Gears grinding in Series III between 3rd and 4th - no overdrive

I am totally new to this forum, so I hope all your enthusiasts will forgive any ignorance I have about my beloved Landy. I purchased my 1978 Santana-built Series III Diesel about a month ago. I had it checked out by a reputable shop in San Jose Costa Rica. They assured me all was well, but since I have never driven one of this classics before, I am wondering if I am doing something wrong or if there may be a problem.

First off, when driving at normal land speed and engine speed, I consistently find that the gears "grind" between 3rd and 4th. I have tried double clutching and even racing the motor to get the engine speed up, but to no avail. I have yet to enter 4th gear without a very disturbing grind. This car does not have Fairey Overdrive. Since I do often use 4WD, I keep the hubs engaged and it is always in low range when 4WD is engaged.

Secondly, I am also finding that 1st and 2nd are somewhat difficult to find when coming from 4th or 3rd. Since it is very hilly here and this is a diesel, we find ourselves naturally doing a good bit of downshifting to maintain momentum and speed.

If anyone has any suggestions, I would be most appreciative.

Respectfully, a new, albeit proud, landy owner.

i guess the gearstick itself is sloppy ( like stirring a can of paint with a golf club )

it sounds just the same as my old series 3 landy and all the others ive driven i think its just the way they are

i used to avoid the crunch by comeing out of thirs and finding fourth but stopping on the edge of engagement ( that shunt you feel as it finally slips into gear ) and just knock it into fourth it was an art form id aquired over the years and nobody could figure out how the hell i used to do it without grinding the box

Yes, kind the gearshift at times seems sloppy, but of course I am used to driving a Mini Cooper where the gears are much more clear.

I guess I am concerned that it might need some tranny oil. Could that be the problem too?

you need to rebuild box if possible ,3rd/4th synchro is buggered and sounds as if 1st/2nd are going that way ,you can just do gear box you dont have to have transfer box done if okay but are often sold as one lump,end of gear stick often needs building up with weld and grinding to shape

if you think you could live with it theres no need for a rebuild. worn syncro cones cant do ant damage to the box apart from the "crashing" which can be avoided,

its something you will pick up from practise. being only 18 myself, i do sometimes surprise poelpe, like truck drivers with my ability to change gears. i can clutchless change up and down with no grinding, i can twin stick even clutchless with no grinding.
normally i always double clutch, even euroboxes.

but i cant explain how i do it?

thats not completely true as if you strip and rebuild them you will find that prolonged use like that will render a box that just needed a few bearings and synchro rings will end up needing all gears and parts replaced as dog teeth on each gear get broken off and synchro debris goes around moving parts imbedding it self in contact surfaces,and good parts are getting harder to find

Good advice. Of course, trying to explain what needs to happen to my Costa Rican mechanic may prove a challenge. I am going to try to find out if he knows how to do that. Is this a major job costing a great deal of money, or is it primarily labor?

you dont need any special tools but reading manual will help ,box parts are relatively cheap ,3rd 4th just needs bell housing taking off ,3rd 4th fork pulling out and synchro hub just pulls of shaft and new refitting (normally there are 3 leaf springs that break allowing hub to jam during gear change but your sounds worn too )(hun only fits one way round if you look at internal splines you will see a recess on one end this goes toward 3rd gear )to do 1st 2nd you need to strip box totally

like he says ^ you can rebuild a box yourself yes. theyre probably one of the most simple syncro boxes about. just take it methodically and if you can get a manual it will probably help quite a bit.