Author Topic: V50 Monza Rear Drive Modification (Read 3657 times)

Jim Malm · « **on:** February 25, 2019, 07:08:29 PM »

I've been searching the forum for those detailed instructions on drilling that hole in the drive box for better bearing oilng and can't find them. Can someone please point me to where they are located or possibly send them to me? I just recently saw that Chuck in Indiana posted a synopsis of that procedure and can't even find that. I found a thread from SED (Hi, Shaun - I'm Si's buddy in Spokane) where he references the drilling of that hole, but the photos were missing. I have the rear drive off my '81 Monza and am ready to drill, but need better guidance than what I have available - I'd really hate to screw that up.

Thanks,

Jim

Chuck in Indiana · « **Reply #1 on:** February 25, 2019, 08:18:01 PM »

Here ya go.. page 3 of the Monza inspection thread.. It's pretty easy. You have to drill at an angle that will get lube up to the bearings. Then the shims are turned to make a pocket for the crown wheel to push oil in that direction.
https://wildguzzi.com/forum/index.php?topic=89034.60

SED · « **Reply #2 on:** February 25, 2019, 10:43:02 PM »

Hey Jim,

Here's the text from Chuck's Monza inspection and some pictures from mine. There is a pocket for the tip of the drill bit and just aim so it will come though between the bearings. My recollection is that you flip the shim/gasket over to form the pocket so the oil pools up around the hole. Let us know how it goes!

Here's a brief synopsis:
Pull it apart, and you'll see the crown wheel bolts with plates under them.

The plates need to be removed, and Shnoor washers installed under the bolts. It'll take a puller to do this.
There is a shim between the two halves with gaskets. You'll need new gaskets.

The issue is not enough oil to the pinion bearings. This was corrected in late '87, but if you have an earlier one, this needs to be done. The idea is to drill a hole at a shallow angle so oil can get to the front bearing.

After that, the center shim can be rotated to form a pocket so the crown wheel will throw oil into it and make it's way to the front bearing. You'll need to open up a hole as the shim isn't symmetrical.

Jim Malm · « **Reply #3 on:** February 25, 2019, 10:54:49 PM »

Hi, Chuck - Thanks for the reply and link. I thought that discussion was somewhere in that thread. All of the photos in that link came up except for the rear end mod reply (sigh). I'm getting the little black square with an "x" where the photos used to be. I got the same thing on Shaun's discussion of the procedure. I have a recollection of where the hole starts, but don't think I've seen where it exits. Seeing a photo of the exit wound would be helpful. Also, what diameter is the hole that gets drilled? I don't remember seeing that in the write-up. It's probably obvious where to drill, but I don't have the parts in front of me right now, so am a little handicapped in visualizing the final product. Don't know if you still have the photos of that you originally posted, since you mentioned they were missing when you went back to find that write-up. If you still have them, could you repost them or send them to me in a PM, my email is listed in the directory.

Just saw Shaun's reply, but would till appreciate any photos that you have and additional comments that you have. Wish I had the parts infront of me to fully comprehend where the hole goes. Sounds like that better order some fresh gaskets. Your patience in walkng me through this is really appreciated.

Thanks,

Jim

Wildguzzi.com · « **Reply #3 on:** February 25, 2019, 10:54:49 PM »

Jim Malm · « **Reply #4 on:** February 25, 2019, 11:12:54 PM »

Shaun, thanks for the reply and photos. There's a chance that I may eventually figure this out. I need that crown wheel in front of me to figure out where those plates are and what to use the puller on. I have the alloy housing case separated from the rest of the drive mechanism and beleive I have access to where the hole needs to be drilled. I'll digest the info you and Chuck have provided and see if I can apply it to the pieces tomorrow.

Jim

SED · « **Reply #5 on:** February 25, 2019, 11:30:01 PM »

It will probably make a lot of sense with the pieces in front of you. Looks like the hole I drilled was about 1/4". I remember sighting down the drill motor and trying to aim the bit as far forward as possible without breaking through to the outside.

Googled Guzzi small block rear drive modification drill bearing and found a thumbnail, but not the full size picture.

Jim Malm · « **Reply #6 on:** February 25, 2019, 11:36:07 PM »

Those photos are really helpful and I think how to do it has finally sunk in. That hole diameter looks like it's somewhere around 5/16"?

Jim Malm · « **Reply #7 on:** February 25, 2019, 11:45:15 PM »

Just missed that reply, will go with 1/4". I need to find that photo of how the shim hole gets enlarged. Seems like I remember it getting flipped or reversed and the shim hole ground out a bit to let the oil flow to the new hole in the case.

pat80flh · « **Reply #8 on:** February 26, 2019, 07:35:52 AM »

I did my V65 last year. I eyeballed it and drilled a 1/4"hole. Had to hog out one or two bolt holes in the plate so the gasket lined up. Put 3,000 miles on in since with no problems.

Chuck in Indiana · « **Reply #9 on:** February 26, 2019, 09:33:15 AM »

Quote from: Jim Malm on February 25, 2019, 11:45:15 PM

Just missed that reply, will go with 1/4". I need to find that photo of how the shim hole gets enlarged. Seems like I remember it getting flipped or reversed and the shim hole ground out a bit to let the oil flow to the new hole in the case.

