Hello All,

I have been putting some miles on my 1991 K100RS since working out a lot of the bugs. What I have noticed is that my right mirror begins to vibrate to the point of uselessness when the engine revs above 3000rpm. Below 3000rpm= same as left. 

The left mirror is always fine.

Is this normal/ curable?

Seems odd that only the right mirror does this. My current theory (plucking at straws here) is that the right side is where the crank shaft is. 

I read before buying the K100 that they can vibrate bad. This bike does vibrate, but not as bad as a Honda VFR I had.

How are the fairing mounts?  Mine were broken away from the fairing shell, though not very obvious until the fairing was removed. Also, how solid is the mirror mount to the fairing? Mine had the rubber insulators missing when I bought it. 

Bill

If you look in the parts catalog there are four foam bushings you can install between the back of the mirror glass and the housing.

Another thing I've done is put a bunch of wheel weights on the back of the mirror glass to increase the mass of it, thereby decreasing the resonant frequency.

My scrapheap project RT has always had sagging mirrors, ie they never stay where I want, they drop while riding to just below where I want them.

I thought of a possible fix and so far its working.  I removed the glasses and covered the "balls" with fingertips cut from light rubber gloves before clipping the glasses back in. The extra thickness of the glove material and the grippy rubber texture still allow adjustment but my mirrors now hold their position. As a bonus most of the vibes/blurriness seems to have disappeared also.

At the same time, both of my mirrors have flat glasses but one of my spare RS mirrors had a convex glass(which I'd prefer), so I removed the convex glass from the RS backing and fitted the RT mirror backing with that mirror glass.

Question: if both the RS and RT mirrors have the same shaped mirror glass, what is the point of having different mounting bases?

Al

99% certain that a mounting somewhere will be loose. Could be fairing or mirror. As your bike is a 16v does it have the correct mirror mountings with the spacers?

Those mirror pod mountings are very important.

A word of warning too. The mirror glass works on a ball and socket arrangement that swivels when you adjust it within the mirror housing.

DO NOT be tempted to lubricate it in any way with oil or any lubricant to get it to fit. If you do it stays loose and will not remain in position due to the fact that you end up with no friction in the ball and socket joint. How do I know this? A previous PO had replaced the mirror glass with lubricant........and they don't stay in position so I fitted some nice little very soft rubbers between the mirror edge and the housing to provide some friction.

Al-58 I suspect it was because they wanted the turn signals in the RS mirror pods [no room in the RS fairing?] but not in the RT mirror pods.

Is the glass truly the same between both models?  If so that is great news as the RS mirrors are no longer available from BMW and there seems to be a dearth of them on the used market while RT mirrors are fairly plentiful.

How did you remove the mount without damaging the silvering on the back of the glass?

BTW, My RS has had a problem with losing mirrors in the past.  I turns out that the bushing in the housing is too long to allow that little wire keeper to fully seat in the groove in the mirror post.  A little work on the back of the mirror's ball joint with a file to allow it to settle further into the bushing corrected the problem.  An alternate fix would be to counter bore the bushing very slightly.

RS and RT mirror glass are the same part number so how can one not be available when they are the same? The dealers order by part number. Here is the info from realoem.com.

Part 46632307640 was found on the following vehicles:

• K589 (K1, K 100 RS)   (03/1989 — 06/1992)
  
  
• K589 (K 1100 RS, K 1100 LT)   (04/1992 — 12/1996)
  
  
• K589 (K100, RS, RT, LT)   (05/1983 — 10/1989)
  
  

That means all Ks with fairings have the same mirror glass, from K75 to K1/K1100. Good information that one.

Hi Olaf

Not quite correct

The mirror glasses are both different

46631455000 is the part number for LT/RT

46632307640 is the part number for RS

K1's have mirrors attached to the bars not on the fairing.

