Broken J -pipes! Help and suggestions please

[wareaglescott]

Just swapped my side pipes to new ones with Flowmaster slimline mufflers welded in.

My setup is Coyote headers, ffr J-pipes, side pipes with mufflers.
The mufflers are quite heavy. I would guesstimate twice as heavy as the original pipes. I had some issues installing them because when I used the hanger method for the regular pipes the weight of the pipe overwhelmed the rubber piece on the hanger and immediately pulled it to full extension. This caused the rear of the pipe to sag about 1.5" which was to low. In an effort to overcome that I used a more rigid mounting system where I made a metal shim to sandwich behind the rubber piece. I just attached one bolt at the bracket on the pipe itself and did not tighten it down all the way so the pipe could rotate some that way. Thinking this would allow for some play
http://thefactoryfiveforum.com/attachment.php?attachmentid=71838&d=1501962498

This resulted in the pipe staying right where I wanted it and just a small amount of play if I pulled on the aft end. I thought I was good to go with that setup. Didn't make it 50 miles and both J-pipes broke at the welds.

http://thefactoryfiveforum.com/attachment.php?attachmentid=71933&d=1502126949
http://thefactoryfiveforum.com/attachment.php?attachmentid=71934&d=1502126965

Obviously my current set up will not work. Now I need to find a long term solution.
I lucked out when I had the issue and pulled into a random body shop on the road and they were able to take the pipes off and weld them right on the spot good enough to get me home. Through a generous friend on the forum I have a new and unused set of J-pipes on the way to me.

I am looking for suggestions on how to find a permanent fix so this does not happen again.

Has anyone else had this happen and what did you do?
My thought is to weld another tab on the pipe further back and support the rear end with another hanger. While doing this I will take the metal shim out of the forward hanger and let the rubber pieces work as designed. I think two of them should hold the pipe in position. Not sure if that will help up front though.
Another forum friend mentioned the J-pipes could be rewelded along the seams for a stronger piece and also had the idea of having a hanger going from the 4 bolt flange where the side pipe attaches and anchoring it to one of the bolts the header attaches to the engine at. Thus allowing the pipe to move with the motor but also providing support for that joint. That seems like a good idea as well.

Im lacking in knowledge in the forces being applied and the best way to support the pipe and also give it the freedom of movement it needs to prevent the welds from breaking.

Any suggestions or input is appreciated.

[Gumball]

Scott,

There used to be a turnbuckle set-up that would work with the "J" pipes to provide a little damped support at that point in the system. I've seen it, but don't have a picture. Since I have the four-into-four headers, I didn't end up using the set-up, but recall that there were many who were running "J" pipes or cats that found it helpful.

Maybe a search through the archives over at FFcars.com will help.

[wareaglescott]

Thanks Chris

Interesting update. I went out to look over the pipes and hangers after the car had cooled down. I first unhooked the hanger from the passenger side pipe. Now that the J-pipe is welded there is absolutely zero sag at the aft end of the pipe and the entire assembly feels very secure.

What would any of you make of this?
To me that indicates when I first started putting this on the J-pipes may have already been fatigued and cracked and unable to support the weight?? Maybe the extra weight was enough to make it reach the breaking point.
Also I did tighten and loosen the J-pipes 3-4 times each side as the pipes were being installed. Could all that tightening and loosening damage the joint there.

[Railroad]

Not having to deal with this, but I would think a mount mid length of the side pipes would offer less resistance to movement.
Probably 2 factors creating the stress, hanging wt of the side pipes and/or the torquing over of the engine, working against the mount. I can see where a front mount, the same as a rear mount would put the flex where the break occurred. A center mount, IMO, would allow the movement of the pipes to pivot. I would be interested in seeing how much engine movement there is under accel and decel.
Honda had to put a sleeve in the header pipe on their early Civics. The pipe was breaking due to engine movement. There are some flex exhaust connectors out there, if room allows.
https://www.summitracing.com/search/product-line/ap-exhaust-flex-couplings?SortBy=Default&SortOrder=Ascending&tw=exhaust%20flex&sw=AP%20Exhaust%20Flex%20Couplings

[wareaglescott]

The current mount is in the center. I may not have been very clear about that. Cant see having enough room for the flex connectors. thank you for the suggestion though.

I emailed with Tony at FFR. He indicated the TIG weld on those is the weak point and it would be a good idea to have the welder go over those seems with a MIG weld. That seems to make sense now that they have been welded and didn't seem to have the sag anymore.
Also found some pictures of some turnbuckle style hangers that attach to the flange on the pipe and go the the frame rail in the engine compartment. I think I will make some of those up for added support up front.

