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 Post subject: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 2:07 am 
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Joined: Wed Aug 27, 2014 3:36 pm
Posts: 80
Hallo Everybody
I'm in the need to change the cranckshaft's bearings of a 350 Alazzurra engine for a project I've in mind.

https://flic.kr/p/WWP9oz

So I ask to a local hardware shop to get them :

Asking for:
7207X2TB
7307
But they don't have in stock, neither on their supplier net.
They have this bearings, the same dimension but without bakelite frame. Just steel frame holding the spheres.
6207
Fag brand
6307
May I use this bearings or I have to use the original one?


Thanks in advance for your help
Ciao
Filippo


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 Post subject: Re: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 3:50 am 
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Joined: Fri Jun 24, 2016 2:38 am
Posts: 43
Location: New Zealand
Maybe import them.
Like these: https://ducati-gowanloch.com/shop/engin ... rankshaft/


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 Post subject: Re: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 4:31 am 
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Joined: Wed Nov 03, 2010 1:29 pm
Posts: 287
Images: 0
http://www.sepamoto.fr/gros-roulement-v ... f6c0b9434d


ciao ciao,

Dick


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 Post subject: Re: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 8:12 am 
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Joined: Wed Aug 27, 2014 3:36 pm
Posts: 80
Nick Gill gill and Dick le dog, thank you for your reply and for suggestions, I see also Stein dinse sell this original bearings.
But is mandatory to use this kind of bearings or I can use he other i find on my place?

https://www.flickr.com/photos/156916018 ... res/4b78ph

See link for pics.
I ask this because this could be a cheaper alternative, but of course they have to be useful.


Thank you again
Filippo


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 Post subject: Re: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 11:59 am 
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Joined: Wed Sep 11, 2013 7:13 am
Posts: 159
Hey Filippo.
The bearings with iron cage are limited to (can not check because i'm near Passo Tonale and no tech info here) 6000-7000 rpm.
The bronze cage go a bit higher.
Strange the originals are so difficult to find. They were used a lot.
Just try to imagine what the damage is to your engine when one of the cheaper bearings fails.
Although 350 engines are not TOO rare, those bigbore cilinders and pistons are precious things.

Ciao
ducadini

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Nego i ricordi peggiori, richiamo i migliori pensieri


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 Post subject: Re: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 2:18 pm 
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Joined: Tue Mar 18, 2014 10:03 am
Posts: 170
Hey Filippo...
The Ducati bearing 7207X2TB is an angular contact bearing. The FAG 6307 is just a regular ball bearing. Angular contact bearings are used to deal with side to side forces. Regular bearings can't do this. The helical cut primaries in the early engines want to pull or push(depending on rotation) the crankshaft sideways. Hence the need for the angular contact bearing. Ducati did start using roller bearings in their superbike engines, but they have straight cut primary gears. Angular bearings come in different angle specs. The Ducati bearing is the least popular of the different angles and that makes them hard to find. I'd stick with the OEM spec bearings.
Best Regards...
Flattop
P.S. How is the race season going?


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 Post subject: Re: Cranckshaft bearing
PostPosted: Fri Jul 28, 2017 5:55 pm 
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Joined: Sun May 08, 2011 12:17 pm
Posts: 279
Location: Europe
I buy them directly from a ducati dealer, they still use those measures is most of their models.


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 Post subject: Re: Cranckshaft bearing
PostPosted: Sat Jul 29, 2017 7:11 am 
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Joined: Wed Aug 27, 2014 3:36 pm
Posts: 80
Ducadini,Flattop900 and 750TT Thank you for replying.
Of course I don't want to waste an engine for a wrong bearing.
I was just trying to find an alternative. considering also that this has to be a track engine I don't will run the risk.
Again, thanks everybody for be so kind and helpful .
Hey Flattop the racing season is going very calm. I just run a race and jump two for various reason, I hope to have the chance to participate to the two remaining races.
Ciao e grazie
Filippo


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 Post subject: Re: Cranckshaft bearing
PostPosted: Sat Jul 29, 2017 6:05 pm 
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Joined: Thu Oct 14, 2010 7:30 am
Posts: 139
Keep in mind the angular contact bearings need to be preloaded slightly so you can't just toss them in. Most builders shoot for .1mm [.004"] to.15mm [.006"] this is a slight but noticeable drag when the cases are torqued up. Time consuming to do but satisfying when you get it right. Check the trans and shift drum end floats too.


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 Post subject: Re: Cranckshaft bearing
PostPosted: Mon Jul 31, 2017 3:58 am 
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Joined: Wed Aug 27, 2014 3:36 pm
Posts: 80
Hi wdietz186 thank for replying.
1/1,5 mm of preload is intended in total, not per side?

"Check the trans and shift drum end floats too."
You mean the transmission shaft float and the clutch shaft float?

By the way I read on the workshop manual that crankshaft had to have any float, is this right?
Thanks again
Fikippo


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