Ian

iTrader: (10)

fitted a set of gt-spec headers and up pipe today, to a version 6 sti classic.

when for a test drive and i get a slight knocking sound, allmost like the same sound as if the exhaust is hitting something.

it happens when driving, in gear and out of gear.
does not happen when parked reving the engine.

any ideas on what to look for?

thanks
ian

RON

Did you remove the entire system to fit the headers..??? i recently had to do this and ended up with the rear tailpipe hitting the diff.....

Ian

iTrader: (10)

no, just the down pipe,

my system from the downpipe back is full titanium, so it was very easy to just move with my hand.

would there be anything the headers could catch on?

RON

There shouldn't be....!!

What about the bracket on the back of the gearbox where the back of the downpipe bolts..???? it's the only thing i can think of that might have been overlooked....

johnnyroper

any chance that they could be hitting on the subframe with engine vibrations?

Ian

iTrader: (10)

dont think it is this, as it is not bolted on, and never has been

Ian

iTrader: (10)

would this be the up pipe bit?

i had to unbolt the engine mount, and lift it up abit to get theup pipe in place.

all went back ok, and at the time there seamed to be enough room

frayz

iTrader: (7)

Im willing to bet that its front part of the header on the side of the up-pipe. The tubular part ton the header that runs closest to the front panel.

There is a slight gap when cold but once the headers get hot they can expand to close the gap close enough that they knock on the panel.

I could be wrong but worth a check as ive seen this before.

Frayz

Ian

iTrader: (10)

what can be done to solve this?

frayz

iTrader: (7)

Only thing i have seen done is to grind a relief in the front panel to allow clearance fella. Its not much, just enough to stop the knock.

Ian

iTrader: (10)

do you mean the pipe on top on the side of the up pipe, where the weild is in the middle at the 180 deg bend?

if it is this, will they need to be removed again to chop the bit off?, or can it be done from under the car?

frayz

iTrader: (7)

Yeah the weld on the 180 degree bend. Maybe you can get to it with them fitted, im not sure as it was a while ago that i looked at a set.

Make sure its that that its causing the problem first.

Hope it solves your problem buddy

p1mark

Have replied to you elsewhere but it will be fouling as Frayz says on the sub frame.

This is what i do now as a matter of course when i fit a set.

frayz

iTrader: (7)

Cheers for the pic Mark, thats what i was trying to explain lol...

jd5217

had this issue on mine, 3 times it has been grinded back now.

ZEN Performance

that isn't applicable in this case, the part pictured above is only fitted on new age cars. My guess is the downpipe.

Ian

iTrader: (10)

where about on the down pipe do you think, i had a look under the car (when cold) and there looked like there was room.

thanks
ian

frayz

iTrader: (7)

Sometimes they can knock on the steering UJ under high load applications... but if its only knocked since fitting the headers id be more inclined to say it was them over the DP to be honest.

Ian

iTrader: (10)

and it only does it when warm, dont hear it when cold.

have looked at the bit at the front like you said frayz, there is abit near, but no marks on the heat wrap, so dont think it is that.

if feels like it is around the gear stick/ arn rest area, and i think i can feel it there, but it could be coming from anywhere.

Ian

iTrader: (10)

been out again on a short trip, and it does it when cold as well, notice it when i pull away abit more than normal.

strange one me thinks

ZEN Performance

On a classic the headers should be well clear of everything, the radiator mount being the closest part. With the 3 bolt headers i've never seen them knocking on a classic. Downpipes are prone to knocking on the gearbox subframe, or makeing the centre section knock on the propshaft centre bearing. Downpipes can often sit slightly differently each time you fit them, especially when changing headers, as the turbo can move slightly (downpipe is removed to fit headers).

Ian

iTrader: (10)

would it be owrth taking the down pipe back off, and re fitting it?

i may trim abit of the radiator mount back abit, but there is no sighn it is hitting there at the mo.

would the downpipe likely to damage anything?

many thanks
ian

ZEN Performance

or just get underneath it and check what's touching what...

Bez300

iTrader: (2)

Had full de-cat fitted to mine and was all fine.
When I had headers fitted they took down pipe off
when put back together the down pipe was close to joint on steering
when started it touched joint.
if it is that you can feel the contact on steering
if its got std steering joint on you can change this part for a small joint that will not touch
good look

Ian

iTrader: (10)

all sorted now, thanks Zen for saying to look around the downpipe,

i have a look at this and it was sitting higher to the under side of the car, I followed it along abit, and just after the down pipe the exhaust was very close to the centre driveshaft bracket, and i gave this abit of push and it sounded like the noise i had been hearing.

some thick hose, tape and cable ties later, it is all sorted and no knocking.

thanks all to the ideas/help etc

job well done