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I just pulled my side pipes off for the first time since I installed the hangers. There is a lot more pre load in them than I thought. The attached pictures arn’t great but you should be able to see the hangers, with the bolts out, are about 3/4” higher than the pipes.
Is it ok to have this much preload pulling up on the pipes? I think there is actually more load on the hangers, they are just against the body now.
I only use one bolt to attach pipes to hangers, I have the hangers mounted to frame per the manual. I have read on here to ditch the bolt attaching the inside end of the hanger to the frame and just use the rubber.
Thoughts?
I have the 4 into 4 bbk 302 headers.
 

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FFCobra Captain
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I've had 4-into-4 headers on my car for a few years and don't run the hangers at all because of reading about the pipes cracking at the hanger mount. No problems at all and they haven't sagged. Ditch the hangers.
 

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Hi Murd. I have about that much tension but also run a heavier slimline muffler so wanted to take some of the torque off the headers. Seems to work ok for my set up.
 

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FFCobra Craftsman
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I am like Dan, 44000 miles on my MkII w/ no hangers at all. But I don't think my headers are the same as the current ones. In the past, the piece welded to the pipe would be cracked and pull out of the pipe. Obviously I don't have your setup but 3/4 inch pre load doesn't sound good to me. I look forward to the experiences of others w/ MkIVs.
 

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I'm down to (I think) the last two items on the build: The muffler hangers, and installing the Drummer Mike shields. So I'm looking forward to some more input on this subject.

As for the shields, I can see where they are going to add some significant poundage to the equation of using/not using hangers. Anyone with the shields running without the hangers?

As for the hangers on my build, the supplied DS bracket looks like it will fit, but the PS will take some redesign or re-hanging of the pipe, or both. So I'm in the process of designing some hangers using heim-joints for the attach point on the muffler and an adjustment feature on the inboard end to add/remove the pre-load of the muffler (and shield).

So far, it looks like I can achieve an acceptable weight bearing pre-load to hold the muffler up, as well as allowing for some muffler movement in all directions and rotations for vibration and engine movement, while at the same time damping out the muffler bouncing and moving around (up, down, in, out, twisting). It's not good for the muffler to be flapping wildly around, but just as bad to clamp it solid and and not allow for any movement. It's a compromise.

One of the issues I'm trying to work out is to have enough of a gap between the bottom of the body and the top of the bracket to allow for movement up and down, but at the same time keeping it high enough off the ground to avoid the bottom of the bracket contacting the pavement on speed bumps, driveway humps, etc. Everything's a compromise.

Well see. (I'll have some pictures in a week or two.)
 

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The early FFR pipes just had a tab welded to the muffler. Newer ones have a pad to distribute the load.

I ran without hangers and cracked a header.
I ran with hangers and cracked a header. (with heavier Flowmasters)

So pick your poison.
 

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Not a waxer
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I am and always have been a believer in using the hangers...50 pounds of pipe at the end of a 4 foot cantilever just doesn't seem like a great idea for header longevity. Additionally, after personally seeing tabs torn from the pipe I recommend only a single bolt (snugged but not clamped tight) the attach the hanger to the side pipe. As Avalanche mentioned the latest pipes have a pad rather than just the perpendicular tab but I still only use one bolt even on those so that the hanger helps support the weight but doesn't torque against the tab when things move. As to the comment about eliminating the inner hanger bolt---simply hanging from the rubber without the secured inner point to act against virtually no weight will be supported and what little is being carried will introduce a twisting motion to the sidepipe tab.

Jeff
 

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Fatigue is the Enemy

Jeff is right, "50 pounds of pipe at the end of a 4 foot cantilever just doesn't seem like a great idea for header longevity." There's no getting around it, the oscillating, cantilever loading from unsupported mufflers puts maximum stress on the top side of the welds that attach the header pipes to the header flange. If those welds aren't made well (specifically related to stress concentration undercut at the toes of the welds), they will eventually fail under high-cycle-fatigue conditions. The hangers will mitigate the severity of this threat.
 

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Header gaskets don't do well without hangers

I have a 347 and a 427, started without side-pipe hangers on both.

Used Remflex gaskets on the 347 initially, you don't torque them down real tight, just like torque. Well in 1000 miles they were leaking badly from many spots. Added adjustable sidepipe hangers and installed a new set of Remflex gaskets, and they are fine.

Used a standard composite gasket on the 427 with no hangers, small leak at one cylinder after 1500 miles. Added hanger brackets and retorqued the manifold bolts and no leaking.

If you decide to not use hangers, I think the best solution is NO gaskets, Orange or Copper Hi temp gasket maker work great. Install, lightly tighten, let dry for 30 minutes, then tighten up. I did this on the 347 before I added the hangers per Gordon Levy recommendation. These brackets require two 5/16 Rivnuts to be installed in the 2x2 lower crossmember. PM me if you want a drawing of the parts.

HTH
Dave
 

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As far as the sidepipe tabs shearing off, it's important to use washers/spacers to keep "lateral" pressure off the tab. on my car, one side lined up perfectly, the other side needed 3/8" of washers.
 

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Cont. from post #7 above

I finally got the hangers designed, fabricated and mounted.

Initially I had 3 Heim joints (one at the muffler, which is a 5/16 hole with an oversized 3/8 inch rod/shank, and two on the inside end of the hanger, which are 5/16 inch). It worked fine, but I didn't need three areas of that much movement/rotation. So I bought a couple of 5/16 rod end bolts to mate with the female Heim joint, but didn't realize they were course thread and the Heim joint is fine thread. McMaster didn't have fine thread (24 TPE, NF) rod end bolts, so I ordered a couple of 5/16 rod end blanks, and drilled and tapped the hole and threaded the rod for 5/6-24 to match the mating Heim joint. I could have just drilled the hole for a 5/16 bolt in the rod end, but I figured if it was threaded, and I used a lock not, it would be a little more solid.

I also put in a couple of bronze bushings in the rubber hanger just to give it a bit better mounting points. I put in 5/16 inch, heavy duty, anti spin nut-certs in the 2x2 cross member.

The end result is that the muffler can move in any direction (fore/aft, up/down, in/out) along with the engine, but I still have upward tension to support the weight. I figure the muffler must weigh 20-30 pounds (I wish I would have weighed it before they were mounted) plus Drummer Mike's heat shield (which only weigh in at less than 3 pounds, with clamps).

I adjusted the hanger so that it is about 1/2-5/8 inch above the mounting hole at the muffler. That equates to right at 20 pounds of upward tension. (I hung a 20 pound weight on the end of the hanger to estimate all of that.). Once I pulled the hanger down and attached it to the muffler, it now is pushing up about 20 pounds. In the pictures, you can see that the rubber hanger is stretched about 1/4 inch to achieve all that. (Look at the little slit in the middle of the rubber hanger).

They hang down a bit more than I would like, but are still above the bottom of the 4 inch frame tubes. So I guess they will be OK, plus they are about the same level as the stock hangers that most people use. And they are articulated with Heim joints at each end, so the hanger can move some if it hits something.

Hopefully the pictures will make sense of all my rambling.

To address the OP query of 3/4 inch between the hanger and muffler mounting hole, I would say that that would be in the 25-30 pound range, since the three holes in the hanger are close to being equally spaced. That should be well in the ball park. At least IMHO.

Pictures cont. in next post.
 

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Well Used Member
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Cont. from post #13 above

More pictures of the muffler hanger.
 

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cont. from post #14 above

Muffler hanger pictures
 

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