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Old 01-11-2012, 02:05 PM   #46
mouthfulloflake
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there is and was some good info in this thread, I wish the BMW hate fest was pruned.
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Old 01-11-2012, 02:13 PM   #47
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My opinion is that the info is excellent. If you need/want to fix a transmission that is going bad it tells you how; if you want to know about a situation that you might prefer to avoid, it is a cautionary tale.

Is BMW, or any of the moto mags providing you with this kind of insight?

You probably didn't grow up reading Dirt Bike magazine bike tests if you think I'm overly harsh in my criticism of the recent offerings from BMW.

Just for the record, I prefer to buy my cheeseburgers at Carl's Jr or In and Out, rather than McDonalds.
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Old 01-11-2012, 02:18 PM   #48
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dont care, Its whinebag drivel

please shut the fuck up.
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Old 01-11-2012, 02:30 PM   #49
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Don't care, it's whinebag drivel.

Please shut the fuck up.

Fixed that punctuation for you, maybe BMW will be as helpful if your FD, tranny, ABS, or Canbus go to pot.

You don't need to thank me...
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Old 01-11-2012, 03:22 PM   #50
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Quote:
Originally Posted by lemieuxmc View Post
Don'tcha think that's the kind of thing that the Bavarian elves in the engineering department might have figured out before you had to do it?

It's not like this is their first effort at building a transmission.

I work for a company that produces high end packaging machinery. The amount of times that someone says "that's good enough" instead of doing the job properly is higher than you'd think. And if you think design engineers always get it right, well They fuck up all the time, it's like a challenge to them or something! Sometimes those fuck ups make it all the way onto production machinery, with the obvious results, usually my sorry arse on a plane to some hick town in the back end of Europe. This is one of those fuck ups, albeit one that has taken thousands of miles to appear, which for BMW is probably good enough. I don't know what BMW test regime is like but we sure as shit don't test machinery for 100's of hours before sending it out of the door.

By the way, you do know this is from a 1100gs don't you, not one of those new fangled Tupperware 1200's
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Old 01-11-2012, 06:58 PM   #51
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You're no Klay.

But, urine asshole.




Quote:
Originally Posted by lemieuxmc View Post
Don't care, it's whinebag drivel.

Please shut the fuck up.

Fixed that punctuation for you, maybe BMW will be as helpful if your FD, tranny, ABS, or Canbus go to pot.

You don't need to thank me...
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Old 01-11-2012, 07:53 PM   #52
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Quote:
Originally Posted by rc mad View Post
I work for a company that produces high end packaging machinery. The amount of times that someone says "that's good enough" instead of doing the job properly is higher than you'd think. And if you think design engineers always get it right, well They fuck up all the time, it's like a challenge to them or something! Sometimes those fuck ups make it all the way onto production machinery, with the obvious results, usually my sorry arse on a plane to some hick town in the back end of Europe. This is one of those fuck ups, albeit one that has taken thousands of miles to appear, which for BMW is probably good enough. I don't know what BMW test regime is like but we sure as shit don't test machinery for 100's of hours before sending it out of the door.

By the way, you do know this is from a 1100gs don't you, not one of those new fangled Tupperware 1200's


I used to work for Biner-Ellison High Speed Packaging Systems. I built the prototypes and special order rotary fillers. Since they are a small company they believed in the concept that it's cheaper to do it right than it is to do it over, but hey... they have a LIFETIME guarantee on the machine you buy from them (unlike BMW) and their products are very reasonably priced in the packaging field.

But what the fuck do I know besides how to punctuate!
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Old 01-19-2012, 11:46 AM   #53
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Well, after viewing the stool sample from someone else's transmission, and an Internet pissing match, lets get back on track.

Here's my refurbished gear, back from my coworker's kid.



I'd say that looks pretty good. The wear was built back up by TIG welding, then machined nice and smooth and flat. None of the gear face depth was sacrificed, so the bearing is now its original depth away from the gear teeth. If the face is, in fact, now harder, I should get better wear than the 45000 miles now on the bike. I will replace the bearing, mostly to satisfy the slightly OCD control freak behind the handle bars. If the money was a big issue, I wouldn't, but I'll feel better this way.

I hope.

Next up, lets think about 2nd / 3rd gear.

I'll post those thoughts and pics later. Technically, I'm at work.
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Old 01-19-2012, 01:31 PM   #54
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Just for comparison. I'd say nice job.
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Old 01-26-2012, 11:14 AM   #55
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Alright. Now onto new worries.

How about shift forks?

Here's what my BMW parts fiche calls the "Shifting fork, 5th Gear" (Dummy alert- this was corrected. Not 2-3rd gear shift fork!). Based on my super knowledge of transmissions, this fork shifts the gears into and out of 1st & second gear, on the output shaft. (no it doesn't - this fork just locks the sliding 3rd gear into freewheel fifth gear, locking it to the output shaft)



Now, this is the worst looking of all the forks. Is this bad enough to be replaced (at the low, low cost of $152)? I've heard any damage on the fork means you should pitch it. Would this fork cause a crunchy 2-3 upshift?

(No it shouldn't- unless someone tells me different)

Notice the shredding at the top of the fork, and the very minor wearing of the two legs where it rides in the gear.

