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Old 10-15-2013, 06:14 PM   #1
headtube OP
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I love the smell of gear lube in the morning...

... not really!

Here's a few pics of the inside of my final drive.







There is gear lube being thrown inside the hub of the snowflake wheel. I suspected for a while that I needed a seal replacement in the drive hub. However, I've never done this repair before so I was hoping someone could verify this for me from these photos. Thanks.
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Old 10-15-2013, 06:34 PM   #2
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... not really!

Here's a few pics of the inside of my final drive.







There is gear lube being thrown inside the hub of the snowflake wheel. I suspected for a while that I needed a seal replacement in the drive hub. However, I've never done this repair before so I was hoping someone could verify this for me from these photos. Thanks.
Yup, you do. You also want to find out why you are getting water in your rear drive oil. Drain it into a clean pan and take a pic maybe.

To fully apprecite the scene, drop $130 on a fresh set of brake shoes and soak them in some old 90wt. for a couple days. Then you can really cry.

That looks like an early "conversion" drive. I dunno if you can get to the seal without pulling the cover. if you have to pull it it's simple enough. but cleaning off the old gasket is a pita. You also want to preserve some perfect sections of that old gasket and mic. the thickness to compare against the new gasket. if they are different, the drive will require re-shimming. Replacing the seal itself is trivial. You also want the outside completely clean before you open it. Don't worry about getting water in it, you can flush with lotsa WD40 later, you just don't want ANY dirt getting into the bearings.
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Old 10-15-2013, 06:47 PM   #3
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Thanks Plaka. Forgot to mention... no drum brake. 79 RS, first year rear disc. Re-shim you say... shite! I won't know what size shim to buy until the gasket comes in from Germany. There's another 2 weeks of waiting for a part to arrive. Oh well, at least we can still get factory parts for these old girls.
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Old 10-15-2013, 06:59 PM   #4
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Thanks Plaka. Forgot to mention... no drum brake. 79 RS, first year rear disc. Re-shim you say... shite! I won't know what size shim to buy until the gasket comes in from Germany. There's another 2 weeks of waiting for a part to arrive. Oh well, at least we can still get factory parts for these old girls.
I know there is no drum, just wanted to give some perspective (mine is leaking like a pig...just redid the seals and o-rings and it then leaked again trashing the shoes again...)

I got the gasket from MAX in like 3 days. be careful to get one for the correct year (pre X vs post X). Also get a FD to swingarm gasket.

I didn't reshim. The new gasket was close enough to the old. You want to find some uncompressed old gasket for the best measurement. I had heard there were some different thickness gaskets so I checked. The new seal is all of $10, again MAX. It's a sub $25 deal--one seal, two gaskets.

If you do reshim, the measurements are delicate, you really want a depth mic. And the shims are expensive, like $12 each. Had I needed to have that done, I would have just had a shop do it. Not a big deal for them to measure it up and say what shims are needed. I can drop them in and stick it all back together. When you pull it apart, (follow directions in manual!) don't lose any shims. The cover comes off, make sure no shims are clinging to the inside, Bag the FD and just work on the cover getting the new seal in correctly. Then back to the FD to scrape the old gasket. New one goes in dry. it's not a complicated job unless you have to correct the shimming, then there are just two very accurate measurements and some arithmetic.

On the later drive, you can just pop the seal out from the outside. I recall doing my /5 that way too. You might explore this. Totally superior and little work if you can. That cover looks like it has the lip and drain hole to keep oil off the shoes. That feature went away with the later covers---my drum cover lacks it, which completely sucks.
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Old 10-15-2013, 07:07 PM   #5
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Had that happen on my old 79 RT. Took one look at it and thought, Nope. I didn't have time for that. Dropped it off at the shop one weekend, rode to California and back on the R45, and picked it up the RT the next weekend. Paid a reasonable price for labour and parts. No issues ever since.

