'60 R69 Tech question

on my 1960 R69
the "speedometer drive retaining bolt" is hollow and has a hole in the end which "gear oil" 80/90 ? drips from.
Is this bolt supposed to be hollow ? and why is it dripping ?

thank you,
mark

heres a pic

R69

The picture doesn't show a hollow bolt as near as I can tell...did you replace it with a standard bolt to keep it from dripping? The hollow bolt allows venting of the transmission. No oil should be coming out of the hole, only air. How's the level of fluid in the transmission? Is it overfilled? Is fluid "backing up" from the driveshaft? Something's amiss for there to be oil dripping out...

Kurt in S.A.

R69

thanks Kurt,

Ok,It is a hollow bolt.My owners manual shows the level should be just at the threads of the "level plug hole".and that my gearbox should use the same engine oil as the engine?
I can smell whats in my gearbox now which is "gear oil".
Could the thicker gear oil,cause it to leak out of the breather vent bolt?

Mark

The oil level sounds about right...it should be to the bottom of the threads not the top. As for transmission oil, BMW switched from basic engine oil to hypoid oil based upon frame numbers. Roland Slabon's book mentions this happened in June 1967. Prior to that, it appears that SAE 40w motor oil was to be used. I don't know what changed in the design to allow this, but I'm sure one of the things was the use of different seals to work with the hypoid oil. If your transmission has never been overhauled and is from 1960, I think I'd be using the motor oil. I'm not sure how hypoid oil could do what you're thinking, but I'd trying switching back and see if your problem goes away.

Kurt in S.A.

My understanding is that the sulfur content in hypoid oil is detrimental to the rubber seals.

While it's certainly true that BMW changed from recommending 40W oil to "hypoid" gear lube in the mid 60s, it's also the case that a number of folks on the slash2 list have reported no problems in just switching over. In my own case, I believe that the trans in my 1961 R60/2 has never been overhauled and it doesn't leak a drop of hypoid oil.

BTW, I understand that 90W gear lube has the same viscosity as 40W motor oil, because the measurements are made at different temperatures.