4wd selector pin is driving me crazy

[McBrain283]

Not sure why but been having trouble with this tonight and it's driving me crazy.

I'm reassembling the front output housing and I'm finding that the hole in the rod (the short one between the Hi/low selector shaft and the 2wd/4wd selector shaft) is not lining-up with the 4wd selector pin (the one that is pulled by the yellow knob). The hole is about 4mm too far forward.

Trouble is that I can't see how there is any adjustment in the position fore/aft of that hole. The only adjustment would be by moving the pinch blocks on the selector shafts, but they are fixed by bolts that pass through holes in the shafts. I've tried a bunch of stuff but I thing I'm missing something!!

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[JDNSW]

I cannot see any way you can have something wrongly assembled to get this effect - I did have a thought that the sliding dog for front wheel drive could be the wrong way round, but I don't think that is possible, and if it was, would put things a lot further out. You need to remember though, that for the pin to drop into the hole, the transfer hi-lo lever (red knob) needs to be right back. And if the gears engaging low range are not engaging properly, due to the teeth being lined up, the lever can't move right back , and the pin can't drop in.

[McBrain283]

Thanks John.

I had another look this morning before work.

The selector shaft is moving all the way back (red knob backward) as I have tried it without the dog clutch fitted and also without the shaft spring. Confirmed correct position as the detent plunger is in the forward-most detent notch.

Playing with it today I have noticed the following:

Some play in the collar that is the forward-end of the selector shaft spring (#15 in diagram). The internal bore may have worn relative to the shaft
Some play in the pinch block in front of #15 above (#16 in diagram). Hole through shaft/block may be a little worn.
Link #21 may have wear inside forks but I don't know what the nominal gap should be.


I think that the stack-up of all this wear, even though slight, may be causing a 4mm error in the position of the hole. The play isn't purely fore-aft, it causes the rod (#20) to go on an angle, but I think this translates to the hole location when the rod is guided by the hole in the output housing casing.

I cant see what else it can be.

I'm not sure I will be able to source new parts for #21, #19 and # 16.

A possible fix may be to make a spacer to go on the shaft between parts #15 and #16 to shim the rod back the 4mm it needs accounting for the play. I might do that and then test the whole mechanism to see if it operates reliably.

[JDNSW]

How about simply boring the hole in the shaft out a bit? And/or taper the end of the pin a little so it will help it go in even if a little misaligned?

I had not thought of the possibility of accumulated wear - this mechanism does not usually get an enormous amount of movement.

[B.S.F.]

I've got some G/Bs and GB parts sitting on the floor. The only way I can replicate your problem is when I remove
part no 27,28,29and 30 on the drawing in post #3
.W.

[McBrain283]

I've got some G/Bs and GB parts sitting on the floor. The only way I can replicate your problem is when I remove
part no 27,28,29and 30 on the drawing in post #1
.W.

So you think it could be a detent alignment issue?

I checked the the fork in the transfer case is aligned with the groove in the shaft - but I could try removing this fork and see what changes.

When the selector shaft #9 is fully rearward, is the detent plunger support to sit in the forward-most groove?

[McBrain283]

How about simply boring the hole in the shaft out a bit? And/or taper the end of the pin a little so it will help it go in even if a little misaligned?

I had not thought of the possibility of accumulated wear - this mechanism does not usually get an enormous amount of movement.

I think it's a bit too far out for that if I want the pin to reliably drop-down

[McBrain283]

I've got some G/Bs and GB parts sitting on the floor. The only way I can replicate your problem is when I remove
part no 27,28,29and 30 on the drawing in post #3
.W.

B.S.F, from memory the diameter of the selector shaft is 16mm. Are you able to please take a measurement of the internal diameter of part #15? That way I will know if mine is excessively worn.

[B.S.F.]

Sorry, I'm not prepared to dismantle the assembly to take measurements, but I can assure you that no.15 is a very loose fit on the shaft.
.W.

[McBrain283]

Sorry, I'm not prepared to dismantle the assembly to take measurements, but I can assure you that no.15 is a very loose fit on the shaft.
.W.

I wouldn't expect you to [biggrin]193386193387

It may be an issue with alignment of the 3 shafts relative to each other which I causing them to jam in the holes and the rod not comeback far enough.

I made a jig to set this better. But have given up for tonight

[whitehillbilly64]

When you tested it was it fitted to the vehicle with floor plates fitted springs etc or on the bench?
I would dry fit everything again on the bench. couple of nuts to hold it.
When moving the red knob lever backwards hold the yellow knob UP and see if the pin relocates replicating the spring fitted. Moving the Red knob lever forward, as the hole passes the pin it should pop in.

whitehillbilly

[McBrain283]

When you tested it was it fitted to the vehicle with floor plates fitted springs etc or on the bench?
I would dry fit everything again on the bench. couple of nuts to hold it.
When moving the red knob lever backwards hold the yellow knob UP and see if the pin relocates replicating the spring fitted. Moving the Red knob lever forward, as the hole passes the pin it should pop in.

whitehillbilly

It's on the bench. No levers fitted.

I did try some pressure on the pin, but it is about 'half a hole' out of alignment.

I'll get some photos today.

[B.S.F.]

Have you got all the correct parts fitted ?
.W.

[McBrain283]

Ok, so I got it working.

I wish I could explain exactly the issue, but it was another case of persistent fiddling and then leaving it overnight and coming back to it.

I think the problem was probably related to some misalignment between the 3 rods (my crappy wooden jig may have helped here), as well as some misalignment/movement in the whole setup that was causing the 4wd/2wd shaft to bind-up in the hole in the casing. I think this was resulting in the 4wd/2wd, and also the small 4wd rod with the hole for the pin, not sliding back far enough to allow the hole to line up.

As soon as I realised if was lining-up I got it all together and bolted-up the casing. It's tested as reliably working.

Thanks for your help and advice!

Hopefully the gearbox will go back-in this week and I can move - getting close to starting on the engine.