Patrol Rear Diff Problems

[solarman216]

Hi all, well this has been going on for several months, but till now have not been able to locate the problem, I will start at when I first noticed a problem, sometime late Oct 19 I was driving at around 40 mph on a straight road when I became aware that I was drifting to the right, like wind hitting me through gaps in the trees, only did it once on that trip so thought nothing of it, but over the next months it did it a few more times, then on the way to Slindon in Dec pulling away from lights I had a hard pull to the right accompanied by loud noise like tyre hitting body aggressively, need less to say pulled over and had a look round but nothing seen, last Wednesday it did it again, so on getting home jacked up and checked all the wheels etc, nothing, then on Wednesday this week coming out of Jewsons yard the OSR wheel locked up momentarily, so this morning lifted the OSR wheel and spun it by hand, sweet as a nut,started the engine and ran it in first gear no problem, scratching my head now, so selected 4th and ran it at about 50 mph, then I heard it, horrible graunching noise from the rear diff, that is it car off the road, stole the Mrs T2 (arnt they small) did some running round and by 2pm all done so started on the Troll, got the diff out by 4pm but had a call so did no more, but initial examination show's nothing other than a bit of swarf in the bottom and am convinced this is turnings from manufacture, cannot relate these bits to anything in the diff, so tomorrow will be the big day as have to strip the entire diff to find out what the problem is, and will take pics through the whole procedure, catch you all tomorrow, Rick

[solarman216]

Having given it some thought, I suspect nothing more than a "picked up thrust washer on the OS planet gear, time will tell, Rick

[Banshee]

Does that mean we're still getting the strip down Rick? :naughty

[solarman216]

Yes got to strip it down completely to find out, starting shortly, Rick

[solarman216]

After dropping the oil these bit were on the magnet, but do not think they are from my diff, more like lathe turnings from manufacture that did not get removed

[solarman216]

Diff lock fork, made it easy to remove carrier

[solarman216]

Diff out

[solarman216]

In the previous pic you can see the heavy dog clutch that is the diff lock, here we are marking so as to get the mating parts back together in their correct places

[solarman216]

Spacer to keep shaft off the oil seal, cannot withdraw them in the workshop

[solarman216]

More marks, you can just see at 12 o'clock

[solarman216]

Dial gauge set to record back lash

[solarman216]

Recorded

[solarman216]

More marks this time light grind to Crown Wheel as it is hard

[solarman216]

After splitting the diff case this is the NS drive gear and thrust washer, all good as gold

[solarman216]

Punch out spider pin locating dowels

[solarman216]

Remove spider pins and gears

[solarman216]

Not what I expected, it is all as good as gold, need a rethink on this one

[solarman216]

Putting it back together, have come to the conclusion it is a malfunction of the vac operated diff lock, will investigate that tomorrow

[solarman216]

Sorry no pics but all back together and at the mo can only say the on lock vac is stronger than the off lock vac so poss a leaky pipe, it still does not fully explain why it only ever pulled to the right, never once to the left, maybe something to do with the lock not fully engaging but just ratcheting, which is the noise I heard, more investigation yet to come, not heard a peep from other Patrol owners so assume not a common problem, anyway real glad I have the experience of stripping it as I now know what a solid bit of kit this rear diff is, Rick

[Barrbeast]

Yeh sorry Rick, my Y60 has a LSD and the only time I had an issue with the difflock in my Y61 was when I stripped a tooth off the dog clutch from over use when I unknowingly had a knackered hub (found the tooth fragments stuck to the sump magnet and when I tested the lock it just gave a clicking sound but didn't engage).

I never tried to fix it, just fitted a Lokka in the front.

[makeitfit]

Never had that issue with mine but have heard that the diff lock actuator is a bit suspect.
No idea why it would shoot off to one side other than local road conditions like camber or wetness ?

[solarman216]

After a bit of rooting around discovered that it is routed through the Glow plug controller, as I do not have an ECU on mine the Glow plug unit handles the plug timings and related parameters like coolant temperature, current battery voltage, how long it has it has been running over a certain revs, etc it also handles the tachometer, and now discovered the diff lock in as much as it will not allow diff lock above a certain speed, now this little box of tricks sits down by the throttle pedal and has been wet a couple of times, certainly the Tacho plays up regularly, for the moment I have disconnected the "lock" vac pipe leaving the "unlock" pipe attached, if this cures the problem then a mod will be required to simply connect the switch direct to the two vac control valves so by passing the "control unit" which I feel is playing about, glow plugs will go the same way via a simple timing unit to keep them on for a few mins after starting, Rick

[makeitfit]

Have you got a pic of that unit please Ric

[solarman216]

No but get one tomorrow, Rick

[solarman216]

Location of unit

[solarman216]

Detail plate. Rick

[macabethiel]

Sorry no pics but all back together and at the mo can only say the on lock vac is stronger than the off lock vac so poss a leaky pipe, it still does not fully explain why it only ever pulled to the right, never once to the left, maybe something to do with the lock not fully engaging but just ratcheting, which is the noise I heard, more investigation yet to come, not heard a peep from other Patrol owners so assume not a common problem, anyway real glad I have the experience of stripping it as I now know what a solid bit of kit this rear diff is, Rick

I would be well hacked off after all that work for it not to be the diff.
Were there any issues such as diff bearing preload on the rebuild or is it okay?
I guess its far more likely to be a loss of vacuum on old pipework or even the control unit.

I assume you have ruled out a sticking handbrake cable or brake caliper / drum.

Reminded me of when I took the gearbox out of my brothers Austin 1100 -twice -for jumping out of gear. Turned our to be lower subframe mountings had ripped out part of the front floor!!

[solarman216]

No problem with bearing pre-load, one cap I did not disturb the other just wound it up to the marks I made, however the pinion was another matter upon looking at the inner bearing when turning the pinion the rollers were not rotating, so stripped that out to check it over, conclusion was that there was insufficient pre-load, the adjustment here is with shims, one 5 mm the other 2.2 mm so took 0.2 mm off the thicker one, assembles it up without the oil seal and now got the prescribed loading, pulled it apart and re fitted the oil seal so bob's your uncle all hunky dorry, as an add, removing the lock vac hose did not cure it, as the control system is clearly the culprit whilst not being able to lock the diff it was removing the unlock vac so the vac chamber is free to move which it did to the tune of nasty ratcheting sounds, cured it now though, put permanent vac on the unlock chamber, Rick

[makeitfit]

Detail plate. Rick

Thanks Rick, I'll go and get mine out for a check over. :)