Gearbox Noise

Gearbox makes a fairly loud rattling sound in 4th gear on the overun. Remnants of the same in 3rd gear., gearbox has new bearings, new mainshaft and gears. 1st and 2nd seem quiet.

Sounds like it could be the layshaft bearings, but first of all, check the oil levels in you gearboxes!

is it going 3rd-4th and 4th to 3rd quietly, was thinking of the 3rd/4th synchro springs come off

mainshaft nut tight?

Yes moves in and out of gear smoothly as long as the engine rpm is fairly low, synchro is not that good, it crunches from 4th to 3rd, and from 3rd to 2nd, for a synchro box it isnt very good in the downshifting. Might be shot baulk rings? double clutching works.

The box has a new mainshaft and all gears and components on the shaft, except baulk rings. All bearings replaced. The chattering noise sounds like excessive backlash or something loose. Its got me beat. mainshaft nut tight to 100ft/lb. layshaft has no end play and new bearing front and back. Its an expensive mystery. Not sure if its worth persevering with.

I have the same problem started today.... Just after fixing the electrics and getting back on the road.

Noisy rattling, rumbling from gearbox on over run - like a bag of pebbles, perfect under drive. Gear changes ok

Worst in 4th, noise is still there but much quieter in 3rd; 2nd and 1st sound ok. Definitely gearbox related as I have the noise with transfer box in neutral

No investigations conducted as yet - first port of call will be oil levels tomorrow night. As ever the bottom of the gearbox is covered in EP90...

I'd be very interested to know how you get on!

it sounds like you have the same problem as i have in one of my gearboxes, if you rest your hand on the gear lever i'll bet you can feel it hammering

i haven't opened that box up yet and won't be in the near future but i'm expecting 3rd/4th to be scrap

to be honest i'm expecting it all to be almost scrap as it howls in every gear and you can actually make out the hammering noise whilst on the power as well (and this is over my tdi )

They all start off with little noises then 1 day it's more of a knock then as you keep going the whole vehicle starts to lurch as you drive
When I opened my box a couple of years ago it was not a good site
3rd gear had 4 teeth missing on each gear set and when I started to look deeper all the collors and bushes were totally ****ed. When I worked out how much it was gonna cost on parts alone it was around £300 and that was using cheap britpart bits
Think about a conversion to a newer box I think is best way forward

It could be just detent spring (40p) popped out of 3rd/4th synchro causing imbalance (RTC1956 Detent Spring / FRC1758 3rd/4th Gear Synchro Clutch Assy).

RTC1956 DETENT SPRING | shop | www.lrseries.com | L. R. Series

Some say you can replace them in situ with selector cover off, I had dificulty replacing the springs on a bench with both hands so would appreciate a video of anyone who can do it in situ.

If you drop the gearbox oil & find blackened chewed up flat leaf bits then it's just a matter of what else requires replacement, hopefully just the detents & ensure they do not pop out again.

Mingdiesel

Mine were in the drain plug of my gearbox. other forums suggest the gearbox will work ok without them.

emwmarine said:

Mine were in the drain plug of my gearbox. other forums suggest the gearbox will work ok without them.

Click to expand...

it will work, i ran mine for about 18months after they fell out, learn to double the clutch and don't swap gear too fast which may help (they're a "slow" gearbox even in fine fettle)

but it won't help to prolong it's life without them

Ive been told the noise came from badly worn input shaft / cluster gear setup, and bellhousing bearing (input shaft big bearing) was loose in the retainer. New 3/4 synchro hub (LR genuine) fitted as well.

Ill fit the box on weekend and test it out. I didn't see the wear on the cluster gears. Hopefully that will be the fix! DW