Stuttering over corrugations/braking bumps

[VicAdv'er]

Hi All, first question here so i'm hoping it's in the right place.
I'm not sure that this is an issue, maybe just a characteristic of this bike.
When I ride offroad, I always turn the TCS off. Every time I ride over corrugations, braking bumps or even small pot holes with the TCS turned off, the bike stutters/cuts power as if the traction control is activating. The TCS dash light is illuminated indicating it is off, it doesn't flash or anything when this stuttering happens. I've tested each TCS1, TCS2 and off and the TCS is working correctly.
It doesn't seem to do this riding in and out of larger holes/bumps, seems to only occur on the short-sharp-repeated ones.
Any tips on what this could be? Or is it just a trait of the bike. It annoys the hell out of me.

 

[gunslinger_006]

That sounds like a loose battery connection or some other electrical issue that is expressed by the bike being shaken.


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[VicAdv'er]

Thanks gunslinger, battery terminals are tight and i've looked over most of the electrical connections but i'll keep digging.

I'm assuming this is not normal then.

Edit: My initial thoughts were that it was a trait of the shaft drive. Not sure.

 

[Sierra1]

She does have a touchy throttle. There not a lot of wrist movement between off, and WFO. Are you sure that it's just not a case on-off-on-off-on. . . . throttle.

By the way. . . . welcome from Texas.

 

[VicAdv'er]

Thanks Sierra1, it's definitely not on-off throttle on my part.
There is a corrugated hill I ride up fairly often and it does it every time, as I'm accelerating up the hill over the corrugations the bike stutters like the traction control is activating. Accelerating more at this point does nothing, the bike stutters until I clear the corrugations and then off she goes!
It's got be stumped. Would the ABS have anything to do with it?

 

[Sierra1]

Maybe? ABS detects wheel lock up, and it might be reading the bumps as lock up. ?? I know that when the ABS on the RT I rode kicked in, the "shaft slap" was horrendous. The ST1300's ABS was totally different. And I haven't locked the Tenere's up yet. . . . so I don't know how it reacts. There's more than a few guys here that know the bike inside & out. They should be piping up soon.

 

[nondairycreamer]

Are you sure it is not the suspension not adjusted to properly respond to those short, sharp bumps? You stated it is not a problem on bigger bumps.

 

[VicAdv'er]

Sierra1, It's interesting that you mention shaft drive slap as an issue on the RT, I wonder if that is what I am experiencing. When my bike is on the center stand in neutral, the drive shaft has a bit of forward/backward play but I it feels normal, not excessive. Is there a way of testing this?

nondairy, I have my suspension set fairly well but I won't disregard any advice. As I have all my settings recorded, i'll make some adjustments and see how it goes but I don't believe it's a suspension issue. I actually loose power/acceleration over corrugations, it feels like the ignition is cutting/retarding out. Similar if not exactly like when the traction control kicks in. The issue isn't just occurring on hills, the bike does it on a corrugated level trail too.

I have installed an ABS switch but haven't tried corrugations with the ABS off yet. I'll do that this evening and see if there is any difference.

 

[VicAdv'er]

Another thought is the Gen1 clutch spring issue? My bike does have the well known shudder that gets reported about these clutch baskets.........

 

[Sierra1]

. . . . I have installed an ABS switch but haven't tried corrugations with the ABS off yet. . . . .

Wow. . . . burying the lead. I'm not saying you installed it in error. . . . but. . . . you've introduced a non OE electrical device into the mix. You also say that the stuttering feels electrical. . . . . the corrugated surface may be outside the device's design envelope. As far as shaft play. . . . what you're describing is normal.

 

[VicAdv'er]

It's real easy to remove the ABS switch, it's just replaces the fuse. I'll try that but I only installed this switch setup a few weeks ago.
I've had this stuttering from day one, I just accepted it thinking it's normal to shaft drive bikes.

Bike has no clutch switch mod and it hasn't been reflashed. CCT has been upgraded to the 2014 model.
So what i'm gathering here is that no other S10 has this stutter over corrugations?

This kind of thing.

 

[Sierra1]

That's a lot of "bump", I'm back to leaning toward the throttle being the issue. I haven't encountered that much "bump" for that distance, but when she starts bucking around. . . . Many on here have flashed their ECUs to smooth out the throttle. I'm an "anti-flash" guy, but, I'm thinking that rough. . . . for that long. . . . your wrist is gonna start jumpin' around. I could be wrong.