Just glad I have another bike to ride when one is down for repairs.
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Old 10-15-2013, 07:21 PM   #6
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Just replace the main seal (closest to the spline) and see how you go.
No point pulling everything apart if not needed,

I replace my seal a few years ago, easy.

But clean it all up first tho'
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Old 10-16-2013, 04:29 AM   #7
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Clearly the drain is clogged, probably both are, and I can't imagine that the inner seal is perfect. Why not do the job right, or get someone else to? The new gasket will probably change the shimming anyway, so that will take some attention (but again, only if you want to do it right).
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Old 10-16-2013, 08:21 AM   #8
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Clearly the drain is clogged, probably both are, and I can't imagine that the inner seal is perfect. Why not do the job right, or get someone else to? The new gasket will probably change the shimming anyway, so that will take some attention (but again, only if you want to do it right).
The cost of having a shop do it all might be worth weighing against the spline wear. What would you roughly charge assuming drive in hand, one shim exchange needed, the gear mesh showing proper engagement from the wear pattern and neither of the other seals showing signs of leakage?

Personally I don't like the look of that oil, but think other factors should be explored (pressure washing, wading, etc.) before suspecting the outer seal.


When I did mine I measured the old gasket carefully and ran statistics on multiple measurements (10 or so). I found the variation, old gasket to new, even accounting for compression of the old gasket (which was minimal), was within the resolution of the smallest shim, so I didn't seek to reshim. But I would consider such measurements necessary for the DIYer without good tools to just set up the shimming from scratch. I only have a digital mic.

I wouldn't assume the gasket I got from MAX, one time, will be a match for any other particular old gasket.
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Old 10-17-2013, 09:43 AM   #9
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When I first saw that mess, I was like Anton, the drain hole is plugged.

Folks figure if they squish in a bunch of grease into the rear wheel drive splines, that will help the splines stay good. Nice thought but not true. The splines will only accept a film of grease in them, the rest just squishes out and becomes good foder to plug the drain holes. That squished out grease never gets back into the splines. Yes, it's good to lube the drive splines but any more than a film is a liability, especially if you have drum brakes.

Course, those little holes can become blocked over time with road dirt mixed with oil film. It's a good thing to check whenever the rear wheel is removed.
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Old 10-17-2013, 10:17 AM   #10
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Don't shoot me for asking but....

I mean this question sincerely as an ignorant question so please be easy on me....

I have owned a few beemers. R100 bumblebee for 15 years, my PD and an 1150 GSA for about 10 years.

I have put 100k+ miles on each.

I always changed my final drive oil with my regular oil change so 3 to 6k depending on the oil type.

I have never had a final drive seal break. I have had it happened to a friend and I have seen a few here on ADV and consequently I travel now with a whole kit in my PD, shims, seal, bearing just to be safe in case I'm somewhere that I can get the work done as long as I have the parts.

My question is....have I been nothing but lucky, or looking at the oil in this thread pictures was this not changed frequently enough....or does one have nada to do with the other and you are either a person who has had a final drive seal leak, or a person who WILL have a final drive seal leak?

Easy on me here...I mean no disrespect to anyone on here, I am just curious.
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Old 10-17-2013, 10:29 AM   #11
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I mean this question sincerely as an ignorant question so please be easy on me....

I have owned a few beemers. R100 bumblebee for 15 years, my PD and an 1150 GSA for about 10 years.

I have put 100k+ miles on each.

I always changed my final drive oil with my regular oil change so 3 to 6k depending on the oil type.

I have never had a final drive seal break. I have had it happened to a friend and I have seen a few here on ADV and consequently I travel now with a whole kit in my PD, shims, seal, bearing just to be safe in case I'm somewhere that I can get the work done as long as I have the parts.

My question is....have I been nothing but lucky, or looking at the oil in this thread pictures was this not changed frequently enough....or does one have nada to do with the other and you are either a person who has had a final drive seal leak, or a person who WILL have a final drive seal leak?

