Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 4/4 Sport: sensible throttle leads to bumpy drive

I own a 2009 4/4 Sport with a Ford Sigma engine. Everything is fine except for one minor thing:

When driving slow on bumpy roads or with potholes I get a very uncomfortable ride (no, not because of the suspension :-) ).

A minimal movement of the right foot results in harsh acceleleration/retardation, the throttle pedal reacts extremly sensitive.
On a bumpy road it is almost impossible to have a steady throttle pedal position resulting in a ruggedly ride.
The only way to avoid this is to release the accelerator completly for a few seconds when crossing a pothole.

Is there a way to 'dampen' the throttle pedal inputs? Or can the mechanics of the pedal be modified to make it less sensitive to minimal movements?

I know it sounds strange that somebody wants to modify a 'lively' engine, but this behaviour is annoying.

Wolfgang
Stuttgart/Germany

I know the problem Wolfgang when in such a situation I rest my throttle foot up against the carpet on the side of the footwell to act as a tempory damper though it does wear the carpet in time but does give that part of my shoe a nice shine.. (-: I have seen the worn carpet to the side of the throttle pedal on some cars covered over with a shaped aluminium plate.

Some might suggest a stronger throttle spring but then that could become tiresome on the ankle in time..

That your Morgan seems likely to be a LHD, thus the carpet may not be as close to the throttle pedal as it is in my +8, you may require to adjust things a tad in order to achieve the same temporary damper arrangement...?

One thing I've seen is using a 'snail-shaped' throttle quadrant on the carb ... its asymmetric shape make the throttle less sensitive at low revs ... not familiar with your age of car so can't be more specific .... will try to find a pic

K

Hi Wolfgang
I have a 2009 4/4 Sport and I don't have the same problem with throttle response that you are reporting, so I would guess that the throttle position module on your car may be faulty. I believe it is part of the throttle peddle assembly in the drivers footwell.
I suspect it could be removed and checked with a multimeter to confirm before replacing.
I hope this helps.

@ All: Thanks for all those prompt replies!

@ Luddite: If I do not find a 'technical' solution that may be the way to go
@ Image: a modification that changes the curve of the activation would be ideal. I have to check how this exactly works in my 2009 car.
@ Barry: checking or changing the throttle position sensor is a good ideal. They are not really expensive, could be worth a try

Wolfgang if you can increase the throttle pedal return spring tension that should fix the problem.

'....if you can increase the throttle pedal return spring tension that should fix the problem...'

Thanks, I will try!

Wolfgang, just out of curiosity, does your 2009 4/4 already have throttle via wire control? Probably yes when talking about the throttle position sensor. My 2014 has it but I haven't had the problem you describe. Have you tried if on a good new road the throttle is also unstable when driving slowly? Is the accelerator still screwed down properly? It could be that the screws have loosened a little and the control of the foot has become worse when the linkage in the housing wobbles.

What sort of throttle pedal do you have? I have an organ pedal and it does seem to allow finer control and as there is a larger area to rest the foot it doesn't seem to be susceptible to pothole induced kangarooing

I agree with C2RM, changing the pedal might help, I didn’t get on with the factory roller pedal so I changed to this one from Wolf Performance, much easier to control and also sits slightly closer. I found the roller pedal too far away.