My 1979 308GTS jumps out of fourth gear; no problem in selecting fourth it just drops into neutral, usually quite soon after selection. I checked and adjusted the linkage control rod using the left and right handed threaded sleeve. Looking at the movement of the gear lever in the gate, the fourth/fifth movement is still slightly offset from the second/third. I have now taken the sump plate off the bottom of the gearbox to expose the internal linkage and selectors. I had wondered if one of the detent springs and balls was missing or damaged (the gearbox was rebuilt before I bought the car 12 months ago) - but they were all there. I am going to replace all three and the new springs feel a bit stronger than the existing ones. By inspection I think my problem could be that the fourth/fifth selector fork is not quite centred - to me, it looks like it is displaced by about 2 or 3mm towards the fifth gear. I have uploaded a photo but I'm afraid it is very difficult to judge the position of the fork from them. I am presuming I can loosen the selector fork on the shaft and move it about 2mm towards fourth gear. At the moment when fourth is selected the fork is about 3 or 4mm from the gearbox casing, moving the selector fork towards fourth will obviously reduce this. I have minimal experience of working on any gearbox, let alone a Ferrari one - does the above sound sensible? is there anything I should do or not do? or is there something else altogether that could be causing my problem? The selector fork pinch bolts are 13mm and I think the tightening torque is 2.5 kgm (18 lbft) - does this sound right. I would welcome views. Steve
Try what you are saying to see if that works. If not, you need to inspect the syncro hub and ring of the 4th gear. You might want to do that now before you close it back up.
