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Old 04-24-2012, 03:57 PM   #1
GodOmelet OP
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Broken Boss on Clutch Release Lever Mount on a 77 R100/7

Hi Everyone,

I just posted a question over in welding: http://www.advrider.com/forums/showt...+rods&page=181

The broken mount looks like this:


However, I am prepared instead to switch out the cover plate on the transmission if the weld ends up looking anything but excellent. Here's the story briefly: I've been steadily restoring this basket case for the last couple months and on the maiden ride the mount on the clutch lever broke as you see above. I have read as much as I could find about opening the gearbox, but I have concerns about doing it without having every special tool in the stable. I know I'm going to need the flange puller and the transmission distance plate to make measurements for shimming to achieve correct axial play with a replacement cover, but I'm sure there's something else I either don't know or understand.

Is there anything else I need to simply swap a new/different transmission cover? I'd love to check all the bearings and tolerances, but my shop facility is a shade tree and a kitchen table right now. I can contrive a bench for mounting the transmission to break the flange nut, but I'd like to know if there are any other big hurdles I'm not forseeing. Thanks everyone and great site! I'm glad to be back after quite a few years without a ride (well I'm still without a ride, but hopefully not for long).
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Old 04-24-2012, 04:34 PM   #2
disston
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This is not considered a DIY repair.

To begin, the output flange puller, the distance plate, accetalyne torch (propane works but is slow) (to get rear cover off (there is also a rear cover puller but you can do it with out that), a pair of parallels, a decent micrometer (digital if you don't know how to use the old timey one), assortment of shims.

Since the box is being opened you should be prepared to replace other parts that appear worn. Amongst these are the bearings. A bearing splitter, good quality, will run a couple hundred dollars and the press for getting the bearings off and on will be $700 to $2000. A cheap press BTW is a waste of money, it won't work.

In the long run and in the short run too. You will have a better transmission, it will take less time and it will last longer, cost less and be prettier if this is repaired by a pro.

You get to spend your time checking the clutch and replacing the rear main seal.
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Old 04-24-2012, 04:58 PM   #3
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Built it up with weld, one step at the time and allow to cool.

Once you got the general shape, drill the hole for the clutch arm pin and reshape the welded area with an angle grinder.
Clean up with a file, sanding paper or blasting.

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Old 04-24-2012, 06:45 PM   #4
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Have a good welder fix it. Carefully file it down to the original shape and use it. I've got a 90S with this repair (A Previous Owner) and it's held up just fine. One day I'll have to give it the finishing touches to make it look better, but for now it's fine. It works. Besides, it's hidden back there and not all that visible.

When welding it, place the trans input-side down supported on a couple of 2x4s so it's not resting on the input shaft. Probably keep some cool wet rags on the cover to help dissapate heat. And as said already, weld a little, let cool, weld some more...

Also, the material around the cracks should be Ved out, but a good welder will know that.

In your present situation, I wouldn't launch into a transmission rebuild - repairing this cover will be just fine and won't require dismantling the box.
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Old 04-24-2012, 08:48 PM   #5
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R100/7 Clutch Lever Boss Repair

Thanks you two. Well I'm really impressed with the welder who is attempting the job (he's a talented machinist also) so I may not have to do the cover replacement. The bike has about 50K miles on it, so a rebuild could be premature, yes? It was shifting fine prior to the break.

If the weld doesn't work out, I do have the ambition to become airhead gearbox savvy, but I agree it would probably be wiser to find a an old hand. I've been trying to contact a fellow named Anton in Charlottesville who runs largiader.com, but he must be swamped right now. No success contacting him. He's my only hope locally. I've heard some folks mail their trannies for service but I'd not know where to start.
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Old 04-24-2012, 08:52 PM   #6
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I'm pretty sure Anton is busy, yes. He is a member here and contributes regularly.

50K is not too early for trans rebuild but it depends on the trans. Yours sounds like it doesn't need opening.
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Old 04-24-2012, 10:27 PM   #7
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Tranny Weld

Thanks again for the quick replies everyone. Mr. Wirespokes, are you suggesting that he could use the broken off part to make the repair? Is that the way yours was fixed? I posted a couple more pics of the break over in the welding thread as Dakar was kind enough to recommend the type of rod to use for the weld if you want to take a peek. The fine welder I'm working with initially suggested we just build up all new material around a machined copper rod. I'll just have to keep trying with Anton. I'll send him some cookies.... or beer.
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Old 04-24-2012, 11:03 PM   #8
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I had a similar problem shortly after taking possession of my R90/6 back in early '86. It can often be caused by carelessness when removing/installing the 'box, by allowing the vulnerable casting to hit the frame cross-tubes.

