Topic: Right turn jerking - transmission likely

[70CB750]

This is something new she just developed.  First time it was on Monday morning commute.  I downshift for a right turn all the way to second, make the turn, accelerate and suddenly there is a jerk in rear wheel.  It felt like the clutch slipped just a fraction or the hub hit the bottom of the torque cushion.

Going home on  Monday, it happened again and it was after right turn in second again.  This morning I was able to reproduce it only once but right turn again.

The clutch feels/works well, the oil needs 100+ miles and change is due (@1500), chain is Tsubaki 5000 miles old and lubed, adjusted and all that jazz.

I adjusted the clutch play at the handlebar, just to try something and it did not make a difference.

Puzzled.

The right turn could mean that I dont corner hard to the left, as off now I am inclined to blame it on hub torque cushion.

Opinions?

[madmtnmotors]

Based on the title of the thread my first impression was to suggest you keep both hands on the handlebars.... 

Right turns are always tighter because of the shorter radius, but it sounds like you could even be getting some wheel slip. Check the road conditions for sand/gravel and check the tread depth too, although it sounds like you maintain your bike pretty well, so I doubt you're running "smoothies". 

[70CB750]

LOL!  Oh well, that's SOHC4 forum. 

Tires are quite new, but there was no slip between tire and the road, it was definitely somewhere in the drivetrain.

[Terry in Australia]

That's interesting mate, you said your chain is good, so how are the sprockets, were they replaced with the chain? How are the sprocket shaft bearings? Also, have you ever checked your primary chain slack? You are probably wondering what drugs I've been taking, but bear with me.

My Suzuki GS1000 has a gear primary drive, but the "Achilles Heel" is the clutch is mounted directly onto the driven gear, and after awhile the rivets that hold the clutch hub to the gear get loose, and apart from lots of clutch rattle, the transmission gets all jerky.

I replaced the hub with one that's been re-riveted, and the transmission is "snatch free". If the primary chains are really stretched, the transmission can get a fair amount of snatch in it too?

Finally, staying with the bearing theme, how are your swingarm bearings and wheel bearings? Cheers, Terry.

[trueblue]

Check for oil leaks that could be getting onto the rear tyre.  I had one a while back that nearly threw me off the bike.  The rear tyre got a little oil on it from an oil pump leak and in a hard right hander the rear of the bike started bucking, I rode it out, pulled up and found the oil all over the rear tyre.  One of the scarier moments on my SOHC.

[70CB750]

Sprockets were replaced with the chain - JT - in good shape now.

I just checked and there is no oil mark anywhere on the rear tire(tyre:)) 

I wanted to take out the old transmission saver out, guess I will pull the wheel and have a look. 

[Dream750]

Sounds like something is shifting around a bit in the swingarm area when on/off throttle. As a minimum, I would double check the rear suspension mounting hardware. This would include upper & lower shock fasteners, rear axle nut and swingarm pivot shaft nut inspection for the proper torque. 

[Cqyqte]

When was the last time you checked the rear drum brake shoes?  It could be brake dust causing the shoes to drag on a right turn, which could be interpreted as slipping or dragging.

[DJ_AX]

... swing arm bushings?

I would check everything lol

[Johnie]

I will agree with the swingarm bushings. I had the same feel of a "slip" and it did not happen all the time. Was bad bushings in the K1. Put the bike on the center stand and check the left / right free play in the rear tire.

[Henning]

Could be inside the gearbox - worn or rounded dogs on second gear or bent selector. You say you were accelerating in second. That's what mine felt like when I had the problem, a momentary jerk. Maybe it was just coincidental that it only happened on right handers.

[70CB750]

Swing arm bushing is tight, now new, but tight.  On the center stand I can move the whole bike jerking the swingarm but there is no (sideways) movement between the swingarm and the frame.

[750K]

Check the torque on the swingarm nut and bolt, my wife's bike did a weird rear end wobble when we first got it running. It only did it entering into left hand turns, turned out the swingarm bolt wasn't torqued down properly by a PO as far as I can guess. It solved the problem imediately.

[Magilla]

Enter it in NASCAR they only turn left

[CrankyOldGuy]

Did you check the spokes?  I had them loosen up once.

Harry O.

[scottly]

Try putting the bike on the centerstand, with the left side on a 2x4, so the bike is leaning to the right. Run the bike in 2nd gear, and see if you can cause the "jerking". You might try dragging the rear brake to simulate load. Was there any noise when it happened before?

[70CB750]

Thanks guys, here is more input:

Yesterday it happened on a left turn too.  There is no noise in the transmission, no grinding I could feel.  I took the wheel off yesterday - to remove the tranny saver - and everything was tight and safe.  Including chain, the axle nut, swing arm has zero play.

This jerk does not happen when I drop the hammer in the second half of the turn, typicaly I am already straight up after the turn when it comes.  It really feels like the torque cushion letting go 15 degrees, but the torque cushion is tight and good.

I will try to test it in second going straight, it should not be influenced by the turn, just the tuirn makes it more likely.

Also this is the first time I am running Delvac oil and the service interval is almost over, maybe it is related to the oil flow in the clutch.

[70CB750]

It is getting more common, but only in second.  Must be transmission related, is there any danger of catastrophic failure - like transmission lock up?  I would not expected that - meanwhile I am trying to avoid situations that cause it.

[dave500]

is it the transmission about to slip out of gear?but sort of changes its mind?

[70CB750]

Feels like slipping and catching itself after half of a shaft turn. 

[dave500]

yeah??,its starting to jump a gear,,if you are under power heavily and it does this and manages to slip out once or twice it will bend the fork and or wear it and the gears groove where the fork lives.

[70CB750]

Thank you, Dave!

[dave500]

if its starting to wear and jump it wont matter if your doing a left or right turn,,itll do it straight ahead under solid power.

[70CB750]

The way it happens now is only when I downshift to a turn.  If I go 5-4-3-2 and turn, than it happens 100% when accelerating.   If I go 5-4-3-2-N and coast to the turn and than shift 2 and accelerate, it never happens.

[trueblue]

I would guess that it has some wear in the selector drum which is allowing the dogs to not mesh properly when downshifting.  When you go to neutral and back it is working the selector differently and engaging the dog properly.  If you allow it to continue it will get worse and more expensive to fix.