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Author Topic: K75S won't shift down easliy  (Read 24012 times)

Offline gmawby

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K75S won't shift down easliy
« on: December 10, 2015, 06:07:51 PM »
Hi everyone,
I've been "lurking"   for a while now and this is my first post.   
My K75 had been sat for years in a garage for years when I bought it and over the last 4 months I've done lots of maintenance tasks including removing the gear box and lubricating the splines.  I used a product called Castrol Optimol which was sold to me by my local BMW dealer/workshop.  Two months on it is almost impossible to shift down from 4 to 3 even with a pre-load.  However if I blip the throttle it changes down easily.     
I  plan to strip it down again and examine the splines as I'm wondering if the lubricant is not up to the job. If anyone has comments or opinions please let me know.

Glenn,
Sydney, Australia.
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  • Sydney
  • 91 K75S
Glenn,

Offline The Mighty Gryphon

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Re: K75S won't shift down easliy
« Reply #1 on: December 10, 2015, 06:23:20 PM »
I use Honda Moly 60(no longer available) on all splines, and my bricks(three of them) downshift like riceburners.

Can't speak to the Castrol product.  Have you double checked your clutch adjustment?
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline drut

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Re: K75S won't shift down easliy
« Reply #2 on: December 10, 2015, 06:28:32 PM »
Optimol has worked well for me(BIG difference after spline lube for me),if splines are already damaged that may not be the case.
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Offline Martin

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Re: K75S won't shift down easliy
« Reply #3 on: December 10, 2015, 07:33:53 PM »
I have been using Castrol Opitimol for the paste 16 years,but now if you read the posts Guard Dog Moly paste seems to be the new recommendation. Having only done the spline lube 4 months ago, I would be looking at something other than the splines. As Gryphon suggested I would look at the adjustment before going on to anything else.
Regards Martin
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  • North Lakes Queensland Australia
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Offline Martin

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Re: K75S won't shift down easliy
« Reply #4 on: December 10, 2015, 07:39:33 PM »
Gryphon Honda moly 60 has been superseded by Honda M77 Assembly paste I don't know whether it is identical.But you can obtain it under that number.
Regards Martin
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline kris

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Re: K75S won't shift down easliy
« Reply #5 on: December 10, 2015, 08:29:04 PM »
The research that I did suggested Optimol would be more than up to the job. Staburags was (is) the lubricant recommended by BMW, I believe. I spoke to the parts guy at a BMW dealership in my area and he said their mechanics used Belray Assembly Lube! They hadn't heard of  Staburags. I spoke with a Castrol rep and he could only provide me with an industrial-sized quantity of Optimol. I went with Guard Dog Moly. These folks are a small operation out of Texas, very reasonable and very pleasant to deal with. I would make your inquiries there first. A little goes a long way!
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Offline Brad-Man

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Re: K75S won't shift down easliy
« Reply #6 on: December 10, 2015, 08:31:10 PM »
Actually, you stating that flipping the throttle helps sounds more like a synchro problem..
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Offline Laitch

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Re: K75S won't shift down easliy
« Reply #7 on: December 10, 2015, 08:49:58 PM »
If you cleaned your input and friction disc splines thoroughly with a pick and solvent, applied lubricant sparingly but thoroughly to dry splines with a brush, aligned your clutch parts properly when coupling the transmission to the engine and adjusted your clutch free play correctly according to procedure and spec, then your shifting should be smooth. Stripping  down the thing to check your work is probably your best move.

