The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Fitzy on 12.04. 2017 22:54

Title: Suggestions for making the primary case oil tight
Post by: Fitzy on 12.04. 2017 22:54
Hi all

I have just rebuilt my engine ( 1954 A7 plunger) I have got around 500 miles on it and all seems well apart from an annoying oil leak from the primary case despite applying well seal to both sides of the gasket

Any tips would be appreciated on trying to make it oil tight
Title: Re: Suggestions for making the primary case oil tight
Post by: mugwump on 12.04. 2017 23:22
Over the years, because of the tendency to leak the screws clamping inner and outer halves of the case have been constantly over-tightened by previous owners. This has caused the mating face of the inner case to become raised slightly around each of the tapped fixing holes. Ensure that both mating faces are flatened by use of a file. Then, you will probably find that you only need 'Wellseal' on one side of the gasket and a light grease on the other, this will allow many re-uses of the gasket.
Title: Re: Suggestions for making the primary case oil tight
Post by: KiwiGF on 13.04. 2017 02:55
On mine I've got o rings under some of the heads of bolts on the bottom as they leaked otherwise, and at least one on the bottom has gasket goo on the threads as it leaks through them  - this being where the bolt hole goes all the way through the inner case, not all bolts do. I fitted a longer bolt and put a nut and fibre washer on one, behind the case, which also helped.

I make my own gasket and it protrudes by a few mm inside and outside the case, this seems to help by making it stronger. I trim extra off the extra gasket where it shows. It's 1.5 mm thick paper "flexoid" brand from UK. I use loctite flexible gasket sealant, red colour.

There will most likely be a weep from the seal around the main shaft, as I don't think that seal design will ever not leak at all! though the sliding plate hole on mine is pretty worn and a loose fit on the scroll and it still doesn't seem to leak much.

I don't use ATF in the case as it made it leak more, I use sae 30.

Mine still leaks slightly from the gasket area a bit, not straight away, but after maybe a thousand miles or so  *problem* *work* *pull hair out* It's been like that for over 5000 miles now, and as  I've no reason to have a look at the 6 spring clutch it will stay as it is until the next tear down.
Title: Re: Suggestions for making the primary case oil tight
Post by: orabanda on 13.04. 2017 03:33
A strategically placed breather works wonders as well, by preventing pressure build-up in the chaincase you have put so much good work into sealing up!

I drill a hole as per the pic, and fit a $5 DT Yamaha breather adaptor. Or you can tap 1/8"BSPT and buy a compact brass 90 degree fitting from an Auto shop, etc.

The drilling can be seen in the rear primary case, at about 7 o├žlock, just below the magneto cover. Can be done without removing the rear cover.

This is a good thing to do in the gearbox as well; reduces (stops) leaks from kickstart bushes, etc. There are a couple of good spots to drill the hole (as the actress said to the bishop).

Richard
Title: Re: Suggestions for making the primary case oil tight
Post by: ralph on 13.04. 2017 06:44
Hi, if its a problem with leaking around the gasket face, Ive had good result using vinyl floor covering from which to cut a gasket from. Its quite cheap and thin the stuff I used, about 1 mm, was easy and durable to mark out and cut (punch the holes first).  Gasket can usually be recovered for reuse if cover comes off. Trim off round the outside when outer cover back on. If you need a pic..........
Title: Re: Suggestions for making the primary case oil tight
Post by: muskrat on 13.04. 2017 10:24
G'day Fitzy.
As well as all the replies so far, another place for oil to escape is the chain tensioner bolt. I use a fiber washer under the lock nut and thread sealer on the thread.
Cheers
Title: Re: Suggestions for making the primary case oil tight
Post by: JulianS on 13.04. 2017 10:31
Now using a cork gasket on my swinging arm model. Just stick on with grease. It does settle and needs to be retightened several time. No leaks. Very easy to take the cover off with no silicone.

With later swinging arm covers the inspection cover for the clutch springs can be replaced with a baffled breather plug as used on the B25 cover.
Title: Re: Suggestions for making the primary case oil tight
Post by: duTch on 13.04. 2017 11:27

 
Quote
... This has caused the mating face of the inner case to become raised slightly around each of the tapped fixing holes...

 Might also be worth slightly countersinking the holes on either side of the mating surface with  a large (1/2"ish) drill bit, and I've considered using 'O' rings in there as well, but would only work if there's a unthreaded shank to work with which would entail slightly counter boring the inner case and non-standard/modified screw fittings...?

