Series III gearbox won't go into first

[Robert]

Series IIA with Series III gearbox. Won't go into first. All other gears and clutch work fine. Suggestions? Thanks

[Robert]

Hello again. Before I delve into the gearbox, it would sure be nice to hear thoughts about the linkage or something internal that won't let the gear to slide. Thanks, Robert

[erik88lr]

How does it not go into first? Do gears grind when you try? Or is the shifter lever frozen? How about if you try with the engine not running? Same symptoms? Reverse work normally? Really need a bit more info.

[jimrr]

did it work previously? was the S-2 gear box just aquired and installed? did the S2 gearbox work 'on the bench test'?, I don't believe 1st is syncr'd but you should be able to spin the clutch plate and get it into gear. does the shift lever act like it wants to go into its slot? I can't believe there is anything that can be done during a installation that'd prevent first gear from engaging. the forks in there are pretty robust but i guess someone could possibly break one off and it'd get stuck in the way of going into first, (my shift lever broke first!) maybe the reverse plate somehow moved over into the way? it does sound like it's in the top of the xmission and i'd avoid driving it in case something in there could fall down on the layshaft and such and cause real problems. i think you should figure it out after pulling the shift lever assy out. let us know.

[Robert]

Thanks for the responses. Much appreciated. Some more details. Series III gearbox was installed some 30 years ago by previous owner. I have owned the truck for some 25 years and have had absolutely no problems with the gearbox. I installed a Fairey overdrive some 20 years ago and have had no problems with that either. That's why this issue is a bit confusing to me. Gear lever will not move the gears into the first position regardless if the clutch is depressed or the engine is running. Lever will move the gears into all the other positions. I can move the truck starting in second. The lever just won't move into the first position. Thanks, Robert

[erik88lr]

Don't mean to sound flippant, but it sounds like something is jammed. There appears to be a bit of the shift linkage that is external to the gearbox - maybe a pebble got thrown up into that area, but it's a long shot. I guess you'll have to do some disassembly....

[Robert]

Agree that something is jammed. Was never off pavement, so probably something internal regarding the forks. Robert

[jimrr]

yes, I'd no idea you had a 25 year history. I agree with eric88, you're going to have to pull the transmission cover off, clean all the 'stuff' off the top of that gearbox, undo the 4 bolts holding the shift assy. down and have a look. the snap ring etc. to where you can look straight down onto those forks, hopefully you'll find a chunk of krap laying in there and you just lift it out with a magnet or something.
let us know, ............

[Robert]

Will need to dig deeper into the gearbox, but not sure how to proceed. Possibly a synchro on first, which is supposed to be a bit weak on a Series III. Thanks for your suggestions, Robert

[jimrr]

it all looks normal, the idea a syncro is cockeyed on the cone or something down in there is no doubt the issue. sorry robert but it looks like you'll be yanking that xmission out of there. at least it happened at home with decent weather. take heart, it's just something all of us deal with after driving these rigs into the dirt. make sure that shift lever moves outside of the box now that you have it on the bench !! and try actuating that rod in the box, maybe move it side ways, twist it some or something, i'm sure you tried this.
maybe you'll have to take it out into the dirt after you get it back, it can help!

[Robert]

Yep, Borescope is next. We'll see what that reveals. I figured gearbox would need to be removed and have planned accordingly positioning the truck in my shop so the engine hoist has access to the truck and the workbench. Robert

[Robert]

The problem is fixed, but I don't know why. In the process of using the borescope I must have moved the fork rods enough to free up the binding of, I assume, the 1st-2nd synchros. Should they be replaced as a preventative measure? My plan is to drive a while and see if the problem reoccurs. Thanks, Robert

[erik88lr]

I think I'd proceed and pull the gearbox and take it apart. Could have a broken syncro spring (or something else) that had things jammed and will do it again later.

[jimrr]

it sounds like you still have that xmission in the truck? whatever stopped that from going into first gear should be fairly obvious somehow and the idea something is floating around in there should be pretty disturbing. you won't get any rest till you've resolved this but if you're not going to pull the xmission at least do a good cleaning of the case, with magnets, borescope and all the rest, look for shiny metal scar marks on all the stuff that moves. if something ends up in the gears ....... well...... !!!

[Robert]

Went for a drive and all is fine with the geafbox. Still a mystery, but will monitor. Delay in the drive was as long as I had the seat out, I wanted to replace the seals under the doors. Getting the sills out and re-riveting new seals was certainly a bigger job than I had anticipated, but finally my long on the workshop shelf seals are in place. Thanks, Robert