I had a few times where the car got stuck in neutral during downshifts. I recall someone mentioning the throttle and/or the shift cylinder may need to be adjusted. Can someone go over how to adjust these?
Throttle cable adjusting, shift adjusting, false neutrals.
- Thread starter John H
- Start date
following along as this has happened to me a few times. definitely not consistent, but has happened like like once every 6-8 sessions.
John the most common issue here on a new car is the throttle cable takes a stretch in the first few days and goes slack. You will notice that the throttle blip cylinder only has 7mm of stroke. Once the cable goes slack from initial stretch the blip is not strong enough to unload the gear box under deceleration loads. This starts to show up with misted or incomplete shifts while shifting down through several gears.
The throttle cable should be adjusted in tension where when letting off the throttle pedal the throttle cam is just contacting the mechanical adjuster screw on the throttle body. This should be checked with the pedal to account for cable friction. If it is not hitting the stop the idle will be too high. If there is cable slack then there is a week blip.
Once the off throttle position is adjusted the full throttle position needs to be checked and set with the pedal stop in the pedal box. The correct way to do this is to remove the air box open the Secondary throttle plates and visually insure that WOT is being achieved without under or over rotation. A quick check can be made by looking at the throttle cam which has an arm with a V point on it. At WOT that arm should be in the vertical position.
I suspect this is whats likely causing your issue, however please also find the cylinder adjustment info below.
The shift cylinder stroke needs to be set at mid stroke when the shift system is at rest. The best way to do this is to disconnect the rod from the shift arm and fully stroke the cylinder in. Wrap a piece of tape around the cylinder rod to mark its fully retracted position. The cylinder has a 30mm stroke so you want to position that tape marker 15 mm from the face of the cylinder with the shift arm making close to a 90 deg angle with the rod. We do sell a 3d printed gauge for the cylinder rod length at mid stroke for those that want it but its really over kill.
Note, the shift system is air operated and has a "small" reservoir, multiple rapid shifts will cause pressure to drop and the cylinder force drops with it. In a scenario where you have a 6th gear straight coming into a 1st or 2nd gear corner you realy need to be timing your down shifts through your braking zone rather than "rushing" them through rapid fire once your speed has decreased. I have included this as there are some drivers with a lot less seat time than John who may not be aware of this.
The throttle cable should be adjusted in tension where when letting off the throttle pedal the throttle cam is just contacting the mechanical adjuster screw on the throttle body. This should be checked with the pedal to account for cable friction. If it is not hitting the stop the idle will be too high. If there is cable slack then there is a week blip.
Once the off throttle position is adjusted the full throttle position needs to be checked and set with the pedal stop in the pedal box. The correct way to do this is to remove the air box open the Secondary throttle plates and visually insure that WOT is being achieved without under or over rotation. A quick check can be made by looking at the throttle cam which has an arm with a V point on it. At WOT that arm should be in the vertical position.
I suspect this is whats likely causing your issue, however please also find the cylinder adjustment info below.
The shift cylinder stroke needs to be set at mid stroke when the shift system is at rest. The best way to do this is to disconnect the rod from the shift arm and fully stroke the cylinder in. Wrap a piece of tape around the cylinder rod to mark its fully retracted position. The cylinder has a 30mm stroke so you want to position that tape marker 15 mm from the face of the cylinder with the shift arm making close to a 90 deg angle with the rod. We do sell a 3d printed gauge for the cylinder rod length at mid stroke for those that want it but its really over kill.
Note, the shift system is air operated and has a "small" reservoir, multiple rapid shifts will cause pressure to drop and the cylinder force drops with it. In a scenario where you have a 6th gear straight coming into a 1st or 2nd gear corner you realy need to be timing your down shifts through your braking zone rather than "rushing" them through rapid fire once your speed has decreased. I have included this as there are some drivers with a lot less seat time than John who may not be aware of this.
Last edited:
