Housing modification for moving bottom bevel gear

[Rocla]

Hello,

Some of you probably remenber when, in 2013, I removed the bevel gears of my 350 Scrambler 1974. Some of you probably remember that I've milled 3x2 cm around the bevel shaft housing, in order to disassemble the bottom bevel gear without dismantling the engine. By this way, I've saved days (I am so lazy bones). But was this modification sustainable ? That was the question. Some of you asked me to give a feedback further.

Here below the modification :

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With my Scrambler, since that modification, I've crossed the south of France during August 2014 and I've attended several classical bikes meeting. Sum total, more than 1500 kilometers, at a sustainable pace without any problem. No specific vibration, and always a very low consumption (3,5 to 3,8 l/100 km). No oil leak at all. No excessive heat. And a good response of the engine at every speed.
If I had to process such modification again, I know by experience that the hole could have been a little bit reduced. Anyway, the kind of aluminium tower that contains the bevel shaft and its cylinder with bearings, is excessively dimensionned. For me, these few cm3 of aluminium were not necessary. Being forced to dismantle the whole engine just for removing the bottom bevel gear, wasn't a little bit amazing?

[BDang]

The outer races of these two bearings must be locked from potential free spinning by the design, but with a bottomless housing after the mod they could spin freely and destroy the housing, and also there is no way to keep the shaft from oscillating up/down which would lead to bottom gear mesh issue and bearings sliding up/down inside the housing. All of this will lead to faster wear out components.

Regards,
Brian

[Bevel bob]

Can't see that it would cause a problem as the steel bucket that holds it all is clamped down on the top flange to the case. Well it would be if you got the gasket/shim in balance.Not so easy!!.Not too happy about the way the gears mesh------work in progress?.

[Rocla]

Hello,

Yes, work was in progress when I've taken the picture. At the end, I've sent to the forum pictures of the gear and teeths perfectly adjusted thanks to blue ink, etc... I've sent the record of the engine, significantly more silent. Some of you told me "it seems very good"... Many thanks again for your support, I did it on my own (thanks to Motoscrubs). Do you realize that the main Ducati garage in the town I live (1. 300. 000 unhabitants) is incapable of doing such a work

About the risk of shimmy, I confirm, the circular housing of the shaft and its bearing is so strongly stuck inside the modified housing (I was forced to warm it and to refresh the bevel in order to remount everything) that I was confident before any test. And the experience confirms that there is no risk. Especially when I run 1000 km in the south of France in August, whith temperatures oscillating from 25 to 35 Celsius degres... It was a good challenge...

[Bevel bob]

The Ducati motor seems not to suffer from overheating , if anything mine runs cold and takes ages to get up to temperature.

[BDang]

The picture shows the two lower bearing's outer races with spacer between are clamped down by the top flange and the bearing housing's bottom lip, both are pointed by the two green arrows. With the bottom lip of the housing cut off, I don't see how the bearings are locked from rotating.

Regards,
Brian

[BDang]

I just realized that Rocla had cut the casting which housed the bearing housing, and not the housing itself. Ignore my comments on the bearings locking issue.

Regards,
Brian

[Bevel bob]

The bearing housing bottom lip is intact . If it was cut off then there would be no way to keep the bearings in there.

[Bevel bob]

The bearing housing bottom lip is intact . If it was cut off then there would be no way to keep the bearings in there. ITs part of the crankcase thats cut.

[BDang]

The bearing housing bottom lip is intact . If it was cut off then there would be no way to keep the bearings in there.

Bob,

If the housing bottom lip was cut off, the bearing would not fall out since the vertical gear and shaft held the bearing, but its outer race is loose.

Regards,
Brian