Jimbob292
Trekker
Morning,
Two weeks ago, all my set points for gear changes suddenly disappeared / moved by about 10 km/h, the Disco would start off in 2[SUP]nd[/SUP] gear, TQ lock up was up at 65 to 75km/h.
I searched the internet looking for that free cure! It doesn't exist.
Some blogs say run it locked in 2[SUP]nd[/SUP] gear @ 4,000 rpm to clear stuck values, didn't try that one.
Others are you need a new box, TQ friction plates are burning up, valve block is U/S, the list is endless, from anything 300 to 3000 grand, disheartening at times.
The box is a stage 2 Ashcroft ZF 4, it's given excellent service up until the morning 3 years @ 50,000km, my specific fault was that I did a short trip, parked up, left it off for an hour, then started off again, bang lost all the set points & lock up, no prior issues up to that point.
Checked all cables, kick down cable was as per the spec. Gear selector cable was locked in place.
Dropped the tranny oil, no metal particles oil was still cherry red.
Refilled with 7litres of new ATF, ran for 300km's to give it a good flush before I decided on stripping the unit out.
If you have the Rave CD, you can see what's need to get to the back of the tranny, Transfer case all prop's, exhaust, cross member etc all has to come off.
I decided to leave the autobox in place and support the sump while i removed the back end of the gearbox.
There's 8 @ 13mm bolts that hold it on, torque is 23NM, undo those, the shaft extension will need an impact driver to shift the 17mm both, (when refitting 100NM with Loctite 271 red, don't use the blue the ATF will eat it away) but be careful as you have the transfer case linkage fixed to the top of the plate. Carefully remove it to show the governor valve.
You'll need a three legged puller to remove it off the shaft, as the splines will have signs of burs.
Once the governor valve is off you will see the three square o rings that cause you all the hassle.
The middle one was broken allowing main oil pressure to dump straight back into the sump of the tranny causing the problem.
This is where you have to be VERY clean & careful in putting back the square 0 rings, use Vaseline and position them into the correct groves, like wise I fitted new governor & housing wasn't taking any risks. All bolts on the governor are 10NM with 271, reassembly with a good smear of Vaseline on the inside the governor hub, then build back up in reverse.
I replaced the oil filter, all the oil seals in the auto box, transfer case, and the main gasket on the back of the tranny.
All transmission parts were from JPAT excellent service and a wealth of knowledge.
LR parts were from LR series.
When i opened the filter i found all the old rubbish from the old gearbox it replaced, this was even after i flushed out all the lines & cooler, just shows what lingers after a overhaul.
A few pictures of the parts, new & old.
Rgds,
Jim
Two weeks ago, all my set points for gear changes suddenly disappeared / moved by about 10 km/h, the Disco would start off in 2[SUP]nd[/SUP] gear, TQ lock up was up at 65 to 75km/h.
I searched the internet looking for that free cure! It doesn't exist.
Some blogs say run it locked in 2[SUP]nd[/SUP] gear @ 4,000 rpm to clear stuck values, didn't try that one.
Others are you need a new box, TQ friction plates are burning up, valve block is U/S, the list is endless, from anything 300 to 3000 grand, disheartening at times.
The box is a stage 2 Ashcroft ZF 4, it's given excellent service up until the morning 3 years @ 50,000km, my specific fault was that I did a short trip, parked up, left it off for an hour, then started off again, bang lost all the set points & lock up, no prior issues up to that point.
Checked all cables, kick down cable was as per the spec. Gear selector cable was locked in place.
Dropped the tranny oil, no metal particles oil was still cherry red.
Refilled with 7litres of new ATF, ran for 300km's to give it a good flush before I decided on stripping the unit out.
If you have the Rave CD, you can see what's need to get to the back of the tranny, Transfer case all prop's, exhaust, cross member etc all has to come off.
I decided to leave the autobox in place and support the sump while i removed the back end of the gearbox.
There's 8 @ 13mm bolts that hold it on, torque is 23NM, undo those, the shaft extension will need an impact driver to shift the 17mm both, (when refitting 100NM with Loctite 271 red, don't use the blue the ATF will eat it away) but be careful as you have the transfer case linkage fixed to the top of the plate. Carefully remove it to show the governor valve.
You'll need a three legged puller to remove it off the shaft, as the splines will have signs of burs.
Once the governor valve is off you will see the three square o rings that cause you all the hassle.
The middle one was broken allowing main oil pressure to dump straight back into the sump of the tranny causing the problem.
This is where you have to be VERY clean & careful in putting back the square 0 rings, use Vaseline and position them into the correct groves, like wise I fitted new governor & housing wasn't taking any risks. All bolts on the governor are 10NM with 271, reassembly with a good smear of Vaseline on the inside the governor hub, then build back up in reverse.
I replaced the oil filter, all the oil seals in the auto box, transfer case, and the main gasket on the back of the tranny.
All transmission parts were from JPAT excellent service and a wealth of knowledge.
LR parts were from LR series.
When i opened the filter i found all the old rubbish from the old gearbox it replaced, this was even after i flushed out all the lines & cooler, just shows what lingers after a overhaul.
A few pictures of the parts, new & old.
Rgds,
Jim
