Re-threading crankshaft on 450

[Carnaggio]

Hey everyone!
I brought my crankshaft with the stripped threads from my 1970 450 scrambler to a friend who has the machinist capabilities to weld and cut the threads but he wanted to know the thread pitch and what type of metal/alloy of the piece. I have not found any information on this and is hopeful that someone could help me out. He also mentioned that he thought there was too much play between the flywheels and the piston rod and asked about the tolerances. I looked through the two books I have and couldn't find that either, so once again, any help would be greatly appreciated.

Any thoughts on gaskets? I was thinking of getting all new sets but someone mentioned liquid gaskets and so wanted to know what all you smart guys thought about that! I have the engine all pulled apart, ready to start cleanin, repairing and reassembling!
Thanks!

[ducwiz]

Hi,

the thread is metric, 20mm dia. by 1mm pitch, thread angle 60°. I presume the crankshaft was forged from a tempering chrome-nickel steel, but cannot proove this.
My french manual from "Revue Mototechnique" (publisher ETAI, France 1972) gives values for lateral play of the conrod on page 56:

typical 0.15 - 0.42 mm
abs. wear limit 0.60 mm

Once in a while I'll manage to upload a scanned version of this manual, but in unpopular djvu format and mediocre quality.
I prefer the gaskets, and coat them with a non-hardening sealing compound named "Curil K2", from german Elring company, http://elring.de/en/03en/0342_dm_en.php. This gives me the chance to re-use them in case of on-the-road service. Notably, valve clearance adjustment gets easier, because the gaskets for the rocker covers don't stick to the head anymore, arduously chipping them off is obsolete.
Btw, if you leave off the gasket between the carter halves, shimming the crankshaft for correct end play gets sometimes impossible; same for the lowel bevel shaft bearing assy holder, and other positions.

rgds Hans

edit: upload done: http://minus.com/l61x66kdm94wA

[Jordan]

if you leave off the gasket between the carter halves, shimming the crankshaft for correct end play gets sometimes impossible

Hello Hans,
Can we please have more information? Do you mean it can get too tight, even with no shims?
I'm curious about it because I intended to leave off the gasket when it comes to rebuild time.

Jordan

[Bevel bob]

If you leave off the gasket its likely you will have to re-shim the gearbox shafts and drum ,barrel bolts may get tighter too in their holes.

[Jordan]

Good points, Bob.
The gear shafts will need re-shimming, that's clear.
The cylinder bolts have a little clearance in their holes - half a millimetre on diameter?
That may not be enough once the gasket is deleted. I guess the holes could be opened up a smigdin if needed?

Jordan

[Bevel bob]

My bolts were a tight fit with a gasket, they may have been looser without!, I have been advised to not shim the drum too close as it will not work on a 5 speed as the design was poor and a bit of slop is essential.The bottom bevel shim will also be afected by no case gasket.

[Jordan]

I have been advised to not shim the drum too close as it will not work on a 5 speed as the design was poor and a bit of slop is essential.

However, it's Ducati bevel lore that the gears, which were made from the usual Italian crap, can benefit from having excess play removed.
I was shown how every gear is individually able to be shimmed to closer tolerances than the factory standard. One can decrease the side play, such that engagement of the dogs is maximised, putting less reliance on the back tapers to pull them in. When I shimmed the cam drum, it had minimum play that I could achieve, and still turn easily. Doing the whole gearbox this way was a big job, requiring many trial assemblies of gearsets and crankcases. Alas, it wasn't my current 350.

Jordan

[Carnaggio]

Thanks Hans!
My apologies for the late reply. That is a tremendous help for me.
Best regards,
Richard