Final Drive Fill Plug MIA....

[AnnapolisAirhead]

I had an odd thing happen. I have just recently gotten my bike on the road from an 8 year hiatus. Yesterday a couple stopped me as I was loading up my groceries and said "Nice bike". My first comment on the bike...well, he knows bikes, especially airheads. So we chatted as he and his gal looked it over.

I told him I probably only have a couple hundred miles on it...he mentioned changing the final drive, shaft and gear box oil. He was pointing out the drain and fill plugs and we discovered that the fill plug and washer was gone. MIA. Took a walk-about....and I know it was there, I'd taken the rear wheel off several times--not happy with the spline lube, new tire were mounted without tubes on snowflakes, etc.

Great, I am (fortunately) only 5 miles from home, clear day. So I cautiously headed directly home. Great, now it's Saturday night.So much for the Sunday morning breakfast run. But I am a sailor and try to plan for any failure--spares, tools, etc. I just wasn't prepared for this.

Here's my emergency plug fix: a rubber stopper plug, just like the ones used in dinghies.

I found several sizes at my local TruValue hardware store, found the one that fits, smeared a bit of lube on it, twisted the lever and flipped it back to lock in place. As the final drive, shaft and trans were draining, I took the plug to a vise, and cut off a little bit of the threaded piece that sticks down close to the innards of the final drive--even though I measured it would not touch any moving parts.

I put the remaining plugs in a ziplock and in the tool tray, just in case. I'll pick a proper part up tomorrow, but this got me through and as long as its not a part of the bike that generates excessive heat or any part of it gets in the way of moving parts--it should help someone out of a tough spot.

 

[169347]

Good idea with the rubber plug for a temporary fix. I had a similar thing happen on my '83 G/S. I used an 18mm drain plug to get me home. Keep in mind that it functions as a breather for the FD, and I would think that extended riding (especially at high speed) could cause undue pressure and possible seal leaks in the housing.

Woodgrain

 

[AnnapolisAirhead]

Good idea with the rubber plug for a temporary fix. I had a similar thing happen on my '83 G/S. I used an 18mm drain plug to get me home. Keep in mind that it functions as a breather for the FD, and I would think that extended riding (especially at high speed) could cause undue pressure and possible seal leaks in the housing.

Woodgrain

Good point. I told a friend who has a '78 R100/7, but his final drive is different than mine and he brought up the breather issue. On mine, I have a drain plug at the bottom, a fill plug at the top and on the aft end, halfway up I have a much smaller plug. I filled it with what Clymer's said, leaving the small plug out as I filled. At the same time as the all the oil in the funnel had gone into the final drive, a small amount oozed out of the tine plug hole--something a fellow airhead (he has an '86 R80) said would indicate the right amount of lube.

Is this just the later model (post /7 final drives??). Doesn't look anything like the R90/6 I had.

 

[grafikfeat]

I took the plug to a vise, and cut off a little bit of the threaded piece that sticks down close to the innards of the final drive--even though I measured it would not touch any moving parts.

Can you show a picture of that? I'm left wondering how the plug would compress if the end were cut off?
My first thought was to not seat it so deeply.

Neat idea nonetheless!

 

[AnnapolisAirhead]

Can you show a picture of that? I'm left wondering how the plug would compress if the end were cut off?
My first thought was to not seat it so deeply.

Neat idea nonetheless!

Updated the picture (sorry for the massive picture size...bandwidth killer), Shown are two plugs, one after the cut and one before. Essentially I found the size plug that fits into the hole with little resistance in the fully uncompressed state (e.g. unscrew the tang). Then, I compressed it so it became snug, but still able to be pulled out with a little force.

The tang is on top and connected to a threaded rod that goes thru the rubber stopper, and is threaded into a flat washer on the bottom of the plug. By compressing it a little, about 1/8-1/4 of an inch of the threaded rod was protruding on the bottom, thru the washer. That little nib is what I cut off. What was left is the flat washer, the threaded rod (Cut flush with the washer), the rubber stopper and the tang. For good measure, I gave the tang on half twist after I'd cut the tip of the threaded rod off. I put a very little bit of gear oil on the rubber stopper because now it is slightly large than the hole.

Before I inserted it into the hole, I measured from the top of the threaded hole on the final drive body into the hole to the metal there. Then, compared that with the length on the plug from the flat washer to the lip of the rubber to make sure I wouldn't grind the flat washer into the moving parts inside the final drive.

A more important note, which Woodgrain pointed out is that the original plug is a breather type....so this would ONLY be a stop gap measure to get to shelter or where you could find a factory vent plug. It is a breather plug after all, I wouldn't go too far or too fast.

BTW: these little breather plugs are $18 at Bob's or $14 at Chicago--but the shipping would be $7, so I'm headed to Bob's tonight. Can't imagine WHY this and the shaft fill plug would be finger tight. At least I caught the shaft plug...and am VERY happy I didn't get caught in a rain storm. Yikes!

 

[grafikfeat]

A more important note, which Woodgrain pointed out is that the original plug is a breather type....so this would ONLY be a stop gap measure to get to shelter or where you could find a factory vent plug. It is a breather plug after all, I wouldn't go too far or too fast.

Thanks for the updated images... Something else to keep in the bottom of the saddle bags!
I wouldn't fret the vent issue so much as keeping the oil in and water/dirt out.
My R1200c rear drive has no breather. Wherein my /5 does. Do other models lack the vent? That worries me. Almost as much as blowing out a oil level site glass!
~ Jim