YA Bean Can thread

[darrylri]

Ok, this is the continuation of my intro article over in the intro area.  In our last exciting episode, I had determined that my new to me '81 R65 with 170k miles had a dead Hall sensor, and you nice folks had pointed me to the article over here:

Technical Discussion / BMW Technical Q&A, Primarily R65 / Re: Another Bum Bean Can Sender
on: 09/06/09 at 14:45:57

So, I bought a new Hall sensor, and today I tore into it.

I set the motor to the S mark on the flywheel, just to make things easy later on.  Then I removed the cap -- needed an impact driver to loosen the two screws -- and the the whole bean can.






I marked things before I took them apart.  





To get the big internal clip out, I put the mounting screws back into it and used my channel locks.



Hmmm.  Something on the back of the clip.  And some debris fell out of the can when I turned it over.  What's this, then?  



I better finish disassembling this and then I'm sure I'll find out what these are and from whence they came.

(cont'd below)

[darrylri]

I printed out the directions from the other article, but for some reason, the first page didn't print right, so I didn't quite follow the correct order.







Ok, here's the timing unit!



But I still haven't freed the centrifugal advance...







Finally, there it is:



Now, back to the timing plate.  Remove the circlip...


...and after struggling for quite a while, and without damaging the shield, get the thing free.  I must be living right, because this is the timing plate that is screwed together.  



And now I can see where those bits came from:

[darrylri]

Finally, here's the disassembled timing plate.




So, as you saw above, I drilled out the old rivets and freed the broken Hall sensor.

The new sensor has what I assume are "proto-rivets" already molded into its body.  The directions from the other article say to put it into place on the timing plate and "rivet it".  

What kind of a tool do I need to do that?  Will I find it at the local Sears?

Alternatively, I have a pop rivet gun and some steel pop rivets; should I drill this out and use those?

Thanks for all your help!

[bruce_launceston]

Hi Darryl

I haven't seen these 'proto-rivets' before. Does the hole go right through? Maybe you can set them with a nut and bolt temporarily tightened through it. Start with a countersunk bolt?
If not I would use a tapered punch and if you don't have a proper rivet set tool you could drill a shallow dimple into the end of a piece of solid rod to make one.
Before pop rivets were around you set a rivet with the round end of a ball-pein hammer and finished it off with a rivet set to give it a nice round top.

Cheers Bruce

[Bob_Roller]

I don't know how much material you have on the rivet, but would it be possible to drill a small hole on the underside of the rivet, and then start using a center punch, to get the material to form a 'bucktail, then finish with a large punch, or other large flat tool ?

I have a couple of sensors from Newark Electronics,, and the best I can tell from my sensors, the rivet is a steel alloy of some sort, it's magnetic .

I don't know if it is a 'soft' steel or not .  

[montmil]

I have overhauled three bean cans within the past year, replacing Hall sensors bought from Newark Electronics. The rivet "legs" of the new Hall sensor can be peened as conventional rivets. A sturdy bench vice with an anvil, a tapered punch and a ball peen hammer will get the job done properly. Note that the hole in the sensor plate is slightly larger than the rivet leg diameter. This is a good thing...

I found that it was helpful to begin forming the shop head of only one of the rivet legs, then stop when you can still move the sensor by using firm pressure with your fingers. Temporarily refit the metal shield. Check the position of the Hall sensor. You do not want sensor/shield contact. The 'window" in the shield is the key.

After confirming your approval of the sensor position with the single rivet lightly snugged down, remove the shield and proceed to form the shop head on the second rivet/leg. Check shield clearance again. Return to the first rivet and complete forming the finished shop head.

You should be good to go with the new Hall sensor.

The mechanical advance mechanism is the anachronism of BMW's bean can design. A modern electronic ignition trigger with an old school ignition advance. OK, it works fairly well...  Clean off all the surface rusting. The weight pivots need lubricant but it is my understanding from lengthy research that the 'floor" of the advance plate should not be lubed as the nylon feet are designed to function without being greased up. A very light wipe of a non-evaporative lube is what I use. Keeps rust at bay.

Hope this assists you with your adventure.   Monte

[darrylri]

Ok, I'm game.  I'm still not completely clear about what's going to happen when I start banging on the rivet with a punch.  I have a couple punches that are intended to put in a center before I start drilling a hole -- are these really going to move the rivet metal to overlap the plate and capture it securely?