The pix are hosted on Photoblockit, and they have graciously unlocked them.

It will be pretty obvious what you have to do to the shim hole. They are not quite symmetrical. From memory,

there is only one that needs to be elongated.

Jim Malm · « **Reply #10 on:** February 26, 2019, 10:56:44 AM »

Thanks, Chuck! I captured and saved the photos, so will see what damage I can do today. The help that you and Shaun have provided is much appreciated.

Chuck in Indiana · « **Reply #11 on:** February 26, 2019, 11:10:01 AM »

No problemo.. gotta love WG..

Jim Malm · « **Reply #12 on:** February 26, 2019, 07:22:41 PM »

Took drill in hand and drilled that hole. Piece of cake with all the help! Now on to enlarging the shim holes. I discovered that there were two shims in there with a gasket in between them. The crown wheel bolt plates have been replaced with washers already - is there any other reason to pull that part? It appears that something bad might have happened inside that box with some nice welding repair being done inside and out. Thanks again for all the help.

Chuck in Indiana · « **Reply #13 on:** February 26, 2019, 07:32:29 PM »

Ideally, they should be replaced with shnoor washers and loctite. Since it is a pain to do, and someone has already been in there, I'll bet you are ok.

MattP · « **Reply #14 on:** March 01, 2019, 10:50:25 AM »

Mite be the one I welded up years ago. Blended the welds on out side of case with right angle air grinder, then hammered 60 grit sand paper on area to restore the sand cast look. I sold a 78 v50 and a 81 t0 Dave halverson in Excelsior Mn ,I think he sold the 78 here moved to cal and I think sold the 81, If this the one it was ridden in salt and snow and should show. Any way it did run well. Turd brown it was,the gears are not the greatest. How ever I would not spent the time to repair case If I thought the teeth would fall off. Matt

Jim Malm · « **Reply #15 on:** March 02, 2019, 09:49:02 PM »

Hi, Matt -

As far as I can tell my bike has always been red and is generally in pretty good condition just showing a little less than 16K miles on the odometer. Not much evidence of salt attack. It doesn't sound like the bike you repaired the rear drive on, but the repair was well done both inside and outside of the case, so it could be. I'd love to know the whole history on the bike. It came into my hands from a bike shop in Waukegan, IL, Tony Prust of Analog Motorcycles had it. He and a friend bought the bike at a Mecum auction in Shaumburg, IL in June, 2016. It had been consigned there by Michael's Motorcyles, St. Louis, Mo. It was advertised on Chicago Craigslist by Tony, but apparently never sold. An earlier post on the forum mentioned it. I stumbled on it on the Waukegan Offerup website and bought it from Tony. It has been resprayed red, had some funky repair panels added to the side covers, lost its airbox along the way and acquired UNI pod air filters and a Dyna S ignition. I think it went down on the left side as the left clipon appears to have a welding repair done on it. I'm currently going through Chuck's list of things to do and feeling pretty good about the condition of the bike. It will get a proper red stock paint job this spring after the mechanical and electrical stuff is taken care of.

Jim

SED · « **Reply #16 on:** March 02, 2019, 11:34:45 PM »

MattP · « **Reply #17 on:** March 04, 2019, 02:06:08 PM »

Jim If this the same bike I got it in the early 90,s .Any that bike I got from a guys grand son. Corroded ass hell, There was a machined flat and a patch bolted on where a bolt must have made its exit. The old guy rode it in the winter with a side car as I recall . I talked to the fellow who rode it, he said just add oil to rear drive once in a while.He had red silicone on the patch that leaked. Thought about jb weld, but since I had a machine shop to work in I decided to repair it correctly. I machined a one inch steel plate with bolt pattern of the case bolted it down heated it up welded up out side let cool welded inside , then bolted back on the plate heated with rosebud to relive stress. I did not want the prick to warp.Any way baught new seals.The 78 was real nice I installed la sleeves ,I rode the piss out of that bike maybe 20000 miles. The 81 maybe a few hundred. My freind sold me a 95 cal, he crashed with 5000 miles I fixed it and rode that over 100000 miles. 60000 after the money creek flood. on that note a thanks to pete rodekill and who elece helped out. Got some $ from God Frank Wedge. Sold the pair for $2500 think $ 800.00 was for the 81.Had to make house payments, no job ect . Any way I think you could do a search at dmv, A guy I know did a search to find his old iron head sportster and got it back. Hey Dave was up here last summer stopped buy asked if I wanted the guzzi shop manuals I gave him. The real shit with the parts book. I will give them to you If and or when he sends them .But I don,t no how to contact him. I did give him my address but the paranoid dildo did not offer his. To much info? Matt

Jim Malm · « **Reply #18 on:** March 04, 2019, 03:06:47 PM »

Thanks, Matt. I'll check with our licensing dept. to see if there's a title trail to be discovered. I'd love to have those manuals if you ever get them - I'll happily pay the postage.

Jim

Jim Malm · « **Reply #19 on:** March 10, 2019, 11:42:20 PM »

Per SED's

request-

Hope this photo posting experiment works. Apologies if this is a big mess.

Jim

Jim Malm · « **Reply #20 on:** March 10, 2019, 11:44:41 PM »

Back to reading how to post photos...

Jim

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Author Topic: V50 Monza Rear Drive Modification (Read 3657 times)

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