Evening all, went down to yarwell quarry recently for a P&P day, approx a couple of miles from the site I changed down from 5th to 4th on a slip road, seemed a struggle to go into 4th gear. Anyway, the rest of the day passed without a hitch, box was fine. Drove the 60miles home with no issues. As I got the work the following morning, I slowed for a speed hump (in 2nd gear) the truck started to judder, I thought it was the engine cutting in and out but soon realised that it was a drive train issue. A cluncking and snagging as if a CV joint or UJ were binding. I gingerly parked and had a crawl around underneath, props were fine. I drove home very steadily after work jacked it up and checked the CV's and props again, all ok. I then went out for a drive and realised I had no 4th gear, won't even go into the gate. All the other gears, if I hold pressure on the stick against the gate without the clutch pressed I can feel it wanting to drive.... but not in 4th. I read somewhere about a baulk ring which is a problem when going 5th to 4th. Is it possible that this ring has broken up and thats what was binding the box? And would it stop 4th being selected? Anyway, I think I've gone on enough, hopefully someone can shed some light on the issue... If you can be a*sed to read this far.

i think you past baulk ring problem, if it drives normally in other gears ,most likely you lost synchro spring which holds the 3 slipper pads in place these rock like seesaw depending on 3rd or 4th selected and hold the synchro in gear .if spring comes out slipper pads can come out of line jamming that gear only way to fix is to strip box,the only other likely thing is very common where brgs wear out letting input shaft drop putting it out of alignment with mainshaft but would be noisy in all gears and will quickly loose all drive ,if you drop oil you will probably find parts of 10 cm c shaped wire spring

Thanks for the reply James, all other gears are fine and quiet, so I suspect it's the synchro spring. I'm not affraid of getting my hands dirty, any idea how hard a job like this is?

yes do it every day,r380 gear box can be stripped rebuilt quickly **** is removal and reit gearbox rom vehicle

Thanks James, I've removed and refitted 3 R380's so I've got a fair idea what to expect with that part of the job. Going to try removing it by craning through the transmittion tunnel this time.

having removed the engine from my 300tdi and removed the gearbox for a clutch change for me i would say using an engine crane through the trans tunnel and dropping the box on the floor was far the best course

Take the top gubbins off the gearbox to get to the bias plate. It could well be that the upright tab has broken off and is preventing the selection of 4th.

I had this where initially I couldn't get reverse, then after bouncing around on a green lane I couldn't get any other gear than 2nd, then on the run home (in second) I suddenly got all my gears again.

Once stripped out I found the broken tab, £4.70 and an hours work and all was good again.

Thanks crazymac, I checked this as a matter of course and all is well. I fitted new bias plate and springs not so long ago. I think it's an internal issue due to it binding up and snagging before I lost 4th.

bigrichsri said:

Thanks crazymac, I checked this as a matter of course and all is well. I fitted new bias plate and springs not so long ago. I think it's an internal issue due to it binding up and snagging before I lost 4th.

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Ah! Bit of a bugger then! Good luck with it.

Just a follow up, I'm hoping to drop my gearbox out weekend of 10-11th sept and was wondering what's involved in stripping the box to replace synchro springs. I guess there won't be a lot to strip if I'm only having a look around inside and doing the springs.

Cheers