SLROC Forum

Hi Everyone,

Can anyone shed any light on the following. When taking my SWB S 3 on a rough track the gearbox grinds and makes horrble noises and jumps out or refuses to engage gear at all in 1st,2nd and 3rd in low ratio. When on smooth track or tarmac road ie no jiggling about the drive is really smooth (apart from occassionally slipping out of 2nd on the overrun) - no problem engaging gears etc, stays in gear -lovely.  When off road or on rough tracks in high ratio no problem at all - stays in gear and drives fine.

As the gear box performance seems to be dependent on road surface ie whether the vehicle is being shaken or not and what ratio it is in , I am wondering whether something is lose as opposed to worn. Are there any nuts/bolts I can tighten up with the box in situ to try and sort this out first before resorting to getting the gear box out and doing a complete overhall.

Any advcie gratefully received

Thanks

Stephen 

from your initial description about 1st 2nd and 3rd grinding etc i would have suspected the layshaft bearings (or layshaft teeth) , Does it grind and stuff when in low box and in 4th? (4th should be straight through so layshaft is idling)

when you say you can't engage 1 2 3, is that while moving or stationary?
if stationary can you engage 4th? does the car want to move when lifting the clutch?

poppong out of gear usually means that the slippers are shot or missing.

are the linkages at the top of the gearbox tight?

hi -I am new to this so excsue me if I get some of the terminology wrong! - in low box (presuming that is the one with the red stick as far back as it can go pie one used for slow speeds - there are now problems at all - everything is hunkydory  on a rough track with lots shaking. In high box (red stick as far forward as it can go) on the road it is fine apart from popping out of 2nd occassionally on the overun. Off road when the vehicles is being shaken about on a rough track in high box ( red stick as far forward as it can go) it jumps out of 1,2 & 3,trouble getting into to gear when moving, lots of grinding and mesh hitting mesh but not engaging. This all when on thre move. Will engage gears when stationary and would move if I lift clutch fully. Have not checked the linkages but as the symptoms are not consistant between hi/lo box I presume linkage would not be the culprit.

in low box the geartrain is under a lot less strain than when in high ratio. the torque applied to the gears is less. and it is usually running slowerish....

if there is grinding of gears  it means the synchromesh is not doing its job for some reason. this could be that the rear of the mainshaft is being driven by the wheels and the front of the input shaft and the layshaft is being driven by the engine. to change properly the synchromesh has to slow down (or speed up) the free wheeling gears and allow the shifting ring to move into position in the gear. this will not happen if both sides are running and hence grinding. so when you dip the clutch you might not actually be allowing the input shaft and layshaft to freewheel, does the clutch fully disengage??

if it pops out of gear then the slippers (spring loaded thingies in the syncromesh) are not holding the splined gear ring in its correct position. these can wear quite a lot and stick the gearbox in gear or not allow it to fully engage allowing it to pop out when encouraged.....

there might be a few things to check:-
1) does the clutch actually *Fully* release?
2) is the correct oil (amount and type) in the box, synchromesh needs the oil to do the speeding up and slowing down of the freewheeling gear AND allows the freewheening bits to freewheel....
3) does the gearstick wobble like mad or is there definite gear engagement and the gearstick stays pretty much in the correct position?

I'll check those things  and get back to you!

First thing is to drain all the oil from the gearbox and transfer case, and put some new oil in. Remember to remove the filler bungs first before you remove the drain bungs. This fixed a very similar problem with my series 2 last year. Put a good quality oil I used Penrite HYPOID 80W-90 for both transfer and gearbox, and it worked like new.

What happens if you hold it in the gear manually does it jump out. If so it would mean that you either have something loose in the linkage part of the gearbox (on the top where the gearstick bolts to the gearbox) and it moves when it is rough it jumps out or part of the layout shaft is worn and again jumps out when the terrain is rough.

As has been said check the fluid levels and check the master cylinder and also get your head in under and see if the slave cylinder next to the bell housing is leaking.

Cheers
Chris