I used Staburag NBU 30 PTM for input spline and clutch rod lube because I believed I couldn't go wrong using a product with that many capital letters combined with numbers arrayed in such pleasing symmetry. The bike shifts pretty good.
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Offline Laitch

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Re: K75S won't shift down easliy
« Reply #8 on: December 10, 2015, 08:57:03 PM »
I started blipping my throttle for smooth shifting for a couple thousand miles before I lubed the assembly. Shifts nicely afterwards. If it's a synchro problem, it's ok with me if it hides out for a while.
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  • Along the Ridley in Vermont.
  • 1995 K75 102,000 miles

Offline gmawby

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Re: K75S won't shift down easliy
« Reply #9 on: December 11, 2015, 01:06:23 AM »
Hello ,
thank you for the advice.
Regarding clutch adjustment I followed the procedure and I think it is OK. However I started the bike on the centre stand today and noticed that the back wheel rotates slowly when in neutral.  If I pull the clutch lever it stops.  Is that due to the oil viscosity or is the clutch not properly adjusted? Do all K bikes creep?

On the subject of oils, I originally had 80/90 W and when it became difficult to change I tried a full synthetic 80/140 but I don't notice any difference.  I'll probably change back to the original specifications.

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  • Sydney
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Glenn,

Offline Scott_

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Re: K75S won't shift down easliy
« Reply #10 on: December 11, 2015, 06:51:42 AM »
Quote
However I started the bike on the centre stand today and noticed that the back wheel rotates slowly when in neutral.  If I pull the clutch lever it stops.  Is that due to the oil viscosity or is the clutch not properly adjusted? Do all K bikes creep?

Both my 1100's do it when the oil is cold on 1st startup, so yes I would say that it is due to the oil viscosity.
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Offline Laitch

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Re: K75S won't shift down easliy
« Reply #11 on: December 11, 2015, 09:16:15 AM »
Quote from: gmawby on December 11, 2015, 01:06:23 AM
Regarding clutch adjustment I followed the procedure and I think it is OK.

Your clutch is properly adjusted if you have the correct free play allowance at the handlebar lever, the correct cable length at the clutch lever and a bolt adjustment that makes contact without pressure.

Shifting in either direction between all other gears except 4 to 3 is smooth?
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  • Along the Ridley in Vermont.
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Offline gmawby

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Re: K75S won't shift down easliy
« Reply #12 on: December 11, 2015, 02:41:37 PM »
I checked the clutch cable length and free play and they are correct.   I went for ride to test and observed that:  going up through the gears is fine,  finding neutral is easy from 1 -N and 2-N , 4 -3 occasionally  shifts but I usually have to blip the throttle, 3-2 usually shifts but sometimes needs help, 2-1 is the same as everyone else's bike.    If I stop at lights in 3rd it won't change up or down  and the LCD indication goes blank.  When it gets in this state  it will change if I slip the clutch.

Others have posted that  (http://bmwsporttouring.com/faq/transmission_issues.htm  and this tread http://bmwsporttouring.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=268144 ) that quick shifts are important.  I do tend slow down in 4th   as I approach lights then change down and engine brake.  I'll try changing sooner at higher revs.  My Honda did not mind changing at any speed, but this is a very different bike.   Curious that it seems to be getting worse, but maybe it is not the bike but me that is getting worse, self fulfilling my belief that something is wrong.

Time to go for a ride.

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  • Sydney
  • 91 K75S
Glenn,

Offline Laitch

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Re: K75S won't shift down easliy
« Reply #13 on: December 11, 2015, 03:24:50 PM »
You're on the right track. Shifts need done assertively instead of with a light touch. Performed like that, shifting should be smooth throughout the range.
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  • Along the Ridley in Vermont.
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Offline rbm

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Re: K75S won't shift down easliy
« Reply #14 on: December 11, 2015, 05:29:15 PM »
Is your gear shift lever solid?  Or is there up-down play in it?
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Offline gmawby

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Re: K75S won't shift down easliy
« Reply #15 on: December 11, 2015, 08:45:32 PM »
Hi,
yes the gear shift is solid as far as I can tell. 

