Muffler pack nut loose

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Bobbbenner
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Muffler pack nut loose

Post by Bobbbenner » Fri May 10, 2019 9:26 am

I have tightened the nut holding the muffler to the engine, the threads seem to be fine but when the TT runs it vibrates,loosens and eventually unscrews. There was a part in the 2015 catalogue, (thanks Tom) 306IL Exhaust pack nut locking clamp that is not online it seems. What have you done to keep the brass nut from loosening?

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REHelgeson
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Re: Muffler pack nut loose

Post by REHelgeson » Fri May 10, 2019 9:40 am

You can use a hose clamp to keep the Pack Nut tight.


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Re: Muffler pack nut loose

Post by Rich Bingham » Fri May 10, 2019 9:56 am

There are a number of past threads on this topic with remedies for keeping the pack nut from coming loose. I believe most of the trouble comes from pipes that are not quite formed correctly. If the flange is perfectly mated to the manifold with the pipe aligned to the muffler without tension, the pack but will stay firmly tightened.
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Bobbbenner
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Re: Muffler pack nut loose

Post by Bobbbenner » Fri May 10, 2019 9:56 am

It is 3061L Exhaust pack nut locking clamp, not 306IL Exhaust pack nut locking clamp. oops

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Paboot
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Re: Muffler pack nut loose

Post by Paboot » Fri May 10, 2019 10:42 am

Bob,I found this.
PaulB
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Original Smith
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Re: Muffler pack nut loose

Post by Original Smith » Fri May 10, 2019 11:00 am

You will get nowhere unless you have a pack nut wrench. All these hose clamps and other stuff is pure junk! Even with a pack nut wrench you have to wiggle the exhaust pipe while you are tightening the pack nut to get it to seat to the manifold.

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Re: Muffler pack nut loose

Post by vwgary » Fri May 10, 2019 11:30 am

Original Smith wrote:
Fri May 10, 2019 11:00 am
You will get nowhere unless you have a pack nut wrench. All these hose clamps and other stuff is pure junk! Even with a pack nut wrench you have to wiggle the exhaust pipe while you are tightening the pack nut to get it to seat to the manifold.
Exactly the response I expected. It's call different strokes for different folks. Many use the pack nut wrench along with a pipe clamp (or other clamp) for extra security.
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Re: Muffler pack nut loose

Post by DHort » Fri May 10, 2019 11:41 am

I used the correct wrench alone and it did not work, so I added a plain pipe clamp. It is holding fine. You can add the extra piece of metal under the pipe clamp if you want even greater stability. Will not hurt a thing, and who is gonna look at it.

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Re: Muffler pack nut loose

Post by Ruxstel24 » Fri May 10, 2019 12:50 pm

Also, do not clamp the muffler, it should be able to move on the pipe.
Normal frame flexing can work the nut loose at the manifold if the muffler can't move.

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Re: Muffler pack nut loose

Post by George N Lake Ozark » Fri May 10, 2019 2:45 pm

I had that issue a couple of times. I snug up with the suitable wrench then start up car and warm up for three minutes. The nut will expand from the heat and snugg a little more, don't over tighten it. When engine cools enough , put on your locking clamp of your choice. I use the one the vendors have but hate the little round headed screw and change to a bolt instead.


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Re: Muffler pack nut loose

Post by Norman Kling » Fri May 10, 2019 4:28 pm

You should tighten it with the proper wrench. If you don't have one you can easily make one out of a bar of aluminum by cutting out the slot. If it slips when you try to tighten it, either the bronze nut threads are stripped or the manifold threads are stripped. A new manifold is approximately $100. The bracket clamped on the pipe with a flat side against the nut is extra protection and helps keep the nut from coming off. I agree that the muffler should not be clamped at the pipe but only have a bolt to the frame in the rear.
Norm


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Re: Muffler pack nut loose

Post by Scott_Conger » Fri May 10, 2019 4:55 pm

Dave and Norman

early cars have the front and rear of the muffler bolted solidly to the frame; the exhaust is simply a slip fit in the front of the muffler and everything is free to flex with no stress

later cars have the muffler clamped to the exhaust and then has one tab at the rear of the muffler attached to the frame; the tab flexes just enough such that the assembly suffers minimal to no stress

I am suspicious that some folks are doing both...using later muffler with rear tab mount only, and then slipping the exhaust into the front with no structural support of a u-clamp. This will lead to considerable movement at the exhaust manifold.
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Re: Muffler pack nut loose

Post by Allan » Sat May 11, 2019 5:16 am

Rich mentioned a very important point. A model T exhaust pipe flange MUST mate with the manifold as close to perfectly as you can manage. I believe the pipe should be installed and fitted to the muffler as demanded by the type in use for the year of the car. Then the flange should be checked for fit at the manifold. If you do the nut up firmly without the muffler in place, there is a chance that fitting a muffler a little 'off' at the rear will add tension into the system. If you use the manifold nut to 'pull' a flange onto alignment, the same thing happens. This puts stresses on the manifold and whatever gaskets/glands/crush rings you use can fail prematurely. Mis-alignment of the flange, and tightening to 'correct' same, is likely to led to a warped manifold and or the loose nut problem.

