Freelander IRD

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Originally Posted by garrycol

The tolerances between the rotors and stators in the VCU are very close and as the viscosity of the old stuff is either solid or close to it I doubt just putting new stuff in will work - the old stuff will have to be washed out first or the new stuff will not get to where it counts.

Garry

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Hi Garry - long time between posts on this - apologies. (New bub, Sold house, new house - no time to muck about with the VCU) The VCU on our freeloader has stiffened up a little more since I last checked it, starting to skip / chirp the inside rear wheel going around roundabouts - Worried about damaging the IRD, so have got moving and removed the propeller shafts / IRD as a unit. (amazing how nippy the car is in FWD...)

I emailed the supplier of the Siloxane and asked about a solvent - received the following reply:

A hydrocarbon like white spirits or mineral turps works well. Being thick fluid it will take a while to mix in, or goes better if you can agitate it.

Which is good news from toxic chemical solvent point of view. I think I'll drill and tap an input and output hole 180 deg. apart on the face of the VCU near the outer circumference, load up what turps I can then button it up and run it in the car around the local roundabout for a few laps - drain and repeat - see if that yields some results. I would expect to feel the stiffness of the VCU disappear as the old fluid is diluted and removed and the stator / rotors inside freewheel more easily in relation to eachother.

Not 100% on how much fluid should be added to the unit when refilling with new fluid - but I'll weigh it before I start and after flushed - that should let me know how much is needed to fill.

Cheers,

Scott.

With regards to removing the silicone based fluid from a vcu.
I drilled a hole 6mm top and bottom of the vcu. Next I obtained a can
of engine degreaser and plastic straw which comes with it.Put as much as
I could into the top hole,bit messy,left it over night.Next day I got
The air gun on the top hole and blew it all out the bottom.This was done
with the vcu in the vice.When this was completed I could turn the vcu
with ease.Hope this helps.

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Originally Posted by hugh

With regards to removing the silicone based fluid from a vcu.
I drilled a hole 6mm top and bottom of the vcu. Next I obtained a can
of engine degreaser and plastic straw which comes with it.Put as much as
I could into the top hole,bit messy,left it over night.Next day I got
The air gun on the top hole and blew it all out the bottom.This was done
with the vcu in the vice.When this was completed I could turn the vcu
with ease.Hope this helps.

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But does it lock when required - the general consensus by those in the know is that there is usually damage to the rotors and stators as well. The experts do not consider them the be cost effective to repair - they need to be cut open (dangerous as they can explode) clean all the fluid (solid) out repair rotors/stators and reassemble.

Garry

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Originally Posted by aikendrum105

The VCU on our freeloader has stiffened up a little more since I last checked it, starting to skip / chirp the inside rear wheel going around roundabouts - Worried about damaging the IRD, so have got moving and removed the propeller shafts / IRD as a unit. (amazing how nippy the car is in FWD...)

I emailed the supplier of the Siloxane and asked about a solvent - received the following reply:

A hydrocarbon like white spirits or mineral turps works well. Being thick fluid it will take a while to mix in, or goes better if you can agitate it.

Which is good news from toxic chemical solvent point of view. I think I'll drill and tap an input and output hole 180 deg. apart on the face of the VCU near the outer circumference, load up what turps I can then button it up and run it in the car around the local roundabout for a few laps - drain and repeat - see if that yields some results. I would expect to feel the stiffness of the VCU disappear as the old fluid is diluted and removed and the stator / rotors inside freewheel more easily in relation to eachother.

Not 100% on how much fluid should be added to the unit when refilling with new fluid - but I'll weigh it before I start and after flushed - that should let me know how much is needed to fill.

Cheers,

Scott.

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If the rear wheel is skipping etc I would have thought that was more diff than VCU - if your VCU slips it is still OK.

I understood Siloxane to be a concrete sealer so I am not sure what that has to do with VCUs.

VCUs are not basically rebuildable - even the experts do not do it - ask Ashcrofts.

Garry

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Originally Posted by garrycol

VCUs are not basically rebuildable - even the experts do not do it - ask Ashcrofts.

Garry

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Ian Ashcroft posted this on another thread related to the RRC B/W VCU - works the same way as the Freelander one.

