2018-09-28 FinalDrive and Tranny Leak

BMW /2 Swing arm leaks, final drive leaks

During a routine oil change, it was noted that the drive shaft housing was empty.   Could it have been stolen by vagrants?   A guy works hard for his oil just to have vagrants come and steal it.

 

Well, before contemplating a move to a safer neighborhood, BMW riders should remember that oil migration from the drive shaft housing to the rear drive is a common problem. 

 

There are three ways that oil can migrate from the driveshaft housing to the final drive and they all have to do with the input gear on the final drive.  This little guy:

 

Here are the three ways oil can get around this gear and into the final drive: 

 

1. Through the seal. 

2. Through the splines.

3. Through the threads which hold the collar in place. 

 

The solution is to goop them up with non hardening sealant.  Old timers used to use Hylamar, available from S. Meyer in Germany and other dealers.   

 

Some stores still stock Permatex.  For example, http://automotive.hardwarestore.com/90-558-gasket-sealer/hylomar-universal-blue-sealant-665467.aspx?utm_source=pla&utm_medium=cpc&utm_term=&utm_campaign=rkg

 

When assembling the final drive input gear, clean parts thoroughly in solvent or carburetor cleaner. 

 

Apply Hylomar or equiv. to the threads of the pinion gear bearing locking ring. 

 

 

Apply a touch of grease to the seal surface of the coupling gear. Don't put any Hylomar on the seal. It's only for the splines and threads.

 

 

 

Next, apply Hylomar to the bottom of the splines on the coupling gear. 

 

 

 

Install the gear and apply more Hylomar. 

 

 

 

Install the locking ring (bent washer with positioning clip) and nut. 

 

Failure to properly seal the splines and threads will allow oil to migrate from the swing arm into the final drive, over filling it. This is not a catastrophic situation, although it can lead to a leaky rear drive and oil-saturated rear brake shoes if the drain hole in the final drive is not clear. 

 

If you do have a leaky pinion junction, you may notice that the fill plug of the final drive overflows when you remove it. To correct the situation,  reduce the oil level in the Final Drive to just below the fill plug with a turkey baster and transfer this fluid to the prop shaft. If the fluid is contaminated, do not reuse it: rather empty prop shaft housing at swing arm drain plug and refill prop shaft with 150cc of 90wt gear oil.  The manual says to use motor oil, but I suggest that you use something thicker if you want to live with this issue. 

 

The three paths for oil leaking into the final drive are:

• 1. Past the seal, in the old days this was the least likely path. Replace the seal.
• 2. Down the splines on the inside of the gear. Goop them up.
• 3. Along the threads of the seal holder. Goop them up.

delete me

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2018-09-29 Swingarm and Transmission removal

Ray Slocomb, my restorer tech, let me know that the swingarm rotates on two tapered needle bearings, and that the swingarm must be adjusted to sit equidistant in the frame to prevent front u-joint loading.

So thought I'd measure the distance from frame to swing arm on both sides. I used my precicely machined allan key set for this job.

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The left side was a weeee bit closer, but this is an eyeball measurement, not all that critical.

Exposed threads for reassembly start point. 15.02 mm.

Brake pivot point attached to swing arm. This is a 'loose' joint so the arm can rotate.

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Speedo drive cable. It has a notch for the retaining bolt. Make sure to align correctly on reassembly.

Note to self.

I think the wire is supposed to enter at bottom, wrap around the side, then attach at top. I had trouble routing it after the wire broke.

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Originally, only one slot. I made the other.

Clutch throw out mechanism. Pic for future reference.

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Ground wire location.

Need new battery for the project, a 1963 R69s.

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Had a neighbor help me remove the transmission so as to not scratch powder coat frame.

Need to check throw out rod. It might be bent. NOTE to self - buy new felt for internal rod end.

I had alot of 90 wt in the groove of the rim, between the two shoulders. It appeared to be coming from the weep hole. So this is my test stand. I filled the pinion area with 30wt motor oil and will let it sit. If it weeps, I have the smoking gun. So far, no weeping so I'm not sure if this is the problem or not.

