Wildgoose Chase Moto Guzzi

General Category => Bike Builds, Rebuilds And Restorations Only => Topic started by: BigB on June 01, 2017, 01:00:26 AM

Title: v1000 rear main bearing
Post by: BigB on June 01, 2017, 01:00:26 AM
Just completed (kind of) my first V1000 total rebuild and oil started leaking from between the engine and gearbox.  Figured that the rear main seal was not seated so pulled everything apart to find oil leaking around the main bearing flange.  Removed the rear main bearing, again, only to find multiple deep score marks on the crankcase and the flange itself.   

The first time I followed suggestions from 'This old tractor' and tapped the flange in 'evenly' until two bolts would thread and then 'rocked' it down to the crankcase.  I'm not sure what went wrong but seems that my approach caused the scoring.  Anyone have similar problems or know a better way?  I'm preparing for a second attempt with a different crankcase and new bearing.  Thanks

Big B
76' Convert (now with a 5-speed transmission) aka the X-Con
Title: Re: v1000 rear main bearing
Post by: Antietam Classic Cycle on June 01, 2017, 08:36:56 AM
"Rocking it down" is definitely not a good idea. It must go in as close to perfectly straight as possible or damage can result. On early engines it isn't a real tight fit and can sometimes be (carefully) slipped down into place with nothing more than a deadblow hammer. I do use four long bolts as guides while driving it into place.

Failing that, I use four long, fully-threaded bolts with nuts and washers to "press" the bearing into place. You just need to be very careful to turn the nuts equally so that the bearing will go into the case opening straight.

I use a light coating of Permatex Super 300 on the case and bearing sealing surfaces in addition to the gasket. Be sure to apply sealer (I use a liberal coating of Hondabond 4) to the two lower bolts of the rear main bearing. Those are below oil level and will leak if not sealed. Same with the banjo bolt on the oil return line - even though it has aluminum sealing washers, I apply Hondabond 4 as well.
Title: Re: v1000 rear main bearing
Post by: BigB on June 01, 2017, 10:38:40 AM
Thanks Charlie.  I appreciate such a quick response and the tips with Permatex and Hondabond.  When originally seating the bearing I snugged the bolts about an 1/16 turn at a time - took forever!  It seemed to go in concentric but the results proved otherwise.  That bearing was very difficult to remove and replace with it being so tight, just wondering why it has to be like that?  I get that a good seal is needed but this seems a bit like overkill.  Again, thanks.  Hope to have a better turn out next time.  Any additional thoughts or ideas are always welcome.  Thanks everyone.
Title: Re: v1000 rear main bearing
Post by: Antietam Classic Cycle on June 01, 2017, 10:59:59 AM
You could try heating the crankcase and chilling the bearing for a bit of extra clearance during assembly.

It has to be like that because it supports the crank, flywheel and clutch - all heavy components with lots of forces acting upon them. If the bearing was a loose fit in the crankcase, then it would move around on the mounting bolts and would eventually end up even looser. Also the oil passages in both the case and bearing need to held firmly against one another or oil pressure would be bled off. 
Title: Re: v1000 rear main bearing
Post by: jwinwi on June 01, 2017, 04:33:19 PM
Put the bearing and flange in the freezer overnight. Just about falls in place so make sure it's lined up correctly.
Title: Re: v1000 rear main bearing
Post by: BigB on June 27, 2017, 11:24:37 PM
Thanks again, everyone.  Been a while since my last post but things have been moving ahead well.  A new bearing (just a little ching) and looks like things are back on track.  No oil leaks and oil pressure is 50-55 on initial start up so seems that things are stable.  Really appreciate all the input.  See you out there.  later