[dvnr] advise needed oil leak
Daniel Sellers
dansellers45 at gmail.com
Wed Mar 25 20:51:11 EDT 2020
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>
wrote:
>
>
>
> ---------- Forwarded message ----------
> From: bsafr at aol.com
> To: SgtNorton at comcast.net, dud at casano.com
> Cc: 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>
> To: William F. Dudley Jr. <dud at casano.com>
> Cc: DVNR <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> 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>> wrote:
> >> OK Mr Dudley
> >> On Tue, Mar 24, 2020 at 8:22 PM richard casey <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>> 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>> 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>
> To: SgtNorton at comcast.net, dud at casano.com
> Cc: 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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