I am in the process of removing the gearbox on my K100. After removing the swing arm, I pulled back on it and it came out; but left the drive shaft still firmly mounted to the gear box. What now? I don't want to tugg and pull/lever unless I will damage something; so I guess I've not pulled very hard on it.

Any advice?

Off course, I can just remove the gear box with the drive shaft still dangling from it; but this is messy.

Grip the rear end of the drive shaft with either Pump pliers or Vice grips, and using a hammer give the grips a whack, it should pop off easily. 

It can be a bit tricky but it will pop off the holding ring. I used some 400 grit wet and dry paper to put between the vice grip teeth and the shaft, rough side down on the shaft, that helped the pliers get a good grip and didn't damage the teeth.
Good luck.

Unless it's corroded and seized to the output shaft splines, a sharp tug is all it takes.

If the bike isn't particularly stable in its semi-stripped state, you can rotate the shaft until you can get a flat bladed screwdriver inside the universal joint and then lever it off.

Thanks for the info re the removal. Tonight hopefully, I will be removing the gear box from the engine. The reason for this is that the bike jumps out of second gear when the bike is under stress. Let me explain. When on a level road and I am gently accelerating, the bike stays in gear. On a slight incline and when accelarating, she jumps out. When I accelerate fast and change to second, she will stay for a few seconds and then jump. In all the other gears, there is no problem.

Just to add: I am a big fellow; tall and round, but the PO was tall and not so round and he had the same problem; although he described it as "very occasionally" (sales talk?).

Now, I've read and re read the postings on gear boxes on the Internet and also the manuals. Seems there are two major causes: one is a loose grub screw, the other is a bent gear selector shaft. Examining the selector imput shaft (the one to which the lever is atached), looks as if it is ok. There is not a lot of free play when you wiggle the lever and there appears no obvious damage to the lever (or it could be a replacement?). I will only see if the shaft is bent when it is out of the box and on blocks with a dial indicator.

What else should I look for? 

Close examination of the bike shows that; at one time or another, the bike did go down. The left crash bar is missing and you can see that this was removed under force as the bottom bracket is still on the engine with the remains of the rubber gasket. There is a small dent in one of the exhaust pipes; but there is no damage to the engine (scrapes etc.) The left handle bar rubber grip seems to be a replacement when compared to the right. The left mirror appears to be undamaged; although this could be a replacement; although they both look about the same age. No other damage I can see. The panniers are undamaged: no major scrapes, marks etc; other than a few very light scratches, which I attribute to normal wear and tear. The tank and other covers are undamaged. So, if the bike did go down, it did not do so with any great force. The PO did tell me (once I had bought the bike!) that it did 'run away' from him on one occasion when he parked it on the side stand on an incline and it fell over.

The bike stood for 12 years before the PO bought it from a deceased estate. The odometer stands at 70 odd thousand kilometers, but the odo gears are toast. I suspect they welded together when the bike was standing. The PO, knowing his riding habits, probably put no more than 10 - 15,000 k's on the bike during the two years he had it. Mostly breakfast runs and the odd long (500km) trip. As he is a wage slave, these trips were very infrequent.

Overall the bike is in a very good condition. The long stand gummed everything up and when they got it back on the road, they did a hash job. This I can see from: The exhaust holding nuts (pipes to engine) were not properly fastened. Some were only finger tight. Some washers are missing under the mounting bolts. Rubbers are not dry and perished, but their fitting is/was sloppy. The tank was a mess. The injectors are unbelievably filthy (sent them away for cleaning.) The fuel rail is gummed up etc. The fuel pump is a replacement (VDO). Hence the reason for the tear down. Just fixing niggling problems when they occur is a PITA.

Oh, and the sprag clutch is stuck. So, while I'm in there, may as well fix this too.

I am going to need you guys ....

If it is jumping out of gear like you say there is about 99% chance the selector fork is bent even if the grub screw is the reason it started coming out. You will need to renew the gears or back cut the dogs on the gears to make them useable.
as for needing us well we'll be here.

For the time, money and effort involved it may make sense to replace the transmission with a good used one instead of fixing the old one.  That's what I'd do.

The gearbox is out. Tomorrow I open it. On draining the oil, I found the finest (dust) particles sticking to the magnet on the drain plug. Rubbung this between my fingers; I felt no metal; so the dust is extremely fine.

