Rapid knocking noise when off throttle

[Jonah]

Hi all,

My girlfriend's Bravo has just developed a strange noise from somewhere up front. It's a rapid knocking noise that occurs whenever decelerating i.e. foot off throttle, even with the clutch down. Braking makes no difference to the sound. The speed of the knocking varies with road speed not engine speed so it's definitely something in the drivetrain. The noise stops completely as soon as you give it any throttle.

I would guess that it's a CV joint, but the strange things about it are:
1. It started completely abruptly without warning, when being driven gently in town, and hasn't got any quieter or louder (I don't think) since.
2. It doesn't seem to get any louder when cornering.

I can't feel any play in the wheel bearings so I don't think it's that.

Has anyone else had this problem, or have any ideas what it might be? It wouldn't be the gearbox or diff... would it??? Is there a common problem with these on the Bravo?

It's a '99 Bravo 80SX by the way.

Thanks for any help,
Jonah

 

[Rob D]

Have you checked that all the wheel nuts are tight?

 

[Jonah]

Re: Re: Rapid knocking noise when off throttle

Yes they are all tight!

 

[Anonymous]

Re: Re: Re: Rapid knocking noise when off throttle

When the car is at idle, does it knock then? (try turning electictal loads on/off to change engine speed). Could be a knackered TV damper at the end of the crankshaft (the Auxilliary belt rus off this). If the damper is knackered, the pulley hits the hard end stop, thus makes a lovely banging noise.

 

[Jonah]

Re: Re: Re: Re: Rapid knocking noise when off throttle

No it doesn't make any noise when stationary. It's definitely drivetrain-related because the knocking speed varies with road speed not engine speed, even with the clutch down.

Thanks for suggestions so far... any others?

 

[Greig]

Re: Re: Re: Re: Re: Rapid knocking noise when off throttle

Hi mate,
You say you think its the CV joint.
If it was then when you go round corners it would almost certainatly get louder. Maybee wrong though
What it could be ???????????????????????????????????????????????????
sorry
G

 

[Dug]

Re: Re: Re: Re: Re: Re: Rapid knocking noise when off throttle

You haven't accidentally bought a diesel, have you?

Does it still make the noise if you put the clutch in? That might help eliminate a few possibilities. Is there any vibration though the pedals, steering wheel, gear stick?

 

[exrovermech]

Re: Re: Re: Re: Re: Re: Re: Rapid knocking noise when off throttle

check inboard c.v could be this(c.v's nearest transcase).

exrovermech