Thanks, that is a relief, i was worried. I guess 5-4 is a natural.
So if I wnat to go 5-3 I need to got through 4 also?/QUOTE]
Well, you tell us! We're not there to see how your car is reacting to your inputs.
If you have an original GT40 (or, an original GT40 gearbox at least), those had a built-in sequential shifting mechanism, which would not allow the driver to skip gears. If you are in 4th gear, it will only allow you to select 5th, or 3rd. If you're in 5th gear, it will only allow 4th, and so forth.
But of the many thousands of ZF gearboxes built, only a handful were built that way (probably less than 150). So, the overwhelming majority will allow you to shift from any gear, to any gear.
Can you shift any way you like when the engine is shut off? If so, then you do not have a sequential-type shifter. In that case, your problem is probably tied to inadequate clutch disengagement and/or worn-out synchros.
Tell us what kind of ZF you have? And try shifting gears with the engine shut off and tell us if it works? If your problem only exists when the engine is running, you have to adjust your clutch for additional release, or your gearbox synchros are worn to the point where it could likely use an overhaul.
Let us know?
Also, FWIW, due to the non-synchro nature of reverse gear, I find it useful to shift into a forward gear (normally I use 2nd gear) before shifting into reverse, when the engine is running, to avoid the CRUNCH you are describing....