The drive shaft came out with a gentle tap as recommended here. The gearbox end of the drive shaft splines were about dry. If you stick your finger in there, it comes out with a grease markings, but that's about all. No damage to the splines though. They are like new. Nice little ring of dried grease where the drive shaft ejected the grease.

Same with the clutch splines. Dry; just a tinge of grease and a nice ring in the bell housing of ejected grease. If nothing else, it was time for a spline lube. Glad to see no oil seepage/leakage from the engine side il sel. that bell housing is as dry as can be.

Think now that I have the box out, might as well give the clutch a look see and measure the wear.

The rubber boot on the clutch lever is shot though. Guess I'll be supporting Moto Bins again ....

Opened the box today.

First thing I noticed was that the gear selector lever was a replacement. BMW does not assemble its boxes with the glue of the parts label still stuck to it. (Heart sinks ...)




Now I wonder, just how bent is the shaft?(Don't know yet, will see when I pull the shaft.)

Then the selector drum. Seems to be the culprit.




The damage is on the second gear selector pathway; right on its apex. You can see the metal is peened back.

Could this be the cause of the box jumping out of 2nd gear?

Now the selector forks:



The fork tips are un damaged nor bent. But, you can see the gears have rubbed on the forks. Is this due to the damage to the selector drum?

The two selector fork shafts are not bent. Runout on these are less than 1/100mm.

The gears are ok, except for this. I guess this is the second gear?



Obviously, with the selector not engaging fully in the slot; and slipping out, this is the result.

Now some questions:

What could have caused the damage to the selector drum? Seems it needed a huge impact somewhere on the bike to deform the metal to such an extent.

Second: what do I need to replace/repair to set the box right? Importing a second hand box is not an option. The postage alone will bankcrupt me.

Moto Bin's inventory of gear box parts are slim. Know anywhere where I can buy a selector drum. Second hand fine, as long as it is in a good condition.

Can the damage to the gear (last picture) be repaired, or am I looking at a new gear?

possible to get a whole shaft maybe ....and new selector drum ....but I don't think that wear on the selector arm is right,  the whole arm must be bent as the wear pattern in the centre should not happen
rickg should know much more

I recon a drop event on the left side could be the reason ???

The selector fork IS bent it wont get damaged like that unless it is bent and they cannot be straightened. I had one on my wifes K75 that was like that and we tried every trick in the book and all we managed to do was totally destroy it.
The drum needs to be replaced, the gears can be salvaged. Any good engineering workshop should be able to recut the slots and dogs to fit and remove that rounded area.

I've been looking at the second hand options. On offer is the innards of a '87 K100LT box and a '87 K75S box. This is all the innards, save for the housing. My questions:

Are these gear boxes interchangeable?

These items are offered on E-Bayand described as coming from good running bikes being parted out. So there is a little buyer protection.

Also, fitting a complete gear set: will there be hassles re fitting this to a different (my) gearbox housing?

The reason I'm looking at this avenue is purely based on postage costs. Including the g/box housing will significantly add to the postage costs.

Any transmission from a K75, K100, K1 or K1100 will bolt right up.

Differences: 

Gears 1-4 are the same on all K transmissions.  On a K75 fifth gear is 1.67 while all of the four cylinder bikes have a slightly taller 1.61 fifth gear.

4V transmissions from K1s, K100RS4Vs and K1100s have drilled mounting tangs under the output shaft for mounting the front of the paralever strut.

You can research part numbers at RealOEM.com.

Here are the parts diagrams for a K100 transmission http://www.realoem.com/bmw/partgrp.do?model=0514&mospid=51754&hg=23

Take any part, for example 23311451100, and see here what bikes have that part in common: http://www.realoem.com/bmw/partxref.do?part=23311451100

Tks. I doubt if I will ever test the top end of my bike in 5th, so the difference in gearing will not make no difference.

Got all the guts out of a K75 box for GB 75 Pounds, postage included. Phew!!!

Yeah, the 5th gears only differ by about 3%.  Chances are you may not notice it.

duck wrote:Any transmission from a K75, K100, K1 or K1100 will bolt right up.

Differences: 

Gears 1-4 are the same on all K transmissions.  On a K75 fifth gear is 1.67 while all of the four cylinder bikes have a slightly taller 1.61 fifth gear.

4V transmissions from K1s, K100RS4Vs and K1100s have drilled mounting tangs under the output shaft for mounting the front of the paralever strut.

