fantastic work bro! (mean that!)

(quick someone (nr Ormskirk.. wherever that is!?!?) buy that man a beer.....)

 

A quick update
I have found a place that can make quad seals to my specification, so they are on order. I have started to clean off and inspect the plates and all is looking very good. It took an hour to do about 15 plates so I have a few hours ahead of me yet. The plates alternate one with fingers/one without. There is not really much to these viscous couplings!

Stack of plates

This shows where the filler nipple locates in the housing to lock the cap.

Stack of cleaned plates.... good god it is sticky stuff to get off (wife is not happy about me using all her kitchen roll!! why are they so possessive about kitchen roll?)

Don't panic, the top plate was from the broken VC that I disected and you can see that it is worn and has bent fingers. Now that we know it is possible to crack these suckers open, it is vital that the fluid is changed every 80k as the silicone goes bad and both wears the plates and increases the pressure until it goes pop. Presumably changing the fluid will extend the life of the coupling considerably.

 

Really?!!

It's just a bleed nipple acting as the lock? Slap me with a side of lamb...I hope that's the case for me. I'm going to have to climb under the DOKA now just to have a squiz as I'm approaching 200,000 kilometres on the clock...

Happily source a seal kit from you if you get it set up someday and would send it to Australia...it'd be my way of thanking ye for having a crack!

 

Yes the bleed nipple acts as the lock. But the silicone enters the threads and we already know it has amazing shear properties as that is how the VC works and so the cap is incredibly tight, i needed a 5ft bar to give me the leverage to open it. and remember, if you undo the nipple, silicone will start oozing out, as at that mileage it will have degraded and will be under pressure. So don't take the nipple out until you are ready to service.

 

I'm in the same boat as Seano. This is ringing a bell with something I read about haldex (I have an Audi quattro) There is a company (or person) in canada that sells a different nipple that effectively makes the haldex 50/50. so sounds like your nipple theory is similar.

 

The bleed/ filler nipple is simply the retaining pin for the cast iron cap. Without taking out first you can't undo the cast iron cover. It serves no other purpose except for factory filling.

 

all very interesting,well done for having got this far with it .keep up the good workA:

 

I haven't even got a synchro and I'm hookedon this thread! T:

 

Well done Ian, keep the pics. & info coming.

 

Ian that is top result!T: No one had worked out how to open these vcs. There's a thread on vwvortex of a guy machining the alloy end cap on a Passat vc to open it - I thought this might be the same on a T4 Syncro! It's a good thread http://forums.vwvortex.com/showthread.php?5958346-Viscous-Coupler-SAE-Technical-Documentation-and-Rebuild-Info/page2

Had you thought how to calculate the volume of silicon fluid to refill the vc? I know T25 syncro vcs have to have a volume of air so they aren't 100% filled, as space is needed for the fluid to expand as it heats up. I have a spare vc and can (hopefully) borrow a set of those super accurate scientific scales - I've used them in school to weigh the air in a balloon. That way you can weigh the complete vc then weigh the empty, stripped down vc and calculate the difference. In the vwvortex Passat rebuild they also calculated the volume from the weight and fluid viscosity! I'm only about an hour from you so happy to come over and help out if needed.

However if you have an alternative method let us know. Have you sourced the fluid too?

 

Yes I had seen the thread on vwvortex, it was that info that convinced me to have a go. The quoted air gsp amount is 7%, Although there was a conflicting volume on the syncro site saying an 86% fill. However, i think this is too low. I'm expecting the volume of the VC to be around the 300ml mark and I'm just goin to fill the top and bottom with fluid and measure the volume. The silicon is so thick that the volume of the VC less the 7% air gap will be converted to weight using the mass density of 0.97 which is quoted on the side of the silicone Bottle I have. I would be interested to know what your VC weighs to compare to another one I have and to the empty one. The more info on this the more likely we are to get it right. If the amount is wrong I can always open up again, now I know how to do it.

I will let you know if I need any help. If you want to come round I can open your VC for you and you can start cleaning the internals.

 

The new wear sleeves are ready. This is the bit that is on the outside and runs in the diff oil seal. It makes sense to replace this as mine had a definite groove.

 

Hello and greetings from Norway.

First of all A: and thumbs up for a job well done! Have you considered to offer reconditioning service for us forum members? If so, that would bee of great! I would like to have this done. My car is getting on with age and the VC have never been touched.

 

Cheers Ian I may well take you up on helping to open up my spare vc at some point. I'll get it weighed and pass on the measurements - yes the more info we have the better.

The spare vc is of unknown condition (I got it with a rear diff as a spare from a breakers a while back). I have welded up some metal work so I could turn it using using a bar to workout if it was seized or failed open, etc. It turns with a some force from a bar so it isn't seized. I got the idea from German 'syncro 16' wiki - I'm sure you've seen that rebuild. Next I want to adapt it so I can put a torque wrench on it.

