GTS MC shift Exhaust flap question

Messages
75
#1
Hi all,
Either I’m hearing things or I feel sometimes the exhaust note in Sport and Mc shift mode is louder ( raspier ) than other times .

Is the exhaust valve single stage or multi ? It works perfectly noticeable between sport and normal mode .
Just sometimes in sports mode is more pronounced and crispier . So thought maybe something activates secondary position of the valve ? If not has anyone else experienced the same thing ?
 
Messages
139
#2
Hi,
I believe they're either open or shut. However it could be that as they're mechanical they may get stuck half way occasionally, or just one side is opening and the other is fully stuck! People do sometimes have problems with the valves sticking/rusting perhaps over.
I've never had valved boxes so this is just assumptions and lurker knowledge!
 
Messages
28,401
#3
They do need a good going over with WD40 and a good wiggling.

I noticed that when I put it in Race (Strad) it takes 30 seconds to open. Think I may have a bit of a leak.
 
Messages
75
#4
They do need a good going over with WD40 and a good wiggling.

I noticed that when I put it in Race (Strad) it takes 30 seconds to open. Think I may have a bit of a leak.
I was thinking to add some wd40 but how can I access it ? I tried to use light to see if they were at the tips but doesn’t seem like it
 

bennzwel

Junior Member
Messages
75
#6
They are just forward of the rear silencer, so just behind the rear wheels. Get underneath and they are very visible.

C
Oh that should be relatively easy , but isn’t the mechanism inside the exhaust ? Which part should I spray with wd40 and is the flap on both sides or it’s one flap for both exhaust tips ?
 

Moz1000

Junior Member
Messages
652
#7
It's one flap per box. Mine were buzzing/rattling as they operated which was annoying, so I dropped the boxes and had the old flap mechanisms cut out and new ones welded in. The new ones were the ones Catman recommended a while ago which are from China on Ebay. Now there is no buzzing and they operate nice and quick.

You could try squirting WD40 over all the linkages on the outside of the flaps, and also check that the vacuum hoses are good and fit tight. I tried all this but to no avail and so changed the flaps. Even with the cost of welding (stainless steel), the cost is much cheaper than new boxes!
Moz
 

bennzwel

Junior Member
Messages
75
#9
I gave both linkages a good soak of wd40 and let the Engine run while I opened and closed them few times . Didn’t go for a drive yet but didn’t noticed any change compared to before . Both sides seem to be working but have to mark somewhere to see how much movement is there when they open and if it’s all the way.

I let it stay so wd40 does it magic for few hours then give it a try tomorrow .

May the difference I noticed is nothing to do with the exhaust but something to do with manifolds ? There is no power change only sound sometimes becomes louder and raspier in a good way .
 
Messages
8,753
#12
I would have thought WD40 would make it worse.

As WD40 is water based, the moment it dries out it will make it stiffer (ooerrr missus!).

I seem to remember Voicey putting silicon grease on mine (ooooerr again!).
 

Ryandoc

Junior Member
Messages
939
#17
I used a touch of molykote on mine, high temp stuff would have to check which type. It’s one of the most common types used offshore. It didn’t work lol. But a replacement SOV did work in the end
 
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775
#18
If you are anything like me, it’s probably nothing to do with the valves. More likely once your select sport and the MC light pops up, the right foot gets much closer to the floor - hence exhausts sounds louder :cool:
 
Messages
75
#19
If you are anything like me, it’s probably nothing to do with the valves. More likely once your select sport and the MC light pops up, the right foot gets much closer to the floor - hence exhausts sounds louder :cool:
I actually think there is something to do with how ECU responds to the driving as well and perhaps the intake valves behaviour during harsher ( more fun ) driving style .

I sometimes can actually feel the vibration of exhaust tone through the accelerator pedal more when the exhaust sound amplifies at times . All in sport and mc shift mode.

Probably someone with detailed knowledge of these cars could provide some details on if my assumption is right or not ?
 
Messages
19
#20
As I have found out the exhaust valves have nothing to do with ECU or gas pedal.
As soon as you press sport - immediately :), they open completely and stay open all the time.
Unless they are stuck ofcourse :(