lucky dawg Posted April 18, 2020 Share Posted April 18, 2020 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? Link to comment Share on other sites More sharing options...
Croc Posted April 19, 2020 Share Posted April 19, 2020 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. Link to comment Share on other sites More sharing options...
fastg Posted April 19, 2020 Share Posted April 19, 2020 FYI, i think what you are calling a bobbin is really called a "Silent Block" Graham Link to comment Share on other sites More sharing options...
lucky dawg Posted April 19, 2020 Author Share Posted April 19, 2020 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. Link to comment Share on other sites More sharing options...
Croc Posted April 19, 2020 Share Posted April 19, 2020 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-gaskets/1075-exhaust-mounting-bobbin.html Link to comment Share on other sites More sharing options...
coffee break Posted April 19, 2020 Share Posted April 19, 2020 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/ Link to comment Share on other sites More sharing options...
David K Posted April 22, 2020 Share Posted April 22, 2020 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. Link to comment Share on other sites More sharing options...
papak Posted May 9, 2020 Share Posted May 9, 2020 I just a replacement from Aircraft Spruce. I’m hoping an “aircraft quality” mount will last longer. You really have to minimize the offset. Link to comment Share on other sites More sharing options...
azw_superlight Posted June 1, 2020 Share Posted June 1, 2020 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. Link to comment Share on other sites More sharing options...
papak Posted June 2, 2020 Share Posted June 2, 2020 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. Link to comment Share on other sites More sharing options...
azw_superlight Posted June 2, 2020 Share Posted June 2, 2020 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. That's a reasonable idea. As is the idea of just a poly bushing with a bolt through it. Anything that has no hope of separating from the car. Link to comment Share on other sites More sharing options...
azw_superlight Posted June 2, 2020 Share Posted June 2, 2020 Thanks I'm off to take care of a fuel line that looks like it is supposed to be part of a sprinkler system. Link to comment Share on other sites More sharing options...
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