[montmil]

Ok, I'm game.  I'm still not completely clear about what's going to happen when I start banging on the rivet with a punch.  I have a couple punches that are intended to put in a center before I start drilling a hole -- are these really going to move the rivet metal to overlap the plate and capture it securely?

Are you referencing an automatic center punch? One that puts a prick on metal or wood as a drill bit locator? Toss that lightweight back in the tool chest. You'll need a solid,hefty pin punch; cousin to your cold chisel. Tapered to allow easier access to the rivet leg and flat on the working end to produce a shop head on said rivet leg.

A HD vise functions as the bucking bar; backing up the Hall sensor plate and the other end of the Hall assembly. Yeah, you've gotta position everything just so based on your vise's shape. That's why you do not totally clinch that first rivet. A slight tweak of position, if necessary, and then move to the second rivet.

It helps tremendously if you can also get your tongue is just the right position. [smiley=thumbsup.gif]   Monte

[Bob_Roller]

It looks like part of the old sensor has been removed, did something contact it, or was it just a case of the sensor itself, coming apart ?

[darrylri]

Montmil, thanks for clarifying that!  I need to buy more tools, cool!  Is there a way to choose or judge the size of a punch necessary to do the job?  Should it be bigger than the rivet?  Bigger than the hole?

Bob, it looks to me like the plastic that encases the small permanent magnet broke on one side and the magnet escaped.  I found the magnet stuck to the underside of the big clip that the brace at the top of the can screws to, and the broken plastic was floating around in the can.  



When I put this back together, I will take Monti's advice because I'm concerned that the shield not interfere with the sensor parts.  It looks to me like the timing shield has marks on it.  

[montmil]

Montmil, thanks for clarifying that!  I need to buy more tools, cool!  Is there a way to choose or judge the size of a punch necessary to do the job?  Should it be bigger than the rivet?  Bigger than the hole?

Bob, it looks to me like the plastic that encases the small permanent magnet broke on one side and the magnet escaped.  I found the magnet stuck to the underside of the big clip that the brace at the top of the can screws to, and the broken plastic was floating around in the can.  


When I put this back together, I will take Monti's advice because I'm concerned that the shield not interfere with the sensor parts.  It looks to me like the timing shield has marks on it.  

The round, flat face of the pin punch should be about one-third larger than the rivet diameter. Somewhere in that neighborhood. Remember, the peened rivet will end up with a larger o.d. Also, the shank of the rivet will expand as the rivet is compressed and lock itself into the base plate. This is the same principle occurring when riveting aircraft components together. Mind the punch as it will be close to the plastic sensor body during the pounding, uh, riveting procedure. A helper, if available to hold the pieces parts secure to the vise/anvil, can be a godsend.

I do not recall there being any "factory" markings on the sensor shield. Perhaps the loose bits created some faux markings. I thought I noticed in your pics a boogered-up corner on the shield. Be sure to either file this smooth or tap it down. Either/or.

Monte

 

[Bob_Roller]

Is that a round pin, that acts like a woodruff key to drive the 'shield' that triggers the sensor ?

Looks like an easily misplaced part if it is not tack welded to the drive shaft !!!

[montmil]

Is that a round pin, that acts like a woodruff key to drive the 'shield' that triggers the sensor ?

Looks like an easily misplaced part if it is not tack welded to the drive shaft !!!

Yes to both your observations, Bob. All the tech articles I've researched mentions the importance of being aware and keeping track of the little booger. Someone said if you loose it, you're done. No replacements available. Well, I'm throwing the BS flag on that statement. I miked the puppy and then checked my supply of model aircraft music wire... Gosh! I found a 24-inch length of bean can parts mixed in with some balsa wood!

Do keep track of the pin. It installs after you've replaced the metal shield. Line of the slots and simply push the pin into place. After all else is assembled, the pin has no escape.

I scotch-taped my pin to a big piece of cardboard and tacked it on the bulletin board in my shop. Red Sharpie arrows said, "Hey, ya big dummy. Don't lose me!" In my shop, I do that a lot with small parts and annoying children.

Monte

[Bob_Roller]

I've gotten to the point, that if I have small parts, I put them in a clear plastic bag, and then seal the bag with a Monokote iron .

[darrylri]

I use either an egg crate or a left over spray can cap.  The egg crate is nice for laying out parts in order of assembly.