[Dave Howard]

Long term fix....ditch the FFR shorty headers and J-pipes and buy the Stainless Header 4X1X4 headers for the Coyote. I installed the FFR shorty headers and J- pipes originally also. The Stainless Headers for Coyote came out just after I made my purchase. I installed the shorty/J combo and it lasted until first start. Once I saw the Stainless Headers, I had to have a set. The main reason for me was how restrictive the J-pipes are in the area where you experienced the crack. I have posted countless testimonials praising the Stainless Headers and others have also. You WILL NOT be disappointed. End of all your headaches

[wareaglescott]

Long term fix....ditch the FFR shorty headers and J-pipes and buy the Stainless Header 4X1X4 headers for the Coyote. I installed the FFR shorty headers and J- pipes originally also. The Stainless Headers for Coyote came out just after I made my purchase. I installed the shorty/J combo and it lasted until first start. Once I saw the Stainless Headers, I had to have a set. The main reason for me was how restrictive the J-pipes are in the area where you experienced the crack. I have posted countless testimonials praising the Stainless Headers and others have also. You WILL NOT be disappointed. End of all your headaches

Ya end all my headaches except your suggestion requires the biggest headache of all in pulling the motor to install those headers! LOL
Not willling to go that route or incur that cost at this point.
Hopefully the additional welds and turnbuckles will do the trick.

[frd2]

Sure sucked doing it at the time, but the headers install with the motor installed. You may want to hire someone with small hands to reach some of the header bolts though!

[michael everson]

I don't think you need to pull the motor. You would never get it back in with the headers on. All the other 5.0 based engines are left in place.
Mike

[Dave Howard]

Ya end all my headaches except your suggestion requires the biggest headache of all in pulling the motor to install those headers! LOL
Not willling to go that route or incur that cost at this point.
Hopefully the additional welds and turnbuckles will do the trick.

Mike is correct. I didn't pull my motor out to do the swop out. Motor in once. Bolted it down and moved forward. The Stainless Headers are easier to install than the shorty headers. The bolts are much more accessible. The flange between the header and the side pipe provide for a smooth transition with NO restrictions. These things have been around for the Coyote since about 2012. There was a thread on the forum from the original guy, the guy who used the custom kit from Stainless Headers to make the pattern for his Coyote. SO he should have all the credit for these things. There are no disadvantages as far as I'm concerned.

Hope the weld/turnbuckle fix works out for you. I might have a sent a J's I can pay forward to you if you want.

[wareaglescott]

Intersting. I don't see any way I could get my header bolts out on the drivers side near the rear. Also cant imagine maneuvering the header into position with the body in place. Are people actually installing headers on a coyote after the body is on?

I appreciate all the input. My immediate goal is to fix the problem with my current setup and not transition to a different setup. Between talking to a few builder friends, Tony at FFR, and the input in this thread I feel I have a good solution and will proceed down that path. Now if I were building another one knowing what I know now I certainly would look more seriously at the different headers.

Thanks everyone.

[grluisi150]

Scott
I interested in this thread because I have the same setup as you and I'm considering installing the slimline side pipes. Did you go with the 24" or 30" slimline side pipes?
Gary

[wareaglescott]

Scott
I interested in this thread because I have the same setup as you and I'm considering installing the slimline side pipes. Did you go with the 24" or 30" slimline side pipes?
Gary

Gary I have the 30". Very pleased with the resulting sound just need to get this issue resolved. I believe I have a good solution and will update in my build thread after I get it fixed. It will be next week sometime.
If you want some more information I have some before and after sound videos in the most recent post in my build thread. Also talked about my mounting which is now invalid! lol

[cgundermann]

Scott ~

Darkwatercustoms use to sell these, but now he's just placing items on a wish list (he's a FFR supporting vendor). Looks easy enough to fab up/Chris -

71950

[wareaglescott]

Scott ~

Darkwatercustoms use to sell these, but now he's just placing items on a wish list (he's a FFR supporting vendor). Looks easy enough to fab up/Chris -

71950

Thanks Chris
That is my exact plan. I'd prefer to buy from him vs stealing his design and making my own but I'm not driving the car until I get this fix in place so the wish list wait won't work for me to this time.

[srobinsonx2]

Scott,

I am not really sure if this helps or not. Maybe I am misunderstanding your set up. From you post, it sounds like your pipes would hang down 1.5" without support. Did I understand correctly? If that was in fact the "unstressed" state, then pulling them up to align would put stress on the pipe and headers. Unless you had created some slack in the pipe to header connection. With vibration from the motor, the stress gets transferred across the system and the weakest point fails.

We see this all the time in the chemical industry. Pipe stress on vessels, pumps, valves, etc creates numerous problems. Cracks in pipes and vessels occur when this is not addressed. Just today we had to deal with a crack in a weld on 3/8" thick nozzle on a carbon steel vessel. Vibration in a stressed system and poor weld quality were the cause.

It sounds like from your second post, you had the J pipe rewelded and this time in the proper alignment with no sag. If you can provide a support that allows the pipe to flex with the motor, that should solve your issue. I don't know about a brace that won't flex. As the motor moves (rotates with torque) a rigid attachment on a long pipe (lever) would still create stress even if it is not pre stressed.

