Alternator driving dog replacement

[pdg]

So, following on from my projekt thread, I need to replace the alternator driving dog (male part of the cush drive, bolts to engine side).

Mine is a little broken...



As are the drive rubbers. Now I like puzzles, but I'm not going to be trying to glue all that lot back together, plus I can't find the missing metal parts anyway :laugh

The question:

Can I remove the driving dog from the shaft as-is or do I have to split the cases to support the shaft/cogs/other random parts?

[richarddacat]

It would be my guess that this bolt would have left-hand threads and a impact gun would spin this right off.

It would also be my guess that Duck or someone who has actually done this will speak up soon enough.

Good luck, :2thumbup:  nice cheap project so far.

[pdg]

Cheers, I'm happy with the condition for the price cool shades

From the direction of rotation I was assuming 'normal' right hand threads, but that's not the important bit - getting the bolt out shouldn't be a challenge whichever way I have to turn it.

What I didn't want to happen (and was looking for confirmation of) was that undoing the bolt and pulling the dog wouldn't result in a heart sinking tinkling sound as all the parts making up sub-assembly 1 (below) fell loose into the case :laugh



If I have to drop the engine/gearbox and split them to do the job, then so be it - I'd just like a bit of warning....

[rbm]

You should be able to remove the drive dog by undoing the bolt in the centre and pulling the dog straight out.  It is on a tapered splined shaft and the shaft is supported by bearings on the bell housing and engine block.  You will need a puller to get it off.

I'd go used parts myself.  That destruction yours suffered was probably because the monkey nutz deteriorated and the PO just let the drive knash itself to death. These drive parts don't usually suffer such damage unless they are ignored.

Also, if you go for the 50A alternator, it should be a drop in replacement for the 33A unit but be wary that you double check critical measurements.  I wrote up my experiences with a swap that went bad.

[TIV]

This was the only thing that was really broken on my bike when I got it. And with only 17.000 miles on the clock. I got a new one from Motorworks in England, they come highly recommended. Super service and competitive prices on new and used items. To change it is as easy as pie.... one bolt off.... one bolt on and tighten to recommended torque setting.

[pdg]

rbm - thanks for that, I just wanted to check that the stub on the back of the dog wasn't acting as a bearing mount / support. If nobody answered I was just going to tear it down and see what happened... Bad luck on your conversion too, did you ever find out why the thick washer was fitted in the end?

I haven't decided on the conversion - the 32A unit is working fine and I'm not fitting extras yet. I might upgrade to the 50A (or maybe something else) later though.

When I bought mine there was a loudish whine from around the intermediate housing / alternator area. As I'd done some reading up online before going to buy it I thought the noise wasn't a problem - I obviously misinterpreted the 'K whine'... The only other symptom that could be attributed to this was a rattle if you 'blipped' twice quickly to over 1/4 throttle from idle (like rev, rev). No rattles or anything else at idle itself, just the rattle occasionally when blipping and the constant whine that increased in pitch with engine speed. I think I can be forgiven on that though what with mine being the first K I've seen up close and taken any notice of. Now I've said that it'll probably continue to make exactly the same noises after I've fixed it :laugh

I'm still not entirely sure about used for these parts, my thinking is that if the donor bike was run with dead rubbers there may be stress fractures etc. starting in the casting that I won't see... As new oem parts are still available and the price difference isn't massive (£39 used / £58 new) I may well do my bit for the K community and leave some used parts in circulation for when they're discontinued.

TIV - was it the cup, or dog, or both broken on yours? Just wondered...

I've looked at Motorworks and so far found that for new parts they are consistently more expensive than BMW, then the postage on top of that as well. I wouldn't hesitate to get used parts from them though - the used prices aren't terrible by any means and, while they may be a bit more than something like ebay, they do give the 6 month warranty which you're not going to get from a private seller (or most other sellers it seems).

[pdg]

Well, this is turning out well...

Had a look this evening at getting the dog off. Bolt wasn't a challenge at all (held dog and undid bolt) then I got my puller - this is where the fun started.

The arms of my puller won't fit behind the dog to pull it out for a start - so I either have to find a different puller or make up some arms for it.

More seriously, the dog retaining bolt (standard right hand thread btw) felt a little 'crunchy' all the way out, but it looks fine. The same can't be said for the threaded hole in the shaft.... I can see where the threads used to be. Not a huge issue in itself, tap it out and either helicoil it or use a bigger bolt. BUT...

To get the clearance to fit tools in (and remove the dog anyway) it looks like an engine out job now.




Ho hum.

(Also, see projekt thread if you're interested.)

[TIV]

Hey Paul, bad luck with the stripped threads. :yow There was a chunk broken of the cup and also one of the three dogs/rims where broken on mine. I stripped down the bike for a major overhaul when I got it and checked everything. I was lucky to find it, could have ended up like yours. Seems to be a week point there.

[rbm]

Pg. 52-53 of the Haynes manual states that the flange is usually slack and can be removed by hand.  Sometimes it is necessary to apply a sharp tap from a hammer and soft metal drift on the auxiliary shaft rear end to jar it free.  BMW recommend a two-legged puller with adapter to protect the shaft end.  It may be necessary to grind down the leg claws to fit between the flange and bell housing. 

When I was fixing my alternator problem, I completely dismantled the bike, removing the frame and transmission from the engine because my goal was to remove the bell housing.  It will be easier to remove the transmission to get access to the flangebut you might be able to rig up a puller that will preclude you going that far with the disassembly.  Can you use a hot air pistol to heat the flange and hammer blow to loosen the grip on the splines?  They are very fine and may not offer a tough grip.

[pdg]

The problems are:

I appear to be able to see through the aux shaft...
The threads are stripped in the aux shaft.
I got a pair of tyre levers in behind the dog and tapped the shaft - didn't move.

Now, when I took the bolt out it felt 'crunchy' all the way out and I can pretty much push it all the way in by hand now. How much swarf has gone through into the shaft cavity? When I got the bolt out, the threads seemed 'packed' with something almost powdery.

When it's like this I suspect the worst - i.e. a PO had an issue with stripped threads when they had to replace the dog in the past and glued everything back in place... I pretty much trust the word of the guy I bought it from, but it had 23 years and 6 other owners previous to his ownership to be buggered about with.

I can helicoil the thread without a problem, but getting a drill and then a tap in is going to require better access - I could probably get in there if I remove the tail and mudguard etc. but lining everything up will be so much easier without the frame in the way, plus if I get the bellhousing off the engine I can make sure it's all clean in there post-drilling/tapping. I've tried bodging before and I'm just no good at it :laugh

Anyway, getting the engine and transmission out of the frame isn't too hard - remove wheels, sit the engine on the floor, undo a few bolts and wires and lift the frame away...

[rbm]

The information below might help you.  It details a bit more how I accomplished the auxillary shaft bearing replacement in my bell housing.  It required me to strip the bike down to the engine.
Pictures and text of my repair to auxiliary shaft
outriggers for the engine to stabilize it on the jack
The official K100 repair manual from BMW gives the procedure for removing the frame from the bike.  It is really simple and relatively quick; unhook ten wires or so and remove the frame mounting bolts is all it entails.  It is possible to remove the entire back end from the engine as one unit but nearly impossible to reattach it to the engine block as such.

Best of luck.

[frodef]

I replaced the drive dog the other day. It was stuck on the splines. For the benefit of nordic brickers, this is biltema item 20-339, with the hooks ground down a millimeter or two.

[Laitch]

  Thanks for the photo.