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  • Sydney
  • 91 K75S
Glenn,

Offline Laitch

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Re: K75S won't shift down easliy
« Reply #16 on: December 11, 2015, 08:52:04 PM »
Go forth, shift and downshift with vigor, Glenn, then please report back.
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  • Along the Ridley in Vermont.
  • 1995 K75 102,000 miles

Offline gmawby

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Re: K75S won't shift down easliy
« Reply #17 on: December 29, 2015, 03:34:27 PM »
Hello,
I've been forth and shifted with vigour and I'm not happy.   I rechecked the clutch adjustment and it is as per the manual so I'll take it apart and check my work.

Happy new year to you all.

Glenn.
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  • Sydney
  • 91 K75S
Glenn,

Offline Laitch

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Re: K75S won't shift down easliy
« Reply #18 on: December 29, 2015, 04:01:03 PM »
Still the 4→3 and 3→2 downshift stubbornness, eh?

Thanks for the feedback, Glenn, and happy new year to you, too. Please let us know what you come across when you take it down.
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  • Along the Ridley in Vermont.
  • 1995 K75 102,000 miles

Offline gmawby

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Re: K75S won't shift down easliy
« Reply #19 on: December 29, 2015, 06:32:06 PM »
Yes,
down shift stubbornness :(
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  • Sydney
  • 91 K75S
Glenn,

Offline johnny

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Re: K75S won't shift down easliy
« Reply #20 on: December 29, 2015, 06:49:11 PM »
greetings...

i find it easier to downshift when taching above 7 thousand rpms... generally in the 7 thousand to 8.5 thousand sweet spot...

j o
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Offline gmawby

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Re: K75S won't shift down easliy
« Reply #21 on: December 29, 2015, 08:39:08 PM »
Jonny,

you are pulling my leg or I am  riding this bike wrong!   When I'm at the legal limit on the freeway (110 km/h in NSW Australia)   it is nowhere near 7 thousand on the tacho. 

You raise an interesting point.  I had a 250 Honda twin that red lined at 13.5 K and I'd spend my time riding at 8K + rpm.  When I got the BMW I "slowed down" in a psychological way , thinking 750cc , loads of torque, smooth and effortless etc. On my daily ride to work (legal speed 60Km/h) I'll do most of that in 4th gear.   I probably need to reset my thinking or buy a Royal Enfield :)



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  • Sydney
  • 91 K75S
Glenn,

Offline The Mighty Gryphon

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Re: K75S won't shift down easliy
« Reply #22 on: December 29, 2015, 08:52:26 PM »
 :mbird  60kph is 2nd gear country, maybe third.   You'll get used to it.  Saves a lot of wear and tear on the toe of your left boot...
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline gmawby

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Re: K75S won't shift down easliy
« Reply #23 on: January 09, 2016, 09:47:09 PM »
Hi everyone,
The gear box is out and on the bench. I've checked the splines and they still have Optimol paste on them, they look to be in good condition , no broken splines etc. Same for the splines on the clutch and drive shaft/final drive.  Checked the clutch alignment with an alignment tool and it fits snug. I've re-read the workshop manual and it says:   lubricate the splines AND the end of the push rod.  I did NOT lubricate the end of the push rod, in-fact  last time  I cleaned it before I put it back together.  Other observations: there is no oil in the clutch housing so seals are good. The rubber boot on the back of the clutch has split and needs replacing.

I'm in two minds whether to measure/replace the friction plate since it's in bits.  Opinions and suggestions most welcome.

Glenn.
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  • Sydney
  • 91 K75S
Glenn,

Offline Martin

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Re: K75S won't shift down easliy
« Reply #24 on: January 09, 2016, 09:58:53 PM »
Glenn at 140,000 Ks I had to replace my slightly weeping rear main seal, so I thought I might as well replace the clutch friction plate as well. I had to special order the clutch plate. Once I had it all stripped down I found there was very little wear, but seeing as I could not return it, I replaced it anyway. Standard thickness is 5.05 to 5.55 mm service limit is 4.50 mm as per Haynes Manual.
Regards Martin
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  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.
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