[Healeys] BN1 Gearbox Leaks

[Bill]

Now this is interesting, Rich, and I was hoping to see some other 
responses.  Prior to 2002 Lake Tahoe, among other things, I had my 
3-speed and OD "gone through" by Eric Grunden of Absolutely British.   
(An excellent LBC mechanic and a bummer for us LA folk that he recently 
moved to the Santa Maria area.  Shameless commercial ends here, NFI!)  I 
asked about the 1st motion shaft O-ring and was told:  "I don't do it."  
"If you want to do it, go ahead."  No other explanation was given.

With a copy of this post to him, I'm asking:  Hey Eric, what do you know 
that we don't?  Please let me know off-list and I'll forward it on.

So, I took my front plate and a spare 1st motion shaft down to my 
favorite machinest.  It was much less high-tech than yours, Rich.  He 
simply lathed out a groove in the front plate where the spiral was and 
added an O-ring for a $20 under the table.

I've put many hard miles on it since then and have had no additional oil 
leakage as you have.  I'm curious, are you running synthetic oil?  I'm 
running straight non-detergent 30W.

Bill Barnett
'53 BN1 #663

Rich C wrote:
> Hello all,
>
> Over the years we've all seen the early 3 speed BN1 gearbox and how much they
> seem to leak oil. They seem to leak out of every possible joint, flange,
> gasket, plug, seal, and so on. The average BN1 will leave not just a drip from
> one spot, but usually from 3 or 4 places.
>
> Recently I worked with a local but really excellent machine shop to develop a
> nitrile quad ring seal that is inserted into a machined groove in the front
> cover scroll surface area. This was developed very carefully to give adequate
> engineering tolerance so the seal would not chafe, but seal effectively to the
> smooth first motion shaft area.
>
> All the other possible leak prone areas were dismantled, cleaned thoroughly
> and new gaskets and seals were installed wherever required. The gaskets were
> "painted" with Permatex 300, as were any bolts that thread into oil areas(side
> cover, front cover, etc. I figured with all this attention to the problem we
> should get a pretty leak proof gearbox.
>
> Just to make sure of things, the breather on the overdrive unit was checked
> that it was clear to do it's job.
>
> The results?
>
> No leaks when topped up and sitting motionless.
>
> Drove the car about 5 miles, and the drips were worse than ever!
>
> Theory: These gearboxes cannot breathe adequately. The only breather for the
> whole assembly is not in the gearbox portion, but way at the back in the
> overdrive. The only opening to this breather is through the gearbox rear
> bearing spinning with a film of oil. hardly an adequate breathing system.
> How did they breathe when new? Perhaps enough atmospheric pressure release was
> allowed through the original reverse scroll design on the first motion shaft
> and cover?
>
> Do I now need to drill, tap and install a breather on top of the gearbox
> casing?
>
> Thoughts? Norman Nock, are you reading this?
>
> Rich Chrysler
> _______________________________________________