Clutch not engaging while driving.

[bryce]

Travelling to MOT today and noticed the clutch wasnt engaging properly.

I was travelling at about 60mph, 6th gear, 1800rpm. Barely using throttle as its kinda down hill. When I applied some throttle the revs were going up then crashing back down whent he clutch came in, but then it'd bump out again. Tried again in 5th (so revs were higher) and still got the same.

Dealers gonna plug her in. Thinks it could be a solonoid.

Anyone had this before?

[bryce]

Just back from dealers.

Plug it in - no faults
Check SMG pump + pressures - all OK

Only suggestion they had was that maybe Ive upset the car by running odd wheels - CSLs on front, M5 on rear - the M5 wheels stand almost 2" taller than the CSL rears.

Gonna swap back now, but the car wasnt doing its trick on the way home anyway.

Any idea lads? Warranty is out tomorrow!!

[SMD]

Pay for the warranty today!

[SpineOnABap]

Originally Posted by bryce86

Only suggestion they had was that maybe Ive upset the car by running odd wheels - CSLs on front, M5 on rear - the M5 wheels stand almost 2" taller than the CSL rears.

Interesting. Did you perform the SMG -> tyre recalibration? Like you should when you change tyres (see the handbook section on changing tyres).
If you don't it can throw the SMG into a bit of a wobbly.

It's what's often referred to as the 'SMG reset' (car into N or 0 at 40mph, pull & hold both paddles for about 4 or 5 seconds then back into gear).

[bryce]

Originally Posted by SpineOnABap

Interesting. Did you perform the SMG -> tyre recalibration? Like you should when you change tyres (see the handbook section on changing tyres).
If you don't it can throw the SMG into a bit of a wobbly.

It's what's often referred to as the 'SMG reset' (car into N or 0 at 40mph, pull & hold both paddles for about 4 or 5 seconds then back into gear).

Ahhh, I have read that before but never paid any heed to it.

The SMG did seem to be having a wobbly as you say. Dipping the clutch while coasting at 50/60mph, then riding it back in.

Im back on standard wheels now again, but I doubt I'll can get it to do it again anyway.

Thanks for that Elliot.

(any further suggestions are still welcome!)

[SpineOnABap]

It does sound like a symptom of not doing that procedure. It tends not to matter if there's not much of a change, but if it's significant then problems occur. I had something similar when I temporarily shifted from 265 to 255 on the rear (without doing the reset). Once I'd done the reset it was ok.

It's kinda like the tyre pressure system in that it needs recalibrating when the rolling circumference changes.

[bryce]

Yeah it makes sense I suppose. The rears are significantly taller (2"), so it'd make sense that the car would get confused cos front and rear axles would be reading different speeds.

[Bealo]

Originally Posted by SpineOnABap

Interesting. Did you perform the SMG -> tyre recalibration? Like you should when you change tyres (see the handbook section on changing tyres).
If you don't it can throw the SMG into a bit of a wobbly.

It's what's often referred to as the 'SMG reset' (car into N or 0 at 40mph, pull & hold both paddles for about 4 or 5 seconds then back into gear).

I never knew that, I never did the SMG reset when i changed from 265 rears to 275 rears.

I'm about to put some cups on my car so i will do the reset just to be on the safe side.

hope you find out what the problem is soon bryce.

[mattbedford]

How do you get it into neutral at 40mph?

[glendog74]

Originally Posted by mattbedford

How do you get it into neutral at 40mph?

Push the gear selector 'stick' to the left