Gear crunch

[Big Uli]

I have a gear crunch 2nd- 3rd on my 14 Qubo but only after the car warms up a little. I can avoid it altogether if I take my time changing gear 90% of the time. Clutch is new, was done last October and th car hasnt been used much due to a works van. Couple of 1000 miles tops maybe.
I suspect a syncro issue but would like to try changing the oil and possibly an additive to give it a little more life. A recon gearbox eventually but with Xmas so close i want to try other things first
Tia ?

 

[Pugglt Auld Jock]

Most gearbox additives contain additional friction modifiers so if your problem is with a synchro not "biting" properly you may well find an additive will only make the problem worse?

You say it's a problem only with selecting the 3rd gear so it's unlikely to be a clutch fault. Changing down without "blipping" the throttle - so push clutch pedal to floor and move gear lever from 4th to 3rd puts more strain on the synchro than changing up from 2nd to 3rd because as you change down the synchro is having to spin the input side of the box and the clutch friction plate up to a higher speed to attain synchronization whereas when going from 2nd to 3rd the input side needs to slow down which it will be tending to do naturally. So is your crunch worse when changing down from 4th to 3rd? If so, given what else you've described, it's pretty conclusively due to a worn synchro cone.

If you know how to double declutch - here's quite a good explanation: https://www.topgear.com/car-news/top-gear-advice/top-gears-guide-driving-well-how-double-declutch - then you could do a double declutch and if the gear didn't crunch you'd know for sure that it's the synchro at fault. If you've never been actually taught how to double declutch though it's a difficult thing to learn without someone sitting beside you and instructing you.

 

[Big Uli]

Thanks for the insight mate
Gear change generally feel a little stiff. Like I said I haven't driven this car in a long time. Just been sitting there while I used the works van. Someone my mate uses did the clutch and steering rack a year ago. Since then I've hardly driven it