Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Bevel Box Noise Survey

Sept 2015,6000 Kilometer, not noise up to 120 Km/h (max. Speed Swiss Street)

Chris this is a great thread. After so many "moving on" I've been wondering how many of us were still flying our M3Ws, and this is the perfect excuse for a nice headcount

Plus, it is a very interesting survey, I hope you or someone take it to the attention of the factory.

Many thanks!




Hi 1903Chris (you're not 113 years old are you? )My M3W is also a Brooklands (#33) and there are a few more within the TM community, it'll be good for info sharing in what's specific to our cars

Bunny | 2012 | 3900 | n | Supermax | y | Redline Shockproof

2012 NVN fitted. 6000 miles

Had the original BB changed early in ownership and factory sprocket upgrade.

BB is generally quiet but last week I adjusted the belt and it was noisy. Let the tension off a bit and it's fine again.

Maybe we need to ask about belt tension as well?

Marian; April 2012; initial very noisy BB replaced after 1500-2000 miles; Current has done 6-7000 has been pretty quiet but noise seems to be increasing on moderate loads as (3rd) aluminium sprocket reaches end of life; no NVH kit (have new/replacement (hybrid) chassis); oil as supplied by Morgan/dealer.

2013 M3W
Noise starts around 45 mph
12000 miles
No NVH
Original aluminum sprocket (pitting not bad)
Front BB shaft seal leaking (again)

Good stuff – keep the info coming.

Now up to 25 responses with 14 noisy and 11 quiet




Of the 14 noisy:

12 are 2013 or earlier, kwb is 2014 and 1905Chris a 2015 (Brooklands)

6 have the NVH, 8 do not (assuming hbatts does not.)

Pretty much all the noise is when the BB is hot and somewhere in a 45 – 65 mph speed range

5 are still noisy with Redline Shockproof oil (1 is quiet)

Of the 11 quiet:

7 have NVH and 4 do not

So some further observations

The noisy BB is speed and temperature dependent which I think confirms that resonance is a big factor.

The Redline Shockproof does not seem to cure it and the NVH kit has a mixed impact.

Belt tension may be a factor with asbojohn, MichaelH and MOG42 reporting going quiet with reduced belt tension, however Laurens, nadvys and RogG still have noise. Maybe you guys could let us know the new tension?

There are a couple of responses which could possibly be sprocket rather than bevel box noise – they can sound similar and be speed/load dependent.

And as an aside, there are a lot of boxes being changed for front seal failures!

Whilst the above is all valid data it is somewhat subjective. Noisy to me, is different to that of my son and the belt tension is another variable that is subjective. A tough subject.

Not very scientific but my belt tension.

In the middle of the belt there is 15mm of vertical movement whilst apply minimal force, alternatively I can twist the belt 40 degrees with some force. Prior to slackening the belt there was only 5mm maximum movement.

These results seem to pointing to the fact that temperature is causing problems with clearances and hence gear noise or insufficient preload of the pinion bearings, as the survey indicates the noise is worst when the bevel box is hot causing differential expansion between the aluminium housing and the pinion shaft. Not knowing the dimensions of the bevel box but If the bevel box is running at 120 deg C the pinion bearings are 50mm apart then the differential expansion cold to hot could be 0.06mm (0.0024 inches) which could be enough to upset the preload.

JVS 2012 M3W
Bevel Box had very little oil in it when I drained it after 500 miles - it was getting noisy.

over six months I changed the oil every hundred miles to get the crap out of the box - until the oil was a clear Red color
(used Redline Shock Proof Red oil) Now 8,000 miles on the unit.

Now the box gets noisy until I change the oil which brings down the noise.

Basically you need to keep fresh oil in the box to keep it quiet.

looks like a rebuilt to happen once the oil changes don't work in keep the unit happy.

would love to see a vendor make an upgraded unit
maybe even chain drive.

Redline is the real deal when it comes to thick lubricant