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Ducati 860 GT Bevel gear lash

Posted: Tue Feb 20, 2018 9:42 am
by rjk40
Hi Folks,

The old man is groping in the dark again:

I am looking for, but not finding, the proper range of lash at the bevel gears on the head. I am likely going to have a new cam and new bevel housing gaskets, thus the gear lash will likely change. New cam is potential, as I am sending my old horizontal cam to Megacycles in San Rafael Ca for evaluation. They currently don't make OEM cams for the 860GT, just the high performance grind. They are currently reworking my horizontal rockers with stellite. Thanks again for referring me to them.

One of you gurus surely must have the lash spec in memory.

Thanks in advance.
Richard in Malabar Florida USA

Re: Ducati 860 GT Bevel gear lash

Posted: Tue Feb 20, 2018 10:32 am
by wdietz186
The original gaskets were thin paper so avoid any new ones that that are stamped out of thick,card like material. If the old ones aren't torn or otherwise damaged you could re use them with a thin smear of aviation Permatex [the thin brown liquid] or other gasket shellac. At the factory the gears were set up in matched sets and have a ground section on them that will line up so the edges are even when the mesh is set properly. You shouldn't be able to feel a step on the transition between the two. One thing that complicates the matter is the tower shaft is mounted in a spherical bearing just under the bevel to allow for some misalignment and expansion when hot. So with the head off you need to make sure the shaft isn't cocked and turns freely. You could bolt the head on with the shaft in the coupler as a final check to be sure. All that said, if you are pretty close it should be OK. A little off won't make it explode, just might whine a bit but you probably won't notice as the engines are pretty noisy to begin with. If Megacycle can't do the cam PM me,I think I might have one in my pile[s] of stuff. Have to put on my spelunking gear to find it I suspect.

Re: Ducati 860 GT Bevel gear lash

Posted: Tue Feb 20, 2018 11:59 am
by rjk40
Thanks kindly for the info, as always.

Pls let me know about the cam; with Megacycles it's likely going to be a while before I hear from them.

Regards,
Richard

Re: Ducati 860 GT Bevel gear lash

Posted: Wed Feb 21, 2018 1:16 am
by ducadini
And if those two options don't work : I (think) I have four sets of spring-cams lying someplace ( also spelunking :-D ) but I don't know what type.
So I think there are two types of 860 and 750. Different groundcircles and lobes, probably because of the shims/screw adjustment.
Not new but in good condition.

ciao
ducadini

Re: Ducati 860 GT Bevel gear lash

Posted: Fri Feb 23, 2018 10:14 am
by Craig in France
Hi Richard,

Also have a look here, page 12 et seq.

http://www.bevelheaven.com/dioc/dioc40.pdf

Ciao

Craig

Re: Ducati 860 GT Bevel gear lash

Posted: Fri Feb 23, 2018 10:36 am
by rjk40
Wow!

That's Great!.

Thanks kindly, Craig. You are truly a wealth of good knowledge, as are your colleagues on this Forum.
Next time I get to south France, I'll buy you dinner.

Regards,
Richard.

Re: Ducati 860 GT Bevel gear lash

Posted: Sat Feb 24, 2018 12:58 am
by Craig in France
rjk40 wrote:
Fri Feb 23, 2018 10:36 am
Thanks kindly, Craig. You are truly a wealth of good knowledge ...
"A Dwarf standing on the shoulders of Giants", Richard - that's all.
rjk40 wrote:
Fri Feb 23, 2018 10:36 am
Next time I get to south France, I'll buy you dinner.
Don't book your flight any time soon ;) . It's horrible freezing cold here at the mo' :shock: :-D