 My main leak point is the drain screw (Plunger Model) *pull hair out*
Title: Re: Suggestions for making the primary case oil tight
Post by: ellis on 13.04. 2017 20:40
I have done the same as ORABANDA with a plastic  90 degree  elbow from Yambits, and the only oil on the ground is a drop or two from the breather pipes. Otherwise a totally dry A10.   *smile*
Title: Re: Suggestions for making the primary case oil tight
Post by: Fitzy on 17.04. 2017 11:46
Thanks for all the replies

I can't see any raised areas around the screw locations so I have refitted the case with grease on the crankcase side rather than wellseal on both sides.Have not started the bike since but no leaks after 3 days in the garage l will see what happens when I take it for a run.

I see SRM do an upgrade gasket for the swinging arm model,anyone know if one is available for the Plunger  *????*
Title: Re: Suggestions for making the primary case oil tight
Post by: bobandbec on 18.04. 2017 23:17
My gasket was cut out from a used cornflake packet. Only done about 500 miles on it so plenty of time yet for it to start leaking. But fingers crossed so far.
Title: Re: Suggestions for making the primary case oil tight
Post by: duTch on 20.04. 2017 05:38

 
Quote
I drill a hole as per the pic, and fit a $5 DT Yamaha breather adaptor.

 Hey Richard (Orabanda), is that like this, http://www.ebay.com/itm/YAMAHA-Genuine-New-Motorcycle-Parts-Jog-Crankcase-Breather-583-15371-00-/282437249232?hash=item41c29268d0:g:1ZQAAOSw2gxYyjxw&vxp=mtr (http://www.ebay.com/itm/YAMAHA-Genuine-New-Motorcycle-Parts-Jog-Crankcase-Breather-583-15371-00-/282437249232?hash=item41c29268d0:g:1ZQAAOSw2gxYyjxw&vxp=mtr) ......or if not do you have a part#
Title: Re: Suggestions for making the primary case oil tight
Post by: orabanda on 20.04. 2017 05:39
Hi Dutch,
That's it!

Richard
Title: Re: Suggestions for making the primary case oil tight
Post by: duTch on 20.04. 2017 07:07
 Thanks buddy- even though mine is not a major problem, I  reckon I'll chase one up but also good for others reference   *wink2*

 I mean to ask where you reckon best for Plunger/Rigid box?  I reckon best would be in the outer cover, like the inspection cover where it would get least splash, but that'd last about one gearchange... *conf*



   ***modified***
Title: Re: Suggestions for making the primary case oil tight
Post by: orabanda on 20.04. 2017 09:33
I drill into the back of the inner cover, just above the nut which secures the kick starter stop. There are a couple of webs cast on the inside. I go into the centre of them; theory being a tortuous path (baffles) which will allow air out, but be a barrier to the oil - seems to work!

Richard
Title: Re: Suggestions for making the primary case oil tight
Post by: Greybeard on 20.04. 2017 11:31
...an annoying oil leak from the primary case...

It's likely that if Allen screws have been used they will have been overtightened which is likely to distort the case and pull up the land around the threaded holes. BSA designed these cases to be sealed by no more force than can be applied by a screwdriver. There is really very little pressure in the cases; it should be easy enough to get a seal. As already described run a fine file across opposite sides of the case mating surfaces at the same time, (to ensure accuracy). On my Plunger model after thorough cleaning I use Blue Hylomar on one side of the gasket only and do not have leaks. I'm using ATF fluid in the primary case.
Title: Re: Suggestions for making the primary case oil tight
Post by: BritTwit on 20.04. 2017 13:22
One tip I have not seen mentioned, is from an old issue of "Twitter" (GSOC news letter) from the '70s.  I personally tried this on my RGS primary which was warped, producing a 1/8" gap.
First remove any high spots and clean the threads.  Next, bolt the inner and outer cover together at approx. 25 ft. lbs.  Place in an oven preheated to 400 degrees.  Heat for about an hour and let cool.  The gap disappeared. 
Title: Re: Suggestions for making the primary case oil tight
Post by: duTch on 21.04. 2017 08:13

 
Quote
  Hey Richard (Orabanda), is that like this,
http://www.ebay.com/itm/YAMAHA-Genuine-New-Motorcycle-Parts-Jog-Crankcase-Breather-583-15371-00-/282437249232?hash=item41c29268d0:g:1ZQAAOSw2gxYyjxw&vxp=mtr

  Called up the local Yaya dealer, and ordered the microscopic part, but it has a superseded number #3YJ-15371-00, instead of '#583-15371-00'  (just for information); au$4 buck smackerooos- can't argue with that but should've ordered one for the box too... *dunno*

Quote
I drill into the back of the inner cover, just above the nut which secures the kick starter stop

 Good spot- never thought of that (obviously)