I installed the Ford Racing M-5220-MB side pipes on my GT about 18 months ago and all was good. About 3 months ago I installed GT500 axle-backs on my car and since then, I've had this bad knocking noise over bumps. Got under the car and saw the driver's side pipe is very close to the floor and there are witness marks from where it hits (right around call out #4 in the diagram below).



The instruction says make sure you have 14 to 23mm clearance, but I have 5-10. I've tried to adjust everything from the H-pipe Torca connectors to the side pipe clamps to the axleback alignment to try to pull everything down, but it keeps going back to the same position.

Anyone have any ideas how I can fix the situation?

 

First, good choice on the side pipes, they're awesome.

Second, it took me a few tries getting under there before I realized how the geometry works.

I don't fully understand where your clearance problem is, but I'll take a stab at it. Try loosening the whole side you're having a problem with. Starting at #4, follow the side pipe back to the first elbow. Pull this elbow up or down, rotating the pipe inside #4. Once it's at the specified clearance at the outlet, start tightening stuff.

Oh yeah, I forgot to mention, if you haven't removed #7, you gotta try it.

 

I've read about this problem before when people were messing with their boss side pipes. Supposedly you just have to try to adjust it where it bolts to the floor.

 

I have the Kooks side pipes, and I was running to a similar issue. When I adjusted it the best I could, I applied thin width strips of dynamat to where there was a potential for contact, metal to metal. Voila, problem solved.

 

Thanks. I'll give it a go this weekend. And yes, I've been driving with no #7 since the start

Interesting. Might as well start from there and try to redo the whole side.

Thats what I was thinking as a last case scenario. No issues with the heat? Or is there a special dynamat for high temp applications?

 

None that I know. I am not sure if Dynamat has specific high temp products (must be - because I have no issues). In fact, it was done at my buddy's exhaust/muffler shop, literally. So they had tons and tons of Dynamat stock that they use regularly for those purposes. I am assuming they are high temp.

 

Standard dynamat is regularly used as a thermal barrier in the hot rod community and its aluminum reflective surface does this work very well.

 

That is an EXCELLENT suggestion.


I have a similar occasional knock, but am too lazy to get up under the car to look. I just open the window and downshift. Problem solved... LOL
However, I will have to try the Dynamat solution.


As to the heat question - the other responses are correct - they do make high-heat Dynamat (mainly for underhood applications, I believe), but standard should work just fine - there is plenty of airflow to cool the Dynamat and the pipe is not making contact with the Dynamat all the time, so direct hear transfer should be minimal.