Sportshift 2 jerking at constant speed

[timbals]

Hi All,

I have a V8 Vantage S with Sportshift 2, if I travel constantly at 9mph in 1st or 14mph in 2nd the car jerks continuously every second. Does anyone else have this problem? The dealership have suggested that this is normal for sportshift. If it is how am I meant to travel at 9mph? Sounds ridiculous but that's London traffic for you!

Thanks

[roughrider]

Allow a gap to develop in front of you, then cover the gap, fully engaging the clutch. If you are at a constant speed just as the clutch is half engaged, you get the symptom you describe.

[V8V Pete]

timbals said:

how am I meant to travel at 9mph?

Actually, you might struggle to go that slowly on a decent road bike so try a cheap heavy hybrid instead.

[Neil1300r]

timbals said:

Hi All,

If it is how am I meant to travel at 9mph? Sounds ridiculous but that's London traffic for you!

Thanks

Drive at 8MPH?

[timbals]

roughrider said:

Allow a gap to develop in front of you, then cover the gap, fully engaging the clutch. If you are at a constant speed just as the clutch is half engaged, you get the symptom you describe.

Would the clutch be half engaged at 9mph? It doesn't seem to be a problem at 8mph.

I understand that going slow would be jerky but the constant oscillations seem really strange to me.

Does anyone else experience the same thing?

[JonV8V]

timbals said:

Would the clutch be half engaged at 9mph? It doesn't seem to be a problem at 8mph.

I understand that going slow would be jerky but the constant oscillations seem really strange to me.

Does anyone else experience the same thing?

I can't tell you if its the 7 or 8 or 9 mph but mine is jerky if you slow gradually through that speed. The clutch shouldn't be half engaged - that means its slipping and thats generally bad.

My technique is when stationary, pull away, then when I want to back off I pull both paddles and drop it into neutral in the same way I might drop the clutch in a manual. I can pull a paddle and it will go back into gear to move away.

[hashluck]

JonV8V said:

My technique is when stationary, pull away, then when I want to back off I pull both paddles and drop it into neutral in the same way I might drop the clutch in a manual. I can pull a paddle and it will go back into gear to move away.

+1

[timbals]

JonV8V said:

I can't tell you if its the 7 or 8 or 9 mph but mine is jerky if you slow gradually through that speed. The clutch shouldn't be half engaged - that means its slipping and thats generally bad.

My technique is when stationary, pull away, then when I want to back off I pull both paddles and drop it into neutral in the same way I might drop the clutch in a manual. I can pull a paddle and it will go back into gear to move away.

If I slow through low speeds it is jerky and I accept that, I pull to neutral and then engage a gear if I need to move off again, no problem with that.

I'm not talking about slowing though. If I accelerate to 9mph and stay there at 9mph with my foot steady, it isn't just jerky movement, I get an more deliberate oscillation of power on then off each half second constantly until I make a concerted effort to change speed to flick to neutral to escape it. The rpm needle flicks up and down with this oscillation, and it isn't random like it is when it is jerky when slowing, it seems very deliberate. Quite possibly it is the car trying to engage the clutch every 1/2 second and failing, but I'm not sure why it would do that?

[hashluck]

timbals said:

If I slow through low speeds it is jerky and I accept that, I pull to neutral and then engage a gear if I need to move off again, no problem with that.

I'm not talking about slowing though. If I accelerate to 9mph and stay there at 9mph with my foot steady, it isn't just jerky movement, I get an more deliberate oscillation of power on then off each half second constantly until I make a concerted effort to change speed to flick to neutral to escape it. The rpm needle flicks up and down with this oscillation, and it isn't random like it is when it is jerky when slowing, it seems very deliberate. Quite possibly it is the car trying to engage the clutch every 1/2 second and failing, but I'm not sure why it would do that?

It could be fuelling and nothing to do with the clutch action. Modern cars do lots of 'clever' things to keep economy up and emissions down etc.

[timbals]

Can you reproduce it?