A friend who happens to be a skilled welder and airhead enthusiast welded the broken bits back on for me, and it has proved to be a permanent repair.
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Old 04-25-2012, 12:31 AM   #9
Wirespokes
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Mine looks like new material was welded to the bosses (yes, both were evidently sheared off), but I don't see why the piece couldn't be re-attached. It probably depends on the welder - I know my machinist prefers to weld in new material rather than replacing broken pieces.

It really doesn't make sense financially or time-wise to purchase a new cover and have it installed, or collect the tools and expertise to do it yourself. In a few hours you could have it welded back up good as new, shaped to look original and ready to go back on the bike. Just keep the cover cool - you don't want it warping!
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Old 04-25-2012, 07:16 PM   #10
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Weld Jig

Quote:
Originally Posted by Wirespokes View Post
Mine looks like new material was welded to the bosses (yes, both were evidently sheared off), but I don't see why the piece couldn't be re-attached. It probably depends on the welder - I know my machinist prefers to weld in new material rather than replacing broken pieces.

It really doesn't make sense financially or time-wise to purchase a new cover and have it installed, or collect the tools and expertise to do it yourself. In a few hours you could have it welded back up good as new, shaped to look original and ready to go back on the bike. Just keep the cover cool - you don't want it warping!
Thanks for that info Mr. Wirespokes. I thought I'd show you the cool jig Mike knocked up to act as both a heat sink and something to weld against. He also centerbored and knurled the rod of copper so he could drill/ream it out after the welding is complete. I'm impressed:




That's it! I'm saving for my very own TIG machine, and lathe, and milling machine, and...
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Old 04-25-2012, 07:30 PM   #11
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Quote:
Originally Posted by GodOmelet View Post
Thanks again for the quick replies everyone. Mr. Wirespokes, are you suggesting that he could use the broken off part to make the repair?
Yes, the broken-off part can be welded back in place. Matter of fact, thats the only way I've ever seen these repairs done.

At the 2009 MOA Rally one of the Airheads had the exact same failier happen a long way from home and the locak welding/fab shop made the repair without dissasembling the transmission. AFAIK, that /5 is still doing fine with the repair in place and it looked fine. No one goes around checking out the backs of transmissions anyway.

It appears as if you have a good welder on hand and youre getting the deluxe job, so from now on lube those pivots once in a while. OK?
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Old 04-25-2012, 08:14 PM   #12
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Thanks for the reply

Quote:
Originally Posted by mymindsok View Post
Yes, the broken-off part can be welded back in place. Matter of fact, thats the only way I've ever seen these repairs done.

At the 2009 MOA Rally one of the Airheads had the exact same failier happen a long way from home and the locak welding/fab shop made the repair without dissasembling the transmission. AFAIK, that /5 is still doing fine with the repair in place and it looked fine. No one goes around checking out the backs of transmissions anyway.

It appears as if you have a good welder on hand and youre getting the deluxe job, so from now on lube those pivots once in a while. OK?
Yeah, he's a good fellow, and I'm sure the weld will cost almost as much as it would have cost to replace the cover itself.

As to the pivot lube, I can disavow any responsibility for this one- it was my first ride on the thing! Even had I gotten to cleaning the inch thick layer of grease and filth from around the clutch release lever mount before my infamous first ride, my suspicion is that I would have found a fractured mount anyway. I couldn't find any circlip after the failure, even though the pin and spring were still hanging by a thread, so that's my theory for the forces that led up to the breakage: missing circlip, slowly displaced lever pin, unequal forces on mount, again and again = craaaakkkk.
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Old 04-25-2012, 10:26 PM   #13
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Yeah, it's not so much the lube as the pin sliding down out of the upper boss and breaking the lower. Some guys run a bolt from the top side and nyloc nut from the bottom just for safe measure. No way that'll fall out.
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Old 04-25-2012, 10:29 PM   #14
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There doesn't seem to be much bending before snapping off so, re-use of the broken piece works. I had one that my local welding shop welded back without disassembling the tranny. I could have filed it and blasted it until it was hard to see, but it is in a hard to see place anyway. Many happy miles since. Mind you, my local welder is a fellow motorcyclist and does a lot of case repair for fallen Japanese bikes, so he is used to welding in place.
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Old 04-25-2012, 10:34 PM   #15
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Good Idea

Quote:
Originally Posted by Wirespokes View Post
Yeah, it's not so much the lube as the pin sliding down out of the upper boss and breaking the lower. Some guys run a bolt from the top side and nyloc nut from the bottom just for safe measure. No way that'll fall out.
Hells yeah. I'm definitely gonna do something. I've got a new circlip on order from Hans at partsHucky, so at least I'll have that to start with. Glad you agree with my theory of how it broke. I still was wondering whether I was somehow negligent on a bike I've only had since February.
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