That isn't quite correct actually.
I did quite a bit of investigation about it and found that the difference is between the 8v engines (K75 included in that) and the 16v engines.
Anything with a 16v engine has the 1.61 gear
The gear that is different is part #16

Part numbers are 1989 K100LT 30 teeth designated as Z30 23211 451074  The K75c from 87 is also a 30 tooth gear designated as Z30 and has a slightly different # 23211 451 075 (one possibly superceeds the other) and a 93K1100LT, K1 and 1990 K100RS all 16v has a Z29 which is 29teeth and # 23211 461900.
Mind the possibility of finding either in any gearbox nowdays is high as we see with what Gunsports is doing and putting a 75 innards into something else, which happens to be a K1008v but could be a 16v just as easilly and considering the other gear of the pair has the same part number so is identical the whole exercise becomes very acedemic.

While in 'shopping' mode, I also ran into an instrument cluster for my bike. (My speedo and odo is not working, and the gear indicaor LCD is on its way out.) This unit is off a 1992 K100 (K1?) and it looks the same size as the one fitted, although cosmetically it is a little different. Cheap and guaranteed full working order.

Question: Will this fit on my '84 K100 2V? Or, could the internals be swopped out?

Next question: this (new) unit has high milage (miles) registered on the odo. Is there a way to turn it back a little to match the milage on my Bike?

If it is from a K1 it will have a very different face although esentially the same unit but far more likely from a K100LT or RS. There are some differences in the fuel warning light, Duck posted about that only about a week ago but as usual I cant find it, I think it was one of postmans threads.

just swap out the fuel warning board in the instruments of the later instruments for the 84 type

all should be good except the colour of the warning lamp

but going to after market instruments will not solve the 84 fuel sender issue unless you change the tank for an after 85 model  with the float type sender   and then the wiring harness ..as it leaves the loom in a different place ...(you could extend the cables though )

Tks, the only reason I was considering an after market instrument cluster was due to the cost of good second hand units. This one was not too expensive. If I have the option, I would like to keep the bike as original as possible, although I am not after a concourse queen. Besides, when I fit the 80 RT fairing, the bike will no longer be 'pure'.

it can be amazing the prices asked for old parts ......but we all live in the hope that we will get a equally weighted price for replacements that we need  from a good or well priced source  in comparison to the average bike price second or third hand

crikey I have seen full bikes for under 500 pounds ....and another asking 100 just for this bit or that bit which is hardly a reflection of true value .   just optimistic bargaining  eh ?

Remember to not throw any parts away because sooner or later they will be worth their weight in gold to someone who hasn't even got one let alone a good one. Things like the selector fork probably will never be any good but the rest of the gearbox is worth keeping even if you only pass it on to the next owner.

Hi there, as for second hands, have you tried www.motorworks.co.uk?.
Best regards

JAP

Gearing: My post was based on what shows up in the factory specs. I've never researched individual parts and part numbers.

2V vs. 4V clusters: 

Tachometer: The tachometers are different part numbers. 2V-62112305263  4V-62112305265. The 2V bikes get the signal from the first coil while the 4V bikes get the signal from the Motronic. (Pin 16 an all clusters.)

Speedometer: The speedometers are different part numbers too but I suspect they'd work on any K since the sensor is common. (Yellow wire on Pin 22 for all clusters.)

Face plates: At least on US models, the 4V bikes have white lines across the bottom while the 2Vs don''t,  And then there's the K1 face plates that are yellow, not white.

Here's an ABS II K1100 cluster with the white lines.  (You can tell it's ABS II because the low fuel indicator is amber.)




Clocks & gear indicators are common to all K clusters.

duck wrote:
Here's an ABS II K1100 cluster with the white lines.  (You can tell it's ABS II because the low fuel indicator is amber.)

Not quite shure about that, duck...........if it have been a ABSII the amber warning light under the
oil pressure light would have been red....and used as the second ABS warning light.

charlie99 wrote:just swap out the fuel warning board in the instruments of the later instruments for the 84 type

If your old cluster is the 7 screw version, you need to do some mod on the pcb...to make it fit into the newer 9 screw version cluster.

Or search a used late version pcb to be used together with the thermistor sender and the 9 screw
cluster (this pcb uses only the 4 liter lamp).

Oops! The cluster I bought is the one as pictured above. It was listed as a 1992 K100 cluster. My bike is a 84 K100 2V. My main interest is to get a working speedo, as this is required to pass roadworthy (MOT?) I guess I'll be asking for hel again to get the rest of the unit wired up. The rev counter on my bike works. Any chance of swopping out parts?

