Resonators or: How I Learned to Stop Rasping and Love the Spec-U.

Discussion in 'N/A Mods & Tuning' started by fishsticks, Oct 12, 2016.

  1. fishsticks

    fishsticks Because fast lifted truck.

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    Title reference: https://en.wikipedia.org/wiki/Dr._Strangelove

    If you have Spec-U longtubes and the (currently discontinued) Spec-U exhaust. There is a reasonably good chance you know what this thread is about. That hissing/buzzing/resonating/rasping/whatever sound that happens just above 2000 RPMs at moderate engine load. Here's a way to fix that. Credit to XRunnerKid for trying this out first. I'm just here to provide some pictures and part numbers.

    I am 100% sure your warranty with URD (if there even is one) is void if you do this. I chose this over continuing to live with the noise or putting my stock system back on and waiting for URD to come up with a solution.

    What you will need:

    Vibrant P/N 1790 Resonators (2)
    [​IMG]

    The updated passenger side collector pipe from Gadget. (Unsure if he's still sending these out):

    [​IMG]

    You need the updated collector pipe because the resonators will not fit between the bends in the original pipe. You could conceivably cut out the slip joint between the collector pipe and the Y pipe, or find a shorter resonator. That is beyond the scope of this post however.

    My shop workbench is full of other projects, so my workbench for this project was the flatbed of my rock crawler with an old traffic sign. Yours may be a more ideal workspace. :)

    [​IMG]

    First mark out all your dimensions. The outer verticals are the alignment marks for the edges of the resonator (12") the inners are our cut lines (10") giving us 1" of insertion depth. Since this pipe has multiple bends, we also draw a centerline to keep proper alignment. I measured 5" back from the rear O2 bung. The resonator will clear the rear bend this way.

    [​IMG]

    Also need a centerline on our resonator.

    [​IMG]

    Cut on the INSIDE (10") lines with a cutoff wheels or sawzall.

    [​IMG]

    We are left with these.

    [​IMG]

    Assemble and tack weld the pieces. Remember to align the centerlines. Not the small relief cut I made in the resonator. The pipe was slightly out of round from the mandrel bender and wouldn't slide into the resonator on its own.

    [​IMG]

    Even though we measured and marked, it's always a good idea to test fit before we finish weld. If your pipe had any fitment issues originally (the bends on mine were slightly off) you can correct them as well.

    [​IMG]

    Finish weld and reinstall. (Let's pretend this is a pretty weld, OK?)

    The driver side is the same process, but since there is only one bend you can skip drawing centerlines. During reassembly, I found it easiest to install the passenger side first, then the driver side. It's a little tight on the passenger side due to the extra diameter of the resonator.

    Enjoy your reduced cab noise and lower blood pressure levels.
     
    nnywg and Torspd like this.
  2. Torspd

    Torspd Moderator
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    Bravo! I believe a comparison drive-by video is in order.
     
  3. fishsticks

    fishsticks Because fast lifted truck.

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    I'll see what I can do. The external note seems to be very similar.
     
  4. GT7

    GT7 New Member

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    Majorly on the to do list. Thanks for the post
     
  5. Superloki24

    Superloki24 Member

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    I'm going to try this out. If it works out, it's a good price for the "Fix".
     
  6. x-runner kid

    x-runner kid Active Member

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    I'm so glad you were able to write this up. Been dealing with a extra heavy work load as well as a big storm so I don't feel like going for the crawl under the truck in it haha. Great write up. I have my go pro all charged up and I have the week off work so I'll get some video come Monday. (Tomorrow is my 30th bday) I have to look at a o2 sensor issue as well. (Not related to the resonators)
     
    Torspd likes this.
  7. MrX-runner

    MrX-runner Member

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    Thanks for the great write up.
     
  8. Superloki24

    Superloki24 Member

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    Well I did this "fix" yesterday and I can say that the noise is completely gone. It makes the highway speed exhaust tone much better and still keeps that notable high end noise that makes this exhaust awesome.
    Thanks for providing this write-up.
     
    easts1d3 and TitanRattler813 like this.
  9. easts1d3

    easts1d3 Member

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    I took a ride in Superloki's truck and its a night and day differance. No more drone at highway cruzing speeds and still has a really nice exhaust note!
     
