[dvnr] advise needed oil leak
William F. Dudley Jr.
dud at casano.com
Wed Mar 25 21:02:46 EDT 2020
Dan, Brian, Frank,
Thank you all for your input.
I really liked Brian's idea of using a socket head screw.
I used a stainless steel 1/4-20 that's about a half inch
longer than the original screw. Since the threaded hole
in the left half case goes all the way through, a longer
screw works fine. It might even be stronger, if the threads
go further than just the length of the stock screw.
I didn't use an impact driver. Since I used a socket head,
I could use an allen wrench. I put a "big grunt" on that,
but I didn't use any torque amplifiers (i.e. cheater pipe).
I did use locktite -- gap filling, with hopes it would run down
into the case seam. The socket head should make that easier
to unscrew in future (than had I used the stock screw).
I also used Yamabond on the shank.
Bill Dudley
On 3/25/20 8:51 PM, Daniel Sellers wrote:
> OK Bill,
> Some of the respondents aren't going to like my advice but I think it is
> best. (1) No locktight, it you need to get the screw out later you will
> have a very hard time. (2) don't over tighten that screw. The screw is
> one with coarse Whitworth threads which are nearly identical to a 1/4-20
> screw, but its a higher strength then a grade 2 machine screw. It's
> coarse because it is screwed into the facing aluminum case. Too much
> tightening will pull the threads on the opposite case and maybe even
> pull the threads out. (3) I don't have any objection to using sealant on
> the shank of the screw but the screw and shank are below where the
> crankcase halves are sealed. At least the oil won't come out of the
> recess for the screw. (4) Once you repair the screw, the 3/8" mounting
> bolts will apply the force between the case halves. (5) By the way, you
> did a great job of getting that hole right over the screw.
>
> Looking at the Norton torque specs for 1/4" screws into aluminum I see
> 60 to 80 inch pounds. That's like 5 to 7 ft lbs. That doesn't seem like
> impact driver force. But, what do I know?
>
> Cheers
> dano
>
> On Wed, Mar 25, 2020 at 5:58 PM Brian Safer via DVNR <dvnr at casano.com
> <mailto:dvnr at casano.com>> wrote:
>
>
>
>
> ---------- Forwarded message ----------
> From: bsafr at aol.com <mailto:bsafr at aol.com>
> To: SgtNorton at comcast.net <mailto:SgtNorton at comcast.net>,
> dud at casano.com <mailto:dud at casano.com>
> Cc: dvnr at casano.com <mailto:dvnr at casano.com>
> Bcc:
> Date: Wed, 25 Mar 2020 22:57:56 +0000 (UTC)
> Subject: Re: [dvnr] advise needed oil leak
> I was wondering if Frank was gonna check in.
>
>
> -----Original Message-----
> From: Frank Mohr via DVNR <dvnr at casano.com <mailto:dvnr at casano.com>>
> To: William F. Dudley Jr. <dud at casano.com <mailto:dud at casano.com>>
> Cc: DVNR <dvnr at casano.com <mailto:dvnr at casano.com>>
> Sent: Wed, Mar 25, 2020 6:55 pm
> Subject: Re: [dvnr] advise needed oil leak
>
> Could use both sealers however you still need the grunt. If you have
> a older style impact driver the kind you hit with a hammer I’d use
> that.
>
> Sent from my iPhone
>
> > On Mar 25, 2020, at 5:44 PM, William F. Dudley Jr. via DVNR
> <dvnr at casano.com <mailto:dvnr at casano.com>> wrote:
> >
> > Dan et al,
> >
> > Dan's measurements and my crude measurement technique (working on
> > the motor IN THE BIKE) were sufficient to get my pilot drill
> > close, and then by some drill bit abuse I was eventually able
> > to drill a .400 hole right over the leaky screw. See attached
> > picture.
> >
> > I have successfully removed the screw (it was "tight-ish", but
> > certainly no struggle to remove).
> >
> > To re-assemble:
> >
> > 1. should I put lock-tite on the threads (after cleaning screw
> > and hole with brake cleaner) ?
> >
> > 2. should I put Yamabond on the shank of the screw near the head?
> >
> > 3. what torque should I apply to the screw? Is there a number,
> > or is "big grunt with screwdriver" good enough?
> >
> > Thanks,
> > Bill Dudley
> >
> >> On 3/25/20 3:53 PM, Daniel Sellers wrote:
> >> OK Mr Dudley
> >> The dimensions for the screw hole on an 850 Commando that
> pertain to your dimension "X" and "Y" are:
> >> X = 1.885"
> >> Y= 2.44"
> >> Mind you I am measuring from two different planes but dimensions
> are taken from one plane. I compared the dimensions to a 750 Atlas
> and they are the same.
