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Old 09-04-2012, 08:55 PM   #1
rebelpacket OP
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R75/5 Retrofit - The Education

Hi folks; A month or so ago, on the guidance and research done in this forum, I bought a 1971 R75/5. Its pretty rough, but the bike was running, and I was even able to drive it down a block or two (even if it was running roughly). Fully knowing that this project would take some time, I delayed breaking into it until I had the time, some parts, and several manuals to consult. This weekend, it finally went on the workstand, and the project started.



Welcome to my small shop. When we moved to Colorado Springs, I left behind a garage for storage, as well as a 1,000 square foot shop I shared with some friends. Packing all of that into a small two car garage makes everything look pretty cluttered. My apologies in advance if everything looks like chaos. I'm still developing an order and storage for most everything.



My purpose is not a restoration. I'm not looking to have a shiny, polished BMW when I'm done. I like the rough, "used" look on most of my motorcycles. Parts get washed when they come off for maintenance, but in general, unless it needs to be cleaned for proper function, it stays dirty. My goal is a reliable, well running motorcycle to handle weekend rides, round-town commuting, and the occasional two or three day ride around the mountains with a minimum of camping gear strapped to the back.



Someone identified this as a brown "ride-off" centerstand. While its pretty easy for around town, so far its been nothing but a headache for maintenance. Do people with this stand simply never get flat tires? I had to jack the bike up and put a bit of 2x4 under the stand to get any clearance for the rear wheel to come off. One thing is for sure, this thing is coming off and going into the parts pile before this bike gets out on the road again.



Dropping the oil pan seems to be the first order of business for most folks starting out. While it looks like there are bits and pieces of metal, it appears to be casting imperfections on the pan itself. I have not been able to identify what kind of oil pan this is, or what year it came from. The sump pickup has been appropriately extended, though I do believe I'll replace the filter and gasket while its off. The oil smelled very strongly of gas too.



Shortly after this point, I started drinking. Why? Because I started finding more and more problems. First off, removing the timing cover, about 3-4 tablespoons of an oily-like fluid piddled out.



I haven't worked on a bike with points in a long, long time. I'm pretty certain they don't operate in an oil bath. I have a new set of noris points on the way from bmwhucky, but I don't want to foul them if there is a bad seal. From what I can tell, this is part 11 14 1 261 193, which is a cam seal 12 x 25 x 8. Does that sound right? Any particular precautions or checks to preform when changing the seal?



Removing the rear wheel showed me that the splines on the final drive look to be halfway (or more) worn down to nothing. I can't seem to find any good idea of how long they would last in their current condition. Is Hansen's BMW in OR still the best shop for getting the splines repaired? Can anyone recommend their favorites? I'd prefer to support a local shop if there is one in CO thats known for good repairs.



I might as well fix the splines, as it appears the main seal for the FD is leaking as well. Max BMW fiche seems to list this as: 33 12 3 004 343 GASKET RING. I presume that the seal simply needs to be seated flush with the FD. Are the /5 final drives known for chewing up crown wheel bearings? I've already reshimmed one on my 1150GS. Is it worth replacing the bearing if I'm opening it up? Or are they known to last for hundreds of thousands of miles?



This was a nice treat; The bolts that hold the seat onto the hinges came to me pre-stripped. I don't -need- to take the seat off the bike, but it appears I don't have the option now (at least not without an angle grinder and a cutting disc).



Also included was some pretty rough wiring. This switch was just hanging freely, and looks like it was shorting out on the case at some point. I hope that didn't reduce the lifetime of the diode board.

To this point, the bike hasn't surprised me too much. The drive splines was unexpected, especially if the bike only has 39K miles. The final drive seal was expected, and I was happy to see that the pinion seal didn't appear to be leaking fluid from the driveshaft into the final drive.

I still have yet to dive into the carbs and the valves yet. I like to take things slowly, accomplish at least one thing (however small) each day. I will update this thread with my progress.

My sidekicks that spent plenty of time wandering around my small work area with me. I'm sure they will show up in many of the photos to come. I have been known to put parts back on a motorcycle that contain dog hair. I'm pretty sure a few made it into the FD on my 1150GS. Not as bad as finding them in ice-cubes, but they do end up everywhere.



