splines okay or shot?

[noahben]

hi everyone,

new to this forum. hope i am not committing any errors here. I have not purchased a K bike yet, but am looking at a K75 in town. The seller kindly took some photos of the drive shaft splines, however, i am not certain i can really tell from the picture if they are in good shape or not. To my untrained eye they look okay. I think he probably lubed them up before sending me the pics, as there is some rust indications.   however, just wanted to see if anyone had any opinion of how they look, or I should run far away from the bike and look for another one. again, maybe the pictures aren't good enough to tell.

thank you very much in advance.
...according to the seller it is a bit of a Frankenstein bike... the engine is from a 1990 K75.

noah
hope to have a K75 cafe... one day soon.

[daveson]

Reading between the lines, it's interesting that he hasn't shown the drive shaft splines,  which are likely to be worn more. You could ask about it or offer less,  or both. Also see if any drive shafts are out there.

[The Mighty Gryphon]

The best way to tell what you have with splines is to look at how wide the flat top of the spline is and if there is a step in the leading edge of the splines. 

Looking at your photo, it's hard to see the top of the spline very well.  It does look fairly good from what I can see.

However, there is a step beginning to form on the leading edge that can be seen even by my failing eyes.

Having said that, if the bike is destined to be cafe build, there is plenty of spline left if properly maintained.  Unlike a normal brick that can often be run ten thousand miles a year, cafe bikes accrue just a couple thousand miles before being abandoned for something new.   

Here's a couple photos that show what a good spline photo looks like.


DSCN3349.JPG (38.13 kB . 618x576 - viewed 715 times)

DSCN3341.JPG (22.8 kB . 609x576 - viewed 736 times)

[noahben]

thank you very much for the quick and succinct reply. 

actually i missed one photo in the upload which may be slighlty better.  here it is.  not sure if it makes it any easier to tell. but thank you again for the feedback. and point well taken on the cafe. it probably won't get anywhere near as many miles on it as keeping it as more of touring bike.

[The Mighty Gryphon]

The driveshaft splines show some wear as well.  It's not bad, and if you maintain them with a good moly lube once every year or two they will last a lot longer than anyone's interest in riding the bike.

[volador]

How many thousand miles on the bike?

Those splines are difficult to photograph unless you have a good camera and flash. Best to photograph outdoors using natural light.

The final drive looks to have minimal wear. The red you speak of is probably residue from the 'red' grease that BMW recommended years ago.
The drive shaft looks like a bit more wear and is usually the part that wears quicker either do to inferior metal composition or questionable heat treatment.

You want minimal amount of play for smoother shifting and on/off throttle response.
Used drive shafts come up for sale on ebay or a new one is like $400 from dealer.
FYI drive shaft come with Z=16 (early motos 1985-86) or Z=20 number of splines on the output end.

[Chaos]

Those look fine.  Bad splines have a distinct ridge, even then they can last for a long time if not abused.

[Past-my-Prime]

This is what you don't want to see, there is basically no spline left at all:



I took a lot of photos and these are the best.

The lower one is after I applied some fresh lube to reassemble because I didn't want to leave the bike in pieces until I got new parts (now stuck in storage until I can cross the border into the US).

You can see how the FD splines are "bowed" towards the rear of the bike.

[volador]

This is what you don't want to see, there is basically no spline left at all:
I took a lot of photos and these are the best.
The lower one is after I applied some fresh lube to reassemble because I didn't want to leave the bike in pieces until I got new parts (now stuck in storage until I can cross the border into the US).
You can see how the FD splines are "bowed" towards the rear of the bike.

Did someone mention splines? LMFAO

Nice touch with the fresh moly on reassemble. Made my day. Priceless!

[Past-my-Prime]

 

Hey, it's never too late!  Those splines deserved a bit of Moly after taking me around the lake in the shape they were in.

[AndreP]

Hello I’m piggybacking onto this spline forum to get more opinions on my bikes splines. It has 84,000 mi on it and hasn’t been ridden in 10 years before I bought it. When I opened them up there was grease! The splines look decent to me just checking with you all to make sure.

[Laitch]

Those splines seem severely worn to me, judging by their sawtooth appearance. A closer, straight-on photo with good lighting would help in judging them. As they appear right now, you could possibly get a few thousand more miles from them if you don't flog the Brick when riding. When the tips become too narrow, they'll break off, the driveshaft will make an unpleasant ratcheting noise, and forward motion will cease.

[AndreP]

Here’s a better photo

[Laitch]

Good photo, Andre!
I stand by my original assessment; you have a few thousand more miles left if your clutch control is smooth and you aren't whacking the throttle.
You have options while you're still riding. Motobins in England sells a replacement socket that can be welded into place.


Ted Porter has a replacement driveshaft for ≈$200 less than the original BMW part that is available.
OEM



Decent driveshafts occasionally turn up on eBay, just don't buy one with sawtooth profiles on the splines.

[AndreP]

Thanks for your help!

[ErikDK]

Double

[ErikDK]

Why post unsearchable screenshots instead of actual links to the product?

https://www.beemershop.com/product/ei-k75k100-driveshaft-20-tooth.html

[Laitch]

Double

Why post indecipherable comments, or believe adults are helpless? 

[AndreP]

Launch has been a big help with this build
I bought that drive shaft and found it with a quick google search
The company sent me two werthers originals with the part
It’s strange I bought they’re product yet they tell me to suck the shafts two balls

[AtLarge]

Do it. We won’t judge you. 

[Laitch]

 

[pinhead]

what I do is every time I replace rear tire I inspect and lube the splines  About every 7-8000 miles.  You have to remove rear drive assembly but the wheel is already off and its not too bad of a job.  When I have done this I have found that the splines are still coated in lube but I clean them any way and re lube them.   I dont use any special type of grease, but have had no problem doing this for the last 8 years and no problem with spline wear.  I usually replace tires every year.