Just hold 9mph for longer than 10 seconds.

[hashluck]

I can try next time I am out (probably Monday now). Mine does something similar when cold but I don't recall it in traffic but not sure how often I am going at either exactly 9 or 14mph!

[Jon39]

timbals said:

Can you reproduce it?

Just hold 9mph for longer than 10 seconds.

We 'old fashioned' manual enthusiasts, can feel slightly smug about the problems being described.

However, I do not drive in London, so understand that pressing the heavy clutch pedal repeatedly, would not be a pleasure.

Hope you find the reason for your difficulty.

[JonV8V]

Jon39 said:

timbals said:

Can you reproduce it?

Just hold 9mph for longer than 10 seconds.

We 'old fashioned' manual enthusiasts, can feel slightly smug about the problems being described.

However, I do not drive in London, so understand that pressing the heavy clutch pedal repeatedly, would not be a pleasure.

Hope you find the reason for your difficulty.

My wifes old manual BMW used to do it so its not just the ASM box. If you drive a manual at the point where its about to stall you'll get a similar problem which is what I imagine is going on here. Its almost an anti-stall feature.

[Grant3]

I think you are describing a touch of driveline shunt, which is normal, it is there on the manual as well, but you can ride the clutch more to mask it.

As others have said the SSII is vastly easier to drive in stop start traffic than a manual - and just as you learn to ride the clutch a tad in a manual you need to slightly modify your slow driving technique when using SS at those speeds .

[timbals]

JonV8V said:

My wifes old manual BMW used to do it so its not just the ASM box. If you drive a manual at the point where its about to stall you'll get a similar problem which is what I imagine is going on here. Its almost an anti-stall feature.

I don't think it is that. At 5mph in 2nd gear is where it feels like it is going to stall and is a bit rocky, this is different. 1st gear at 9mph is into decent revs.

[roughrider]

timbals said:

I don't think it is that. At 5mph in 2nd gear is where it feels like it is going to stall and is a bit rocky, this is different. 1st gear at 9mph is into decent revs.

OK, i've got it now. If you've ever seen a clutch plate, there are several radially/circumferentially mounted springs that serve to take the shock out of the driveline. Your Vantage does not have the traditional big rubber donut built into the propshaft. Its a direct drive carbon fibre propshaft. So, you are feeling the radial springs doing their job in the driveline. Try it in non-sport, and the throttle pedal becomes less sensitive to your foot movement. Maybe this will help?

Edited by roughrider on Friday 17th July 20:55

[timbals]

Grant3 said:

I think you are describing a touch of driveline shunt, which is normal, it is there on the manual as well, but you can ride the clutch more to mask it.

As others have said the SSII is vastly easier to drive in stop start traffic than a manual - and just as you learn to ride the clutch a tad in a manual you need to slightly modify your slow driving technique when using SS at those speeds .

Grant I don't think it is driveline shunt. I'm used to that and can drive around it (general jerkiness). This is literally driving the car at a constant 9mph with constant input, no change.

[timbals]

roughrider said:

OK, i've got it now. If you've ever seen a clutch plate, there are several radially/circumferentially mounted springs that serve to take the shock out of the driveline. Your Vantage does not have the traditional big rubber donut built into the propshaft. Its a direct drive carbon fibre propshaft. So, you are feeling the radial springs doing their job in the driveline. Try it in non-sport, and the throttle pedal becomes less sensitive to your foot movement. Maybe this will help?

Edited by roughrider on Friday 17th July 20:55

This isn't in sport mode. I literally am keeping a steady foot, I'm sure it isn't my foot that is causing it as it is a regular oscillation not a random one (which is what you would expect if I were causing it).

[roughrider]

It could be throttle position sensor, or the throttle body needs cleaning.

[Jon39]

roughrider said:

It could be throttle position sensor, or the throttle body needs cleaning.

Please allow me to go off topic.

Paul, if you would like to, an outline of your motor racing history would be of interest to the enthusiasts here. Thank you.