1979 1000SP Gear Box vent

[mach1mustang351]

Hello,

I have been riding my 1000SP quite a bit this season and as the season is winding down and i am planning my winter maintenance, I wanted to come up with a plan for my Gear box.

After I ride the bike a while it will puke oil out of the gear box vent and onto the ground.  I did about 70 miles this morning and when i came out of the gas station it was an active consistant drip onto the ground.

I found the vent hose was directed straight down.  I corrected that weeks ago so it is up high under the seat. 

Any other known common reasons the gear box is building that much pressure??

Any help appreciated

[guzzisteve]

Either you are going over 100 too much or the levels too high. I never had any faults w/hose on and up.

[mach1mustang351]

Either you are going over 100 too much or the levels too high. I never had any faults w/hose on and up.

I don't know that it has been over 100 ever... so that eliminates that.  It does like to cruise at 80 though.

I drained it and filled it halfway through the season and the level was fine, but the fluid looked to be in bad shape.  Is it general practice to under fill it a bit??

I am not looking at a parts diagram, but is it possible for it to have a seal out that is causing it to share fluid with the diff??

[Tom]

I ran the hose up and stuck a small shampoo bottle on the end. (the hotel kind) Punched a small hole in it.  No more mess.  The oil mist will condense in the bottle and drain back into the trans.  An old trick from others.

[pete roper]

When filling you aren't filling it to the bottom of the filler hole are you? There is a level plug that is much lower. Drain it again and just add 750ml see if it persists.

If the oil was highly discoloured it's a bad omen. Have you or anybody else removed the speedo drive of late? If so are you certain the washer under the pinion was seated correctly? If it wasn't that can cause havoc. Also is the nut on the output shaft tight? There is no end float detectable?

Pete

[Tom]

 :1:

[mach1mustang351]

When filling you aren't filling it to the bottom of the filler hole are you? There is a level plug that is much lower. Drain it again and just add 750ml see if it persists.

If the oil was highly discoloured it's a bad omen. Have you or anybody else removed the speedo drive of late? If so are you certain the washer under the pinion was seated correctly? If it wasn't that can cause havoc. Also is the nut on the output shaft tight? There is no end float detectable?

Pete

When I drained it out when I rerouted the vent hose a month or so ago, I drained the fluid and measured 750ml.  I did not use the fill hole. 

I have had the bike for a little over 2 years and before that is sat for at lease 5 years.  I have never been into the speedo drive, it worked, so I didn't go down that road.  I haven't had the drive apart, so no idea on the output shaft nut or end float.  I haven't had any weird vibrations or odd things like that, so I didn't go in that deep.

Stuff to look into I guess.  I am curious now, how the fluid may look.  Wondering If I need a winter overhaul

[JayDee24ca]

On my 87 SPII the vent tube goes up high then bends back into a small plastic bottle zip tied next to the battery, just as Tom mentions for his bike. In the eight years or so that I have owned and operated the bike I have never found any fluid whatsoever in either the tube or the bottle. Of course now that I have said that, tomorrow I am bound to find a bunch of oil, right? 
JD

[pehayes]

What gear oil are you using?  Some are more prone to foaming than others.

Patrick Hayes
Fremont CA

[mach1mustang351]

What gear oil are you using?  Some are more prone to foaming than others.

Patrick Hayes
Fremont CA

I was using Lucas 80/90 synthetic

[Stevex]

Last time I took my LM2 out for a quick run down the motorway at 100+mph, it chucked oil out of the gearbox breather hose. This was after it had been routed half way up to the head stock and back down to the front of the battery. I've had a catch bottle read to fit for the last year!