Rick G wrote:Yeah it's a design problem all the way and how BMW managed such a monumental cock up is amazing when many of the Japaneese bikes before them were quite good and apparently did their homework.
And thinking back on it the 16 spline units can't have been that good or why did they change.

And as for the TPS just feed it to the dumpster they'll eat anything, although not having the full throttle rich could cause problems with sustained high speed work which was where the L-Jetronic was at it's worst and does lean out.

Yep, CX500 production stopped in 1983. Shaft drive was a superb, most precise bit of engineering ... I just loved it.

I left it on the bike but "tuned" it out. Simply adjust the throttle off position never to activate the micro-switch. Done by simply rotating the TPS until the "off" position micro-switch never activates. That way you can keep your full throttle function.

BTW for people who are not familiar with this... The TPS contains two micro switches, one for full throttle to inject about 10% more fuel into the engine (enrich function) and the other is the "throttle off" position that shuts off power to injectors. This one causes problems because it is a simple on/off thing. Effectively it stops/starts the engine thus inducing the twisting forces onto the spline each time in both directions. A pest in my opinion that has very little practical value.

Great idea Paul! Keep us posted on how its working for you? Thanks for posting the info about the TPS/Injection guys.
Thanks,
OG

just need to find a solution of the slop through the gearbox to the crank ......50mm rear wheel slack (between takeup )doesnt bode well for keeping that torque against the splines at a constant rate with stop go riding .

the tps solution of winding it out of effective switch position, does help .

If you don't have some clearance in the dogs on a constant mesh box you will have big problems changing gears.
30-40 deg rotation on engaged gears is quite acceptable for that type of gearbox. If you don't have that much free rotation the dogs would have a very hard time trying to mesh.

Rick G wrote:If you don't have some clearance in the dogs on a constant mesh box you will have big problems changing gears.
30-40 deg rotation on engaged gears is quite acceptable for that type of gearbox. If you don't have that much free rotation the dogs would have a very hard time trying to mesh.

ahhhh thanks for that... I checked the brand new BMW on the centre stand and it just as much slop as my K100, now I know why

+1 ...thanks rick

Paul Thanks for posting a pic of that seal line, great topic people

I understand the rational here, but don't agree. Hammering damage results in plastic deformation (you 'push' the material away) and I have not seen that on worn splines.
Furthermore I don't believe in the TPS cause, as it comes on again when the engine gets to 2000 rpm. The resulting braking on the engine should than wear the splines opposed of the drive side and you normally don't see anything on that side. You could have instances where the splines get loaded or not by normal road use on a bumpy surface or during deceleration where you don't close the throttle completely. Further you'd expect the rubber inside the shaft to take up some of this if not all.
Has BMW ever commented (or a dealer or similar?)?

Rene,
I guess that BMW design their bikes with an expected life span of, say 5 years, so if our splines are worn out after 20........

Paul.

;-) Had a good laugh out of that one!!

Indeed, sales department overtaking the technical part....Nothing new there
Then again it was my understanding that everything was very over-dimensioned to assure longlivity to convince the boxer crowd to buy into the new bike.

Guess we'll never find out the reason for the actual construction; interesting nonetheless!

ReneZ wrote:I understand the rational here, but don't agree. Hammering damage results in plastic deformation (you 'push' the material away) and I have not seen that on worn splines.... Further you'd expect the rubber inside the shaft to take up some of this if not all.
Has BMW ever commented (or a dealer or similar?)?

Hi, I am a little unsure about the "rubber inside the shaft" ... is there a coupling somewhere... I guess that i am too lazy to check I can't recall any couplings designed to take the sudden loads on the splines.

The shaft has an inner which has the female spline and an outer tube which has the uni joint, the two are joined with a rubber sleeve between. If you look from the rear end up into the tube you will see a gap of about 4mm which is filled with rubber to isolate any vibrations.
Please don't ask how they get it in coz FIIK

Non just wispered in my ear that FIIK is a technical term, he he

Rick G wrote:The shaft has an inner which has the female spline and an outer tube which has the uni joint, the two are joined with a rubber sleeve between. If you look from the rear end up into the tube you will see a gap of about 4mm which is filled with rubber to isolate any vibrations.
Please don't ask how they get it in coz FIIK

Oh yes, I remember now. I don't think much of that as a coupling device. I don't want to start a flame wars about this, but this is what i call a coupling system. It is a 1976 Goldwing shaft. Note spring loaded coupling that works very well. I hope that the link below works.

https://lh5.googleusercontent.com/-KqDEt1ezSSQ/UAOy3QnTQBI/AAAAAAAACYg/Zno5lhAWbds/s517/Clipboard01.jpg

The BMWs have exactly the same thing internal to the gearbox on the input shaft and have had eversince I have been pulling them apart.