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Old 01-06-2013, 08:00 AM   #736
Les_Garten
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Quote:
Originally Posted by Jim K in PA View Post
Thanks Patanga. Nicely presented.
Indeed, awesome site!
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Old 01-09-2013, 10:28 PM   #737
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Quote:
Originally Posted by patanga View Post
Just loaded this tech tip on our web page. Thought you guys might be interested. The speedo cable boot is often neglected and is a common source of water contamination in to the gearbox. Easy enough to do for the experts but can be a pain for the less experienced. A quick & simple method. http://rter.co.nz/Airheads/airhead_t...ocableboot.pdf
So simple I must say, Genius.
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Old 01-30-2013, 09:03 AM   #738
RonZacapa
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Be careful of the "Double Reserve Trick"

Having ridden airheads for the most part since the mid '80's my observation regarding the double reserve trick.
NOT A GOOD IDEA! when you are running at anything more than 3/4 throttle for any extended period of time. The two fuel taps are just big enough to allow for sufficient flow of fuel at high revs. My 1983 R100 had a 336 degree cam fitted with a decent pair of pipes. Used to go really well and 210-220 km/h on the clock was nothing unusual for it. Coming back from Cape St. Francis with a stiff South Easter pushing from behind I just had to see how fast she would go, the needle on the airhead does go past the 220 mark so I guess I was well onto 235 - 240 indicated when she decided to run the two floatbowls dry. Beeing a mechanically sensitive kind of fellow I decided to cruise a bit slower at the 200 km/h mark and all was good. This was with both fuel taps on.
Long Story Short: The double reserve trick is fine when you are ambling along and cruising at moderate speeds, when caning the beast switch to both taps and your airhead will thank you for it. After all it was designed that way. Other point of concern is that with one fuel tap on the "on side" cylinder will get most of the fuel flow with the opposing cylinder may be running lean at times.
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Old 01-30-2013, 09:42 AM   #739
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I see no point in a double reserve "trick". You have the same amount of fuel, you can only go the same amount of miles. I don't know about you but I am going to stop at the first station I see. I don't need to be told twice I'm almost out of fuel.
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Old 01-31-2013, 12:25 PM   #740
Kai Ju
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Double reserve trick

The first time I tried it was also the last time. I had turned only the left side on and got 25 miles further just on that side so when it ran out and I switched the right side over I figured I was good for at least another 15-20. Not quite, I got to call my wife 5 miles later from the side of the freeway. Luckily I wasn't all that far from home and it was a Saturday, bad part was I had to get my wife out of bed..........
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Old 02-19-2013, 12:44 PM   #741
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Have read from the beginning..

Great tips and tricks all the way. I am working on my 2nd R75/7 project.

I have discover this:

1. take time... if something is not going right.. go and have a beer.. think about it.
2. take lots of pictures... especially on the wiring stuff. (before you pull it apart) connect well.
3. I have found that disconnecting the drive shaft and pulling the engine mounts and sliding the engine a head makes it very easy to unplug the tranny and lube the spline, inspect for leaks and change the neutral electric sender. I think the brass senders are better then aluminum and are available at Hucky's

And lastly I know you all do this.. enjoy.

Jim, Ketchikan Alaska
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Old 02-20-2013, 10:48 AM   #742
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this is so helpful ^_^
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Old 02-22-2013, 05:37 AM   #743
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Quote:
Originally Posted by Plaka View Post
Plus, you have to use fresh bolts of the correct length every time. This adds to the cost of the project.
The driveshaft bolts can be re-used, they do not have to be replaced each time. While it may be an okay idea to get new ones, it is optional.
edit: http://bmwmotorcycletech.info/drvshf...oolstorque.htm
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Old 02-24-2013, 03:50 PM   #744
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Totally wrong on Loctite screwing up the torque - Locktite is formulated so that the required torque stays the same.

Achieving that was the biggest problem the makers of Locktite faced when they originally formulated the product.

Unless otherwise advised, all torque figures are for clean and dry threads, so there is never any need to state that - it is only when you oil or lube them that it has to be stated.

