Charging System: removing the rotor

[R65LS]

I started a recent topic on my GEN light not coming on ..... all of that discussion is found here:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1330669123

TWO QUESTIONS:
[size=12]1)[/size]  How difficult is it to remove the rotor ??  My Clymer book simply says, "use a puller."  Lots of danger in those 3 words.  Also, I know there is some special tool needed, I can get one.
[size=12]2) [/size] Any problem(s) re-installing the new rotor, other than just sliding it on and installing the bolt ??


Cheers and Thanks,

Carl

[montmil]

1. How difficult is it to remove the rotor? My Clymer book simply says, "use a puller."  Lots of danger in those 3 words.  Also, I know there is some special tool needed, I can get one.
2. Any problem(s) re-installing the new rotor, other than just sliding it on and installing the bolt?

Carl,

1. IIRC, you were planning to deal with Rick Jones at Motorrad Elektrik? Excellent decision. He has the simple rotor removal tool for about five bucks. Excellent quality, simple tool, bargain price.

As you begin to tighten down the rotor removal tool, a gentle hammer tap on the end of the tool will often help to 'shock' the rotor and it'll pop right off. Operative word here is "pop". Be ready to catch the rotor... even if it is Tango Uniform.

2. Confirm the tapered rotor attach portion of the crankshaft is clean; no burrs, rust or dirt. Wipe it off with a lightly lightly oiled shop towel. Eyeball inside the new rotor. Check for any debris or mouse droppings, then slip it on and tighten 'er down.

It may be helpful to put the transmission in gear and hold the brake pedal- a friend or bungee cord will work- to keep the crank from turning. Torque to manual specs and you're done with that chore.

[tvrla]

+1, plus a little more...

These rotors tend to pop off - actually more like jump off of there when they break loose. So there's two things to plan for.

First off, place some thin plastic - maybe a slice of a plastic oil or shampoo bottle - between the rotor's slip rings and the brushes. The reason for this is to keep the front brush from hanging up on the second slipring as it shoots by. When the brush snags, it'll break out the brush holder and you don't want to know how much that little piece of plastic costs these days!  

Secondly, when it pops off, usually I have both hands full and can't catch the thing before it hits the floor. It's got a bit of mass to it, and the copper slip rings are soft and get mashed pretty easily. So be ready for that - and perhaps position a box with some pillows or rags below to catch it.  

[R65LS]

montmil,
    Yes, I'd buy everything from Rick.  Today my local BMW dealer quoted a price of $450 just for the rotor !!  Rick's website says $125 for a new one from him .....


wirespokes,
    I'm confused here ..... seems to me you are saying the stator & brushes are still in place during rotor removal ??  I'm pretty sure that's not so.  Am I missing something ??

Cheers,

Carl

[Barry]

1)How difficult is it to remove the rotor ??My Clymer book simply says, "use a puller."Lots of danger in those 3 words.Also, I know there is some special tool needed, I can get one.

The rotor removal tool is an M8 hardened steel bolt which has the threads at the end of the screw turned down to 6mm so that it only engages in the threads of the rotor. (the exact opposite of the rotor Allen bolt which has the upper section turned off and only has threads at the end).

To envisage how it works note that when you remove the rotor Allen screw it comes out in 2 stages - first it releases from the threads in the crank and then from the threads in the rotor.  The end of the removal tool which is turned down passes through the centre of the threads in the crank until it bottoms out so that turning the screw in pushes on the end of the crankshaft and pulls off the rotor.

There's a diagram of this some place which is vastly better than any number of words. I'll post it if I can find it.

[montmil]

Remove the stator prior to detaching the rotor. Makes like much easier and potentially less expensive.

[tvrla]

You're right - remove the stator first!  

A couple of things to be careful of there - still watch out for the brushes when pulling it off. And the stator can be difficult to remove as it gets rather comfortable mated to the mounting. It's also a rather tight fit, so work it up a little at a time from different sides.

And when re-installing, make very certain it's going in evenly. It's possible to get it cocked, then in an attempt to draw it in (or just not noticing) apply too much force to one of the screws and snap off a mounting ear. So be careful and watch it closely!

[Barry]

Here's the diagram that I had in mind courtesy of Joe Cuda who has a full write up on Airheads.org but you can't access technical articles there any more without being a member and not even then at the moment as they are doing a revamp and having problems with the web site. If you have Microsoft word (or open office) I could e-mail an old copy of Joe Cuda's full article on rotor removal.


Note this is Joe's home made version of the puller but the principle is the same.  

[R65LS]

been out of town for a few days .....

THANKS MUCH for the extra info, and to Barry for that picture that shows what is happening.  Now I have a full understanding of how the rotor is attached to the crank, and the concept of how the tool works.

This week is "call Motorrad week" to order the rotor, brushes, and tool.  I'll update as things progress.

Cheers,

Carl