These mirrors still seem to be both available from Motorworks

http://www.motorworks.co.uk/vlive/Shop/Parts.php?T=5&NU=15&M=40&Ct=NG&SbCt=BA_15_40_NG_20

Unfortunately the RS ones are the most expensive

Did you notice that Motorworks has no link to purchase the RS mirror?  The Max BMW fiche shows these mirrors to be on back order for well over a year with no expected delivery.  Basically, they have been discontinued, as have the turn signal lenses. 

This is why I ask how to remove the glass from the frame without damaging the silvering.

Ringfad wrote:Hi Olaf

Not quite correct

The mirror glasses are both different

46631455000 is the part number for LT/RT

46632307640 is the part number for RS

The RS and RT/LT have the same shaped mirror glass, but the plastic backing is different for each. My convex mirror glass from an RS mirror fitted my RT mirror backing perfectly.

As for removing the glass with damaging the silvering, it was attached with a large patch of doubled sided adhesive with a white foam core.  Judicious use of a long thin hobby knife cut throughwithout touching the mirror backing.

As for RS mirror glasses, I got all the stock from Motohansa when they closed so I have some in my personal stock.  I did not sacrifice one of the new ones to fit to the RT.

Al

Thanks AL

Now I understand (never having seen an LT mirror)

The part numbers refer to the complete glass and plastic backing plate that fit in the pod.

Great tip to know as I have lost a few RS mirrors in my time and they are expensive if not now impossible to replace.

Now to eBay looking for cheap LT/RT mirrors

How come they all have the same part number then???

The part numbers are different:

RS  46 63 2 307 640

RT/LT  46 63 1 455 000

These numbers were taken directly from the BMW fiche.  The parts are not interchangeable because the mounting of the glass to the housing is different for the two different mirror assemblies.

I can't explain why Real OEM has the information they have.  It appears from the pricing they show, they are woefully out of date.

BobT wrote:How come they all have the same part number then???

I can assure you that the RS and RT/LT mirrors are not interchangeable.  Glasses are the same shape is the only similarity, The way the plastic backing fits into the mirror body is different for each.

Al

This is from Real OEM

RT/LT Part#   46631455000
RS Part#       46632307640

Where on earth did you get that from Bob?

Part 46631455000 was found on the following vehicles:

·       K589 (K 1100 RS, K 1100 LT)   (06/1989 — 04/1999)

·       K589 (K100, RS, RT, LT)   (10/1983 — 10/1991)

·       K569 (K 75, K 75 c, K 75 s, K 75 RT)   (01/1989 — 06/2005)

Part 46632307640 was found on the following vehicles:

·         K589 (K1, K 100 RS)   (03/1989 — 06/1992)

·         K589 (K 1100 RS, K 1100 LT)   (04/1992 — 12/1996)

·         K589 (K100, RS, RT, LT)   (05/1983 — 10/1989)

RealOEM is good but cannot be trusted 

So before any more confusion as said before

RT/LT Part#   46631455000
RS Part#       46632307640

and to get back to the initial query I suffered the vibration issue on a few RS's and it was down to the mirror not being correctly located in the pod and the wire circlip not being fitted at the back.

Funny that the Germans also think that they are the same see:
http://www.kfm-motorraeder.de/cms/en/genuine-spare-parts/bmw-spare-parts?itemid=46632307640

I think that you will find that BMW used this item to supersede 46631455000. Which went out of production in 1993.

The K1100RS used the same mirror glass that the K100 RS used so that isn't right.

BobT wrote:Funny that the Germans also think that they are the same see:
http://www.kfm-motorraeder.de/cms/en/genuine-spare-parts/bmw-spare-parts?itemid=46632307640

I think that you will find that BMW used this item to supersede 46631455000. Which went out of production in 1993.

Bob, aftermarket parts sellers are the last people I would trust as to advice on part interchangeability.  I mean, do you really think that the k100rs mirror is actually used on the K1?  Really? 

Right now I am trying to sort out a clusterduck with a helmet dealer over cheek pads for a brand new helmet.  People who have no hands-on experience with a product and rely on third or fourth hand information are easily confused and create further confusion in a geometric progression.