Slop in drive train

IanC

Guest
Mine seems to have developed a nasty slop, possibly in the drive-shaft, at about 600 miles (now on 1000). The dealer (CW) also noticed it at first service (750 miles), but is waiting to try another customer's bike for comparison.

Not really my problem (hopefully!), but the dealer is none the wiser as the BMW technical chap is away till the 16th. I'm planning on a 4000-5000 mile fortnight's tour starting later next week. Just wondrered if anyone's and ideas, or had a similar problem? I appreciate it's all warrantied etc., but I'll be more than slightly p****d off if it breaks down part way through my tour. No amount of warranty and/or BMW recovery can compensate for that. Also, it's not nice on a "brand new" bike feeling that things are not what they oughta be!
 
Noticed it up here as well, doesn't seem to a problem at moment
 
Any idea excatly where the problem is - in the shaft joint, or gearbox? I can't pinpoint it. And not sure whether it's a general problem, or just a few bikes.
 
Can you explain please in more words what the problem is? :)

My english fail me more and more.

I just don't understand what you mean by slope in drive train. Anything that can be photographed at least?
 
NLS more words

NLS
Slop in the drive train,(gearbox to rear wheel) is exess movement betwean gears /bearings/, causing a similar sensation when riding to riding a chain driven motorcycle with a very loose chain
hope this makes it easier for you to understand
Trev
 
aha!

I noticed this on the second test ride I took... I am not sure if it was there in the first test ride too

I notice it when going to 1st gear from stop but I am not sure I felt it for other gears

I couldn't pinpoint where it comes from too...
 
Slack in Drive Line

I have also noticed a significant amount of slack in the drive line.

It is not in the rear bevel drive, but seems to be at the output end of the gearbox.

If you put the bike on the main stand so that the rear wheel is off the ground, engage first gear and rock the rear wheel backwards and forwards whilst feeling the front drive shaft joint through the rubber boot, it seems to move exactly in unison with the rear wheel. i.e. slack is not in bevel drive.

I have tried to quantify the amount of slack movement, and would like to know how it compares with other bikes.

I have measured the free travel in the rear wheel whilst rocking backwards and forwards as before, and on my bike it is 2.5". (in christian units). This seems rather a lot of slack.

I would be grateful if others could measure movement on their bikes so I can get a feel for how bad mine is.

Mentioned it to the dealer at first service but mechanic says everything is normal.
 
They're gonna change it

Just been to dealer's today so's the BMW-GB chap (Howard?) could ride my bike. It now has 5600 miles on the clock, and unsurprisingly the "slop" problem hasn't gone away, although I have actually got more used to it.

Upshot of it is that they've ordered a new final drive, supposedly arriving from Germany Friday and being fitted Saturday. Meanwhile I'm on a 650GS loan bike, which seems very cramped! Better to have one fitted before it goes, but I hope the new one's an improved version, as I don't fancy having one fitted every 6000 miles! There seem to be a few reports of similar on www.advrider.com.

I'm a bit racked off that the bike needs work after so few miles, but what really p****d me off is that I asked them if they could do a 6000 mile service while it was there (all week), and they were unable to help. The dealer's 70 miles away, so I've spent a day today and will spend another half-day picking the thing up, and then another day hanging around about a week later! 2-3 days in a fortnight. As a result I'm thinking of doing my own servicing in future, which BMW tell me won't invalidate the warranty, although it does need to go on the dealer's computer and have an "ABS bleed-test", so maybe they've got me by the short-and-curlies anyway? Not sure how long/how much this procedure takes/costs?:p1zzed:
 
I've measured the slack and have approx 2.5 inches. only 650 miles on the clock so far so assume it is supposed to be there. I don't notice it while riding.
Regards
 
After asking them to supply a Workshop manual if they were unable to do a service, the dealer will now fit it in after all.....

I'll measure my slack when it comes back - afraid I didn't before it went in.
 
On the other hand, having been the top mechanic at a Yamaha/Suzuki shop many years ago, I can offer that (what we called) "ungeared motion" or "drivetrain slack" at the rear wheel for many motorcycles is often in the same neighborhood that folks are seeing in the new GS. So, the fact that there is some driveline slack should not in itself be a cause for alarm.
 
It was more the "clunking" noise than the actual slack that alarmed me (and the dealer). If it was a chain drive you'd have tensioned it pretty urgently!
 
Philip said:
I've measured the slack and have approx 2.5 inches. only 650 miles on the clock so far so assume it is supposed to be there. I don't notice it while riding.
Regards
Click to expand...
Can you explain in which direction you are getting 2 1/2" of slack as that seems unbelievable. Is that circumfrentially (spelling!!), of wheel movement??


AndyT :(
 
yes, it's the forward/backward movement measured at the circumference - i.e if you were to take the bike off the stand and roll the bike forward and backward while in gear, it would move about 2.5 inches. I have no side to side movement in the wheel at all.
 
I've got 2" of play, and my R12GS has 8,650 miles on it. I think that number is fine. The reason I say that is that I also have an FJR1300 with 27k miles and it shows 1.75" of play. Seems reasonable to me.
 
Er...........

............don't want to worry you guys, but I noticed increasing & excessive driveline 'slack' in the days before the 'Nordkapp Incident'...........

Related perhaps.........?

Dutch
 
Another 10 days !!!

CW phoned this morning to tell me that new drive will be another 10 days getting into the country! Never mind about fitting, inevitable delays, etc. That's after BMW's own man (Howard) organised it last Tuesday (8 days ago), and said it would be coming to the dealer's on Friday, for a Saturday fitting.

Perhaps they can't make the drives fast enough to keep up with demand? Or, maybe wishful thinking, but could they be coming up with an improved unit? I don't mind waiting if that's the case.
 
The 'slack' you're seeing is a multiplication of the spacing between the engaged gear dogs on the gear faces.
If it didn't have 'slack' you wouldn't be able to change gear so easily.
The bigger the gear cog diameter, then the choice is either more dogs or more 'slack'.

The fact that there is movement at all is good. You can only determine a difference between similar machines.
Designers choose the movement allowed and any difference can only be something lke a mis-machined or missed off gear face dog
- or excessive play in one of the 90 deg bevel gear sets - which is unlikely as it would be unbelieveably whiney.

8 thou of pinon/gear clearance ( rear wheel bevel gear) would give you about 3/8" movement at the outside of the tyre staightaway.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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