Safest way would be to mount the "new" speedo in the old cluster.

yep good thinking inge

Inge K. wrote:

duck wrote:
Here's an ABS II K1100 cluster with the white lines.  (You can tell it's ABS II because the low fuel indicator is amber.)

Not quite shure about that, duck...........if it have been a ABSII the amber warning light under the
oil pressure light would have been red....and used as the second ABS warning light.

Hmm...  that's very odd. You're right about the choke amber being replaced by a red ABS. The only clusters I've ever seen with an amber fuel light other than 85s are ABS II.  The part number in that picture is 62112305258.  I have a 258 in my hands right now and the low fuel is red - just like it's been on every 93- 4V I've parted/owned.

Edit: In thinking about it, since that's a brand new zero mile cluster, it may be an ABS I 258 but BMW now makes the fuel light amber.

duck wrote:

The part number in that picture is 62112305258.  I have a 258 in my hands right now and the low fuel is red - just like it's been on every 93- 4V I've parted/owned.

Edit: In thinking about it, since that's a brand new zero mile cluster, it may be an ABS I 258 but BMW now makes the fuel light amber.

cluster #62112305258 was used up to 07/93....ABSII was used from 07/93 on.

I got a ABSII model.......and it got a amber low fuel.......I would guess the cluster in
the picture is a just in between model.

The speedo should be repairable by cleaning the contacts on the outside and inside of the cluster,

and /or the rear wheel sensor,

this will fix the odo too unless there is damaged gears. That only leaves the gear pos indicator

to worry about, i'm assuming it has just bled a bit and probably is partly readable, nice to have fully workable

but not really essential? Above repair is very little $ wise (DeoxIT contact cleaner/protectant)

Just another option and keeps it "original" and cheap (like me Ha Ha).

I've had that instrument cluster out so many times, I know it off by heart!. In fact, I dismantled it far beyond what is recommended and still no joy. The odo gears are gone - crumbled into a heap of dust. The sender unit works; it rattles when a soldering iron is brought close and it is clean. I've even gone and bought one of those cycle speedo's that mounts the pickup on the front wheel (rated to 199 MPH, can you believe!). Buying this instrument cluster is a desperation move, believe me.

And talking of cheap: you've seen nothing yet  

Fact is; when I bought the bike, I prepared myself for spending up to its purchase price in getting this bike back to 100%. Not that the bike had so many obvious faults; just that experience has taught me that; what you originally see and are told about; often is not what you get. Fact is, I am getting pretty close to that limit and this is what's upsetting. When I hit this limit, the bike would then cost more than it is worth in the resale market and then becomes a financial loss.

Speedo and gear box repair is the last of the work needed to get this bike back to 100% (I hope!) All the other work has been done (Brakes, brake rotor, injectors, electrical.) Still left is making new brackets for the panniers; a job I can do myself without great cost.

Another thing that I've found: Never buy a classic bike and not expect to do your own restoration. leaving this work to 'professionals' is a short road to financial ruin. That is why this site is so valuable.

Another question: My starter sprag clutch is sticking. The bike is in pieces right now. I've dismantled up to the stage where the clutch has been removed. I now need to remove the bell housing to get to the sprag to clean this. It is working, just gummed up. Now, can I remove the bell housing without having to drain the engine oil? The engine is still in the frame and the oil in it is new; less than 50 klm since the oil change. (Talk about cheap?) I plan to wash the sprag clutch unit to remove the gunk; hopefully I will not need to dismantle it. When you turn the idler wheel; it sometimes catches, other times not.

Keeping an older bike/car on the road is always a financial loss but nuying a new car/bike is even bigger when you factor in depreciation.  My dad sais to me if it's got tits or wheels it will cost you lots of money

RicK G wrote:Keeping an older bike/car on the road is always a financial loss but nuying a new car/bike is even bigger when you factor in depreciation.  My dad sais to me if it's got tits or wheels it will cost you lots of money

And if it's n Alfa or a red head with big t*ts; it's trouble and money .....

Gunsports, twincarb wrote a fine piece on reassembling the gearbox; might be a useful read?

 https://www.k100-forum.com/t3980-putting-your-gearbox-back-together

Paul.

