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Thread: Coyote J-pipe Cracks

  1. #1
    Member dforthof's Avatar
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    Coyote J-pipe Cracks

    Hey all,
    I got some mileage out of my new Cobra this last week at the dream cruise (I'll post graduation photos as soon as I get some nice ones). I'm running a Coyote with the FFR J-pipes and unfortunetly had to cut my weekend short due to a crack that developed in the J-pipe on the drivers side. I'm not certain what caused it, it's possible that some kid decided to step on my side-pipe when I wasn't looking, but most likely it happened because of fatigue. Since the entire side pipe is supported from only the manifold donut and the small braket in the back, there is a lot of moment where the side pipe exists the body, my guess is that the wonderful Michigan roads I was driving on bounced the side-pipe enough to cause this crack to develop. Obviously, I'll be replacing the J-pipe, but I'm also going to support the end of the J-pipe where it attaches to the side pipe using an exhaust hanger on each side of the car. I'll post final picks when I have it done, as I have to assume everyone running this equipment is eventually going to have this same problem if the exhaust system isn't supported better.

    Anyways, the purpose of my post is:
    1). Has anyone else had this issue? If so , how did you fix it and did the fix work?
    2). If you're building your car now, you might want to plan for an exhaust hanger on the end of the J-pipe before the body is on and it gets tight in there.
    Attached Images Attached Images

  2. #2
    2bking's Avatar
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    Looks like a poor weld where there wasn't any penetration in the area at the center of the crack. The weld thickness should be as thick as the parent metal so apparently no filler rod was used while welding this area. Sometimes a good looking weld is paper thin thus the crack. Maybe you should talk to FFR for a replacement. It would be called a latent defect.
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

  3. #3
    Senior Member edwardb's Avatar
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    If those are FF part number 15442 (pretty sure they are) I have a brand new set still in the box that came with my Mk4 a couple weeks ago. I won't be using them. I was going to sell them along with other unused parts at some point. But could make a deal for them now if you're interested. Close in Lake Orion. PM if you're interested.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
    Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.

  4. #4
    Senior Member
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    Gee, let's see ... 304 SS, thin wall, temperature cycles, pressure cycles, 2 welds meeting at the same place on a tight bend where mechanical stress is applied by the exhaust flange. 304SS work hardens like crazy just from the heat of drilling. Combine in all the pressure, temperature and mechanical cycles and that joint must be like glass.

  5. #5
    Member dforthof's Avatar
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    I agree, it looks like there was poor penetration on the weld, coupled with the temperature cycling and vibration I shouldn't be surprised. I called FFR tech support and (as always) they were more than helpful. They are sending me a new set of J-pipes and said that they do see this issue from time-to-time, however it's not all that common. Because I'm ADD, I'm going to do two things to enhance this design before installing the new set: 1). I'm going to install hangers on the end of the J-pipes to support the connection point of the J-pipe and the side-pipe and 2). I'm going to install a stainless steel piece of flex pipe on each one so that there is some "give." I'll post pictures of the final install once I get it all done.

    Thanks everyone for the comments and suggestions.

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