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Thread: Rear Exhaust Mount

  1. #1
    Join Date
    Nov 2011
    Location
    Seattle area
    Posts
    454

    Default Rear Exhaust Mount

    Has anyone else had a problem with their exhaust mount that attaches to the body in front of the rear wheel? I have had two break so far. Both times the rubber bobbin broke apart. Is the stock CSR muffler too heavy for the mount to hold up? Is it a design flaw because there is no reinforcement inside the bobbin? Something else?
    2012 CSR 260, registered as a 1966 Super 7

    Still in the massive grin stage. Damn bugs!

  2. #2
    Join Date
    Feb 2009
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    NYC
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    Default

    I had this happen years ago on an old Caterham of mine where bobbins used to fail every few years. Took me a while to work it out. Whats likely happening to you is that your exhaust pipe is not likely seated into the collectors all the way or some part of the exhaust is slightly out of alignment. Could even be the engine mounts out of alignment ever so slightly or failing. It will be subtle and not easily detectable visually. So what ends up happening, is that very slight misalignment is transmitting a shear load down the length of the exhaust onto the bobbin. They were not designed to take that given the angle they are mounted at and so fail early.

    Never had a bobbin fail on my CSR. Original 10 year old one still looks in good condition.
    Mike
    2010 Caterham CSR with Cosworth 2.3 Duratec
    2018 Caterham 420R with 2L Duratec 210hp at Donington UK
    1975 BMW CSL Group 4 (restoration - engine and dry sump install time)
    1977 Holden Torana "A9X" (awaiting restoration)
    1985 Holden Commodore SS Group A
    1985 Holden Commodore Group A
    1982 Ferrari 400i
    1965 Ford Mustang Fastback "Holman Moody"
    1992 Ford Escort RS Cosworth WRC (fettling after long period of storage)
    1990 Range Rover 2 door Classic
    and another project car coming....

  3. #3
    Join Date
    May 2010
    Location
    Laurel MD
    Posts
    177

    Default

    FYI, i think what you are calling a bobbin is really called a "Silent Block"

    Graham

  4. #4
    Join Date
    Nov 2011
    Location
    Seattle area
    Posts
    454

    Default

    Quote Originally Posted by Croc View Post
    I had this happen years ago on an old Caterham of mine where bobbins used to fail every few years. Took me a while to work it out. Whats likely happening to you is that your exhaust pipe is not likely seated into the collectors all the way or some part of the exhaust is slightly out of alignment. Could even be the engine mounts out of alignment ever so slightly or failing. It will be subtle and not easily detectable visually. So what ends up happening, is that very slight misalignment is transmitting a shear load down the length of the exhaust onto the bobbin. They were not designed to take that given the angle they are mounted at and so fail early.

    Never had a bobbin fail on my CSR. Original 10 year old one still looks in good condition.
    That makes some sense, thank you.
    2012 CSR 260, registered as a 1966 Super 7

    Still in the massive grin stage. Damn bugs!

  5. #5
    Join Date
    Feb 2009
    Location
    NYC
    Posts
    4,890

    Default

    Quote Originally Posted by fastg View Post
    FYI, i think what you are calling a bobbin is really called a "Silent Block"

    Graham
    Probably is but Caterham calls it a bobbin
    https://caterhamparts.co.uk/mounts-g...ng-bobbin.html

    Name:  exhaust-mounting-bobbin.jpg
Views: 189
Size:  11.8 KB
    Mike
    2010 Caterham CSR with Cosworth 2.3 Duratec
    2018 Caterham 420R with 2L Duratec 210hp at Donington UK
    1975 BMW CSL Group 4 (restoration - engine and dry sump install time)
    1977 Holden Torana "A9X" (awaiting restoration)
    1985 Holden Commodore SS Group A
    1985 Holden Commodore Group A
    1982 Ferrari 400i
    1965 Ford Mustang Fastback "Holman Moody"
    1992 Ford Escort RS Cosworth WRC (fettling after long period of storage)
    1990 Range Rover 2 door Classic
    and another project car coming....

  6. #6
    Join Date
    Feb 2012
    Location
    Roswell GA
    Posts
    974

    Default

    McMaster has a variety of these items to chose from. It may take some poking around to find what may work for you.

    https://www.mcmaster.com/vibration-damping-sandwich-mounts/general-purpose-vibration-damping-sandwich-mounts-with-studs-6/
    Life happens while you're making other plans
    1995 Caterham Crossflow RHD
    1990 Miata
    2007 GMC Sierra WT
    2013 Mini (Her's)
    2014 Outback
    JOHN DEERE D130

  7. #7
    Join Date
    Feb 2017
    Posts
    10

    Default

    I sandwiched a bushing with a through-bolt after going through three bobbin/silent blocks. As others mentioned, it's probably a symptom of another problem. In mine, I'm certain it's engine mount welds (long story). The result was the new fixed point pushed all the vibration to the muffler, which soon was making an unpleasant rattling noise.

    The sooner you re-adjust the exhaust, the happier your muffler and bobbins will be.

  8. #8
    Join Date
    Dec 2014
    Location
    Los Angeles
    Posts
    256

    Default

    I just a replacement from Aircraft Spruce. I’m hoping an “aircraft quality” mount will last longer. You really have to minimize the offset.

  9. #9
    Join Date
    May 2020
    Location
    Fremont
    Posts
    3

    Default

    I know I'm ressurrecting an ancient thread here but does anybody have a thru reinforced version of the bobbin. I've gone through more than half a dozen in 18 years of ownership and the last one failed at turn 7 in Sonoma and put the exhaust into the left rear wheel.... I'd really like to have a better solution to this but still have some compliance.

  10. #10
    Join Date
    Dec 2014
    Location
    Los Angeles
    Posts
    256

    Default

    You could cut a valve spring in half with a cutoff wheel and sandwich it between two fender washers and run a through bolt through the whole "sandwich". Just use a locknut. That should work.

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