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

Hi Tony
Thats correct, the original bevels in my bevel box after 20,000 + mls are like new.
Totally unmarked but roughly finished.
Some time back an owner in NZ had good results after a self rebuild, that is a good start.
Super polishing would sort the roughness.
My view is that some noises are caused by shaft deflection because of bearing movement in the housing due to bad machining. Quaife do not have a good reputation for quality machine work, maybe it is subbed out ? but the bearing housings on the noisy boxes are machined too loose.
I know the2 speeders are technically different I meant that to work on either box is relatively simple. The fact that Quaife wont sell you spares due to Morgan blocking it is bad but we got around that.
Morgan had 12 years to get a grip of this particular issue, one of many that have engineering solutions.
Ian

Hi Fasteddie
Have PM,d you some info
Rgds
Ian

For myself, I do not think that the deformation of the casing is the first cause of the noise, the first cause of the noise would be poor quality machining of the teeth, having dismantled and reassembled the bevel box three times, two mine and that of a friend each time before reassembly I put marker on the teeth of the spiral crown to see the traces of the wear of the input pinion I realized the traces on the crown wander while going completely around the crown toothed, I am used to rebuilding or building 901/911/914/915 gearboxes for which some have crankcases in poor condition and conical torques which have hundreds of thousands of kilometers, the problems with noisy gearboxes are so do not change the damaged bearings and if the distance of the conical torque is incorrectly adjusted or a poorly manufactured adaptable spiral conical torque is installed.

For me I use 85w140 I tried the 90 which is fine too, the Redline 75w250 is cat pee for me, the thicker oil you put the more it helps to heat the bevel box that said more it heats up the more it liquefies.

In winter I don't pay attention to the noise, I always have the impression of driving in a vehicle from before the Second World War and, as the old mechanical repairmen say, if it sings, it's happy.

Lapping the teeth and super-finish polishing can certainly improve certainly improve the sound level, the teeth of my bevel box.

After replacing only twice the cracked crankcase without the gears which have more than 100,000km everything is fine.

To check the contact of the teeth, women's lipstick is better than the stilo marker.

I have a 2023 Super 3, and it has almost 700 miles on it now. The BB definitely made a loud whine when it was new but it seems to be quieting down as miles are added on (either that or my new helmet filters out the frequency). I wonder why Morgan went this route, they could have just used the drive shaft setup from BMWs motorcycles. I know there is extra weight with that but it would have been much quieter....

Pete Larsen used a Honda drive shaft for his M3W predecessor but because of the angle from centreline to drive sprocket wheel-side means the passenger seat is cramped. No easy answer to go from the driveshaft to the wheel drive. The original 3 wheeler put the gearbox where the bevel box is and the output was offset enough to clear the skinny rear wheel they used then.

The only solution for Pete Larsen was (with his Ace) to put the engine behind the seats, altering the aesthetics completely. Meanwhile we are stuck with bevel boxes which bizarrely sound worse than diffs from the 1950s…

Several swing arm/ drive shaft conversions have been considered using BMW, Honda, Moto Guzzi and Triumph Rocket 3 even. They all have the problem of the off set driveshaft and other issues I am sure if you look deeper. Mark Grinnall (I had a Grinnall Scorpion 3 once and knew him) tried to talk me into leaving my then fairly new M3W with him for a few weeks as he had a lot of Triumph Rocket 3 swing arms from trike conversions that he saw a market for. I declined the offer but maybe I should have taken it as the Scorpion was a much better engineered car than the M3W.

I have often wondered if a Honda Gold Wing bevel box could be mounted in the same sort of way as the M3W bevel box, with a drive belt sprocket in place of the wheel and leave the standard swing arm in place. Probably the ratios would be wrong? All these conversions would be a major job with a lot of hacking about required and would you have a 'proper" M3W left at the end of it?

Hopefully some progress is being made with sorting out the noise with the M3W (and Super 3?) bevel boxes. It's not like they are failing, just noisy and even then only at some speeds.

The bevel box on my 2103 M3W howled between 50-60mph, I tried various different oils with no notable change. I then put in Amsoil 75w 140 Severe Gear oil and that did make a difference, the howl hasn't gone away completely but it is quieter and less ear piercing.

By way of an update I have taken out and cleaned the bevel box. I have given it to Nova Racing who we know and are just down the road from us. They build gearboxes for superbike racing and they are going to take it apart and have a look.
Hopefully they can work a bit of magic and when I put it back in the car I will let you know.