Driveline Snatch & Stalling

[PEPPERONI BROS.]

When I took my prospective V11 sport out for it's 100 mile test drive last weekend, the only negatives that I noted were, A] a fair ammount of driveline snatch off and on the throttle and B] stalling when coming to a stop, especially on an incline. Is it possible to dial some or all of that snatchiness out? Any ideas on the stalling? Things That a potential V11 owner should look for? Thanks, Tom

[Steve G.]

Well, as those more knowledgable on this forum/site have taught me, something as simple as a valve tappet clearance being too tight can be the main problem with the stalling problem. My bike stalled, so I loosened up the clearances to "euro spec" and now it doesn't.

The drivetrain lash I am assuming was/is an issue. It never was for my '01 V11, but when I took the bike in for the infamous world recall on the gearbox, not only was the gearbox nicer shifting, but it had no lash present. Whether or not this machine you are looking at is an early one which would fall under this call, I would not know. I do believe the recall still stands even on second hand bikes out of warranty, as it is something of a safety issue should the rare occurance happen and the offending gear sleeve crack, locking the rear wheel.

Ciao, Steve G.

[Guest Jeff Kelland]

Steve's right. Open the valve clearance to at least .006 in. and .008 ex. The stalling issue should disappear. Driveline lash concerns are likely your inexperience with the bike. It took me 1000 to 1500 miles to "learn" how to shift it smoothly. The best advice I ever got was, "put a couple of thousand miles on it and see how you feel about it".

[Guest Bruce]

Me too! Even with tons of experience there seemed to be a learning curve to riding an MG smoothly. Now it all seems like second nature.

 

Also, a fully broken in and properly tuned bike may be a factor as well. A while back I swapped with a K-bike rider. Truth be told I wasn't all that impressed with the BMW but my friend was grinning from ear to ear. "What a gas", he said.

 

My bike is in for the transmission upgrade right now and MGNA had kits on the shelf. For what its worth the bike shifts beautifully. It got noticably better after 4k miles and the shift linkage, although well designed and of quality parts, was poorly set-up.

[PEPPERONI BROS.]

When I took my prospective V11 sport out for it's 100 mile test drive last weekend, the only negatives that I noted were, A] a fair ammount of driveline snatch off and on the throttle and B] stalling when coming to a stop, especially on an incline. Is it possible to dial some or all of that snatchiness out? Any ideas on the stalling? Things That a potential V11 owner should look for? Thanks, Tom

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Thanks for all the advise, the tight valves make sense, I thought that motor was too quiet!

[Guest WildJackal]

Break in. These bikes run so much better one they are broke in.

[twhitaker]

The driveline snatch will likely never go away but it can be minimised with technique. It seems that the final drives in these machines have a little more gear lash than the older drives. The six speed gearbox has an additional shaft which results in another gear mesh and more lash.

[Guest ratchethack]

When I took my prospective V11 sport out for it's 100 mile test drive last weekend, the only negatives that I noted were, A] a fair ammount of driveline snatch off and on the throttle and B] stalling when coming to a stop, especially on an incline. Is it possible to dial some or all of that snatchiness out? Any ideas on the stalling? Things That a potential V11 owner should look for? Thanks, Tom

37279[/snapback]

 

FWIW - After much thought and effort on this, my take is that however annoying it may seem, the actual amount of driveline snatch in the 6-speeders is actually small, about as limited as it can be. I found a few contributing root causes that exacerbate the perception of driveline snatch that can be dealt with, to the point that "feel" and operation are greatly improved.

 

The straight-cut constant-mesh gearsets in the box, and the pinion and crown-wheel set in the final drive are not contributing factors unless the bevel box is substantially worn out and not properly shimmed. I suppose a badly worn clutch hub and/or worn splines would also be factors. Contributing factors on low-mileage machines seem to be limited to the angular rotation "gap" between the shift dogs themselves, and the "flex" provided by the cush-drive. Both, though not very significant IMHO, could be reduced with extensive custom engineering efforts, but my take is that the resulting trade-offs would be neither pleasant nor advisable (hard shifting and the addition of unwanted, destructive, and potentially dangerous shock to the driveline, respectively).

 

When I purchased my '00 Sport (18 months and 10K miles back), I went to work on the annoying "bucking" that tended to upset the chassis in high-speed sweepers in gradual off-on throttle transitions - what I believe is most commonly mis-perceived as driveline snatch. As mentioned above, opening the valve lash to .006 and .008 immediately helped a great deal (along with providing other benefits, including virtually eliminating stalling at idle). Adding a PC III helped even more. The last thing I did reduced overall perception of driveline snatch to the point where I hardly notice it.

 

That was to convert the throttle from a 1/4-twist to 1/3-twist to provide a more gradual and progressive throttle control, allowing much finer control at low throttle opening angles. The way I accomplished this was to 1. Make sure the cable end at the twist grip was set in the least aggressive of the 2 available positions (it already was), and 2. Fabricate a custom throttle-body cable-end "cam" with a much "easier" and more progressive profile than the stock piece.

 

The progressive 1/3-twist throttle is much more forgiving. It's been one of the most effective modifications I've done, providing a smoother, far more relaxing and rewarding riding experience overall. As far as I'm concerned, racing "wall switch" 1/4 twist (or less) throttles have no place on these machines outside the track.

[Guest RossGuzzi]

Ratchethack,

I`m very interested in how you made another cable end cam. I have herd/thought about doing this, any chance of a photo-sketch-tech drawing? I`m sure there might be others who could benifit as well. Well done!

Cheers,

Ross.

[Guest ratchethack]

Ratchethack,

I`m very interested in how you made another cable end cam. I have herd/thought about doing this, any chance of a photo-sketch-tech drawing? I`m sure there might be others who could benifit as well. Well done!

Cheers,

Ross.

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Ross and Al, the first shot below is the throttle cable cam I made out of 1/4" plastic. It took a fair amount of trial and error, and I tried & tested a few cam contours. This is the one I like best. It increases the OEM cam radius from throttle-shaft center to cable at idle by 18 mm, while keeping the radius at WOT (wide open throttle) the same as OEM. The second shot is the OEM throttle cam on top of the custom one with the shaft holes lined up to illustrate the differences.

 

Try it, I bet you like it

 

Jaap, thanks again for your help!!

 

 

Edited November 23, 2004 by ratchethack

[Admin Jaap]

Send the picture to me. I'll post it for you.

 

info at v11lemans.com

[Guest ratchethack]

Send the picture to me. I'll post it for you.

 

info at v11lemans.com

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I already did, Jaap - per instructions yesterday and the day before. No response

[al_roethlisberger]

I am very interested in this modified cam as well. I would appreciate a slightly milder throttle transition as well.

 

...although I also thought that someone had sourced a milder grip cam from the vendor(Domino??).

 

al

[Admin Jaap]

I already did, Jaap - per instructions yesterday and the day before.  No response

37708[/snapback]

 

It didn't arrive... maybe my spam filter... could you try jaap at veldhorst.nl, please?

[Guest ratchethack]

I am very interested in this modified cam as well.  I would appreciate a slightly milder throttle transition as well.

 

...although I also thought that someone had sourced a milder grip cam from the vendor(Domino??).

 

al

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Al, see photos inserted in previous post courtesy of Jaap (thanks again, Jaap!) If I remember correctly, there's a larger radius plastic throttle-end cam available somewhere that fits, but it has a constant radius that doesn't allow WOT because there isn't enough cable travel available at the grip end. The progressive profile I used works great.