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Exhaust mount quality

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57_BN4

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I got some exhaust mounts from one of the usual suppliers a while ago and they are all failing. So far I have fitted three mounts and they only last about half an hour each, then the smaller plate comes unstuck from the rubber due to the heat from the muffler. The delaminated metal and rubber joint shows that it wasn't ever stuck together apart from around the edges and the plate is quite rusty in the middle under the rubber.

It seems there are two problem- firstly the quality of the repro rubbers is no good and secondly- it does seem to be asking a lot of a rubber mount to expect it to perform when bolted to the front of the muffler which probably gets to 300degC after a good hard run.

Anyone found a supply of properly made original style mounts? Is there a recommended mod to help with the front muffler mount getting too hot?

On a related topic, does anyone have a pattern for the original tail pipe plates that attach to the two rear mount points. They are kind of a pear shaped 1/8" thick plate with a hole in the middle for the pipe as can be seen behind the muffler on this car

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Andy.
 
I got seven-plus (>7) years out of the last ones I used, but recently had to replace them after an 1150 mile ride on a transporter. I've already beeaten your time of thity (30) minutes with the new ones, so I'm hoping the manufacturing process isn't to fault; these were sourced through Moss Motors in the USA.

One (1) thing that you could try, would be to pass a bolt with an all metal locking nut on the end through the two (2) plates in the approximate middle of the rubber. Leave the bolt *just snug* (a pair of Belleville washers would be even better) to allow the rubber to continue its job to isolate the vibration. The bolt should take some of the shear strain away from the rubber, extending the usefull life of the part.

Another option is the generic rubber exhaust hangers; cut to the appropriate length, bolt to the chassis (using a suitable threaded insert__NOT a coarse self-tapping bolt...) and affix to the pipe with a U-bolt. Certainly not as glamorous, but effective.
 
For the case where the unit has delaminated I have repaired them by cleaning the metal up and then regluing the rubber to it using Super glue.--Fwiw-Keoke
 
I glued mine like Keoke but also added a couple of #10 metal screws (don't remember the length) into the rubber though the plates on each mount. They are holding up so far.

Doug
 
Thanks everyone for the replies and suggestions. Seems like exhaust mounts are a bit of a weakness of the original design.

I'd still like to keep the original look of things so I'm investigating ways to get the mounts re-vulcanised but maybe incorporating some mechanical interlocking so that even if the rubber bond fails, there is still some mechanism that stops complete failure of the mount. Maybe if I can weld a couple of short bolts onto the plates before vulcanising, the bolt heads won't be able to pull through the rubber if it de-laminates.

Andy.
 
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