Im not proud, i will ask 
how do you get back down into 4th gear on a scania 3 over 3 without leaving metal shards in the box ?
never driven one, but im assuming you are using your hand to shift gear, try just pressing the gearstick with your thumb, should give enough pressure to move the stick one space. if that makes sense
4th is always tricky on that configuration in a Scania. Worse when gearbox oil is cold make sure youâre allowing enough time for the range change before you even start pushing in and if it has, and you heard it, but still stiff try switching again anyway.
Have you got a trailer on, as they often seem harder work to get gears if just driving the unit?
if its anything like the scanny I drove at my last place then 
it was more like grind crunch clunk ah its dropped in 
, although the noise does make folk think you cant drive
turned out that in the case of my wagon the synchros in the gearbox was rather worn and ended up with a recon gearbox in it,just before I left
Just because its a synchromesh box you still canât rush it, take yr time and feel it in. All Grs900 boxes are like it. Forcing it will cause long term damage, very quickly if yr not careful. Always leave in high range when stopping for any length of time and, what ever you do, ALWAYS pull away in first gear, even just to get the wheels turning. First high, third low is my preferred change up, a fully frieghted 420 on the flat wil take that in its stride.
Experience in these matters is expensive. I hope this is of some help to you.
3 over 3 ainât a quick box, so take MrVains advice. 1st high,3rd low was always good on the 420 I drove, but that was only a rigid 6 wheeler.
Iâm not a fan of the 3 over 3, which seem a popular manual choice with Scania and Volvo, might be me and too used to 4 over 4. As mentioned always seems easy to go too high too fast and doesnât half let you know about it.
I like almost everything about Scanias. But the 3 over 3 setup is just daft.
You have to be gentle with it. If it dosnât drop straight in, Then back to neutral and try again. If you try to force it, it wonât go in. Nice and gentle.
Slow your gear change up as these boxes will not be rushed!
Thank you all for the input, i knew i would get answers here. The only way i could get back into 4th was come to a standstill, it wouldnât have it, even climbing air balloon hill it wouldnt go back in and i had a low loader on, will have it back to the dealers to rule out probs or rule in my newby status.
In any of Scanias boxes,I have found getting it into neutral,giving it a wee rev and then âfeelingâ it in usually works. If you are using the clutch or not.the fact that itâs a mechanical linkage rather than a â â â â â â (volvo) cable system helps.
I agree with the above the one I drove change up as normal but double de clutch on the way down
I used to a 4 series 420 rigid with a 3 over 3 box which was lovely to use, eventually the syncro on the range change went but they sorted it and it was as good as it ever was. It was getting on a bit and \I did about 200k with it, nicest thing to drive ever.
However we had an identical engine & gearbox in a unit that had been worked hard pulling a stepframe lowloader and the box in that was a bit woolly, 4th was hit and miss sometimes itâd drop right in like a hot knife through butter, other times it would crunch and bang and not go in no matter you did, you could double the clutch, make some tea whilst waiting but it wouldnât have it. The dealer wasnât interested in fixing it and when I got lumbered with it Iâd skip it where possible and go from 3H to 5L.
It was so unpredictable you could be running empty along a busy street with loads of people about and itâd fight you all the way, but try it when no one was around and itâd slot in fine.
8wheels:
I used to a 4 series 420 rigid with a 3 over 3 box which was lovely to use, eventually the syncro on the range change went but they sorted it and it was as good as it ever was. It was getting on a bit and \I did about 200k with it, nicest thing to drive ever.However we had an identical engine & gearbox in a unit that had been worked hard pulling a stepframe lowloader and the box in that was a bit woolly, 4th was hit and miss sometimes itâd drop right in like a hot knife through butter, other times it would crunch and bang and not go in no matter you did, you could double the clutch, make some tea whilst waiting but it wouldnât have it. The dealer wasnât interested in fixing it and when I got lumbered with it Iâd skip it where possible and go from 3H to 5L.
It was so unpredictable you could be running empty along a busy street with loads of people about and itâd fight you all the way, but try it when no one was around and itâd slot in fine.
This is how i was yesterday, i tried double declutching but no difference atall, has done 370k so you wouldnt think it would be knacked but other posters have said it is not good to abuse them then as to who went before!! I have a Scania 112 and has a lovely box in comparison
MR VAIN:
Just because its a synchromesh box you still canât rush it, take yr time and feel it in. All Grs900 boxes are like it. Forcing it will cause long term damage, very quickly if yr not careful. Always leave in high range when stopping for any length of time and, what ever you do, ALWAYS pull away in first gear, even just to get the wheels turning. First high, third low is my preferred change up, a fully frieghted 420 on the flat wil take that in its stride.Experience in these matters is expensive. I hope this is of some help to you.
words to live by Rob, words to live by 
As above, always a pig cold but usually improve once warm.
Synchronising engine speed to gears with a blip of the throttle as you would with a crash box helps, double declutching should improve it further still.
Never liked Volvo or Scania manual boxes (Scania auto not much use either TBH except its good for manual override), too flaming slow and the synchro baulks, rubbish compared to proper manual boxes.
Slow down to about 15 mph then match the engine speed to the speed of the gear box and itll just slide in
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Oh bugger. I was asking a Scania 420 driver on the washdown bay in the cattle market about the gearbox and what change patterns he used, he said look i will show you, anyways he was saying that with a heavy load to start i might use âcrawlerâ gear, i said pardon, âcrawler gear alongside firstâ i replied âoh buggerâ.
In my defence it was my first day and why mark it âcâ and not first 
Crawler really is just that, the speed that it will give you will be virtually negated by rolling resistance as you change up meaning that you are back to square 1