Easy on me here...I mean no disrespect to anyone on here, I am just curious.
All seals fail eventually.

it is not years that count as much as miles.

I had the big seal give out on my /5 @ <100k, and then the whole drive later broke so I never learned the life on the new seal.. I have a FD with about 50K on it that had a bad seal and another with >90k with no issues. A third with perhaps 160k on it was leaking badly.

I change the gear oils yearly, usually in the fall. Unlike engine oils, they don't get contaminated by combustion by-products. They do get contaminated by metal worn off the gears, and they age/wear out. They should not be getting wet. if they do, they should be changed (including a flush) immediately. The gears oils in autos get changed at enormous intervals, especially in differentials. Unless it's a Rover or certain other British makes. Then it's self changing, you just keep topping it up every week and overall it's always fresh. Clever design.

If you can R&R the seal from the outside, and many can be done that way, then you might carry a spare seal on a pretty remote expedition but you won't need gaskets, shims or bearings. you will need a pair of drywall screws and a beer can to change the seal. . In any event, you can ride without the rear brake and if the shoes get oiled (common) you need to replace those too. So you can just leave it. It isn't an all-the-oil-gushes out type deal. just keep it topped up and you can ride thousands and thousands of miles with nothing more than a pretty goodly mess.

it is important to keep the breathers clear. pressure buildup in the drive will push oil past even a good seal.

Plaka screwed with this post 10-17-2013 at 10:35 AM
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Old 10-17-2013, 10:45 AM   #12
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Excellent Plaka`

thank you for that...that gives me the info I needed. I figured considering my lottery luck that I was not just lucky. Will happen to all of us at some point.

Good to know about the whole kit, that bearing is heavy so leaving that behind is better on me anyway and that thing wasnt cheap either.
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Old 10-17-2013, 11:04 AM   #13
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The big crown seal cannot be changed from the outside, the crown cover must be removed as well as the bearing.

Don't let all this talk freak you out, it really is not a common problem to have. Yes, it has happened to some folks but many have never had a problem. Usually when this seal goes, it will leak for a long time before it REALLY needs fixing. If you do develop a leak, just keep an eye on the level and fix or have it fixed when it is convieinent.

You can go ahead and breath now.
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Old 10-17-2013, 11:07 AM   #14
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thank you for that...that gives me the info I needed. I figured considering my lottery luck that I was not just lucky. Will happen to all of us at some point.

Good to know about the whole kit, that bearing is heavy so leaving that behind is better on me anyway and that thing wasnt cheap either.
Unless damaged, the bearings should last the life of the gears. The bearing inside the cover is a snug fit in the aluminum cover. Warm up the cover (a rag soaked in hot water will do) and the cover pulls off with no strain on the bearing. The cover is tapped for a pair of bolts that you insert to pull it. Pretty simple. Warm it again to replace, it goes on by hand.

The entire drive can be replace in a few minutes. If you have a spare at home all packed up with a fresh FD--->swingarm gasket, ready to be shipped to you wherever...
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Old 10-17-2013, 11:13 AM   #15
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The big crown seal cannot be changed from the outside, the crown cover must be removed as well as the bearing.



Don't let all this talk freak you out, it really is not a common problem to have. Yes, it has happened to some folks but many have never had a problem. Usually when this seal goes, it will leak for a long time before it REALLY needs fixing. If you do develop a leak, just keep an eye on the level and fix or have it fixed when it is convieinent.

You can go ahead and breath now.
It depends on the drive, some are trivial to replace from the outside, some are not. Want a pic.?

Some drives had drain holes, others did not. Without the drains, smallish seeps get to the brake shoes on a drum brake, trashing them. they are expensive. Snowbum documents this although if you'd like to look at one with no drains I'll be in your neck of the woods sometime this week and can pop off a wheel and show you one of the &*%*&ing things.
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