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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: 2000rsv on February 16, 2013, 02:43:32 PM

Title: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 16, 2013, 02:43:32 PM

Well, I picked up an '86 K75C last summer and my son rode it around a bit.  Only has 21,600 miles on it.  Getting around to doing a spline lube and I found this on the drive shaft.  Sorry about the bouncy video.  Was using my HF Centech Inspection Camera.

(http://2000rsv.smugmug.com/Other/BMW-K75C/i-HcVhJqH/0/M/Drive_Splines-M.jpg) (http://2000rsv.smugmug.com/Other/BMW-K75C/23796500_9XkCnp#!i=2367709356&k=HcVhJqH&lb=1&s=A)

OK, how screwed am I?

New (per MAX BMW website) is $400.  From searching on here Bruno rebuild is $800. 

Suggestions?  Recommendations?

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 16, 2013, 03:51:15 PM

Those are pretty worn.

Splientology (http://www.motobrick.com/index.php/topic,490.0.html)

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 16, 2013, 05:02:29 PM

I have read thru the Splinetology several times.  Looks like I am out $400.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: Scott_ on February 16, 2013, 08:48:40 PM

Consider yourself lucky, you are home, in controlled conditions.
Better than on the side of the road, in the middle of who knows where......spending how much more to get it home......

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 16, 2013, 08:57:02 PM

Quote from: Scott_ on February 16, 2013, 08:48:40 PM

Consider yourself lucky, you are home, in controlled conditions.
Better than on the side of the road, in the middle of who knows where......spending how much more to get it home......

Or 1,600 miles from home at a gas station in Pipestone, MN. (Clutch splines.)

(http://home.comcast.net/~smithduck/tours/bmw5/bmw5album/slides/bmw5_2538.jpg)

Still beats crashing though.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 12:01:06 AM

Haven't gotten to the clutch yet.  Have the swing arm off and removed the drive shaft.  Splines on the xmission output were still wet with lube and looked brand new.  That's good.  Hoping to do some work tomorrow on getting the transmission off so I can look at the clutch.

There is a sensor of some kind on the rear of the transmission.  It is round with two wired coming out of it.  Is this the neutral switch?  It appears to be cracked.  However, the neutral light never had a problem coming on nor did I have trouble starting due to it not being in neutral.

Few questions about this sensor (looked it up on Max's - $106.00 - ouch)
1: What does it do?
2: Should I leave it alone or clean it up and fill the crack with RTV?
3: Should it be replaced?
4: Can I jumper the two wires to bypass it if I needed to?

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: motodude on February 17, 2013, 12:19:41 AM

Quote from: Scott_ on February 16, 2013, 08:48:40 PM

Consider yourself lucky, you are home, in controlled conditions.
Better than on the side of the road, in the middle of who knows where......spending how much more to get it home......

Casper, WY.  Then the tow-truck strap breaks on the way to the Honda dealer (bike falls over on the truck).  Then it takes two days to get a new drive shaft from Denver (final drive splines were, "good enough" given brand-new drive-shaft splines).  Good times.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: Qdude on February 17, 2013, 05:00:09 AM

I believe that device is the gear position sensor for the dash indicator.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: billday on February 17, 2013, 08:56:06 AM

Yes it's the gear position indicator switch. If it's working leave it alone, no need to take it off the tranny for any of the work you're doing.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 09:27:44 AM

OK, Thank you.  If the gear indicator quits working, it isn't that big of deal (at least not $106 big).  None of my other bikes have ever had one.

OK, let's what surprises today brings as I tear into it further.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: Inge K. on February 17, 2013, 09:47:23 AM

Quote from: 2000rsv on February 17, 2013, 09:27:44 AM

If the gear indicator quits working, it isn't that big of deal

If it quits working, you need to pull the clutch to start.
Some have cleaned the switch housing, and covered the whole housing outside with silicone sealant......

Inge K.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 09:59:21 AM

Ahh, so it is the neutral indicator for the starting logic also.  That makes a difference.  Will likely leave it alone.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 17, 2013, 10:26:06 AM

The circuit that lights the N indicator sends power to the start button.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 11:01:00 AM

Quote from: frankenduck on February 17, 2013, 10:26:06 AM

The circuit that lights the N indicator sends power to the start button.

Does that circuit include this transmission sensor?

