gearbox backlash

[disco95]

How ya going guys,
I'm looking to do the output shaft and gears on the disco soon. I've heard there's a fix to stop these wearing out again, can any body fill me in on the details of this? and what exactly do I need to do this job properly. I'll go over and over the manual to make certain I'm doing the right thing, but can you guys, with all your experience, lend me any advice?
Thanks in advance,
Sean.

[daddylonglegs]

There is a modification that uses a drilled mainshaft gear to feed oil onto the mainshaft splines . also a spiral oil slinger in pto cover plate.
When reassembling you should make a silastic gasket between transfercase and gearbox to prevent leaks if the seal in either unit fails.
Bill.

[cols110]

I was under the impression that the spiral slinger (ACME screw) helped feed the shaft/gear but could strave the rear bearing, perfect for stop start running but for longer runs the rear bearing suffers.

Cross drilled gear and a good synthetic oil, will certainly help.

[daddylonglegs]

Oil must pass through the rear bearing in order to be picked up by the spiral slinger.
Bill.

[cols110]

Thats the word I got from Dave Ashcroft, maybe we are talking about different plates.

[red90]

Just to confuse the issue, there have been a few people theorizing that the main reason for the spline wear is not lack of lubrication be misalignment of the splines. As there really is no reason for movement at these splines, they really should never wear. Make sure when fitting that the boxes are well aligned.

Some of the reasons to believe this theory are:

1) Many R380 owners are wearing there splines out even though they all have the cross drilled gear.

2) Many LT77 ownes never wear the splines, even at high mileage.

3) The locating dowels are said to be soft and not great at maintaining proper alignment.

This is all second hand information, so don't flame......

[daddylonglegs]

I will theorise a little and say that all the lT77's that I have seen have a coarse male thread protruding out the back of the mainshaft which is there to assist in pressing on the gearbox/ transfercase oil seal ring and 5th gear synchro hub etc.
Maybe this protrusion picks up drops of oil from the rear bearing and screws it onto the splines enough to reduce wear. The R380's dont have this threaded protrusion so the mods such as cross drilled gear(centrifugal force throws lube off the splines rather than feed them) and a fixed spiral rear plate aren't as effective as a spinning coarse thread.
your thoughts ? Bill.

[RUFF]

I had to replace the Spud shaft and Main drive gear in my ZF-LT230. It originaly had the early short spline non cross drilled shaft and gear but i replaced it with the Later Cross drilled gear and longer splined shaft. With the cover plate(steel type not alloy) i just welded a 25mm piece of 32mm exhast tube cut in half so it just forms a half circle that protrudes into the rear of the drive gear so any oil that flows through the bearing and lands on this then feeds into the gear.

With a ZF and a 1.22 transfer there is no reason to remove the transfer or gearbox to fix this problem. The shaft and gear will both fit out the back of the transfer. I beleive with a 1.4 transfer you need to remove the transfer to get the gear out.

[daddylonglegs]

That sounds like an inexpensive and elegantly simple solution Ruff.
Bill.

[RUFF]

That sounds like an inexpensive and elegantly simple solution Ruff.
Bill.

Yeah if it helps or not i guess i wont find out for at least another 100,000ks.

It cost me less than $500 to fix the backlash prob with all new parts.

Im lucky its an auto as the Output shaft on the Manual requires removal of gearbox and complete disassemble and usually full rebuild.

[ISUZUROVER]

With the cover plate(steel type not alloy) i just welded a 25mm piece of 32mm exhast tube cut in half so it just forms a half circle that protrudes into the rear of the drive gear so any oil that flows through the bearing and lands on this then feeds into the gear.

I have done the same on my LT85/LT230. A friend did this mod a long time ago when he bought a brand new 200Tdi 110 when they first came out because he thought it would have problems. After 300000km with just the oil feed "trough" the non-cross-drilled gear and mainshaft were still fine.