 

[VicAdv'er]

That pic is just an example and not my particular rd but it's the same, it's quite common for a gravel/dirt rd to look like that here. Especially in high traffic areas.
They are not whoops like an mx track, they are very shallow 'waves' close together. We call them corrugations but I think it might be refer'd to as 'washboard' there. I have the same issue exiting a corner over braking bumps.
I'm definitely not on-off throttling it, the bumps are that close together it's like 'buzzing' over them but with the loss of power/acceleration.

Thanks for all the ideas. I'll keep digging.

 

[jrusell]

It is not the ABS.
Abs when activated releases the brakes. Since you are steady on the gas and not on the brakes how is it going to give you less than the zero you are already applying? ABS unit will not apply brakes on it's own.

If you look at an exploded view of the tenere driveshaft/transmission you will see there is a spring loaded cam in the driveline just inside the cases where the shaft ends and the direction turns 90 degrees. I would guess this is to lessen impacts to the tranny gears and extend tranny life.
Bigger whoops are very low speed compressions and the suspension is able to keep the tire in contact with the ground with no significant wheel spin.
Sharp bumps like those cause the wheel to lose contact slightly and the resulting wheelspin and inpacts put much more impact into the driveline.
I would guess you are feeling a combination of slight wheelspin and the spring loaded cam is compressing and releasing rapidly which makes it feel even worse.
Also the normal slack in the rear gear may contribute some to this feeling.

I have experienced similar in exactly those conditions and consider it normal for our bike.
Lugging the engine or being low in the rpm makes it feel much worse. I try to stay in a lower gear and keeps the revs up, it reduces the severity.
Depending what tire you have may have an impact as well. A street tire will easily slip more than a knobby would. I would think you would find it less pronounced the more aggressive your tire is.

 

[VicAdv'er]

Thanks jrusell, your explanation is spot on and explains exactly what I'm feeling. I was not aware of the cam setup in the driveline.
I did a few runs over the corrugated gravel rd this afternoon and instead of holding a steady throttle, i wound it on. The engine revs cleanly and there is no stutter or cut out from the ignition. It's definately rear wheel drive that I'm loosing.
Nondairycreamer mentioned rear rebound so I checked the setting and it was 3 out from full. I've backed it off to standard and will go from there. Might be that the rear tyre (E07+) is skipping over the tops of the bumps making the situation worse.
Thanks for everyone's input, i appreciate it.

 

[jrusell]

Thanks jrusell, your explanation is spot on and explains exactly what I'm feeling. I was not aware of the cam setup in the driveline.
I did a few runs over the corrugated gravel rd this afternoon and instead of holding a steady throttle, i wound it on. The engine revs cleanly and there is no stutter or cut out from the ignition. It's definately rear wheel drive that I'm loosing.
Nondairycreamer mentioned rear rebound so I checked the setting and it was 3 out from full. I've backed it off to standard and will go from there. Might be that the rear tyre (E07+) is skipping over the tops of the bumps making the situation worse.
Thanks for everyone's input, i appreciate it.

Yes too slow rebound will not allow the tire to respond quickly enough and it will pack down making things worse. You want it fast enough to be able to respond to the bumps.
Good luck making it better.

 

[Don in Lodi]

All bikes stutter over corrugations that bad. Try leaving it in TC2 and see how it does.

 

[ballisticexchris]

Welcome from California!! You beat me to it Don. I was going to suggest TC2 as well. It's very rare that I have had to turn off TC even in moderately deep sand or silt. The only time I can see turning it all the way off is in terrain that will bury you or steep hills that require a lot of wheelspin to navigate.

It's real easy to remove the ABS switch, it's just replaces the fuse. I'll try that but I only installed this switch setup a few weeks ago.
I've had this stuttering from day one, I just accepted it thinking it's normal to shaft drive bikes.

We get that kind of washboard on the over traveled entry roads to riding areas. I've only ridden mine over that kind of stuff a few times and can't remember experiencing what you have. I suggest to experiment on the same section with leaving the ABS on and put it in different traction control settings and see what changes.

It might be something as simple as a brake pedal adjustment. I know that it's easy to drag the rear brake if it's set too high.

 

[VicAdv'er]

Just a quick update,
I sped up the rear rebound and did a few runs over the same section on TC2 as suggested above. It's definitely improved. I've got more rebound adjustment to play with so i'll do some more testing till i'm happy with it.

Thanks for pointing me in the right direction.