If you are considering the purchase of a K75 (1986 ~ 1995) or a K100 (1985 ~ 1990) you need to perform this one simple task before you commit to purchasing the bike. Failure to do so could cost you over $1000.
Thanks for this pretty in-depth video. The fact that you included the torque specs in Nm is next level service from you, thank you! All the best to you and yours, mate.
What a superb video - this is something EVERY potential K75/100 buyer needs to know about. I have had my 1991 K100LT for 17 years now, it has 142,000 miles on the clock & I clean/lube the driveshaft EVERY time I change the rear tyre (5000ish miles). I also remove the shaft entirely & lube the front splines although they never seem to suffer from drying out so much. Keep up the good work!.
Thanks Chris- excellent video ( as usual ). As a longtime owner of an early K 100 have not had many if any issues until recently ( age ). While I have used Max's about the only choice I can find in my area ( CT ) I am less than thrilled with them the more I deal with them. Unfortunately not to many options in CT- at least that I am aware of so finding your videos here has been a big help in tackling jobs and getting to really know the ins and outs of the bike better. Thanks again hope you are able to keep doing these for all of us.
I bought my last K75 four years ago with a pretty good maintenance history. The bike had 63, 000 miles. At my first spline lube there was plenty of grease and very little wear. I cleaned and greased with Honda Moly 60. Great video and very, very helpful.
same here, just bought and old (new to me) 87 K100RT, and this video was invaluable, as were your others...you're a bloody gem, Chris...good on ya...I would also get my bike serviced by you if you ever move to Australia. Until then, I'll just have to keep watching your vids and doing my own wrenching. BTW, sprouting torque settings off the top of your head impresses the shit out of me!
Going to check a K75RT from '95 today. Has 25k miles on it, dealer maintained. Hope i can enjoy it for a long time and i will use your advice, thank you very much for this upload.
It never ceases to amaze me that people & dealers do not give the PROPER attention to such a critical and costly maintenance item, given all the knowledge through the years, of ruined drive lines! Just like the piss poor plastic original lower intake gaskets GM used on the 3100/3400 & 3800 V6 engines, you have to replace them with the aluminum framed GM or Fel-Pro gaskets. You are doing a super job with these videos!!!
Hi Chris, I bought an '87 K75s last Feb and am slowly working through it - it's back on the road for the summer :-) I'm new to this spannering lark and your videos are brilliant, really helpful, please keep doing them. Next job is grease the clutch splines (having some pretty clunky gear changes), oh and there's a petrol leak on the left-hand-side of the fuel tank that I need to patch (was thinking petro-patch and JBWeld might do the trick on the outside of the tank), All the best, Ian
Very useful and informative on several levels. Thanks for posting it. As others said, it's probably a rare seller who'd let a buyer do any wrenching on a bike, but an inspection of some sort seems mandatory.
Indeed they are, provided that they are properly maintained. Please remember that there are thousands of these old K bikes on the streets all over the world, many with 300,000+ miles and no problems. But maintenance is the key to survival. Thanks for posting your question, Chris
I know this is an old comment but take from someone who has done large miles on both when i say your hands and feet would thank you for going with the k75 over the 100 due tk vibrations
Thanks for a great public service video. I did this service (and more) after I bought my 1985 K-bike and won the lottery. Everything looked excellent and I believe the very low miles on the clock was pretty accurate. I don't understand why you didn't pull the drive shaft and service the splines on the front too. That was a bit of a hassle, but this shade tree mechanic was able to do it. I encourage others to try, given that you often can't be sure it's done at the dealers. :-(
Glad I have the 85 with the bigger teeth...also only 23k on the bike also helps ;) will make sure to do this every tire swap! Thanks for the walkthrough!
Cool tx for the info and I will be replacing the tires and will have them check and take pic's of the splines so I can decide on if i want Bruno to redo them not picking it up till next year.
Couple of things. 1. I've never been a big fan of Max's. Just because I'm only 18 they blow me off at the rallies. 2. Ive always been a big fan of the old Texaco StarPlex. Use it for the splines, and on all the clutch throw-outs when i service airheads. Last, When my final drive failed on my k75 (housing broke and dropped the shock, causing the seat to hit the tire and roast my tail cowel) I picked up a used rear drive from Beemer Boneyard for about a hundred bucks. great video. love the fbombs
Amazing coincidence. I just purchased a 1985 K100RT (13K miles). I'm looking forward to working my way up the drive train. I've also order a new rear brake reservoir as the current one was eaten by mice! That' scopes the project I have ahead of me (but I'm looking forward to it!)
