Beatrice's first 50 mile ride reveals oil leak

[Holysmoke]

Finally got my '78 R100S on the road. Took her to a car wash to clean up the bottom of the engine So I could possibly see where the oil leak is coming from. I'm pretty sure now that it's coming out where the motor and tranny meet. This is probably a must fix now issue, right? It looks like a big job, but if it's a doable one, I don't mind tackling it. Recommendations? Cost to have it done?

Oh yeah, the bike ran great for this 50 mile ride. Had a little hesitation for a 1/2 mile after power spraying, but didn't miss a beat after that. Possible electrical seal issue somewhere? This was my first Beemer ride. It was very nice, a little clunky shifting, but good torque and highway cruising performance. I'm guessing, probably a little different to handle in the twisty?

Thanks in advance for your input
Ron

[grant81rs]

Gidday

Ron, glad all is fine in the world of new to beemer ownership mate, just keep riding n sorting, riding n sorting, you get the picture, then things will iron out and its smooth sailing from there on in.

Not sure about the oil leak but most likely sounds and could be the rear main seal, the oil drips down off the lip, or shelf type of section behind the gearbox... its something that sounds daunting and a little difficult to repair for a novice but I done my first one a few years back now on a new to me R100RS that I brought..

There are a couple of very good "walk thru" procedures kicking around on the internet and also Chris Harris BMW Motorcycle repairs on youtube has a excellent 3 or 4 part video on this exact job which I recommend watching a few times.

If it is the rear main seal leaking then:

Have a big clean bench to lay out the parts in order that you removed them from the bike, have some disposable white large plastic plates and a black texture and when you undo something like the swing arm or drive shaft you can write on the plate what each thing is for, this I found bloody handy and easy to follow.
Put the word out in the area where you live for a bike lift to hire, lend, borrow or steal..... to work from, it certainly makes the job easier on your back and more enjoyable and aim the complete it in one day, its a job you want to start and finish asap and not have sitting around, complete while the mind is fresh!!

This vid link is part one of four parts for a spline lube on an r100... It will get you part on the way into the bike.
https://www.youtube.com/watch?v=uVKPGcf0xag

Best of Luck!!!

[Duane Ausherman]

Smell the oil and it will be either the tranny or the engine oil.

[bbelk]

Where ever it is coming from, you will be pulling the transmission out to get to it. Lots of steps, but all pretty straight forward and not really any special tools until you get to the seal. I am not sure about that.

I have a 1979 R65 and I am not sure how similar they are. I bought mine with just 11,700 miles on it. The clutch was weird for a year before it finally gave up. I bought all the parts in advance, so I replaced them all, but I am pretty sure the only thing that needed replacement was the diaphragm spring. It was the only thing out of spec. It would have saved a lot of money to change just that.

You will need new drive shaft bolts and flywheel bolts, cheap, but order in advance.

[SteveD]

If you need to remove the trans, it's easy enough.

About 90 minutes the first time, taking your time.

Gearbox removal, R100 BMW.
1 - Disconnect battery ground and speedo cable at the transmission

2 - Remove the front boot clamp, peel back the boot and loosen the 4 driveshaft bolts
(The reason to do this first is so you can use the rear brake to hold the shaft from turning)

3- Disconnect the clutch cable and remove the clutch cable/arm/spring/boot from the transmission.

4- Remove both swing arm pivots and pull the rear wheel rearwards against the fender and strap it there. (this will entail removal of the brake pedal and/or linkage and/or boot on some models).

5 - Remove the 4 driveshaft bolts you loosened earlier. push the driveshaft rearwards into the swingarm.

6 - Remove the left carb, the air filter and airbox, and shifter linkage.
You don't have to remove the carb cables, just carefully move the carb out of the way.

7 - On some models it's easier to remove (or partially remove and tilt) the battery and the battery box.

8- Remove the 2 lower trans mounting bolts

9 - Disconnect the 2 neutral switch wires.

10 - Pull the transmission rearwards to disengage the input shaft from the clutch and lift it out from the left side of the bike. Sometimes the clutch pushrod stays stuck in the clutch, you have to move it backwards to disengage it or you won't get the transmission out.
Protect the frame paint with rags and duct tape if it's important to you.


Assembly is the reverse.

[Rob]

9 - Disconnect the 2 neutral switch wires.[/color]

Prepare your curse words in advance - both directions.

[montmil]

Just to confirm the source, I would suggest taking a good, long look at the neutral switch before I yanked out the gearbox. Sniffing the oil that's weeping will tell you if it's engine oil or that stinky trans lube.