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 17, 2013, 11:05:01 AM

Gear Position Indicator (GPI) (http://www.motobrick.com/index.php?topic=517.0)

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 02:38:16 PM

OK, kept digging into the bike and found the transmission input and output splines to both be in great condition. :2thumbup:

Was having some clutch slipping last fall so I was going to see what the clutch looks like.  Was worried the O-Ring went out and got the disc wet or something.  Not so.

Having never worked on a BMW style single disc clutch before, I still feel this clutch friction disc is in sad shape.  Measuring the thickness in various places, it went from 0.174 to -.185 inches (don't have a metric micrometer).  Manual says anything under 0.177 needs replaced.  Therefore, it's gone.

Interestingly, the rear cover has rust all over the outside.  Coupled with that, the friction disc surface looks strange.  Almost like there was water in the clutch area (perhaps condensation).  Any input?

The O-Ring looks in good shape but I will be replacing it anyway since I am already in there and it is likely 27 years old.

Got to say, clutches on Japanese machines are a whole lot easier to deal with.

The clutch disc:
(http://2000rsv.smugmug.com/Other/BMW-K75C/i-rX4wCvS/0/M/P1000687-M.jpg)

Close up of clutch disc:
(http://2000rsv.smugmug.com/Other/BMW-K75C/i-xcMjRZ2/0/M/P1000690-M.jpg)

Transmission input splines:
(http://2000rsv.smugmug.com/Other/BMW-K75C/i-nZsMvsk/0/M/P1000681-M.jpg)

K75 feelings particularly naked:
(http://2000rsv.smugmug.com/Other/BMW-K75C/i-MKHmHkq/0/M/P1000677-M.jpg)

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 17, 2013, 02:51:30 PM

If the bike has spent a lot of time in a wet climate then water vapor gets in the bellhousing so it's not uncommon for the rear pressure plate to have some rust on it.

Yes, 0.177" is the wear limit for k bike clutch plates.

Good idea to replace the O-ring while you have the clutch off. :2thumbup:

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 02:57:35 PM

The fiche from Max's calls out the clutch housing main nut as a one use item, as well as the spacer between the nut and the O-ring.  It also calls out to replace the 6 clamping cap screws and star washers.

The nut is a specially deformed nut to stay locked on the shaft.  I could see replacing that (maybe).  The spacer between the nut and O-ring?  That's ridiculous to replace that.

The cap screws?  I'm going to re-use.  The star washers?  4 of them were broken anyway.  Will replace from the local hardware store.

Let me know if I am on the wrong track with these decisions.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 17, 2013, 03:12:25 PM

I've re-used all of the hardware on several bikes with no issues.

You might want to consider using hex head bolts for the six bolts.  Will make them easier to get off next time.

I put some grease on the three rods and use anti-size on the 6 bolts to make it easier if I have to go in there again.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 03:23:17 PM

Just ordered all the parts from Countryside BMW and saved over $100 with the Motobrick discount code.  You rock!!

Now, I hope I will not have to 'save' this much money in the future.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 17, 2013, 03:27:50 PM

What code did you use?

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: 2000rsv on February 17, 2013, 03:36:41 PM

Promo15.  Tried Promo20 but it came back as expired.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 17, 2013, 04:47:27 PM

Thanks.  I may need to order some parts soon.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: pallum on February 18, 2013, 10:29:50 PM

M7-1.00 x 25 hex head bolts from Lowes replace the 6 clutch housing bolts. 15k miles and holding.

Title: Re: Oh CHIT - Lack of Spline Goodness
Post by: frankenduck on February 18, 2013, 10:43:31 PM

Quote from: 2000rsv on February 17, 2013, 12:01:06 AM

There is a sensor of some kind on the rear of the transmission.  It is round with four wires coming out of it.  Is this the neutral switch?  It appears to be cracked.  However, the neutral light never had a problem coming on nor did I have trouble starting due to it not being in neutral.

Few questions about this sensor (looked it up on Max's - $106.00 - ouch)
1: What does it do?
2: Should I leave it alone or clean it up and fill the crack with RTV?
3: Should it be replaced?
4: Can I jumper the two wires to bypass it if I needed to?

1: Click here:  Gear Position Indicator (GPI) (http://www.motobrick.com/index.php?topic=517.0)
2: Worth a shot if your gear LCD in the cluster still works properly.
3: If 2 doesn't work.
4: Just pull in the clutch to start the bike. (Provided the clutch switch still works.)