Thanks. The front end of the shaft does not get any wear as it does nice ride back & forth along the spline like the rear does when the suspension is compressed & released. Keep the maintenance up and you'll pass 200,000 mi. without any difficulty. The 1990's were the best years for K bikes. Enjoy, Chris
I had a k100rs great bike had to replace drive shaft once did myself toured Europe on it with son on back have Honda superblackbird now😁 enjoyed your vid 👍🏻
Most certainly! All BMW K models with this type of single sided swingarm should be inspected prior to purchase. The later Para-Lever rear suspension as found on the K1, 1992 K100RS, all K1100RS and K1100LT models do not need to be inspected. Thanks for your question, Chris
Hi Bob, I hope the splines are in good condition at least! Use of Honda-Moly 60 on these splines (driveshaft) is OK w/ me so clean the splines and lay on a very heavy coat, reassemble and RIDE! Thank you for taking the time to comment. I appreciate it, Chris
Thanks Ian. Your fuel leak was caused by years of use and failure to remove the fuel pump and clean the fuel tank innards each time the fuel filter was replaced. Good luck and thank you for your comment, Chris
I plan to get K100 model soon and i wish i cant checked like this before buying it but however, this is good point to know about K100 Thanks a lot Chris
I too purchased a k-100. It was a barn find It had a dry spline at 40,000 k.........I read the ingredients of never sieze, an they put moly grease in there. So....yup, I used it......I'll be taken the rear off again for a season inspection, I;ll post here with the results.
just spent some major coin on the correct gel battery for my k 100.....Chris I'll face book ya when I head up this summer. Ya can give me what I need to do...I know I need a pair of dust covers for the shocks...mine are split from age.....( I have them vinyl taped for now, don't laugh it works)
Bought a '92 K75/RT from a friend and promptly rode it from AZ to TX pulling a small trailer. Never had an issue with the bike on that trip, just the trailer (leak in airbag suspension = tires rubbing on fenders at 60+ mph. BAD.) I did have splines checked when I had new tires put on the bike, and the local Old BMW's Guru pronounced them well maintained and in top shape. So got lucky there. One thing I did notice (and Perry chewed me out on it) was that the clutch cable tension needs be adjusted ALL THE TIME. Doubly so if you ride it as if it had a wet clutch, because the K75's have a dry clutch. Ride it without feathering the clutch as much, and this is of course less of a concern.
Hi, The splines really need to be thoroughly cleaned and then lubricated. This can not be done properly without removal of the transmission. You can cheat and just slide the gearbox back but the labor that is saved is mere minutes. Thanks, Chris
Para-Lever equipped bikes do not wear the splines of the driveshaft as 2 valve K bike do. The only issue with Para-Lever rear drives is that they are often not assembled correctly. A sign of that is a leaking pinion seal visible at the accordion boot between rear drive and swingarm but even this is not a problem. However, grasp the rear wheel at 12 o'clock and 6 o'clock. See if you can find any play. If there is is needs to be rebuilt. If not check 3 & 9. Play there indicates play at the pivots.
Listening to your video and I'm getting on sentimental for some reason. I then see the license plate portion of the video and see that you're from Mass/the Northeast where I grew up. Love the home swag buddy
I'd start with a check of the throttle body synchronization. K's can make a racket when out of synch. Are all the rubber vacuum caps in place and not split? Once the balance is correct if the noise still exists it could the the gear cluster at the back of the engine which is generally nothing to be too concerned about just irritating as the noise sounds like the engine is ready to grenade. Does the noise go away when the clutch lever is pulled in?
Thanks for replying Chris. My 75 is like a bloody 2 stroke sometimes, at least I now know it's nothing to about worry about. Should stop the silencer (muffler) rotting out anyhow.
if the splines are worn the shaft engages with a bit of a bang as you set off, mine eventually snapped as I was pulling out of a junction. the replacement was much quieter. 10 year old bike with 40k
The driveshaft can be pulled rearward, pull past it's detent, and then lube the front part of the driveshaft spline. You can then shove it back into the long swingarm housing and nudge past it's detent.