You have done well. Like you were saying the tricky bit is the selectors and those rings, I use some vaseline on them to hold them and it helps with the vaseline if you put the forks in the freezer for 10 minutes before you start then the vaseline is real sticky. Don't use grease, the vaseline disolves in the oil where the grease wont.

The K75 will only have a different ratio top gear if yours is a 16v K100 the 8v K100 were all the same as the K75

Mine is the 8V, so it seems all is ok.

On reassembly, I used Wynn's Gear Oil and Assembly Lube. Stuff is sticky as hell and supposed to be added to the oil. I used it neat on all the bearings and the sliding bits.

The assembly lube would be good, all thats needed is like you say something sticky and that will mix with the oil.
If the assembly lube is the usual black moly stuff its good for the splines as well.

Me again ....

Still waiting for the gearbox seal set from Moto Bins (they said 2 weeks; been six weeks and counting.) In desperation, went to the local enginnering supply shop and asked about oil seals. Said they had, bring the old ones and they'll match. Stripped the box (again) and took the casings, with the seals to them. Amazing, they matched the oil seals down to the name. The three seals cost me all of 3 pound 50! Gear box is now assembled and will be fitted this weekend. Now the rebuild begins.

Also got my new instrument cluster after many weeks of waiting. (Sender put the wrong address on the box - a miracle it got to me.) Now, I need some advice:

The part numbers on the (new) instruments are: 2-305-258 and 616-038-3524. The date stamp inside is 1991. I don't have the part numbers of the old set of instruments; the lable is gone long ago.

First, the pins differ on the new set (input/output) the old ones were oblong, the new set is round.

Now, it was suggested that I just swop out the instrument units and retain my old cluster. But, the PC boards feeding the instruments are so different, that this will be far beyond my capabilities and knowledge. Also, where the old cluster as a 4 & 7 lit fuel warning lights, the new one has just one (I think).

The pins were(are) a major problem; untill I tried them on the bike's oblong plugs. A tight fit, but a fit nevertheless. Has anyone tried fitting the round pin instrument cluster to the oblong plugs? If so, can I not just swop out instrument clusters or are there other problems that I must bear in mind?

Help please.

I think I have the part of the harness with round pin thingies and a square pinned instrument I will have a look tomorrow and get back. Its 10pm and besides the mosquitoes are as big as B52s only needs one to suck you dry and 2 to carry you off.

Unfortunately they are both late type and for the rectangular pins.

It has been eight months since I bought my bike. An eight month period where; from knowing nothing about the mechanicals of a motor cycle and especially, nothing whatsoever of a BMW motor cycle; I took my bike on the road today; and she ran beautifully. For the first time, I have a completely functioning gear box; one that I rebuilt myself; and a working speedo; abet a MPH unit; but a working speedo none the less. I will; GW, put het through MOT in the next few days.

I guess I could have done all the work in a shorter period of time; but the past eight months has been my apprenticeship' on bike mechanicals so to speak. I lot of things I did unnecessarily; because I did not know exactly where to look for the faults. Also, I probably spent money on parts that were not needed.

But, running the bike today; was reward for all the slog and frustration. Now I know why K bike owners are so nuts about their machines. It is a magnificent machine!

I bought this bike cheap; about a third of what bikes in a simmilar condition/year/milage sells for retail in SA. I spent another 80% of the purchase price in buying parts and some tools; needed to get the bike 100%. In total; I am still below what these bikes sell for here, and I deem it a bargain; especially after restoring/rebuilding a 30 year old bike; where most of the parts had to imported; and paid for; in a heavily devalued currency.

One probem remins however. On the new (old) instrument cluster I bought, the low fuel warning lights do not work. My tank is fitted with the 4 & 7 Lit sender unit; the new instrument cluster has the later fuel warning light. I looked at swapping out the circuitry in the new cluster with those of the old cluster, but the wiring ribbons are just too different for me to try this.

Can one get the tank sender unit that will be compatable with the new cluster; or is there another fix?

Congrats!  What you have learned will be invaluable if you ever have any issues on the road.

The 85 and 86+ fuel level senders operate much differently.

It MIGHT be possible to trigger a relay that's hardwired to the low fuel lamp in the cluster.

The brown/white and brown/black wires are for the respective indicators. I'm not sure which is which.  I don't know the exact details of how they work but it's something like when they are exposed by the lack of fuel they heat up and complete a circuit - or something like that. (Inge probably knows)

Now lets see some pics!