Drive shaft backlash, ya know clunk cluck :)

[Jmyd56]

Hello all. My fist post. ST1300 ‘04 rider.
My ride is not feeling as smooth as it should. I have drive shaft backlash, at least that how it feels. Very noticeable when shifting gears or when I’m on and off the throttle. Has anyone else out there experienced this? TIA!

 

[dduelin]

Only when the bike was new to me. There is always some gear lash in a transmission then the ST adds a little more in the drive shaft splines and final drive gear set and splines. If the bike is new to you concentrate on smooth on/off throttle inputs and fan or slip the clutch a little to soften the throttle inputs. This ST was designed in the first generation of PGM-FI fuel injection and the injectors go dry on closed throttle. Upon opening throttle the fueling begins but the ramp up is steep. Slipping the clutch a minute amount upon a closed throttle roll-on changes the throttle application input from a stair step to a gentle slope.

How many miles on the bike?

 

[Bmacleod]

As @dduelin posted, this is the most common explanation for perceived excessive driveline lash. Also, check that a brake isnt dragging as this will exaggerate any lash, excessive or not. With mileage and age, the rubber drive "cushions" in the rear wheel become suspect. I changed mine in my '05 and noticed a "tighter" rear drive because of it. As you ride the bike more, concentrate on smooth throttle application and the driveline lash should seem better, assuming no mechanical issues.

 

[Andrew Shadow]

Check your throttle cable adjustment as well. To much free-play exaggerates the sensation of backlash in the drive-line. Reduce it to between 1/16" and 1/8", the least that you can get away with while not having the throttles be operated when the bars are moved left and right from lock to lock. This will give you smoother throttle control.

 

[rdmnt2002]

Hi Jmyd,

Especially with shaft driven motorcycles, you can’t open and close the throttle rapidly without causing drive train lash. Unless you are exceptionally smooth going from open to closed throttle, you have to feather the clutch during that transition if you don’t want any lash.

Hope that helps,
Ray

 

[jfheath]

When changing up a gear, raise the revs slightly and let the clutch out a little more slowly until you feel the engine pulling again - once you do, you can let the clutch out fully and start accelerating as fast as you want.

The same applies if you have been slowing down and then need to accelerate again. No need to change gear or use the clutch - just apply the throttle gently until you feel it turning the back wheel again

In the slow down- speed up scenario, it can help to use the brake pedal. The brake keep the engine pulling on the rear wheel, so that it doesn't get chance to go faster than the engine is pulling - which is what creates the slack.

Its always a good idea to feel that you have got drive at the rear wheel, before you need to use it. That way you spot the odd occasion when you have slipped it firmly into neutral. It's always a crowd pleaser, that trick. You rev the engine to pull away. The engine races to the red line 'cos it is in neutral. Everyone around looks to see what is happening. Just in time to see you perform a pratt fall onto your side.

Get rid of most, but not all of the throttle cable slack.

Put a pillion on the back. You'll know when you are getting it right. You won't be banging heads.

 

[vstrom.zrxdude]

I end up changing my cush drive rubber blocks about every 40,000 mi I take off kinda fast and am a fat ass.only about $25.00 for parts.Keeps bike feeling fresh

 

[RaYzerman]

The other thing I would do at some point is pull the rear drive and the U-joint, check the U-joint and grease up the splines..........

 

[Jmyd56]

All great stuff guys thanks! Riding is down for a few days rain coming for the weekend

 

[Bmacleod]

All great stuff guys thanks! Riding is down for a few days rain coming for the weekend

Why not pop it up on the center stand, put it in gear and measure how much driveline lash there is.

 

[Sadlsor]

Just as an aside, I routinely try to shift such that even I can not feel the transition from one gear to the next. Sometimes I wish I had a passenger to appreciate it. (Roz, are you listening?)
This practice results in smoother shifting even when I'm not trying. I know, it sounds pitifully obvious.
Still, I continue to be amazed - and pleased - at just how doggone smooth these V4 engines can be.

 

[OhioDeere]

Just as an aside, I routinely try to shift such that even I can not feel the transition from one gear to the next. Sometimes I wish I had a passenger to appreciate it. (Roz, are you listening?)
This practice results in smoother shifting even when I'm not trying. I know, it sounds pitifully obvious.
Still, I continue to be amazed - and pleased - at just how doggone smooth these V4 engines can be.

When the drive line components go bad, you won't know until you relax the torque going to the wheel to make slack in the shaft. During shift and torque always to the wheel it will feel normal.

I have same issue currently. Plan to take it apart and replace the u-joints, cushions on wheel, and inspect. Its a deal to get that apart so might as well replace the "moving parts and seals" while I'm there.. 120,000 miles.

 

[DavidR8]

Along with checking all of the things mentioned above the one thing that really helped on my 05 was to install a Throttle Tamer. It’s a replacement throttle tube which has a shallower ramp at the beginning which slows down the throttle opening at the beginning so that it’s easier control at low speeds.

 

[dduelin]

Saddle time will take care of it.

 

[vstrom.zrxdude]

Cush drive hub bearings also can fail.converted my bike to roller brg many miles ago, kinda makes area more bullet proof