upper bevel help

[double diamond]

Checking backlash with the head torqued in place is only a concern if the backlash is set to almost nil.

Matt

[Scottish888]

Beginning upper bevel adjustment, can anyone advise on how to tighten the camshaft nut while the head is off, is it possible?
I think there is a camshaft locking tool, where would that fit and has anyone tried making one?
For a start, I fitted the original shim behing the cam bevel and tightened the nut as far as I could, still a little bit of lateral play, I fitted the bevel shaft and housing with the correct gasket thickness.
When trying to make the bevel shaft housing tighter, the bevel gears became too tight and rough to turn (only slightly hand tightened), sackened off the two allen screws a little and the bevel could turn freely again.
I could adjust the bevel shaft shims to lower the bevel gear but how to determine if the camshaft bevel needs to move further in rather than the shaft bevel needing lowered?.
I know the cam nut will need fully tightened and that could make the difference, drawing in the cam bevel a little more.

Regards,

Alex

[ranton_rambler]

I did mine with the head off. I think I just nipped the camshaft nut up. According to my notes it took 7 adjustments until I was happy. If you follow the factory manual you need to adjust until the ground surfaces are flush and the gears rotate with minimal backlash but not too tight. It sounds like yours are too tightly meshed.
Ian

[Jordan]

Ian is right, work to the ground surfaces on both gears.
To be clear, these surfaces are hand-ground with a rotary abrasive tool.
The grinding is done after the bevel gears' meshing and shimming is carefully done, to simplify later assembly of the same gear pairs.
It's a good method, as each grinding produces a unique pattern - to identify pairs as well as provide the reference plane for subsequent shimming.
Because roadgoing Ducatis use helical bevel gears, setting them up is more complicated than if they were straight cut.
Not only should the gears be shimmed for correct backlash (which could be in any position) but also so they are in the only position where correct meshing of the gears' teeth occurs, due to the convex/concave shapes of the mating tooth flanks. (Thanks to Nigel Lacey for pointing this out.)
With a new or mismatched pair of bevel gears (more likely nowadays), a helical gear set should undergo a 2 step process of clearance adjustment and depth-meshing. Engineering blue paste is used. When completed the gears can be hand-ground for reference.
Royce Creasey wrote on this topic:
http://www.bevelheaven.com/duc-mags-CamDrive-index.htm

[Scottish888]

Thanks for the advice and info, will be trying this today
I think I have to tighten the camshaft nut until there is zero lateral play with the camshaft? At the moment I can still move the cam in and out a fraction.
Is there a method to stop the cam turning while the nut is nipped up a bit more, I am using a small wood or nylon wedge against the bevel wheel and head but worried to apply any more pressure.

Regards,

Alex

[Jordan]

This is a home made cam locking tool.
Make it in steel, because being aluminium, the maker (Rob from Bevelheads) said it wasn't strong enough.
Having this should make working on the top end much more pleasant.

[Scottish888]

Thanks, I can see how it works now, remove the end cap and lock the tool onto the cam lobe.
I can have one made in brass which hopefully will not damage the lobe.
I had assembled the cam, rockers and end cap already, oh well, more assembly practise coming up.

Regards,
Alex

[themoudie]

Aye Alex,

Have sent you an email! I am having computer problems, so not sure if this will end up on the forum?

Regards, Bill

[themoudie]

Aye Alex,

DO NOT USE WEDGES TO JAM THE CAM OR GEAR! 30 years ago I thought that I could save time and money, with some bush engineering by jamming a wide flat steel bar between the cam and the top of the cam tunnel! The top of the cam tunnel/head casting fractured off! Required more expense to have the head welded up and then purchase the proper tool for the job.

Steel tube is the only material strong enough for the job and an alloy bush is also required to ensure a good fit. The tommy bar is not essential as the tool maybe held in a vice and the head/cam sat on top of it whilst the nut is torqued. Nigel Lacey told me that he used 35 ft/lb or ~47Nm (say 45Nm).

I sent you an email. Not sure if I have cleared my computer glitches!

Good health.

My regards, Bill

[Bevel bob]

I spent a few fruitless hours attempting to set the top bevels before realising that the special bearings (angular contact?) were shot. Also if some PO dork has tossed many of the shims you have to go back to basics. Also its necessary to arrive at the total shim pack thickness to get circlips a snug fit and then distribute the shims to get the mesh right.A sort of mechanical chess game that can go on and on. A good selection of spare shims and a micrometer are right at the top of requirements.Plus lots of time and patience. Do a good job and they will go forever.