Does any of that make sense? Hopefully this helps. PM me is you want. I can throw some engineering on you and dazzle you with BS. Just kidding. It just sounds like vibration is being transferred into a rigid system. Something will probably fail eventually.

[srobinsonx2]

After thinking about this a little more, your two hanger idea might work. With the one in the middle, you might have just created a pivot point that allowed the end of the pipe to flex. If you don't want two connection points, could you just move the single contact point further back?

Another thought was that two of your current rubber hangers might provide enough support and not stretch. What about finding a rubber hanger with a little more rigidity?

Just brainstorming. Sorry for the double post. Keep us updated. I am curious to see how you get this fixed.

[wareaglescott]

After thinking about this a little more, your two hanger idea might work. With the one in the middle, you might have just created a pivot point that allowed the end of the pipe to flex. If you don't want two connection points, could you just move the single contact point further back?

Another thought was that two of your current rubber hangers might provide enough support and not stretch. What about finding a rubber hanger with a little more rigidity?

Just brainstorming. Sorry for the double post. Keep us updated. I am curious to see how you get this fixed.

Thanks for the input. Sending PM

[CraigS]

I wonder if you could adapt something w/ longer bolts and springs so the joint seals but can move. See the first jpeg in the second post here;
https://www.allpar.com/forums/threads/springs-on-exhaust-connections.163374/
Here are some parts
https://www.amazon.com/Walker-35129-Exhaust-Spring-Bolt/dp/B000CQBG1O
Google this "spring bolt exhaust joints" for a bunch of pics and search results

[Gumball]

Scott ~

Darkwatercustoms use to sell these, but now he's just placing items on a wish list (he's a FFR supporting vendor). Looks easy enough to fab up/Chris -

71950

Yep - those were the hangars I mentioned early on... thanks for finding a pic!!!

[wareaglescott]

I wonder if you could adapt something w/ longer bolts and springs so the joint seals but can move. See the first jpeg in the second post here;
https://www.allpar.com/forums/threads/springs-on-exhaust-connections.163374/
Here are some parts
https://www.amazon.com/Walker-35129-Exhaust-Spring-Bolt/dp/B000CQBG1O
Google this "spring bolt exhaust joints" for a bunch of pics and search results

This is an interesting though Craig. Thanks for the links.

Since I had all the play at the beginning and now that the J pipes are welded up good and have basically zero play it seems I need a tight union at the J-pipe to header joint to keep the play down to a minimum at the far end of the pipe. I am thinking if I added these springs that would have to much of a negative effect as the play got magnified over the length of the pipe.

I think my main problem is I now realize the J-pipes were likely already weakened or cracked that I did not notice when I installed these pipes. So my concern about the excessive droop at the end of the pipe was not actually being caused by the weight of the pipe it was being caused by the already failing J-pipe. By diagnosing the problem wrong that caused my mounting system to be wrong as well.
Now that I have FFRs recommendation to have them welded up better as well as an additional method to support the J-pipe at the junction with the header by using the above brackets or a variation of those that ties into a header bolt I am hopeful that is a good solution. I am going to try that first and see how it goes.

[BEAR-AvHistory]

I had one J-pipe crack at the weld just below the flange. Did a quick & dirty junk draw parts fix in March 2015. Have not gone back to do a visually pleasing solution (you can't see it on the COYOTE) but have not had to touch the pipes in 7,000 miles. Also used a piece of the exhaust hanger fabric to hang the back end of the side pipes inplace of the rubber FFR pieces.

http://www.bimmerfest.com/forums/picture.php?albumid=14742&pictureid=60929

One end is attached to the square frame tube the other around the Jpipe. Was all from spare exhaust hangers I had in the draw. The perforated metal is just old pipe hanger strap & the vibration insulating material is standard exhaust hanger strap. A piece of it is also used as a pad in the Jpipe bracket. Some nice CNC brackets for the jpipe & frame tube would be nice.

FFR had sent me replacement parts as a warranty issue. So the object was to take the weight of the exhaust off the ball joint flange & weld to prevent a re-occurrence.

Not having to continuously re-tighten the flange bolts was a bonus.

[clancypm]

I also was wondering how I would get my header tightened on the the back driver side bolt. I have a 4.6 4 cam motor. I bought a very long closed end ratcheting wrench from northern equipment (40 some bucks). Got the bolt started by crawling underneath and using my hand. Then I used the ratcheting wrench to tighten up the bolt from the top side with wrench coming along side of the heads. Hope that helps.

[bobl]

I can't speak to the J pipe issue as I have the 4-4 headers, but when I installed my Slimlines I welded just one set of brackets very near the end of the muffler. I through bolted the rubber hanger to the 2" square frame/body support. I then supported the muffler with a floor jack a bit higher than the desired height and tightened them up. That way the hanger is actually holding a bit of the weight but can move up or down easily. 3000 miles, so far so good! When I was running my engine on the dyno with the mufflers unsupported one of the header tubes cracked, so I knew they needed some good support.

Bob