Will follow your progress with interest.T:

 

brilliant thread and has come at a right time. I am in the process of stripping a syncro with a view to add it to my 2wd van. So since the VC will be off, after a 160k, it would be right to service it, given I know the diff has been previously serviced.

So I like to tinker, dont exactly have a workshop with a vice etc at my house but I manage. Similarly if you need access to my VC to measure weight/fluid just to add more data to the spreadsheet, then I will happily obligue and come round for a brew A: Not sure what help I will be but will do my best T:

 

If this all comes to fruition it will be fantastic and will be great to put an end to that nagging feeling (when my vc goes its gonna cost a load to put right kinda thing)that crops up in my noggin every so often.Again nice one fella keep up the good workA:

 

Ian you are a brave and resourceful man. We took off our Syncro parts with intention of refilling the coupling but it still lies under the bench.... If you need a 5' bar to move the top how did you hold the aluminium casing without damage to it? Any tips please.

What solvent works for cleaning everything? It looks a very messy business. Put us on the list for one of your kits please. We shalln't be doing it until the winter. Cheers, Andy

 

A bit of progress, finished cleaning the disks and whilst her indoors went outdoors to do some shopping, loaded them all into the dishwasher for a final clean
Silicone is weird stuff, you can get it all over your hands and yet it just wipes off and a bit of soap and its all gone. I just wiped all the disks with kitchen roll(used 2 rolls) and sprayed some contractors solvent every now and again. I have taken the aluminium casing for a vapour clean so will be sparkly when it returns. I held the casing in my lathe and locked the chuck. An average person may get away with a shorter bar but as I weigh less than 9 stone, I was jumping on the b*gg*r. There are some marks where I tightened the jaws but nowt too bad. It may be possible in a big vice with some wood blocks.

I picked up the quad seals today and o rings, I am assured they are the right ones but they seem big to me. I will have to do some checking on that.

As soon as I get the case back I will need to measure the interior volume. I think I will do this in a variety of ways with the top and bottom separate and then together and compare.

 

Wow - love that dishwasher shot - my wifey would kill me if she found I'd loaded it up with Syncro bits...
Thanks for advice anyway. Can't wait for next gripping instalment.

 

Lol, brilliant, that pic should be your avatar, its no wonder you waited till wifey went out! Not got a synchro but a great thread to read. Its great that peeps try things and post for all to see and hopefully fix themselves so saving a bob or two. Also its fascinating to see what's inside these units.

 

I have got the case back after vapour cleaning. it looks very good
before

After

and this is the inside of the lid after another risky manouvre with her indoors dishwasher.

So now I need to work out the volume of silicone required. will have a go later.

 

I have got the case back after vapour cleaning.

What's vapour cleaning? Not a term I've heard before. Looks like some form of bead blasting or sand blasting.

 

keep it up ,im loving this threadA:

 

Aqua blasting is a process of cleaning parts back to their original 'as new' finish. Also known as Vapour blasting or Wet blasting. Various media is used to achieve the correct finish to the metal. The media is forced under pressure with hot water to give a silky satin finish which can then be painted, laquered or left bare. An anti corrosion additive is also included to help prevent studs, etc. from rusting after cleaning. This process is not as harsh as dry blasting so can be used on delicate items such as carburetors. Aqua blasting is suitable for all non ferrous metals including Aluminium, Magnesium, Titanium, Brass, copper and Stainless Steel. (not my text, just taken from the website were I took the part)

Had a bit of a mare moment last night, the top screws on to the base very easily now it is cleaned up but screwing it back on I could not work out were it was originally tightened to. I had marked the case or at least I thought I had but the markings on the cast cap appear to have disappeared. Anyway I tried to tighten the cap to the point I thought it was supposed to go to and I couldn't get it to within a quarter of a turn of the point as it bottoms out on the Aluminium part. I was using a 6ft bar as leverage to tighten and then I couldn't get the blighter undone again, so it was back in the freezer. Anyway after much cursing I decided to study the large number of pictures I had taken and it appears that the cap screws on to just before it locks up on the base. This is really important as it obviously varies the volume of the VC. So by the time I had messed about getting the thing undone again it was late and I only managed to have one attempt at determining the volume. This is also a really good thing and it explains why I could undo the VC in the first place as it is not tightened by force, it is simply the locking pin and the silicone entering the threads that stops the VC opening. It almost appears as if VW made this VC with a view to easy servicing!!
Mare over and with renewed focus
I filled the VC through the filler hole keeping the hole at the highest point and shaking every now and again. I am not convinced that all the air pockets will have come out doing it this way, so tonight I will part fill, with water, dropping the disks in individually and then add additional water to get the final volume.

Here is a nice pic of all of the disks in the case.

