Help freeing up front and rear diff locks...

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Help freeing up front and rear diff locks...

Postby Gary. » 12 Sep 2016, 18:22

Hi all,

I've been under the truck this evening to try and understand the access and process needed to free both diff locks. I've read through a couple of guides and they are not very clear. I poked about with a screwdriver and 10mm spanner, but there was not sufficient space to rotate the spanner on the bolts holding the brackets on. It seems common to cut through the thinner captive nut type bits - is this sensible?

If I do this, is it safe to just remove the actuator? I guess I can then test the actuator functions & free up the diff lock mechanism at the same time?

Could anybody advise on the process / tools involved? I'm looking for minimal disassembly and to simply get them moving again.

Thanks
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Re: Help freeing up front and rear diff locks...

Postby Winchweight » 12 Sep 2016, 18:43

Not done the front one but I guess it's similar.

Jack up the rear of van. Insert axle stands and chocks. Detach driveshaft from gearbox and immediately bag it up. If necessary you could remove the gear linkage to get more space.

The actuator is held on the bracket by two small screws (small but long, usually Allen key or small flat screwdriver head) which pass through the actuator casing and into captive nuts. Fiddly blighters. Undo those. Then halfway down the pin that goes into the gearbox, probably behind a rubber cover is a roll pin. This needs to be drifted out with a punch (3mm IIRC) and use a magnet to catch it when it comes out. Then remove actuator. Leave the mounting bracket in place.

You can then test the actuator function without load.
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Re: Help freeing up front and rear diff locks...

Postby Gary. » 12 Sep 2016, 19:09

Is it really necessary to remove the driveshaft etc just to check these little actuators and what's behind them?
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Re: Help freeing up front and rear diff locks...

Postby axeman » 12 Sep 2016, 19:25

Your going to have to remove the diff from the van to free up the front diff lock. Once removed your gonna have to remove the rear section (as if your going to change the vc) and you will see the locking pin this will need to be tapped in and out with a copper mallet several times to free it up.

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Re: Help freeing up front and rear diff locks...

Postby Winchweight » 12 Sep 2016, 19:42

Gary. wrote:Is it really necessary to remove the driveshaft etc just to check these little actuators and what's behind them?


Up to you really. Just gives more space. My fingers and hands are like pigs breasticles and I need the space....
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Re: Help freeing up front and rear diff locks...

Postby Winchweight » 12 Sep 2016, 19:43

breasticles

I didn't write hat but like it... Love forum swear filter.
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Re: Help freeing up front and rear diff locks...

Postby Wedgbury » 12 Sep 2016, 20:09

Depends if you have had them working and they have just decided to stick but try removing the actuators switches on top and dropping some lube in, also spraying up the outside of the actuators with penetrating spray to start with helps.
Have you tried the vacuum lines to make sure they actually have enough pressure. Worth having a spare vacuum actuator to use as a test.
If all that fails it is a strip down.
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Re: Help freeing up front and rear diff locks...

Postby Gary. » 12 Sep 2016, 20:26

I think I'll try the spray method first...
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Re: Help freeing up front and rear diff locks...

Postby max and caddy » 14 Sep 2016, 17:34

All the above methods are are somewhat excessive...best approach is to remove the diff lock switch and fill the hole with plus gas or similar penetrant...to the top...and wait..then remove the two actuator screws ( should have a 7mm head) and you may need the driveshaft off to get the screw out...or cheat and grind of the captive nut and pit the bolt in the wrong way after...then you can work the locker pin in and out hopefully...if it moves ...a bit of pipe looped out in the actuator will lock it so it can be pushed and pulled...if the pin is really stuck remove the roll pin at this stage and get the actuator out the way. when the pin is free it should pop out by itself...bear in mind if you clout it in with a hammer the lock castle will need to be aligned in the diff and you can't tell when it will be...also once it's in it will be tricky to get back out if it's stuck..

The front diff is best removed...and access is from the front plate not the VC side as stated above..getting the full diff out is actually not at all bad..but remove the actuator first as it is very vulnerable.

Before doing any off the above check the vac system is working as a single split pipe will take out the full system. The lockers are applied with a vacuum but also sucked off :oops: afterwards so if there are is a leak vac won't build up.
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Re: Help freeing up front and rear diff locks...