Thanks in advance to everyone for your help and insight. I've been amazed at not only the wealth of information available, but the number of people willing to share the information. A very strong community here. From a guy that isn't a typical BMW rider, I really appriciate it. I will be sure to update this thread as I proceed, in the hopes that it'll help someone else, just like me.
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Old 09-04-2012, 09:25 PM   #2
Lomax
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Nice find and that looks like a fun project. do NOT keep track of how much time and money you spend on it.

On the seat you should only have to take off one of the seat brackets and the other one will slip off the hinge. There may be a small clip on the hinge as well. If memory serves me correctly on the /5 SWB bikes the hinges are mounted opposite each other forcing you to remove one of them. The later bikes has the hinge pins mounted in the same direction and you could just slip off the seat.

Rear wheel splines are very subjective. I had a 74 /5 with 1/2 worn out splines that I rode for over 50K miles with no more wear. When I finally did get around to fixing it I found a final drive and rear wheel on flea bay for a lot less than having the splines fixed. If you go this way pay attention to the gearing, it is marked on the final drive.

They are very fun bikes and well worth keeping on the road IMHO:

Marc
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Old 09-05-2012, 07:10 AM   #3
senatorperkins
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pretty bike, you've got a lot of work ahead of you. enjoy it as much as you can..

is your only tie-down on your front wheel? you need more. airheads are heavy.
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Old 09-05-2012, 07:38 AM   #4
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There are two seals in the timing cover. One for the crank, under the Alternator. And one for the cam, under the points. Then there's the gasket for the cover and the two small O-type gaskets, that are a seperate part # when you seal the cover up. So are you doing a timing chain anytime soon? I wouldn't suggest going that route just to do the seals but how old is the chain? If it is anything over 60K just do the whole thing. They don't last 100K. Some of them don't last 70K.

You can put the seals in from the front with out taking the cover off, if you are a half assed mechanic that has done a couple of seals before.

Those rear splines look weird. On the left side of the picture they look worn irregular? Is this some photo effect. If all of the splines look like the ones to the right in the photo then you have plenty of spline material. Your problem is the seal in the rear drive seems to be no good. There is a possibility the oil came through the through cam for the brake. Clean it up good and see if you can determine if this oil is the seal or the brake cam.

If it is the seal it is a problem to fix because the final drive comes apart to replace the seal, that's not a big deal. But the new gaskets sold by the dealer are thicker than the old gaskets and the FD is supposed to be reshimed to put it back together. That is a big deal.

Pretty bike.
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Old 09-05-2012, 08:45 AM   #5
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Is oil actually drooling from the seal? There is a very inexpensive O ring or two on the brake shaft which are common failure points.
Interesting that the brake shoes look dry.
good find! It'll be fun.
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Old 09-05-2012, 09:32 AM   #6
rebelpacket OP
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Quote:
Originally Posted by Lomax View Post
On the seat you should only have to take off one of the seat brackets and the other one will slip off the hinge.
Unfortunately, all the fasteners for BOTH seat brackets are all nicely rounded out. Not enough clearance to drill the bolt heads out, so I'll just have to cut the brackets. Kinda sucks. Thanks for the tips though. I'm wondering if I couldn't just drill out the mounts for the seat hinges, add just add a cotter-pin to the end.

Quote:
Originally Posted by senatorperkins View Post
is your only tie-down on your front wheel? you need more. airheads are heavy.
The bike is on the centerstand. The strap is just to keep it from rolling backwards. My 1150GS is a heavy bike. The R75 is a lightweight by comparison. :)

Quote:
Originally Posted by disston View Post
There are two seals in the timing cover. One for the crank, under the Alternator. And one for the cam, under the points. Then there's the gasket for the cover and the two small O-type gaskets, that are a seperate part # when you seal the cover up. So are you doing a timing chain anytime soon? I wouldn't suggest going that route just to do the seals but how old is the chain? If it is anything over 60K just do the whole thing. They don't last 100K. Some of them don't last 70K.
I'm 97% certain that the leak is coming from the cam seal, under the points. The seal from the ignition system to front cover looks to be in good shape. It was holding all the oil in the points area. There isn't evidence of oil anywhere near the stator.

The bike reads 39K miles currently, though with the wear on the splines, I wonder if its gone longer. I don't yet know enough about how the bikes wear, to estimate mileage or use from parts. I won't be slogging miles on this thing, so if the timing chain will last 10K miles, I'll wait to do that until next winter.

