Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Clunking noise from the back

Hello all,

I finally bought a Morgan 3 wheeler after years of wanting one. The car is a 2012 version, fitted with a new chassis and many upgrades and has about 12.000 kilometers on the odometer. However, the first weeks of ownership have not been trouble free so I have been tinkering around with it a lot. This was expected and I don't mind it, but now I've run into an issue that I can't seem to wrap my head around. I have this weard clunk coming from the back of the car. It's most audible on the right side of the car.

When the car is cold, everything seems to be perfect. I can perfectly drive it without the noise appearing. After about 30 km however the noise slowly starts to appear. It's faint at first, but it gets louder the more you drive it. I can only hear it at slow speeds, but if you keep driving it the noise even becomes audible at speeds over 60km/h which is worrying to say the least. The noise is speed-related in frequency, but not in loudness. The noise appears with the engine off or on, in gear or not in gear, .... so I don't think it's related to the engine, clutch or gearbox.

In this video I start rolling down a bridge with the engine off and the car in neutral:
It's clearly there and pretty loud + the intensity increases as the speed increases. After making this video I let the car cool down and the cracking had again gone away until the next time it's warmed up.

I don't think this is a unique example. You can hear it in this video as well and that is a completely different car. When I slow down at 9 min 16 sec, you can hear the faint sound coming from the rear as well:
That's a friends car and I didn't notice it at the time, but when I hear it now it seems to be the exact same thing.

I suspect it's the rear bearings, but maybe someone else has experience in this field?

Other than that, what a machine

Congrats and great colour!

Suggest check rear belt alignment / rear belt flange? Knocks I had were the NVH kit (replaced by the Bleazey bevel box mount) but that was only under acceleration. Maybe check the bevel box / rear wheel bearing anyway?

Check the belt “guides” on both the bevel box and rear hub are not damaged. It sounds like the belt is rubbing on these.
If you jack the car up and rotate the rear wheel you should be able to see what the issue is the noise is quite distinctive.

Jacking it up and rotating the wheel is something I'll try tonight. It only does the noise when it's been driven for a while and it doesn't do it very long, so I'll need to be quick but it will indeed help me narrow it down.

It seems odd to me that it would be the belt rubbing on something, but you never know with these things.

Agreed that it doesn't sound like a belt issue, but belt guards, especially at the wheel, can come loose. The rear brake and handbrake assembly is prone to issues from sticking wheel cylinder and dry handbrake cable that can cause wheel speed noises at temp, but in my car those noises were a muted scuffing sound until I rebuilt the assembly. Your sound is more 'open' metal on metal to my ears.

Have a close look just behind your head at where the roll hoops pass through the body, You will have to lift the rubber seals a bit to do this. On some cars, the roll hoop doesn't line up very well with the hole in the bodywork causing intermittent metal-on-metal squeaking/rubbing sounds. The solution is to remove the roll hoop and open up the aperture in the bodywork. One or more of the rubber seals may need to be replaced too.
Check out this THREAD for more info!

Update: I've just listened to your video and obviously the noise is related to back wheel rotation. As others have said, it could be related to one or other of the sprocket side fences (also mentioned in the above thread by the way). Remember that you can happily remove the outer fence and run without it. Alternatively, could it be a stone caught in the belt? Unlikely to be wheel bearing related IMO.

and check the bevel box outer flange - your need a torch - from underside check the small button head retaining bolts for the flange - they sometimes start undoing and the bolt heads are so close to the swing arm they start to clip the swing arm - they continue to unwind and then get sheared off due to this action.....one by one, then the flange lets loose and wraps around the belt and you come to a sudden halt......hopefully not on a motorway...

I was going to test some things this evening but after a test drive this afternoon where I experienced serious vibrations over 100km/h I decided to stop the search and just take it to the dealer.
On the way there the passenger windscreen broke on its own (I don't see any impacts on the glass nor did I hear anything). Also on the way there (100km of driving), I didn't hear the sound once.... really strange. It was 7°c outside this evening, so maybe it is a temperature related thing.



Lets hope they get it sorted quickly as I have an event to attend on april 6th, I have sent the dealer a mail to check the bevel box outer flange for loose bolts. I'll keep you guys posted and really appreciate the help and ideas

I am not a three wheeler owner... however I hope your dealer can resolve the mystery and to your schedule, it will be interesting to know what caused the anomaly... keeping my fingers crossed and looking forward to reading of the resolution.....

Some years ago (2018) on a long European trek in Spain/France, we had a rather similar sounding "clanking" noise from the rear that was related to rear wheel rotation. It started after some big climbs in the French Alps. We had a serious look around but could not locate anything obvious wrong - we were however limited in what we could do while on the road. We cut the trip a bit short (missing the Grindelwald gathering) and made our way home taking it relatively easy. As we approached northern France, it stopped ...

Once home we dismantled the rear end and found nothing obvious ... frustrating ... but it is a Morgan

Conclusion/suspicion is that it was something knocking in the rear drum brake. We have not had any recurrence but a lot of recent miles have been with a replacement disc brake supporting a hypothesis that the original drum might have been the source...

Good luck to PJH for a successful resolution.