Postby Gary. » 14 Sep 2016, 18:21

max and caddy wrote:All the above methods are are somewhat excessive...best approach is to remove the diff lock switch and fill the hole with plus gas or similar penetrant...to the top...and wait..then remove the two actuator screws ( should have a 7mm head) and you may need the driveshaft off to get the screw out...or cheat and grind of the captive nut and pit the bolt in the wrong way after...then you can work the locker pin in and out hopefully...if it moves ...a bit of pipe looped out in the actuator will lock it so it can be pushed and pulled...if the pin is really stuck remove the roll pin at this stage and get the actuator out the way. when the pin is free it should pop out by itself...bear in mind if you clout it in with a hammer the lock castle will need to be aligned in the diff and you can't tell when it will be...also once it's in it will be tricky to get back out if it's stuck..

The front diff is best removed...and access is from the front plate not the VC side as stated above..getting the full diff out is actually not at all bad..but remove the actuator first as it is very vulnerable.

Before doing any off the above check the vac system is working as a single split pipe will take out the full system. The lockers are applied with a vacuum but also sucked off :oops: afterwards so if there are is a leak vac won't build up.


Thanks, this is certainly more like my type of approach. I'll try at the weekend.
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Re: Help freeing up front and rear diff locks...

Postby HarryMann » 14 Sep 2016, 19:43

If you get to the stage with the vacuum actuator removed (vac throttle unit in VW speak) having succesfully driven the rollpin out (you must use a 3mm or less than 3.5mm parallel drift, start damaging the operating pin itself and its a downward spiral)...
then a 3mm allen key can be inserted in the rollpin hole to help shuttle the op. Pin in and out. As Neil says a few taps with a copper or soft hammer may initially be needed, you'll have to assess the state as you go.. it may operate fine once initially unseized and cleaned up, if indeed they're seized.


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Re: Help freeing up front and rear diff locks...

Postby HarryMann » 14 Sep 2016, 19:51

So a word of caution... there's a good few gotchas and it's a somewhat delicate arrangement butvworks very well if rebuilt properly and kept in use... can just about last a season and work reliably next time out.
1) Note the pipe colours go back correctly !
2) the telltale switch, rubber cover and the ally washer (critical thickness /they corrode ) must be removed if the internals are seized to get WD or similar in there as you shuttle and free it up.
3) pause
4) the 3.5mm rollpin is in at an angle (I drive it bottom right up to top left)
5) the vac unit support bracket can get twisted /distorted if the long thin M5 screws have been over tightened.
6) when the vac unit is out visually inspect the boot/bellows' integrity. Hold the pin and blow (or suck) into each chamber in turn to check it isnt leaking or cracked.
7) Re-assembling carefully (alignment is critical) with the two overlapping (much protecting) hoses in a small space isnt that easy (some even fill them with grease).
Leave the vac unit supported but unbolted as you 'push' the rollpin back in... notice the rod needs to be fully home inside the op.pin so the waisted section aligns with the hole).
Then insert the long M5 screws but DO NOT overtighten.
8) Take it steady the first time you do this job and good luck.
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Re: Help freeing up front and rear diff locks...

Postby Gary. » 08 Feb 2017, 18:17

So there I was googling diff lock issues, the came across my own post on this forum!

Seems it took me a few months to get to that weekend where I attempt a basic fix. Used a screwdriver to open up the rubber gasket, front and rear, then liberally applied penetrating oil.

Image

Front works a treat, but the rear, oh dear no show...
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Re: Help freeing up front and rear diff locks...

Postby Gary. » 15 Mar 2017, 18:05

Well, that was fun! Managed to remove the long thin bolts and 6mm nuts, super awkward and fiddly. The actuator came away, but was retained by pin through shaft. I found this easier to get to once I realised the rubber seal came apart in the middle. It was easy enough to drive out.

With the actuator removed it is easy to access the shaft, which should easily push in and spring out on it's own accord. I jacked up both rear wheels so I could rotate to allow pin to slide in the correct position to engage diff lock.

WARNING TO ANYONE ABOUT TO ATTEMPT THIS PROCEDURE: Do not tap the pin with a mallet as it may be very stiff, subsequently extremely hard to release outwards. I did! Had to improvise a leverage system to get it to come out again.

Using multiple squirts of penetrating oil, I managed to get the pin moving in and out. Which I probably did several hundred times. Though I ran out of time and it was never free enough to push in with my fingers, though it partly sprung out. I decided to re-assemble and try another time.
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Re: Help freeing up front and rear diff locks...

Postby garyd » 15 Mar 2017, 20:49

I made my own simple tool to avoid risking the vacuum actuator to push and pull the rod in & out.

It is basically 'T' shaped with the centre shaft matching the vacuum servo rod in diameter and with a similar groove filed around it. After removing the servo, the tool can be fitted in it's place with the roll pin and used to push/pull the actuator rod.

Adding this to the oil in the switch aperture and lots of effort has worked well for me.
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