upper bevel help

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Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

upper bevel help

Postby Scottish888 » Mon Jul 22, 2019 9:14 am

Problem is with a new gasket fitted the bevel shaft can move up and down, without a gasket the shaft can be locked up but there is a 0.7mm gap between housing and head. I don't have any 0.7mm gasket paper.
Should the camshaft bevel also be shimmed in and out if needed? I ask as there were no shims there on stripdown, I understand I may have to re-arrange the shim set in the upper bevelbearing.
What diameter roll pin is needed for the cam shaft end to force more oil to the cam lobes, I think I read somewhere this was a sensible mod or maybe I an thinking of the crankshaft

Thanks
Last edited by Scottish888 on Mon Jul 22, 2019 1:07 pm, edited 1 time in total.

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: upper bevel help

Postby Jordan » Mon Jul 22, 2019 10:02 am

Use silicone sealant to fill the gap.
That avoids risk of damaging the head by not positively clamping the housing.
The camshaft bevel is shimmable.

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: upper bevel help

Postby Scottish888 » Mon Jul 22, 2019 12:45 pm

Thanks Jordan,

How about when you need to keep removing the housing to get the shimming correct?
Quite a difficult setup.

Regards

ducwiz
Posts: 604
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: upper bevel help

Postby ducwiz » Mon Jul 22, 2019 5:13 pm

http://www.bevelheaven.com/duc-mags-CamDrive-index.htm describes the shimming process for the lower bevel gears, but is basically valid for the upper, too. But there are some special issues at the upper end:

Before starting the mesh job, make shure that the protection sleeve for the bevel shaft presses the edge of the upper bearing's bush against the cylinder head, so that no axial or radial play is noticable. While doing this, tighten both screws equally and slightly, but dont bend the protective tubing's flange. If you can't achieve zero play, put an appropriate shim between the bearings outer race and the projecting end of the sleeve. You can use the 29x35mm shims which normally sit between swing arm and the frame, or inside the lower bevel bearing sleeve respectively. If zero play is accomplished, measure the gap width for the gasket, and add shims until a thickness is reached which fits your gasket material. You might hold the shims in place by a smear of grease.
Now you are done.
Very important: When you check the gear backlash, always use the centering tool pushed over the lower end of the bevel shaft and the outer surface of the protective sleeve. I dont know if it is offered by any retailer. I made one myself on a lathe.

cheers Hans

double diamond
Posts: 555
Joined: Thu Apr 28, 2011 1:20 am

Re: upper bevel help

Postby double diamond » Mon Jul 22, 2019 5:48 pm

I’ve had to shim the upper bevel bearing on a number of occasions to eliminate bevel shaft vertical movement. You cannot effect correct bevel shimming if the upper bevel bearing isn’t retained. A shim can be placed below the bearing. In this position, you might not have to adjust shimming of the bevel gears but the shim isn’t retained in place very well in this position. It’s better to place the shim above the bearing but you will probably have to adjust shimming of the bevels. If the bevels were correctly shimmed before you replaced the gasket with a thicker gasket, you should only have to adjust the height of the bevel shaft. But I’ve found both the cam gear and bevel shaft usually need adjustment. Also, the head should be torqued in place to confirm that the shimming is correct even if you’ve used a centering tool on the bevel shaft or or with the head in place on the lower end.
Restricting the oil passage on the cam drive end is good practice. I haven’t found roll pins with different I.D.s so it’s usually just a matter of finding a roll pin with the correct O.D. and calling it good enough. On race engines the oil passage is plugged completely but with lower rpm of a street engine, it’s good to allow some oil into the upper bevel.

Matt

ranton_rambler
Posts: 439
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Location: Stafford UK

Re: upper bevel help

Postby ranton_rambler » Mon Jul 22, 2019 6:22 pm

You can’t rush some of the jobs on these engines. I took mine apart 6 or 7 times before I was happy with the top bevel meshing. I used a socket to keep the shaft centralised but maybe was lucky I had one which was a nice fit.
I measured the gasket thickness and protrusion of the collar and all seemed OK, but it does weep a little oil from that joint.
Got another gasket for when I get round to taking it apart again.
Ian

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: upper bevel help

Postby Scottish888 » Tue Jul 23, 2019 9:40 am

Thank you to all for the good advice, very much appreciated.
Nigel Lacey has also been most helpful with advice.
Without the contributions made here by the Ducati singles community I would be struggling to carry out a decent job with this rebuild.
I am sure I will have more daft questions to ask.
Thank you.

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: upper bevel help

Postby Scottish888 » Tue Aug 13, 2019 12:47 pm

I have had a aluminium part made to interference fit inside the bevel tube, it has a 15mm ID so can centralise the shaft.
I may be wrong in my thinking but if using the aluminium locating piece I think I do not need to have the head on and bolted down to do the upper bevel shimming? The bevel shaft is retained by the oldham coupling but should have no vertical pressure?
Is hylomar suitable as a seal if not using a gasket (new gasket was way too thick) or should I use std silicon sealant?

Regards

double diamond
Posts: 555
Joined: Thu Apr 28, 2011 1:20 am

Re: upper bevel help

Postby double diamond » Tue Aug 13, 2019 3:42 pm

Reason suggests that you should be able to shim the bevel gears (with the tool you’ve improvised) and be done with it. Experience suggests that you at least verify that backlash has not changed when the head is finally bolted in place.
I’ve never assembled a bevel tube without a gasket so can’t address your question about sealants.

Matt

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: upper bevel help

Postby Jordan » Tue Aug 13, 2019 5:08 pm

Sealant seems like a good idea, used only on final assembly of the bevel tube after getting the shimming correct.
Silicone OK if used sparingly I think, but Hylomar probably is safer as it's less likely to form troublesome dislodged beads.
I always add sealant at the bottom of the bevel tube. The O-ring isn't always up to its job there due to vibration evidently.
Would bolting on the head make a difference to shim clearance?


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