 

Aqua blasting is a process of cleaning parts back to their original 'as new' finish. Also known as Vapour blasting or Wet blasting. Various media is used to achieve the correct finish to the metal. The media is forced under pressure with hot water to give a silky satin finish which can then be painted, laquered or left bare. An anti corrosion additive is also included to help prevent studs, etc. from rusting after cleaning. This process is not as harsh as dry blasting so can be used on delicate items such as carburetors. Aqua blasting is suitable for all non ferrous metals including Aluminium, Magnesium, Titanium, Brass, copper and Stainless Steel.

Thanks Ian. I have seen where earthmoving equipment has been wet blasted prior to painting but as I said not heard the term vapour blasting.
BTW, this thread is the one we have all been waiting for. Thanks for your efforts in taking us all along your journey.
Thanks also to freek for his additional piece of information.

 

would be good if someone can get some info from germany about the quantitys of silicone some one must know !

have you posted this on the german t4 forum ?

 

This is an interesting topic Ian and the first I have found about taking apart the viscous coupling of a T4. I'm living in Holland and there are not many syncro's around here. Our T4 syncro has now run over 350.000 kms and I still do not get any signs of wear of the viscous coupling. I have also called the man of Dorfbrunnen Garage. It's in Switserland in fact. And I also had a very strange and long conversation over the phone. I assume that he is quite old. He told me that he had a son who had left the company and that still made him mad. But it's is indeed the only adress in Europe I could find for servicing the viscous coupling.
The man of Dorfbrunnen stated that it all the fault of the owners of syncros that they wear out. They treat the syncros as normal cars (I do as well ) and they do not look at tire pressure which is very important (and that I do).
I wish you lots of succes with the refill and I'm very curious if you can get the right behaviour. I have understood that the amount of silicon fluid is very very important. Btw a new viscous coulpmg in Holland costs about 1600, euros at VW.

 

freek,please elaborate on what you mean by treat as normal cars ,do you mean driving to excess on tarmac ,motorways etc also the tyre pressure thing do you mean they should all be equal ,they should be run at a certain pressure or what .would love to know these things if they prolong the life of the vc .i did read somewhere about high speed motorway driving being negative to vc units but i dont know if its true or not

 

I also consider the remark from the Dorfbrunnen man about the treatment as 'normal cars' a bit strange. I interpreted it as that Syncro's are meant to drive at moderate speed and for conditions where you profit from the 4wd like on Swissa roads. So he made me worrying as well because we drive mostly on highways with a speed of 100 to 130 km/hr and on holiday on the German motorway we even drive at a speed of 150 kms/hr. Which I consider as 'treating as normal cars' and against the rules of the Swiss synco specialist... But untill now I do not see any signs of miss treatment what so ever.
And about the tire pressure: the silicon oil can be 'çooked' when front and rear tires run at different speed during a significant duration. This occurs when the diameters of front and rear tires are different because of different specifications or differences in tire pressure. And when this is the case, driving for hours on the motorway will definately cook your silicon oil. And when this has occurred the coupling blocks to soon and finally will destroy your drive train. According to the Dorfbrunnen man: if your silicon oil has not been overheated the viscous coupling will last for ever. So it all about taking care of your tires.

 

Lets face, it the VC has been a story of myth, legend with a good measure of smoke and mirrors for too long, but the reality is that it is an incredibly simple device. A series of alternating plates one connected to the case, the next to a central shaft. The plates don't touch and are separated by a layer of silicone. The silicone has a sheer force when the plates try to turn independently. The plates are finely ground and coated to increase the surface area. So as the silicone goes bad the plates wear out. That's it. If your tyres are unequal then the VC will be used more.

I have measured the volume of the VC twice tonight by partially filling with water and carefully lowering the disks one at a time into the water so not to splash, then put the top on and turned to the final sealing point. Then continued to fill via the hole. Both times I came out with 327.5ml. I used a 50ml syringe to fill the VC. So there we have it I am very confident that I have this spot on now.

Minus 7% means 306ml
Using the specific gravity of silicone 100,000 of 0.97 means a fill volume of 288grams. So anywhere between 285 and 290 should be bang on the money. As soon as I work out how to fill the final 50ml I will get it back together and I am sure the mini grease gun will work.

 

This is it. the moment you have all been waiting for (well actually I guess you will want to see it working on the van and that will have to wait for tomorrow!)

Grease gun arrived so I gave it a thorough clean then loaded with about 100grams of silicone, tested with a few squirts and it worked well.

Next I put in the new seals and filled with about 238grams of silicone leaving 50 gram to be filled with the grease gun.

Then put the discs in, pressing down every few and trying not to get any silicone on my hands to affect the weight.
All the discs in, new outer o ring, greased and on with the top. It tightens easy just holding in a vice (which confirms that the reason it is hard to open is due to the silicone entering the threads.) (this also gives me an idea for servicing options - more on that later ). Now weigh grease gun and top up through the filler nipple with 50 grams. job done

So here we are the first DIY service of a T4 VC complete with new outer wear sleeve.

looks the business!
I will hopefully have time to put back on the van tomorrow.