I've just had a 14 speed gearbox of a 4 series Scania repaired. It was going to have 1st gear rebuilt & there was a broken ring/collar gear (for synchro). I was hoping it would fix the problem I have of when in high range (the top 3 gears), when trying to change down into "1st" (7th/8th gear), it's locked out for a long time, before it will go in. I assume forcing it still makes it grind like before. So if I want to change down to 1st, it needs to be revved to go in, like a non-synchro.

Could there be something else, like a external air valve component that needs replacing, for it to operate smoother?

Or likely to still be internal, like a heat-damaged shaft causing it to be clunky?

-I haven't timed how long it's locked out of gear, but if it's 10 seconds or so, I'd have to ride the clutch for a long time.

1 Answer 1


False alarm, clunky gearbox is still tight from rebuild. Doesn't grind when given a bit of persuasion. I'd gotten into a habit of avoiding changing down to the 1st gear in high range (aka as 4th on the gear knob), so not enough experimenting when it'd warmed up. Hopefully a end to revving & double-clutching until the next time I use a crash-box

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