  10. Tom2769

    Tom2769 Member

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    For those of you who have done this (besides fishsticks), did you locate your resonator in front of or behind the transmission crossmember? I see on fishstick's truck (he's a non-x lifted truck I believe), he had plenty of clearance for his resonators to live directly above the tranny crossmember. My X does not have enough clearance for my resonators to live there. I think I've got room to fit them in front of the crossmember, RIGHT after the headers, but I'll lose the O2 sensor bung. I could get a longer O2 harness and use the bungs near the end of the headers for the sensors, though, I think.

    Or I could try to get them in behind the crossmember. I don't have URD's straight passenger side modified tube, so I may have a bit more fabricating to do anyway. What did you guys do?
     
  11. Superloki24

    Superloki24 Member

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    It is very tight but it works. I have a resonator just above the cross member on the drivers side and the passenger side one I trimmed down and put in the "bend portion". It was just long enough to fit into the straight section after the first bend.
    I will try and take some pictures and post them up for you to look at.
     
  12. x-runner kid

    x-runner kid Active Member

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    Sorry should of posted in here as well I took some pictures and sent him some via pm. It fits best if you have the upgraded Y section from G but it fits above the crossmember just right.
     

    Attached Files:

  13. NHXRUNNER

    NHXRUNNER "New Hampster"
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    So I went ahead and did this but the hiss came back under load after a month or so. I'm wondering if the welder didn't install them forward enough. I've also thought about going to the 18" version of the resonators. Would there be room? Any other thoughts?
     
  14. Superloki24

    Superloki24 Member

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    Try checking your V-Band clamp Matt. Mine came loose a little bit after a month or so (due to heat cycling and road use they tend to expand a little). The hiss was coming from a leak between the two flanges on the V-Band.
     
    x-runner kid likes this.
  15. NHXRUNNER

    NHXRUNNER "New Hampster"
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    I'll give that a shot and report back. And I should be able to answer my own question about the 18" resonator while I'm at it.
     
  16. x-runner kid

    x-runner kid Active Member

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    The bigger the resonator the better however I'm not sure about them fitting. As for the hiss check that V band those things suck.
     
  17. GT7

    GT7 New Member

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    Did this a few days ago. World of difference IMO and wish I had done it sooner. I dont have a v-band so all annoying noises are gone for now
     
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  18. NHXRUNNER

    NHXRUNNER "New Hampster"
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    So I got under the truck tonight to install the new O2 sensors. There was sooting around a couple of the pipe connections, but not the v-band. However, I was able to tighten the v-band quite a bit. I'm hesitant to tighten anything else much father because last time I really torqued on the clamps I snapped one in half. Hiss may be slightly less noticeable but is still there. I also measured for the 18" resonators, passenger side would clear, not enough length on the driver side.

    Passenger side
    IMG_3610.JPG

    Driver side IMG_3611.JPG

    V-band after I cranked on it. Anyone else tighten theirs further? You can see on the threads how much more I got tonight.
    IMG_3613.JPG
     
  19. Superloki24

    Superloki24 Member

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    That's about how tight mine is. Keep in mind though, you wouldn't see any leaking until you took the V-Band clamp off completely. If it was leaking then the "soot" will be on the inside of the clamp. When I took mine off I gave it a good coat of Copper RVT silicone and it helped quite a bit in sealing it up.
    As for the other clamps, when I put the resonators in I just welded that entire joint up. This way my Y-Pipe comes off as one complete piece and I don't have to worry about another joint to seal up. I'm pretty sure the only reason that there is that joint there is to make shipping the entire system a lot easier (i.e. break the pipe up into smaller sections).
    Hopefully you can get it sealed up, because I love the sound of mine when it's sealed up and working good.
     
  20. NHXRUNNER

    NHXRUNNER "New Hampster"
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    I'll probably follow your lead on the welding and the copper RTV. Thanks brother.
     

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