IMHO if you cant afford or just cant bring yourself to fit new bolts each time I think you should seriously consider if you should be riding a bike at all, but I appreciate that not everyone will agree with this viewpoint
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Old 02-24-2013, 04:30 PM   #745
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Quote:
Originally Posted by Beemerboff View Post
Totally wrong on Loctite screwing up the torque - Locktite is formulated so that the required torque stays the same.

Achieving that was the biggest problem the makers of Locktite faced when they originally formulated the product.

Unless otherwise advised, all torque figures are for clean and dry threads, so there is never any need to state that - it is only when you oil or lube them that it has to be stated.

IMHO if you cant afford or just cant bring yourself to fit new bolts each time I think you should seriously consider if you should be riding a bike at all, but I appreciate that not everyone will agree with this viewpoint
Would you care to cite any sort of authority for this statement? Web page or something from anyone else. You are the first person I have heard say that Locktight was formulated to not screw with torque settings. I find it hard to believe for this reason. You may be right, I guess I would like that, but never having heard this before it's hard for me to believe.
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Old 02-24-2013, 06:39 PM   #746
Les_Garten
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How often do you have to un-button the driveshaft?

It's a cost versus benefit analysis

or

cost versus risk analysis

It's it's $6 versus catastrophe and you do it every 10-20 years I'm not sure I appreciate the argument for re-using the old bolts.

One of the risks of these bolts letting go has to be death as well. I never tempt fate with Clutch Bolts or flywheel bolts either.
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Old 02-24-2013, 07:48 PM   #747
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In my experience, the bottom line is that IF those bolts are properly torqued, new or good used, it makes no difference, those bolts do not need loctite. They never come loose if they are properly torqued with no loctite. They don't need to be periodically checked IF they are properly torqued. If they are in good shape, they don't need to be replaced.

Cost versus risk analysis? There is virtually no risk in my experience IF they are properly torqued. It makes no difference if the bolt is used or not as long as it is in good shape. A new bolt might be a bad one? Maybe the risk is less with used and tested bolts? Personally, I wouldn't worry about it that much. As a professional BMW motorcycle mechanic and almost life time airhead rider, I have literally hundreds and hundreds of drive shaft bolt installations under my belt. As far as I know I have never had one come loose and I never use loctite. I never check them. I torqued down the used bolts holding my driveshaft on right now around 70,000 miles ago. No loctite and I am not going to 'check' them. "Checking" them is for people that didn't torque them down right to start with. Same with using loctite IMO. NO need for it if the job is done right. I have seen a lot of drivehaft bolts come loose but all them were not tightened enough. Maybe a few too much? End of story IMO.

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Old 02-24-2013, 10:56 PM   #748
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http://ken-co.com/permatex/threadlock-blue.pdf

This data sheet confirms no torque compensation is required with this product, but Loctite make a huge range of products and the assumption I made that no compensation is needed with any product in any every application is probably much harder to prove, and more than likely incorrect.


But generally on a motorcycle forum we are discussing medium/high strength fasteners in a limited range of sizes, and a limited range of thread locking products.

And the statement seems to hold in these circumstances.

We are often given a torque range of around +- 5%, so if you have any concerns it would seem prudent to go for the bottom end of the recommended scale, or if you have only a single figure just leave the torque 5% under, but with the factor of safety commonly used with mass produced fasteners in non critical situations it isnt going to make a lot of difference if you dont.

But, as Henkel said, if you want to change things with the flywheel or conrod bolts just make certain you know what you are doing.

The last two sets of drive shaft bolts I bought came with a hard red compound on the threads, so if you are buying current factory stock you are going to have to clean it off if you dont want locking compound.
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Old 02-25-2013, 11:21 AM   #749
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Quote:
Originally Posted by Plaka View Post
The engineering of the joint is a particular torque applied to a particular bolt that is intended to distort and provide a locking action. The bolts are not re-used because they can only meet the specification once.

You can deny any bit of engineering on the machine that you want. You say you have had no problems. great, you have one data point. The people that engineered that joint have thousands of data points and more testing than you will ever do riding. personally I'm going to go with what they came up with. I know they've changed the joint and I also know they didn't do it for production economy reasons---they had a problem. it wasn't a big enough proplem to do a recall, but they did spec the newer bolts for service on the older machines. The torque specs have a tolerance. From the factory, some bolters fer at one end of the tolerance, some at the other. The variation tends to be sinusoidal. it may be that only fasteners at one extreme of the tolerance had problems. on solution is to tighten the tolerance. But this is costly. Another is to change the fastening system to be more reliable across the tolerance range. I suspect this is what they did. The fastener will distort enough throughout the tolerance range to give acceptable locking.