Quote:
Originally Posted by disston;
If it is the seal it is a problem to fix because the final drive comes apart to replace the seal, that's not a big deal. But the new gaskets sold by the dealer are thicker than the old gaskets and the FD is supposed to be reshimed to put it back together. That is a big deal.
Is there something special about the shimming? Can you just measure the thickness of the old gasket, versus the new and order the appropriate sized shim (or sand your existing one down on a plate of glass)? Or is there some special german ritual dance I'm missing out on? :)

Quote:
Originally Posted by mykill View Post
Is oil actually drooling from the seal? There is a very inexpensive O ring or two on the brake shaft which are common failure points
It does look like its drooling directly from the seal. Good tip though, I might as well change that o-ring while its apart. I'm guessing the brake shoes are dry simply because it hasn't been ridden. It often seems sitting for long periods is far more damaging to seals than regular use.
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Old 09-05-2012, 09:38 AM   #7
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Quote:
Originally Posted by disston View Post
Those rear splines look weird. On the left side of the picture they look worn irregular? Is this some photo effect. If all of the splines look like the ones to the right in the photo then you have plenty of spline material.
They are worn in almost a "U" pattern it seems. Below are some alternate photos. From a side profile, It looks a bit like:

Code:
      _        
   _/   \      
_/        \_

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Old 09-05-2012, 10:08 AM   #8
disston
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You can sometimes buy a used FD cheaper than fixing the splines. A mater of luck tho.

Shimming the FD is supposed to be a big deal that requires some special tools or special procedures or something. The people that own the tools tell me. So I do realize there is a vested interest in this if you look at it that way. But I don't know how to do it.

Maybe we could do a long thread on how a Shade Tree Mechanic would do this. It might be interesting but how much value would it be?

I have rebuilt a rear end in a car. I was lucky I think. I actually changed the ring and pinion and they will jump up and down screaming, "You can't do that." I did.

I did do the Final Drive in my bike about 10 years ago. I think the gaskets then where the old style and the same size as original. I had the splines replaced and put it back together. Have never had a problem with it since then.

If you are looking at FDs, do realize the /5 matches the /5 wheel. Some riders are swapping around wheels and FDs and this all seems to be not the way to do it if you can help it. If you don't really care if it is kept stock then you can go with a later FD and use a later wheel.

That is weird wear and I think this bike is over 39K.

Because it is worn in a step? Is there a corresponding step in the wheel?
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Old 09-05-2012, 10:23 AM   #9
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Sorry to be so wordy but there is another aspect to FD repair that should be mentioned.

The splines in the wheel are worn to match the wear in the FD. When the splines in the FD are replaced they are usually sent off where they will be welded and recut. This is a standard procedure but we will recommend a place that you should use for this, not your everyday machine shop, but somebody who does a lot of BMW spline repair.

And the spline cup in the wheel should be replaced also. It is removable but again you have a /5, I have a /6. My /6 spline cup is available. I think you'll be able to buy the cup for a /5 but I'm not sure. Check to see this part is available. Or if not how to deal with this.

The splines in a /5 are shorter than the other bikes.
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Old 09-05-2012, 11:15 AM   #10
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As handy as the seat hinges are to have vs the cost to replace, I'd go spend a couple of bucks and by a set of Easy Outs to remove the old fastners. They are already drilled out for the processes!
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Old 09-05-2012, 11:34 AM   #11
rebelpacket OP
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No kidding rufusswan. I've had terrible experiences with easy-outs though. Worth a try anyways. Not like I have anything to lose.

Disston, the splines on the wheel look fantastic. Almost no discernable wear, whatsoever. Maybe this bike was just flogged to pieces? The clutch was very grabby on the short test ride I did. I've got the worry beads out, and wondering if the input shaft on the transmission is buggered.

Is Hansens MC in OR still the folks to go to for spline repair? (http://www.hansensmc.com/default.asp?page=spline)
I like how they weld on the existing spline and then re-machine it, rather than the chop and weld.
I can't find any information on if this is better or not, other than the chop and weld method can blow out seals when done incorrectly. (http://web.eecs.umich.edu/~deroo/bik...ne.repair.html).

Regarding the re-shimming of final drives; I'm not terribly worried about what folks say about it. The tooling for "proper measurement" is expensive, and the bearings/seals are cheap in comparison. I will document my procedure here and be sure to follow up if it goes horribly wrong. Its the "cardan" gasket that is different size, correct?
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Old 09-05-2012, 11:48 AM   #12
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BTW, I don't think the original seat hinges are available? Not sure tho.