> >> Good Luck with the oil leak.
> >> Cheerio
> >> dan
> >> On Wed, Mar 25, 2020 at 2:34 PM Daniel Sellers
> <dansellers45 at gmail.com <mailto:dansellers45 at gmail.com>
> <mailto:dansellers45 at gmail.com <mailto:dansellers45 at gmail.com>>> wrote:
> >> OK Mr Dudley
> >> On Tue, Mar 24, 2020 at 8:22 PM richard casey
> <saxmanrich at gmail.com <mailto:saxmanrich at gmail.com>
> >> <mailto:saxmanrich at gmail.com <mailto:saxmanrich at gmail.com>>>
> wrote:
> >> I second what Mr Sellers has stated.
> >> On Tue, Mar 24, 2020 at 7:03 PM Daniel Sellers via DVNR
> >> <dvnr at casano.com <mailto:dvnr at casano.com>
> <mailto:dvnr at casano.com <mailto:dvnr at casano.com>>> wrote:
> >> Bill
> >> The screw circled in red is one of two machine screws
> that
> >> fasten the left
> >> and right crankcase halves together independent of the
> >> larger bolts that
> >> fasten the engine to the cradle. The oil is likely
> leaking
> >> from the same
> >> location and some coming from the crankcase half
> joint and
> >> some getting out
> >> of the same leak an weeping out the screw hole. Did the
> >> bolts mounting the
> >> engine to the cradle work loose? Good luck sealing a leak
> >> externally after
> >> oil has gotten between the existing seal between the case
> >> and sealant. You
> >> might be able to reduce the leak by tightening the 1/4"
> >> machine screw and
> >> mounting bolts.
> >> These are my thoughts. I'm sure you will have some
> experts
> >> explain it
> >> better.
> >> Dan Sellers
> >> On Tue, Mar 24, 2020 at 5:47 PM William F. Dudley Jr.
> via DVNR <
> >> dvnr at casano.com <mailto:dvnr at casano.com> <mailto:dvnr at casano.com
> <mailto:dvnr at casano.com>>> wrote:
> >> > Hi,
> >> >
> >> > My 71 Commando is weeping oil out of the motor.
> >> >
> >> > There are two leaks. One is the case joint between
> left and
> >> > right halves, aft of the oil drain/oil screen.
> >> >
> >> > The other one is from the screw around which I have
> drawn
> >> > a red circle in the attached photo.
> >> >
> >> > I don't want to disassemble the entire motorcycle
> for these
> >> > stupid leaks. I can goober up the case on the seam
> with some
> >> > RTV and stop that leak, but the one at the screw is
> harder,
> >> > since the screw is hidden behind the engine
> mounting plate.
> >> > (I also have some more sophisticated means to seal
> that leak
> >> > on the seam. So I may not end up goobering it up
> with RTV.)
> >> >
> >> > I thought that if I drilled a hole in the engine
> mounting
> >> plate,
> >> > right over that screw, then I could then sort out
> that leak
> >> > one way or another.
> >> >
> >> > Questions:
> >> >
> >> > 1. what does that screw do? Does it just plug an
> oil way
> >> after
> >> > the factory drilled the oil way during manufacturing?
> >> >
> >> > 2. Does anyone have a Commando case not mounted in a
> >> motorcycle
> >> > from which they could measure 'X' and 'Y' as shown
> on my
> >> drawing?
> >> > That will help me locate where to drill.
> >> >
> >> > I plan on putting a stainless plate between the engine
> >> mounting
> >> > plate and the crankcase when I drill, so that I don't
> >> overshoot
> >> > and make a mess of the case.
> >> >
> >> > Thanks,
> >> > --
> >> > Bill Dudley
> >> > _______________________________________________
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> > <drilled_engine_mount_1k.jpg>
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> ---------- Forwarded message ----------
> From: Brian Safer via DVNR <dvnr at casano.com <mailto:dvnr at casano.com>>
> To: SgtNorton at comcast.net <mailto:SgtNorton at comcast.net>,
> dud at casano.com <mailto:dud at casano.com>
> Cc: dvnr at casano.com <mailto:dvnr at casano.com>
> Bcc:
> Date: Wed, 25 Mar 2020 22:57:56 +0000 (UTC)
> Subject: Re: [dvnr] advise needed oil leak
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