By making sure that everything fits well before any part of the system is buttoned up, I have been able to avert the loose nut problem in all but one of my T's. On that one, the flanges mated nicely, but the flare was off centre enough to bind a little on the inside of the packnut.

On our RHD T's making exhaust pipes that fit takes some doing. 2" from the flange it needs to kick outwards to get around the pedals. Then it kicks downwards and back, before kicking down again to clear the starter switch. Then the kickdown has to be corrected before the pipe heads rearwards.
Our club delivered a running chassis to an exhaust shop in the city and they developed a computer controlled bending programme to make exhaust pipes for us. We went from one in ten that fitted without work, to one in ten that did need work.

Allan from down under.

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Re: Muffler pack nut loose

Post by Tim Rogers » Sat May 11, 2019 8:03 am

Once again this topic has come up and once again many of the replies are full of misinformation. It's not a matter of "what floats your boat" or "different strokes" and other assorted nonsense.

Good manifold threads, good pack nut, proper wrench and correctly fitted pipe is all you will ever need.

If your pack nut continues to come lose then something is wrong. The cheesy hose clamp is a band aid for worn out parts or for lack of knowledge. Why not do the job right?

We have an obligation to pass on factual and correct information if this hobby is going to survive into the future.
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Re: Muffler pack nut loose

Post by Scott_Conger » Sat May 11, 2019 9:48 am

Tim

we missed you!

I am so glad you're going to save the hobby from oblivion due to bad pack nut info! Please do share what was factually wrong on this thread, so that others may learn!
Scott Conger

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Re: Muffler pack nut loose

Post by Paboot » Sat May 11, 2019 11:23 am

Scott,
I think he was referring to the picture I posted.
Sorry, didn’t know I was causing such angst in the
model T restoration world.
And NO I don’t have a lot experience with T’s, but have worked on cars for over 50 years.
Just trying to help. :?
PaulB


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Re: Muffler pack nut loose

Post by Norman Kling » Sat May 11, 2019 11:39 am

One thing not mentioned is sag of the frame under the rear motor mounts. If you don't wish to straighten the frame, you might need to bend the exhaust pipe. To do this, attach the pipe at the manifold tighten up the clamp making sure the flange is straight. Then slip on the muffler. Everything should line up without any binding or prying. If you find that it does not line up, take a note of which way the pipe should be bent and then remove from manifold and heat the pipe at the area you wish to bend and use a pipe bender. Re clamp and check again. It might take a few times bending to get everything to line up without a bind.
Norm


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Re: Muffler pack nut loose

Post by Roz » Sat May 11, 2019 8:17 pm

I love Model T’s, but I think sometimes we need to be reminded that the Model T was designed and built during the period of automotive infancy. Henry Ford was smart and had a keen mechanical mind, but he was not perfect. Let’s face it. There are some less than perfectly designed parts on the car, due partly to the state of the technology at the time, and Ford’s insistence that costs be kept to a minimum. Is it possible that the exhaust pipe to manifold interface with the brass pack nut is one of those less than optimum designs? Three different materials there, three different rates of expansion when heated.

I am a retired tool and die engineer and have designed many stamping tools and dedicated special machines. I am fully aware that even though what I designed worked, there very possibly was a better way. Even in a situation where the design is a group effort, this holds true.

I would never condemn someone for putting a clamp on their exhaust pipe. I have other things to occupy my time. :D

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Re: Muffler pack nut loose

Post by Doug Keppler » Sun May 12, 2019 8:10 am

Dave H, I believe you are correct. If you think about it when the muffler is clamped to the exhaust pipe and then bolted to the frame when the car flexes over uneven roads the muffler is transmitting the twisting torque all the way up to the pack nut causing it to loosen. Is it possible that everyone who has their nuts coming loose has their muffler clamped? Henry Lee told me he never clamps his muffler and has never had a pack nut come loose in all the years. I makes sense ;)
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Re: Muffler pack nut loose

Post by Original Smith » Sun May 12, 2019 9:52 am

We have people in our group who refuse to learn the proper way to do things, thus they rely on crazy gimmicks that only make the problem worse. The Ford Service book is the best information you will ever need, and the hose clamps in that book are for what they were designed for!

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Re: Muffler pack nut loose

Post by vech » Sun May 12, 2019 10:47 am

Our '22 coupe kept spitting the new brass nut off of the threads of the new exhaust manifold, so the last time, I made a clamp for the nut, using a everyday modern muffler clamp, that I welded a short piece of scrap flat bar, in the center of the stamped sheet metal part of the clamp. Worked like a charm, easy to install and position exactly where you want it, and has never loosened up again!
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Re: Muffler pack nut loose

Post by Doug Keppler » Sun May 12, 2019 10:50 am

Craig is your muffler clamped to the pipe?
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