Bevel Drive Questions

[Langanobob]

The recent discussions on timing belt adjustment and Aprilia gear drive cams got me thinking about the old Ducati bevel drive system.  Unfortunately when Ducati was making them I was riding around on a Triumph vertical twin and thought it was just about the perfect bike and I don't know anything about Duc bevel drives.

Were they replaced by the belt system purely out of economics?   Are there some other trade offs where belts might be better, other than cost?  Did the bevel drives have maintenance or performance issues of their own?

If the decision was purely cost based, it seems now that Ducati has reached some of their marketing goals and is selling a lot of bikes, or at least a lot more than they were back in the bevel drive days, that they might consider re-introducing it on some bikes. More expensive yes, but now the cost would be somewhat less due to making more of them and I think a lot of riders would be willing to pay a reasonable premium for a bevel drive motor.

Appreciate any comments.

Bob

[Slide Panda]

Were they replaced by the belt system purely out of economics?   Are there some other trade offs where belts might be better, other than cost?  Did the bevel drives have maintenance or performance issues of their own?

Wel I'm sure economics did factor in - but hopefully it got passed down.
And I'm not expert, but some up-sides to belts vs bevel
- Weight. The belts and rollers will have much mess weight penalty than the bevel drive system
- Mass. The belts and rollers will have much mess mass penalty than the bevel drive system.
- Service. Get a little practice and you can do belts in under 30 min. Getting into a bevel system, in earnest is probably very time consuming.
- Space. The belt system is more compact.

[ducpainter]

Firstly, the Apes aren't bevel driven.

Setting up a bevel system literally takes hours. Every shim adjustment requires complete disassembly and reassembly.

Once set up it lasts a long time.

In todays world where harmonic measurement devices are necessary just to make simple belt adjustment repeatable...and tolerances are loosened to lower costs and reduce the necessity for techs to have to perform adjustments at all...

who is going to set up the bevel drives?

[Speeddog]

Downside of Bevel:

Can't disconnect the cam drive to do valve clearances, making it a real PITA.

Also (not inherent to the drive) there's no clips on the opener rocker shafts, so you have to pull the shafts and rockers out to change shims.
And there's washer-shims on each end of the rocker, so you've got to deal with those too.

[sbrguy]

those clips on the rocker arm stafts are probably one of the best patents that ducati has for their 2 valve engines.

as stated they make the job a lot easier.

[Langanobob]

Firstly, the Apes aren't bevel driven...

I just mentioned the Aprilia gear drive since it seems pertinent to the discussion because it performs very well, didn't say it was a bevel drive.

[ducpainter]

I just mentioned the Aprilia gear drive since it seems pertinent to the discussion because it performs very well, didn't say it was a bevel drive.

I know you didn't, but you're suggesting re-introducing bevel drive which is more cumbersome and I'd bet less efficient.

The two systems are markedly different aside from both employing gears. I don't think you can really compare the two.