You can set up one bike and reuse your fasteners and have absolutely no problems. You can also buy one lottery ticket and win the lottery. it's a statistical game either way and you really don't know what the statistics are. BMW does know. If there is a problem they hear about it.

BTW, you mention you have seen a lot of drive shaft bolts come loose because they weren't tightened enough. Were you there when they were tightened? How do you know they weren't tightened enough? (aside from simply assuming it---ie, some seriously circular logic). What is inarguable is that you have seen loose drive shaft bolts. (I ain't gonna call you a liar). it could very well be that they were tightened just fine...but they were re-used. Do you really know the history that caused the problem?

You can say you are a professional mechanic but if you don't follow a spec on something like this you aren't one I would patronize. You might be re-using conrod bolts too. if I want an engineer I hire one. i expect a mechanic to be exactly that even though many (like many machinists) feel they need to play engineer for...I dunno what? Status? In my experience both machinists and mechanics often know things the engineers don't simply because a lot of engineers are clueless about either discipline. But it cuts both ways and when things go wrong it isn't because engineers are trying to be machinists or mechanics.

There are a number of critical fasteners on my bike I have Re-engineered. I changed the material to stainless. It has less strength than 8.8 and has a habit of galling so it usually gets antisieze. My brake caliper bolts are an example. These suckers come in and out every time I take a wheel off. I decrease the torque because of the lubrication and check them a lot. I'm taking the risk on myself. So far they have not loosened between checks. When tight they are in pure shear and a pair of them is plenty for the forces the brake pots can exert. So I don't worry---but they are right out in the breeze and easy to check.
For starters, the bolt washer WAS a problem but loctite OR new bolts isn't going to help that issue either.

How do I know that the bolts weren't tightened enough when they came loose. Because I have never seen one come loose when I knew it was tightened right. Deduction. Plus it's not just my experience I am relying on but a number of other professionals.

Any professional that plays by the book 100% of the time is not being professional. The book is a great source of info but it is far from perfect. BMW is not a religion. Even religious zealots pick and choose what parts of the bible they are going to follow. A good mechanical zealot SHOULD do the same thing out of any manual. That is unless he finds one written by god. Personally, I will replace those bolts any time someone insists. Sometimes the used bolts need replacing anyway for being damaged. Other than that, all it is going to do is increase their bill but BMW knows that!
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Old 02-26-2013, 07:39 PM   #750
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Quote:
Originally Posted by supershaft View Post
For starters, the bolt washer WAS a problem but loctite OR new bolts isn't going to help that issue either.

How do I know that the bolts weren't tightened enough when they came loose. Because I have never seen one come loose when I knew it was tightened right. Deduction. Plus it's not just my experience I am relying on but a number of other professionals.

Any professional that plays by the book 100% of the time is not being professional. The book is a great source of info but it is far from perfect. BMW is not a religion. Even religious zealots pick and choose what parts of the bible they are going to follow. A good mechanical zealot SHOULD do the same thing out of any manual. That is unless he finds one written by god. Personally, I will replace those bolts any time someone insists. Sometimes the used bolts need replacing anyway for being damaged. Other than that, all it is going to do is increase their bill but BMW knows that!
I agree with SS - The bolts don't need replacing if they're not stretched and in good shape, and they don't need loctite if torqued properly.

Simple as that!

I haven't had any come loose - and that's even from before the days I was able to torque them and found out the specified torque was more than I previously thought. Up till then I used a long ten mm box wrench and applied enough force to feel really tight to me. But the specified torque was even higher than what seemed reasonable to me. Maybe it made a difference the threads weren't totally clean - in which case, any oil will reduce the required torque value. So maybe I was getting them to the proper torque.

But the point is that they don't come loose when properly torqued.

And to aid understanding here - the reason for replacing bolts is that either the head can shear off or the threads stretch. Frankly, I've never even heard of a head shearing off, so that's not an issue. And the threads stretching? That's easy enough to check - if the bolt threads in by hand, it's not stretched.
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