Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Muted Bevel Box- Name Your Price?

Skullmog, would you please share your findings?

Sure will !

switching to metal rear pulley made a big difference in noise. high pitched frequencies disappeared.

The noise from my BB almost disappears above 60mph. Its quiet for first 10 miles from cold. With my new chassis & NVH kit its changed a bit & now most noticeable around 40 - 45mph.

Tim

Did a quick search, didn't find a definition, just a description. Looks like part of the manufacturing process where they set the gears where precisely how they should be, then shim them in place:
http://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_bevel-box.htm

Relevant bit:
" The way they are manufactured involves in it's final stages a lapping process where the gears are set up in a dolly that places them in their ideal running format and they are then lapped together to make a mating pair.

Once this has been done whenever the gears are used they must be set up in precisely the same configuration, or very, very, close to it. This is the reason that the gears have to be shimmed up. What you are doing is getting as close as possible to the ideal."

This might help understand

WHAT IS GEAR LAPPING?
Gear lapping servicesGear lapping is the process of imparting a very fine finish and high degree of accuracy to gear teeth, by using a lapping tool and applying a fine-grained abrasive between a work material and a closely fitting surface, called a lapping plate. By running mating pairs together in a gear lapping machine and feeding a liquid abrasive compound under pressure into the gear pair, small amounts of metal are removed as the gears rotate, thus refining the tooth surface and achieving the desired contact pattern.

Lapping typically improves the wear properties of gear teeth, and corrects the minute errors in involute profile, helix angle, tooth spacing and concentricity created in the forming, cutting or in the heat treatment of the gears. Therefore, gear lapping is most often applied to sets of hardened gears that must run silently in service. It is important to bear in mind that gear lapping is a mating process; two gears that have been matched by lapping should be operated as a set, and also replaced as a set, rather than singly.

Thanks for that explanation - I thought I knew what it meant but I do now .

Why isn't it done at original manufacture?
Silently in service would be nice.

The cost to remove the bevel box have the gears lapped and re install was $1,300.00. Once the bevel box gear set is lapped they are a matched set and there is very little noise from the bevel box. The 3 Wheeler is a joy to drive without the bevel box scream, at 110 klm per hour it was howling like a banshee, now just the wind and the engine song.

I reckon that's $1,300.00 very well spent!