It might be the exhaust contacting something on overrun - worth a quick look?
You could also have a look at the diff mountings to check they are tight. Also check anything that might be loose under the car, or anywhere really. After that, if no joy, you have to try and pin-point the noise…
That’s a gearbox buzz or rattle, to verify remove the gear lever gaiter and any padding and take it out for a run, the noise should become obvious if it is gearbox…
Hi all, thanks for the many suggestions, unfortunately haven’t had time to properly investigate other than the dash is secure so next is a cursory check underneath and drive without the gear gaiter. Will keep you posted.
+1 exhaust
While under there check the UJs. I had a failure of these that sounded similar on the overrun.
Cam Chain? Would have gradually crept up on you without you noticing…
Is the noise new & fully formed when it became apparent or has it been gradually getting worse?
Take a look at the long post in the Plus 2 forum with the name “Metallic Rattle.” Two of us on that post have (and for me still have) the noise you have recorded on overrun. Mine sounds like it comes from the gearbox and, although several knowledgeable mechanics have been inside it, no one is able to eliminate it. I explored other sources of the noise even going to ridiculous lengths including having my drive shaft shortened. Finally, I put some sound proofing material around the shift lever, put the center console over it and have learned to live with it.
I hope that someday someone has the answer to this annoying noise. I’ve given up trying to find it…
Hi Lee, that is a truly epic battle you’ve had and hats off to your determination! thanks very much for the pointer.
With regards my car, I’ve taken it out on 1 hour journeys again and it hasn’t presented again. Perhaps very very slightly but not anything like it was when I first heard it.
Do Elan’s self fix?
I think I will still have a nosey under the car for anything loose.
I have the exactly the same noise as you (and Lee), and although I haven’t found either the definitive answer and solution, I’m 95% sure I know what it is and have managed to reduce, but not eliminate it, in my car.
I’m sure it’s gear lash/mesh rattle, which is that the gears that aren’t in use rattling against each other, as a result of resonance from the drive train and/or the chassis. It doesn’t mean impending gearbox destruction, but it is really annoying! I haven’t the level of skill as Lee to whip my gearbox in and out in an afternoon, but I have managed to reduce the noise.
What worked for me was reducing the vibrations that the gears seem to rattle in harmony with.
Two things made the biggest impact. The first was the rear silencer/muffler mountings were not as tight as the should be, and the second was switching to solid driveshafts from rotoflexes.
Also using a recipe of higher viscosity of gearbox oil helped too. There’s an interesting page here store.uucmotorwerks.com/articles … rattle.htm as BMWs seem to suffer from a similar thing! You have to be careful with gearbox oil though, as modern additives in some can damage brass synchro rings. There are multiple threads on here about what you should and shouldn’t use! I’ve currently got a blend of Redline synthetic oils in mine.
If this were a Morgan forum I would suggest the noise is “Deathwatch Beetle”. Ash frames and all that……
My wife gets annoyed at me for always wanting to find out what’s rattling or causing a noise in any car I’m driving, be it a modern or one of the Elans. I think it’s just down to the inherent engineer inside or an enhanced case of mechanical sympathy.
I’m not happy unless it’s working and sounding correct and then I get paranoid my senses are failing me when everything seems okay.