Yes the large round gasket is the one they talk about because it will change the spacing. As far as I know the difference can't be that much? But again I don't know. I think I would try it personally.

The wheel may have been replaced. It may not be a /5 wheel. Check this thread out for what happens when people start swapping wheels around.

http://www.advrider.com/forums/showthread.php?t=823154

So far they haven't done anything yet. But what if it doesn't work? This guy is trying to use a /6 wheel on a /5 because that is what he has.

Yes Hansen's in OR.

In case nobody has told you yet, the best way to do Airhead ownership is to have a spare everything. So two Airheads works for me.
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Old 09-05-2012, 07:47 PM   #13
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Lots of questions! I'd just replace the points seal; the early seals are a chronic problem. Be careful getting the seal out. It's easy to damage the seal journal when doing so. If neccesary, drive one side of the seal in a bit, then ease a sturdy hook under the higher side. Clean the seal bore thoroughly and lightly wet the OD with a temporarly lube like WD-40, and apply assembly lube or motor oil to the ID. Be careful tapping it in, too. It's easy to push the seal in too far. Don't get carried away retightening the nut on the advance unit; the drive quill easily stripped. If there's room, use a self-loclking nut, removing the washer if need be.

There are no o-rings on the povot shaft on a /7. The cover gasket seals the shaft on these bikes. You don't need special tools to check/adjust the shimming on an RDU on a twin-shock. You do need a couple of short straight edges and a depth gauge and some patience. It is nice to have the special tool to install the seal, but you could probably make something appropriate. For best results with this seal, leave it standing proud by a millimeter. That spline has a lot of life left in it. I'd wait until winter to replace it. Any of the shops who repair splines have long lead times.

To remove the seat, cut off one hinge, then slide the seat off the remaning pin. You may be able to get the bolts out, once the seat is removed by drilling their heads off. This releases the preesure on the threads and they can usually be removed with vice-grips. New hinges are available the last time I checked.

That looks like one of the good 3-Quart pans. Loctite the pick-up bolts. They have a tendency to fall out, and bearing destruction is the result.

The Ride-Off stand was made by Reynolds. Nice part, but they drag easily in corners. It'll scare you the first time it does.
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Old 09-06-2012, 09:08 AM   #14
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Lots of tips bmwrench; Thanks for all those.

I can't find an idea what the "special tool" is for installing the seal. Is it just a proper OD PVC pipe cut in half?

I really hope the factory /5 workshop manual that is on its way is better than the Haynes 2-valve BMW manual. Doesn't have any parts breakdowns, so I end up looking up fiche to understand how the groups go together. Really frustrating.

I'm going to clean and grease the splines and I'll repair them some other time. My hope is to get the bike roadworthy in time for my 30th birthday, at the end of October. I figure I'll ride it around a bunch until the snow flies and then park it for the rest of the work.
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Old 09-06-2012, 12:37 PM   #15
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The factory manual is a plus but it leaves out a lot of stuff. I have one for /6. There's data in the factory manuals that is not duplicated in the after market manuals.

Sometimes the pictures are helpful in the factory manual but they will only show parts being installed with the factory shop tools. A complete set of those I don't think exist anywhere.

So you'll get some good clues from the manuals and the advice here on Adventure Rider will help but ultimately you have to figure out how this is done. Be observant. Don't hurry. Most stuff will not really be all that hard once you figure it out.

Most of the time deep sockets from a ratchet set can be used as seal drivers. If these are not deep enough then PVC plastic might work. The factory tools often correctly set the depth of seals but this won't be automatic with a make shift tools. So...before removing any seal notice how deep it is set. Often seals are set all the way in so they get driven in till they stop. Or they are driven in to be flush with the edge of the Aluminum bore. This is not the case with our motorcycles. A lot of seals on your bike stand proud of the Aluminum bore. (a term mentioned by bmwrench) It means the seal is higher than the bore. How much can be critical.

You should be able to find a socket that has an outer diameter that matches the outer diameter of the seal you want to drive. A little bigger sometimes works but be careful of too much smaller in diameter. This can deform the seal. The socket should be tall enough to clear the tip of the cam when the seal is all the way in. In this instance the height might be a problem. If not a socket then something that matches the seal diameter and is tall enough has to be found or has to be made.

That's it.
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