Second to third gear problem - again

I posted this problem a while back and thought the problem - occasional difficulty changing from second gear to third on a syncro gearbox - was down to interference with the console cover.

It isn’t. I finally got the problem to occur with the covers off and discovered that the first/second gear shaft might not always return all of the way to neutral (by about a half inch) but would still allow the shifter to move across to attempt to select third gear. The problem of course is that the transmission is still “locked” in second until the shaft can return to its home position.

Now I know where the issue is, I can always change gears successfully if I am careful, which precludes any “racing” gear changes…

Before I remove the gearbox top to investigate further, can anyone suggest how to adjust for a more positive neutral position or where the “slop” might be in the linkage or in the lid which causes this problem? Is it something common?

I know the problem is in the gearbox top/linkage because two previous gearbox lids did not cause this problem when I was experimenting with a sedan gearbox lid.

Thanks for your help
Steve

Hi Steve, This sounds like a whole different situation that I had on my previous 69 4.2, as I had like “symptoms” occurrences. It ended up the synchro’s needed replacing, Hopefully you will not have to go down that road.

Happy Motoring,
Todd

I was thinking synchros too. I’ve looked for, but failed to find, a figure for acceptable synchro gaps for the various Jaguar gearboxes. Does anyone know these off hand?

Hi Steve,
I hope that you have diagnosed it correctly as I had the exact same problems last year tried molyslip oil, then adjusting the gate / selectors etc but in the end turned out the synchros were shot & needed replacing but the car had covered 103,000 miles from new, so hopefully that is not the case with yours ?

I know it isn’t the synchros because when I do accurately locate neutral from second, gear changes are quiet and smooth even at speed. Looks like the top will need to come off for a closer look
Steve

I just looked back at my original thread and realized that Peter Crespin has given me an excellent description of how the “speed change” lever is aligned. Forgive me I am getting old! I will take the cover off tomorrow and ensure everything is properly aligned
Steve

I removed the top of the gearbox and with the help of a good friend, dismantled the gear change shafts. The O rings were replaced with good quality Viton replacements after thoroughly cleaning shafts, casing, locking rod/ball bearings. We re-assembled the top using fresh locking wire and lots of oil. The shafts now move much easier and have a very positive click into each position.

After replacing the top, the shifter "knuckle was re-assembled with Tufnol washers in all the right places.

I also replaced the nasty, new and very stiff rubber boot around the shifter with a nice supple one from Mr Gasket and replaced the center console. We did consider adding some weld to the "paddle at the end of the shifter to remove some of the play and ensure that the shift lever could not move from the first/second to third/fourth plane and vice versa without both shafts being in the completely neutral position. We decided against it, figuring that the work we had already done has solved the problem and we did not want to modify the shifter from what seems to be its original dimensions.

My final report back will be after I put a few miles on the car, but feel confident that all is well once again
Steve

Perfect! Cleaning the speed control rods and replacing the O rings did the trick. I now have a lovely smooth gear change and all selections are positive. This is a job well worth doing
Steve