Here's the other side of this fork:




Theories anyone? Or facts. I'd appreciate nice juicy facts. No rants along the lines of "If this was a honda, the fork would never look like that"

mark883 screwed with this post 01-31-2012 at 06:12 AM Reason: factual correction, re: action of pictured fork.
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Old 01-26-2012, 01:44 PM   #56
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Judging from the shift forks in other bikes that I have seen, and that looked worse, I don't think that's a problem.

Having the clearances in spec after it's assembled is what's important.
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Old 01-26-2012, 02:38 PM   #57
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Quote:
Originally Posted by mark883 View Post

I suppose this gear deativates 2nd gear, while another fork activates 3rd gear, and any mis-timing may cause crunchyness?
The shift forks are 'timed' as you say, by the channels cut into the shift drum. But if the shift forks are worn or bent, they will not slide the shift dogs enough to fully engage or disengage. Someone may have mentioned this, but when a shift dog pops out when under motor load, that force can bend its shift fork.

Usually what happens when a dog disengages under load is the disengaging dog pushes the shift fork 'back the way it came' along its shaft. Depending on the position of the shift drum, that 'reverse' shift fork movement will turn the shift drum. That's backward from normal operation.

During normal operation the shifting 'indexing mechanism' moves the shift drum, which in turn moves any number of shift forks. For normal operation the drum moves the forks. But if you do it the other way round and push on a shift fork, that movement will rotate the drum. Like the tail wagging the dog so to speak.

Usually that isn't a problem since the shift drum isn't rigidly held in place. It's only held in place by the spring-loaded-roller detent mechanism. So when or if a disengaging dog pushes back on its shift fork, the shift fork rotates the drum. This typically isn't a problem because the shift drum doesn't present too much resistance to being rotated, and the shift fork can turn the drum without the fork bending.

If the shift drum were more difficult to turn then the shift fork could bend. Sometimes the rider will inadvertently provide the necessary force through the shift lever. The chances of bending a shift fork are increased if when the dog pops out the rider is also applying pressure against the shift lever. You know, the shift lever pressure gives the shift drum and shift fork something to push against. Something much stronger than the roller detent mechanism


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Old 01-26-2012, 03:12 PM   #58
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Ok guys... continue to follow my though process (which could be wrong)

If I'm thinking straight, that fork is what shifts this gear, below:



the fourth gear from the left, with the dogs showing. By moving right, first gear is locked to the shaft. Moving left, second gear is locked in.

Note that the gear dogs are not undercut (maybe not easy to see here).

Here's a better shot. I think is shows how flat the dogs are:



Now, best I can tell, the other dogs are all under cut, like this- look to the right:
(this is the intermediate shaft)



So, would anything be gained by undercutting that gear set? The M97s aren't known for the stutter shift, but could something have happened at some point in the past? Yeah, probably my fault.

Poolside, you gave a good explanation of what's happening in there. So, if the tranny kicked out of gear once, and it was fought with, the fork may be bent, right? And I bet there's no way to tell if the fork is truly bent. Unless you do this for a living, right?
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Old 01-26-2012, 03:59 PM   #59
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Quote:
Originally Posted by mark883 View Post

By moving right, first gear is locked to the shaft. Moving left, second gear is locked in.

Note that the gear dogs are not undercut (maybe not easy to see here).

Now, best I can tell, the other dogs are all under cut... (this is the intermediate shaft)

So, would anything be gained by undercutting that gear set? The M97s aren't known for the stutter shift, but could something have happened at some point in the past?

Poolside, you gave a good explanation of what's happening in there. So, if the tranny kicked out of gear once, and it was fought with, the fork may be bent, right? And I bet there's no way to tell if the fork is truly bent. Unless you do this for a living, right?
Can you dimensionally compare your shift fork(s) against a new one? Mic the thickness of the fork at the wear pads for example. Maybe your local BMW store can work with you on that. Perhaps they will waive the 'restocking fee'. The part can go back and forth to the parts distribution warehouse without too much cost to the dealer.

If the fork is bent, then the spring-loaded roller detent on the shift drum will maintain a slight constant pressure on the shift fork. That pressure will greatly increase wear on the shift fork, and the fork slot in the gear dog. A couple of measurements and visual comparisons to new parts might be enough.

Can you reassemble the shafts, forks, and drum, into the small half of the case? Turn the shift drum and see if the forks fully engage the dogs. And check that the forks ride freely in the gear slots without any side pressure. If something you need to see isn't visible, put some modelling clay in between the parts to check the clearance. Shift the gears and look at the thickness of the clay afterward.

Regarding the undercut, if it isn't a problem, then maybe it doesn't need fixing? Hey, those undercuts on the intermediate shaft shown in the picture, are the dogs undercut on the drive side too?

Regarding possible earlier damage, if the top of your shoe was pushing against the lever and the drive dog popped out, you would know it! It isn't a wrestle sort of thing, it's a pop in the mouth.


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Old 01-27-2012, 07:47 AM   #60
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Quote:
Originally Posted by mark883 View Post
Ok guys... continue to follow my though process (which could be wrong)

If I'm thinking straight, that fork is what shifts this gear, below:



Maybe it's the photo above, but the third gear from the left looks like it has a problem to me. Those small teeth that engage the dogs on the right side look worn. Especially the top tooth. They should have nice squared off edges and that top one looks like the tip might have been sheared off. I'm no transmission expert, but have done a couple of them in my time so maybe someone else can chime in.
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