muffler clearance question

[SCWDP911]

On the 1in 1out M&K install last night, I have one question and concern: The muffler clearance to the framework is about a 1/4-1/2 and inch: See in this dark picture:





The pictures do not show it very well but there is actually a gap. Well, when I shut down the engine, it shakes a little as it stops and that tight gap between muffler and frame cause a knocking to occur.

Question 1. Is it normal for the 911 motor to shake a little bit at shutdown, or should I be looking at my motor mounts?

Question 2. Assuming it is normal for the shutdown shake, I am still trying to decide best fix. I loosened up the muffler straps and tried to shift muffler over a little, but it seems to be where it needs to be. I have been thinking of grinding the excess edge off a little to see if it would be enough to avoid contact. After that, I am not sure what else can be done. Anyone else run into this before.

Thanks

[SCWDP911]

I wanted to add that the only time I am hearing the contact made is during the shutdown and when going over bigger bumps. Startup and revs don't seem to matter.

[mb911]

that one was a very early model but if you can fit a finger in between there it should be fine. I wonder if your engine mounts might be worn causing for vibration??????

[SCWDP911]

I would not be able to squeeze a finger in at all. It is not much clearance at all. I too have been concerned about the mount issue, but not sure what is normal on a 911. The motor had a topend rebuild about 20k ago. Is there anything else you can think of Ben as far as trying to align it, I was thinking about loosening up the three flange bolts tomorrw and the straps and try to nudge it over and lock it down with the straps, and then retighten the flange.

One thing I have to admit, is now on the second day, it is a little louder than I thought! Not sure really that I am going to want the euro premuffler, unless maybe it tones it down somehow. I will probably go ahead and try it for the heck of it. I am about to start a new thread with a vid of a launch today.

[Mike Andrew]

I also have a very early M&K on my '80SC (like the first) and I had a similar clearance problem. Rather than grind the frame, I removed the muffler and used a ball peen hammer to deflect the end of the muffler inward slightly. When I reinstalled it, I shifted it to the passenger side and tightened it up. I have had no problems since.
Just be patient with the hammer and check frequently.
Ben would have done it for me but I just didn't feel like driving to his place to have him do what I could do myself. How is your clearance at the rear valence?

[SCWDP911]

Originally posted by Mike Andrew
I also have a very early M&K on my '80SC (like the first) and I had a similar clearance problem. Rather than grind the frame, I removed the muffler and used a ball peen hammer to deflect the end of the muffler inward slightly. When I reinstalled it, I shifted it to the passenger side and tightened it up. I have had no problems since.
Just be patient with the hammer and check frequently.
Ben would have done it for me but I just didn't feel like driving to his place to have him do what I could do myself. How is your clearance at the rear valence?

Thanks Mike...

Rear valence clearance seems to be fine - no issues. Just that one spot on the d.s. frame. I might try your method first to see if that will help mine. It does not look to need a lot... I have tried to sift to passenger side as much as possible with muffler/cat flange tight. Iam going to try tonight to loosen that and shift, tighten down straps before the flange, and see if that might help as well. Mike, how long have you had yours on. Are running it wiht stock cat? Were you also amazed at how much louder it is. I was expecting it, but maybe not quite as loud as it is. Maybe raising 6 kids is starting to prematurely age me!

[Mike Andrew]

I have had it on since June of 2004 and it was truly the first early SC muffler that Ben built.
No longer running a cat. It was replaced with a bypass on Thanksgiving morning last Fall just before I stored it for the season. I must say that it is louder than with just the M&K but only drove it a few miles after the install. Not too loud in the cabin, but definitely louder than it was with just the M&K. Personally, I love the sound of the M&K and look forward to driving season here so I can enjoy the new sound with the bypass.
Trust me, it is not as loud on the exterior as you may think.

[Early_S_Man]

What is the gap on the other end of the muffler?

The best shot for more clearance would be to loosen all four M8 bolts [until finger loose] for the rear motor mounts ... then use a winch or Come-a-long to pull on the fan belt sideways to widen the gap. Tighten the four M8 bolts and nuts to 18 lb-ft ... and hope that you have improved the clearance! If not, try, try, again!

[SCWDP911]

Originally posted by Early_S_Man
What is the gap on the other end of the muffler?

The best shot for more clearance would be to loosen all four M8 bolts [until finger loose] for the rear motor mounts ... then use a winch or Come-a-long to pull on the fan belt sideways to widen the gap. Tighten the four M8 bolts and nuts to 18 lb-ft ... and hope that you have improved the clearance! If not, try, try, again!

Thanks for the suggestion Warren.

Shane