I've bought a k75 rt and completly dismantled the whole bike to check before use it. you can lube the spline just by removing the rear drive and remove the axle. lube it and reinstall it without removing the gearbox.
Awesome. It is possible that the previous owner fogged the cylinders with oil before putting the bike into storage. This is done to add a layer of protection to the cylinder walls while the bike is left in storage for an extended period. Thank the previous owner if you meet him again.
Make sure the horn works. If the horn does not work check the fuses. If the fuse is blown the cooling fan is likely seized. While not 'expensive' this defect would reduce the bikes value by up to $500. Point out to them that these instrument clusters were notorious for failing and the mileage might be inaccurate. Seized fan = many miles. If they are not willing to reduce the price ask to see the rear drive splines. If they are still unwilling then walk away unless it is an incredible deal. Chris
I read somewhere that one way to keep the grease where it should be is to plug the shaft with a rubber stopper. The idea being that the grease can't travel up the arm, away from the splines. What do you think of this idea? And if it's an option, what's the internal diameter of the shaft?
Very informative, thank you very much. So the main question is "When was drive shaft last serviced". If you do not have all those tools can you bring it too a bike shop and ask them to check it out?
I had an '85 K100RT. I was the only owner. It never had it's rear drive separated from the swingarm in it's entire 158,000 mile life, and the drive never failed. I'm thinking it was likely ruined, but it still worked. Wish I would have had these videos back then. Why destroy a good bike?
I had a K75, beautiful bike, in like new condition. It was difficult to shift. Since this was my first bike, I sold it after 2 years and bought an Aprilia RSVR1000 with low mileage. After about 3 years I sold this bike, now I wan't a BMW touring bike.
Chris i also saw your vids bout the k1.’’’amazing almost futuristic design and lowest windresistance...amazing, isnt it? The kmodels somehow are derived from this topnotch engineering...doing quite some downsising of its phenominal features...my k100 to buy has 45.000 miles on it...wish me luck!🤜😅🇧🇪
Hi TheCsipke, What year K100? Does it smoke when started after being parked on the centerstand or only when the sidestand is used? The 1983 - 1989 (87?) K100 did not have pinned piston rings. This results in the end gap of all 3 rings lining up sometimes and causing an incredible amount of smoke. This does not mean that there is an engine problem at all. Good luck and enjoy your 'new' K100RS. If it was stored on the sidestand it might take many hundreds of miles of use before the smoke subsides.
Hi Chris ! I'm going to buy K75 from '89 in a week. Thanks for great video. I have a question - were they any noises or weird sounds in that particular model that can forecast that the shaft and splines are in bad condition ? I think it would be impossible in my case to unscrew the covers and wheel and look at the splines, so I was wondering if I could do some "ear diagnostics" :) Greetings man - great job and videos
Chris, did you use any kind of sealer on the flanges in reassembling the rear drive back onto the tube? I have a "rescue bike" that was neglected. Spline-check is next on the list. Also, I discovered the fuel tank has a couple of pin-holes and some corrosion on the inside. Looking to give it the Caswell treatment, any suggestions would be highly valued.
Chris, awesome video. I just bought a 1991 K100rs with 18,500 documented miles. I also got some of the service records. Just changed the fluids, but noticed that my 1991 model drive shaft is not the same. You mention in the video if it has the bottom arm, which mine does, the process is different. Do you have a video for that model as well? Would love to hear from you. Thanks.
Hi Chris, thanks for all the excellent videos! Did a necessary spline lube a month ago on my K100RT '88 (125.000KM) using your vids as a guideline. I do have a question though. My bike has developed a rattle/clunking sound at idle. It goes faster with higher RPM and is unhearable/disappears at ~2000+ RPM. It sounds a bit like a tractor, but I have difficulty tracing it. I suspect either the output shaft (not sure if 6 or 12 rivets) or the chain tensioner. What would you advice me to check?
The old K bikes are great. Just check the rear splines and the cooling fan and negotiate the price accordingly. The K's require far less maintenance than the Airheads and Oilheads so that keeps the cost of ownership down. Good luck, Chris
