes hard. I feel a knocking that vibrates up through the shifter and I hear the knocking noise like somoeone is knocking on your door really fast and the tempo slows as the car slows. I almost feel like it would be my emergency brake pulling tight for what ever reason, but I dont know... Anyone else ever have this problem?

This could be a lot of things. Certainly a warped rotor could cause this problem. I'm leaning towards worn steering or suspension parts, however. Have all the moving parts in the front suspension checked for wear.

Bluevista · October 30th, 2009, 01:09 PM

It sounds like it could also be the rear end/differential or universal joints if it's knocking that fast then slows. I would check the U-joints soon, don't want the driveshaft falling off and doing major damage.

gearheads78 · October 30th, 2009, 02:54 PM

Busted transmission mount letting the driveshaft hitting the floor?

dallasite21 · October 30th, 2009, 05:29 PM

I think the transmission mount sounds like the most logical thing... You are about the third person I have had tell ne that. The next question is how difficult is it to replace?

gearheads78 · October 30th, 2009, 07:23 PM

Quote:

Originally Posted by dallasite21

I think the transmission mount sounds like the most logical thing... You are about the third person I have had tell ne that. The next question is how difficult is it to replace?

Real easy. Should be 3 or 4 bolts. Get the car up on stands or ramps, loosen the bolts, jack up the back of the trans a little to pull the old mount and install the new one. If you don't have tools or equipment and are in Dallas (assuming from user name) I can knock it out for a few bucks. PM me if you need to.

October 30th, 2009, 11:41 AM	#1 (permalink)
dallasite21 Registered User Join Date: Jun 2009 Posts: 11	Slapping Noise when brakes applied I have a 1971 Cutlass, and I am having a problem when I hit my brakes. This only occurs when I am going faster than say 40mph and I hit the brakes hard. I feel a knocking that vibrates up through the shifter and I hear the knocking noise like somoeone is knocking on your door really fast and the tempo slows as the car slows. I almost feel like it would be my emergency brake pulling tight for what ever reason, but I dont know... Anyone else ever have this problem?

October 30th, 2009, 02:54 PM	#4 (permalink)
gearheads78 Super Moderator Join Date: Apr 2008 Location: Dallas TX Posts: 1,563	Busted transmission mount letting the driveshaft hitting the floor? __________________ -Richard 66 Cutlass ragtop my way Keep watching your cotton candy coated TV while your world falls apart around you...

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October 30th, 2009, 01:09 PM	#3 (permalink)
Bluevista Cruisin' the Vistas Join Date: Jul 2006 Location: Northeast Ohio Posts: 1,720	It sounds like it could also be the rear end/differential or universal joints if it's knocking that fast then slows. I would check the U-joints soon, don't want the driveshaft falling off and doing major damage.

October 30th, 2009, 05:29 PM	#5 (permalink)
dallasite21 Registered User Join Date: Jun 2009 Posts: 11	I think the transmission mount sounds like the most logical thing... You are about the third person I have had tell ne that. The next question is how difficult is it to replace?