"Hi we used to rebuild/repack the viscous units but stopped when new became more economic. The silicon fluid in the coupling, when overheated, changes state and becomes solid, very like a solid lump of rubber. BE VERY CAREFUL if you attempt to split a unit, when the silicon changed state it expands and it often splits the weld, if it doesnt split the weld and you put it in your lathe to turn the weld off it will most likely EXPLODE blowing the end off, be warned.
Anyway assuming you split the coupling chances are a couple of plates are scrapped and will need replacing so you will need a second sacrificial unit, obtaining the silicon, with the correct viscosity and the anti oxident added is a nightmare (in the UK).
Hope this doesnt sound too negative but do be careful, I found out the hard way, ouch.
Regards Ian Ashcroft"

** Massive apologies to Woko for the almighty thread hijack here.... let me know if you'd like this all moved to a new thread **

Hi Garry and Hugh - thanks for the info, and definitely appreciate the warning - I'll definitely take a lot more care when drilling into the unit after reading that (and start with smaller pilot holes...)

I guess my thought process about it is this - the VCU hasn't seized yet - it's still slipping - but has become much stiffer in the last 12 months than it was previously. The VCU test still works - but it requires a *lot* of force and significantly more leverage to rotate than the examples on youtube etc. (even to move it very slowly) As I understand it - the higher the force required - the more wear you have on the IRD Pinion, until you break it or chew out the bearings supporting it...

Likewise - marking the front and back propeller shafts with paint - you can see their relationship to eachother is changing.

The the inside rear tyre skipping / chirping when going around roundabouts - after removing the propeller shafts / VCU completely - the symptom is gone.

So assuming that the VCU is *still* operating - albeit very stiffly - the stators / rotors are still undamaged - and drilling the 6mm holes on either side and flushing the unit out with turps / degreaser would result in an open VCU - which would a) spin freely and b) provide absolutely no 4WD benefit at all.

Pumping in the new siloxane until the VCU weighs the same as it did prior to flushing, should result in a VCU that works correctly again - however... Ashcrofts point about the anti-oxidant additives is really important. How long the VCU performs before the siloxane starts to break down again will be the mystery. I wonder if using C02 (love the home brew) to pump in the fluid and flushing any headspace with it as well before sealing the VCU up might help with that...

I would completely agree that it would be pretty unecomical to do these on a commercial basis with so many unknowns - on the flipside - it will be interesting to see how much longevity (if any at all) $100 of fluid and a few hours stuffing about with the VCU / propeller shafts can give an old (but not seized) VCU. If you got 12-24 months out of it before it thickened up again - I think it would be worth it.

I mean - compared to the cost for a new one anyway...

We don't take the hippo (who coined that? - it's awesome) off the reserve very often - but it's been very handy in a number of situations to have that 4wd engaged (wet freeway evasive action included ) and it niggles me to have the thing crippled in 2wd at the moment.

Anyway :) I do really appreciate the advice and thoughts - keep it coming.

** edit - here's the thread i found that started me down this path http://forums.lr4x4.com/index.php'showtopic=51912 I don't know if Polydimethyl Siloxane with a CS of 12500 (relative viscosity ?) is the same grade / composition as siloxane used for concrete stabiliser....

Cheers,

Scott.

Found this today - gotta give it to the VW guys for a user serviceable VCU - I wonder if these could be easily adapted to the Hippos...

[ame=http://www.youtube.com/watch?v=PFn9-jnO5nc&feature=mfu_in_order&list=UL]YouTube - ‪T3 syncro Visco Kupplung zerlegen und instandsetzen Teil 6 - Das Zusammensetzen (4)‬‏[/ame]

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Originally Posted by woko

All bearings have been ordered and should be here by Wednesday.
Removed cooler with out damaging but crown wheel had been rubbing on it so have to replace.
Crown wheel and pinion have been damaged and the current manufacturer has gone broke, so these parts are scarce at the moment until another manufacturer starts making them. I did find a supplier but it has doubled the price of crown wheel and pinion.
I'm going to convert to be a 2wd in the mean time. The only off bitumen this freelander sees is about 500m of a gravel road once a month if lucky.

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How do you convert them to 2wd buddie? Just grabed a 1999 freelander for the wife suburb driving and dont want to worry about the issue with the vcu locking. Anyhelp would be great and i know sweet fa about 4wd's lol have owned sadans my whole life.

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Originally Posted by 2_stroke

How do you convert them to 2wd buddie? Just grabed a 1999 freelander for the wife suburb driving and dont want to worry about the issue with the vcu locking. Anyhelp would be great and i know sweet fa about 4wd's lol have owned sadans my whole life.

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Easiest is to simply remove the two tail shafts and the VCU in the centre. Guess you could even leave the VCU in place if you wanted. Just remove the two tail shafts.

With the mod done there is just a little more backlash in the front drive but not an issue and you tend to spin the front wheels a bit more but the car does feel a bit more nimble.

Garry