Vibration in pedal

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Jan 19, 2022 | 02:52 AM

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

Likes: 15

From: Maryland

Vibration in pedal

Started driving my recently acquired C3 1982. Starting at around 55 mph I feel a buzz In the accelerator, and a slight noise. I can't really describe the noise, its like a buzzing noise. Im not sure how much the sound persists after 55mph, I didn't push it past that. What could be the causes?

Jan 19, 2022 | 04:55 AM

Budryzer

Instructor

Joined: Oct 2021

Posts: 157

Likes: 29

From: Montezuma Ga

Typically, pulsating of the brake pedal is a result of having warped brake rotors. Possible resulting in the buzz from the pulse/vibration????? I bet its the front rotors, not the rear.

Jan 19, 2022 | 09:39 AM

interpon

Le Mans Master

Joined: Jun 2019

Posts: 7,658

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From: Indiana

New to you?
tires balanced? How old are they? Does it run smooth other than that?

Jan 19, 2022 | 09:57 AM

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

Likes: 15

From: Maryland

Quote:

Originally Posted by Budryzer

Typically, pulsating of the brake pedal is a result of having warped brake rotors. Possible resulting in the buzz from the pulse/vibration????? I bet its the front rotors, not the rear.

buzz is in the accelerator pedal. It’s slight, not as much as a brake pedal with bad rotors.

Jan 19, 2022 | 09:58 AM

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

Likes: 15

From: Maryland

Quote:

Originally Posted by interpon

New to you?
tires balanced? How old are they? Does it run smooth other than that?

Yea runs amazing until 55. There’s a jerk in the car sometimes when I shift from park to drive.

Jan 19, 2022 | 12:09 PM

AKjeff

Pro

Joined: Apr 2010

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From: Carson Valley

Have you checked the u-joints? Does it do on deceleration and coasting as well as acceleration?

Last edited by AKjeff; Jan 19, 2022 at 12:34 PM. Reason: grammar error

Jan 19, 2022 | 12:31 PM

calwldlife

Team Owner

Joined: Jan 2007

Posts: 53,648

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From: Southern Cal Ca

St. Jude Donor '22

I believe an 82 has an IAC.
this will control idle with a piston.
maybe that system is broke?

Jan 19, 2022 | 10:34 PM

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

Likes: 15

From: Maryland

Quote:

Originally Posted by AKjeff

Have you checked the u-joints? Does it do on deceleration and coasting as well as acceleration?

only with pedal depressed, so in acceleration

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Jan 19, 2022 | 10:34 PM

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

Likes: 15

From: Maryland

Quote:

Originally Posted by calwldlife

I believe an 82 has an IAC.
this will control idle with a piston.
maybe that system is broke?

how would this affect it? As far as I know, my iac works on idle.

Jan 20, 2022 | 03:39 AM

#10

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

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From: Maryland

Quote:

Originally Posted by interpon

New to you?
tires balanced? How old are they? Does it run smooth other than that?

Also yes I believe tires are balanced. Tires look near new. Runs smooth otherwise, vibration and buzz sound only happens when hitting accelerator over 45. on today's test run sometimes it did it, sometimes not, complete random.

Jan 20, 2022 | 09:19 AM

#11

interpon

Le Mans Master

Joined: Jun 2019

Posts: 7,658

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From: Indiana

Suggest posting lots of pics..
check motor mounts ( must pry to check) u joints, transmission mounts etc..even overall suspension bushings etc..

Jan 20, 2022 | 11:23 AM

#12

diehrd

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Joined: Jan 2009

Posts: 4,000

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From: New York

Quote:

Originally Posted by nitan2k

Yea runs amazing until 55. There’s a jerk in the car sometimes when I shift from park to drive.

Check Trans mount , and rear diff snubber , make sure the ebrake cable is not in contact with drive shaft .

Jan 20, 2022 | 04:27 PM

#13

nitan2k

Thread Starter

Racer

Joined: Oct 2021

Posts: 436

Likes: 15

From: Maryland

Quote:

Originally Posted by interpon

Suggest posting lots of pics..
check motor mounts ( must pry to check) u joints, transmission mounts etc..even overall suspension bushings etc..

Quote:

Originally Posted by diehrd

Check Trans mount , and rear diff snubber , make sure the ebrake cable is not in contact with drive shaft .

will do. Could it be a problem in the transmission itself? I don’t feel the body of the car vibrating, just the pedal and the floor a little

Jan 20, 2022 | 05:07 PM

#14

diehrd

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Joined: Jan 2009

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From: New York

Quote:

Originally Posted by nitan2k

will do. Could it be a problem in the transmission itself? I don’t feel the body of the car vibrating, just the pedal and the floor a little

Possibly but not likely .

Jan 23, 2022 | 01:12 AM

#15

nitan2k

Thread Starter

Racer

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From: Maryland

Ok so after some more test drives, I can't consistently recreate the problem. It just happens 50% of the time. All I can say is that It tends to happen more when accelerating on uphills, and whenever it does happen if I let my foot off of the accelerator and press it again gently, it goes away. Any ideas? again, its like a slight vibration in the pedal and a slight grinding noise under the car.

Jan 23, 2022 | 02:17 AM

#16

4-vettes

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From: Sunshine Coast, Queensland, Australia

2025 C3 of the Year Finalist - Modified

2024 C3 of the Year Finalist- Modified

2022 C3 of the Year Finalist - Modified

Cruise-In VIII Veteran

Have you checked all the U joints? If original the grease in them dryes up and or the go rusty in the needle bearings.

Jan 23, 2022 | 02:18 AM

#17

nitan2k

Thread Starter

Racer

Joined: Oct 2021

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From: Maryland

Quote:

Originally Posted by 4-vettes

Have you checked all the U joints? If original the grease in them dryes up and or the go rusty in the needle bearings.

nope, how do I check those? Don’t see the section in the manual

Jan 23, 2022 | 05:36 AM

#18

4-vettes

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From: Sunshine Coast, Queensland, Australia

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Step one. Grab the drive shaft or half shaft with both hands rotate back and forth. Observe the u joint. Any movement, twist in it? Check all 6. Step two. unbolt the straps on U joint. pull it free. grasp the joint and move it in all directions.
Feel smooth? Feel rough or gritty? Any movement in joint (looseness) Bad joint. Any roughness or gritty feeling when moving it. Bad joint!
One gritty joint can give you a light rumble vibration.
When it let's go! Whooo Hooo! can be catastrophic!

Jan 23, 2022 | 11:07 AM

#19

AKjeff

Pro

Joined: Apr 2010

Posts: 603

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From: Carson Valley

Sometimes you can identify the bad joint by the thin line of rust around the bearing cap.
However if the car were new to me I'd pull the driveline and half shafts and check them all as 4-vettes described.