Wide Case Parts Manual. ?

[Jordan]

I made a sketch, might be useful.

https://www.flickr.com/photos/28257637@ ... ed-public/

[graeme]

Thank you so much Jordan, I’ll try to print this and start again.
Will report back.
Regards
Graeme

[graeme]

Report back...

This is with the left case half laid on blocks with the transmission up.

The Haynes manual shows a "thrust washer" between the case bearing and the large gear that meshes with the kick start gear.
This 1.2mm "thrust washer" is shown in the parts manual as a 0.5 shim. So I swap the thrust washer for a .5 shim.
Better, but in (first?) the selector fork that engages the dogs on this gear (the one that meshes with the kick start gear) and the one above it is trying to force these 2 gears together more.
This makes the lower fork rub hard on the slot. Trying to force the gears together more than they can move.

If I add 2 more shims under the selector drum it is better but this lifts the selector drum up enough that the drum is compressed between the cases when bolted together.

It's as if the case joint has been machined at some point in time ???
Or the bearings are not pressed home. I did press them again with heated cases.

The only fix I can imagine is to machine 1mm off the nose of the selector drum to free it when the cases are bolted together.

What am I missing ? Keep in mind the complete engine was apart when I bought it 15 years ago.
I tried another selector drum, selector forks and gear shafts. Same result.

Any suggestions ?

Graeme

[Duccout]

Hi Graeme,

The wonderful art of gearbox shimming, hours of fun for those lucky participants.

As you say, you cannot allow the engagement of the two gears to be forced together when they are already fully engaged, so you are faced with moving both gear shafts and the selector drum until it all works. I would ignore the parts book and use whatever shims that are necessary to achieve (near) perfect mesh.

Checking with a torch shone through the cylinder mouth and a screwdriver to see how close the dogs are engaged, you can turn the drum and select each gear in turn; each gear must engage fully with its neighbour's dogs, and not push the neighbouring gear away in the process. One dodge that you can use is to fit a shim between the first and second gears, which leaves the first gear in place but moves the whole shaft over to help engagement with the opposite shaft and the drum. The picture in the Hynes manual 29.5f shows this shim in place. Pay particular attention to the second gear on the mainshaft which is very weak, and make sure that it is fully engaged with the dogs on the third gear next to it, as this is the gear that tends to jump out if not fully engaged. When each gear is engaged, you can use the screwdriver to rotate it and check that it is not engaged so tightly that it is binding on the neighbouring gear dogs.

When all is done, try to use the thickest shims rather than a lot of thin ones to make up the total. Like most shimming jobs on Ducatis it is frustrating and time-consuming, but it works in the end. Let us know how you are doing.


Cheers,

Colin

[graeme]

"The wonderful art of gearbox swimming, hours of fun for those lucky participants."

Thank you Colin, I needed that laugh !!!!

If I take the shim from under the shaft where it sits in the bearing and place it above first gear (big gear that meshes with kick start gear) All seem ok.
I can remove the 2 extra shims from under the selector drum, and don't think it will need machining down. Something I would only do as a last resort.

Report to follow,,,,,,

graeme

[Duccout]

Damn predictive text, it always does something that I don't spot....

It is possible to get the gearbox working properly, it just takes time and hair loss.

When you are happy with everything, bear in mind that when you tighten the sprocket and clutch nuts up, they will pull their respective shafts hard up against the bearings, so it is a good idea to check everything with those nuts tightened.



Colin

[graeme]

Yes you are correct.

I’ve done 4x 450 complete rebuilds.
Some more than once as I wore them out.
But this one is trying to beat me.
It’s been definitely been played with at some time.
Like having to add a 2mm spacer under the cylinder to stop the piston hitting the head.
And on it goes,,,,,

Graeme

[Jordan]

Hey Graeme,

I can't find the thrust washer sizes you mentioned, in either Haynes shop manual or the Ducati parts list.
If it's part no. 0608.16.270 we're looking at, the parts list says it's 1mm thick.

Colin suggested closing the cases to check clearances, which is OK but it can be tedious to do it at every step of shimming each gear.
It must be done for the input, output and cam shafts themselves of course, otherwise you can check clearances of gears and forks sitting in a half case, as you are doing. Just push down on the shaft ends when inspecting.

Have you collected the shafts clearance data you need?

[graeme]

Hello Jordan

Item 40 from Haynes manual

IMG_1779.jpeg

[JimF]

I built the website long ago using Microsoft “Front Page.”

It was simple to use for amateurs like me. Microsoft got out of web design software business and support for the Front Page program disappeared.

If any forum member is a web designer I’d like to hear from you.

Jim