After 4 hours, dry as a bone. Of course, this isn't the correct orientation so this test might be inconclusive.

Need new rubber thingie.

I have no clue why I took this picture..

I was getting some 90 wt on the shelf under the rear engine /  trans input area. It looks like it's this seal based on the oil still there. The big question is does this seal remove externally or does it require tranny disassembly?

As she sits at end of day 2.

Thanks for reading, more to come.

Well OK then:

1. New transmission seal installed. Used a screwdriver with tip bent at 90 degrees to left the seal out externally. New seal installed using dead blow hammer and appropriately sized socket. It went in nicely.
2. Final drive leaks - I now think the FD is oil tight. I filled the pinion nut area with 30 wt Royal Purple engine oil (easy to see purple if it leaks!) and let it sit for > 24 hours. No leaking into FD spline area.
3. Filled the FD gear area with Royal Purple. Noticed leakage from two places:
   1. The drain plug (DUH!)
   2. The filler plug/custom made relief valve. Someone took a Circle Seal RV then modified both it and the FD plug. When the FD temperature increases, it's pushing 90wt through the RV.

So, it's time for reassembly.

Found the proper wire routing for neutral indicator light. Simple!
 

Much better than what I had done before... (routing wire through slot in protective cap, run up the side to then terminate at the top.

Here's how I previously had it routed.

Lesson Learned. Clutch cable front ferrule can't be inserted into case slot with tranny installed! Gasp. Had to loosen trans, move it back about 1/2" then route cable.

There it is, correctly installed.

Noticed heat deformation at battery connection. Replaced. Lesson Learned - R60/2 BMW's don't use earth as ground! Wired it like a conventional bike, negative to frame, hot to battery. At first start up the red discharge light was b r i g h t. Not good. Reversed the leads and all is good now. I was wondering why SuperTech Ray had the exposed male as the hot lead... Now I know why.

Per the factory OEM manual, (yes I have the original OEM stuff) both the Final Drive and Shaft Drive require 150cc. I drained the FD, it was at 110cc. So added correct amount to both locations using StaLube GL4 as GL5 contains materials that eat at the so-called yellow metals that the /2 transmissions have. Think bronze bushings.

Making progress. Lesson Learned:
1. Place rear wheel in position but don't place onto final drive hub until *after* rear fender is installed. Not much room under fender for the various fasteners.
2. Installing the rear rack and top case is a true PITA. Holes don't want to line up, making starting the bolt through the top case mounts and rear fender difficult.

There sits Uncle Dutch, Hopefully the new trans input seal will seal. For the Final Drive, I may just have to give up on the custom CircleSeal RV and plug it like it came from the factory, not vented.

While Uncle Dutch was in pieces, I cleaned and waxed all the areas one normally can't get to. 
And, Uncle Dutch is now a trailer queen. No more dirt roads.

Thanks for reading, fini!  

Wanted to say Thank You to Don W and Mark M for replying to my BMW questions during this project. Much Appreciated guys! Here's  some of the email that went back and forth..
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Hi Guys,

New seal in, got to wondering about the push rod. 

Turns out it’s a felt pad that ‘seals’ 90wt from escaping?

 

Really?

 

Makes me wonder if the rear input seal was ok all the time.

 

I mean, how can this felt prevent 90wt from escaping out?

There’s no other seal than this one for the push rod.

 

Maybe, just maybe, some degree of ‘weeping’ is just normal and I did all this for nothing?

 

Just wondering out loud.

 

Gotta love old skool technology!

 

 

The reply -

The felt "seal" is the same thing they used up until 2015, when they did the complete redesign.  There should be no way for gear oil to get into the center of that shaft... the front end is the clutch, and the back end is the actuator mechanism.

Snap On Part is: FRDHM10  https://store.snapon.com/Product-Details-FRDHM10-P631799.aspx