Knock under acceleration

NeverWinter

NeverWinter

NeverWinter

Soldato
Joined
25 Mar 2003
Posts
5,776
Location
Birmingham
Hey guys, just noticed my car knocking under heavy acceleration, kind of sounds like it's coming from underneath the car. It only seems to happen once until I slow right down then accelerate again. I've noticed it happening in 1st, 2nd and 3rd (only once) gear.

Any ideas?
 
Assuming its the one in your sig (doh). Id check for any worn bushes. Bottom arm bushes sound like the offending problem here. Does it knock when cornering?
 
I've checked for children (also animals) and this does not seem to be my issue.

It doesn't seem to do it when cornering.

Also, yes it's the car in my Sig.
 
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I had exactly this fault on a Mk5 Golf GTI and it was a broken rear spring. I was sceptical this was the reason for the knocking noise as it sounded like it was coming from the front and was almost certainly going to be wishbone bushes but two new rear springs solved it. They were £117 for the springs £30 fitting.
 
Do these have dual mass flywheels? Could be on it's way out and knocking as you bottom out the springs under heavy acceleration.

I've had my Fabia vRS remapped and flooring it under 2k will cause the DMF to go mental as the springs bottom out and cause a knocking noise.
 
Could be the actual exhaust knocking against the bottom of the body - accelerating makes the engine move which alters the angle of the exhaust making it knock. Could also be the gear linkage moving. If it was from the front instead of underneath I would say engine mounts are knackered.
 
Mine does this under acceleration or semi-harsh braking. For me in my Vectra it's a cracked lower engine mount which I'm taking to the garage later in the week.
 
It's only a single knock, i'm going to try some harsh braking tomorrow to see if it does it under braking. I was thinking it's a loose exhaust, gonna try and get it up tomorrow too to have a proper look underneath.
 
had a similar noise from my astra this week, turned out to be a faulty wheel hub.


try produce the noise when you have a mate standing near the car (ie in a drive way etc) to narrow the noise down to a location.
 
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