Johnny sti

Hi all
Fitted my magnex down pipe after wrapping it and now there is a very annoying knock somewhere from the exhaust.
It only happens after ive floored it. I dropped the other half off in town and it was fine. Went for a drive after dropping her off, went to over take a car, put my fot down, the car juddered twice then went flying past the car. When i came off the gas, it was knocking like a piece of sh*t all the way home!
I have looked under the car and the back box pipe (ninja) has been touching the rear drive shaft. There are occasional rub marks on the green part of the shaft but the pipe wasnt touching it.

Can an exhaust expand under pressure?
Have my baffles gone?? (if it has any)?
What can i do to sort it?

Many thanks

Johnny

mista weava

assuming it is coming from the back of the car, then the problem is probably as you describe. i too have annoying knocking sometimes if i have been caning the car in the twisties. bending brackets to suit is probably the best solution if it is the case that it is rubbing on the back shaft.

Welloilbeefhooked

iTrader: (3)

I found that my knocking was the rear anti roll bar bushes that had failed. The noise started after fitting a new exhaust, so I too thought that it must be the exhaust, but obviously not.

Might be worth checking these?

Johnny sti

Hi all
Think ive sorted it. When the car hasnt been driven, the gap between the pipe and the rear drive shaft was about 5-8 mm but after its been driven a bit the gap goes down to 0 mm!!
I can only put it down to the pipe expanding under the heat but after rolling around under it for 20mins i found that removing the rubber mount right at the back of the car to the right of the back box it dropped considerably and assume that all should be ok because the rest of the box is held up by 2 other mounts.
Have to wait and see tomorrow!!

Thanks all

Johnny

jogyp

just had same problem resolved today, after i had decat downpipe put on the problem is the decat flange that connects to cntr pipe is slanted slightly only about 1mm difference from original but imagine by the time it gets to the back box its out by quite a bit

what i had to do was cut a slit in cntr pipe and alter that way then when it was in correct position re weld it up nightmare i know put that knocking was so annoying
hope this helps