A new chapter about my VC

Post by **Macflai** » 13 Jul 2006, 08:09

I think the van is a nice house, sooooooo....

Here houses are also a big expensive, in the capital city, Las Palmas de Gran Canaria. New flats are more or less 80m2 and you have to pay almost €250,000, maybe you think is cheap but here the salary is not so good so you have to ask to the bank and then being 40 years paying them!

The only thing you can be saved by is a lotto

By the way when you get the Dart from Greystones to Dublin you can see after Dun Laoghaire a very big beach, there was a french guy living in an autocaravan... (next to the buildings and next to the beach) he usually have a lot of friends there and he makes parties and bbq's! Next time I go there I won't pay more for a flat!

Post by **Macflai** » 20 Jul 2006, 11:23

Anyone knows the best viscosity of the silicone oil for a VC?

Post by **HarryMann** » 20 Jul 2006, 11:35

Dependent on air gap but at 7~8% between 80 and 100,000 mm sq. per sec. Siloxane must be of a high molecular weight.

At 60,000 mm sq/sec air gap would have to be reduced, say to 4~5%

If you get the air gap wrong you will have either no auto-clamping or a burst VC first time its used. So, do you know the exact weight of siloxane to fill to this accuracy? And have the gram scales and the equipment to fill it?

Was the existing fluid damaged (overheated) or leaking? What are the plates like? Require cleaning of debris and varnish?

Post by **Macflai** » 24 Jul 2006, 14:24

I know i have to respect a % of air inside... but VC is installed yet so I am waiting to get the Silicone oil to try to repair it... I will check the quantity of old oil to put the same and maybe a bit more but new...

Yesterday I went to a beach in the north of the island... it has a track if you want to get close to the sea and the most of the track are stones... something like US tracks in the desert, made by rocks... I was thinking about the VC function there, but tell me:

Does the VC engages if a rear tire is slipping? If so, do you imagine a tire slipping over a rock (smoke)? Thats not exactly the best thing for a tire... if I have to wait the VC engages destroying the tires I prefer a decoupler. Tell me if I am wrong about that...

Post by **Russel** » 24 Jul 2006, 18:23

ure VC should operate imediatly if u are getting smoke from a tyre without
drive to the front the VC isnt working.

Post by **Macflai** » 24 Jul 2006, 19:53

Yeh yeh I know that, but the question is, in normal VC status I mean when the VC is perfect, is new... I think the VC engages when "feels" a loosing traction in the rear tires... Is that right?

Because when you are driving on muddy sections you don't mind the rear tires slips... but it's different when you are driving on a rocky track, when a rear tire is slipping over a rock, the tire is damaging itself...

I think I having driving Land Rovers for a very long time, so I feel VC is not the same...

Post by **HarryMann** » 24 Jul 2006, 22:32

No Victor, the VC is quite different to the Land Rover system which uses a centre-differential. This can be both open or closed, depending on if the driver has locked it. Normally driving on rioads and many surfaces with it a normal 'open' diff, then its almost the opposite of a VC, in that it only transmits power to the wheels if both axles are gripping ~ the vissous coupling does require 'some' relative 'slip' between them but a very small amount, maybe 2 or 3% and will virtually lock up (300Nm) at 5 rpm difference - that means the back wheel sliiping at 1 revolution every 12 seconds and its transmitting quite a bit of torque before that.

Last weekend we were scrabbling up quite steep loose rock and limestone shale climbs, and around steep corners littered with rocks or steps up to maybe 9" high, more in some case. Only the big steps on steep climbs required diff-locks, I drove the whoel saturday in fact without using them once, so the VC was quite able on its own to shove a 2 ton truck up them, and one chap managed one of the steepest loose rock climbs in a Syncro with a supposedly failed 'open' VC.

You need a good VC, a guaranteed refurbed and tested one, to drive your syncro reliably almost anywhere sensible, and a few quite silly places too... VCs work just fine, else the Syncro wouldn't be such a renowned vehicle and 20 years after its production - still raising a few eyebrows

Post by **Macflai** » 25 Jul 2006, 08:13

Ok then, understood...

I think I have no more questions about that... Just need to fix mine to check if I can do it by myself or just wait to get some money and spend it on a refurb one.

Thanks for your patience

Post by **Russel** » 25 Jul 2006, 19:28

Glad to be of help, i asume i can say that from all of us.

Post by **HarryMann** » 25 Jul 2006, 20:29

Post by **manxman** » 05 Feb 2008, 22:42

humm reading this I think I have a failed open VC

[IMG:480:640]http://img258.imageshack.us/img258/4708/dsc00180qk2.jpg[/img]

here's me taking it off road for the first time on sunday, I'm sitting on my prop rails in reverse, both lockers engaged, smoke comming from the rear tyres not much happening at the front, did eventually drive of, then after going up a bit faster made it over the hump and went on to supprise me what it could do (with the rear locker engaged)

now some times when parked on a bit of a grassy slope outside the house I need to use the rear diff lock to get off, driving round in circles I can feel nothing happening either (not like my old Syncro)

does the 4x4 work in reverse, just grasping a straws here! (in my golf it disengages in reverse)

dont want enything else to be wrong

but its not looking good is it!

what sort of job is it to swap the vc and is the one from my 14" single cap 1.9 the same as the one in a 16" double cab 2.1?

grrrrrrrrrrrrrrrrrrrrrrrrrrr!!!!!!!

Post by **HarryMann** » 05 Feb 2008, 23:15

Yes the syncro drive train works in reverse of course..

re: your exploits on your prop-rails... are you sure the weight wasn't off the front (balancing on the prop rails) whereupon you wouldn't have had much help in that direction?
Yes they're the same (or were when made)

PS. When there's a sharp ridge contour at the top, sometimes it pays to do it like this...

[img:160:120]http://www.club80-90syncro.co.uk/Syncro ... hm-082.jpg[/img]

but no overdo it either....

If you're in doubt, find someone local who drives a syncro off-road a lot and let them have a go when they will quickly tell you if the VC seems Ok or not... with both lockers on you should be able to climb a fairly steep hill that is wet grass or muddy, if you've got decent tyres on and sit the engine at max torque. If it really has failed totally open you won't get anywhere at all on even a mild wet slope, even with the rear locker on.

But then there's a 'failing' VC and a 'failed' VC... so take your prop off and see how you get on, then put it back on and see - should transform the behaviour off-road (look after those fine threaded nuts and bolts well and store the prop flat on the ground, they're thin-walled and don't like knocks and bangs, take the opportunity to chek the prop's UJs out, for play or excessive stiffness).

Post by **manxman** » 06 Feb 2008, 00:51

Hi HarryMann,

Thanks for your advice, pretty sure it has gone to be honest, just wishing it hasn't. one problem after the next at the moment!!

With regard finding some one local I'm the only syncro here (isle of man) apart from my mates but his is a karmann gypsy type of camper so not much help available localy.

like I say it feels different to my old single cab did but I put that down to it not being too tight (only about 50,000 miles on the DoKa)

I'm going out at the weekend with the local 4x4 club for a bit of green laneing so I'll find some wet slopes and test again, then if I'm still not sure and take the prop off and see how it goes.

one question, with no lockers in and traction lost to one rear wheel, I should get power to the front is that right?

Post by **HarryMann** » 06 Feb 2008, 01:47

Yes..

in fact this idea that the front only pulls when the rear or one of the rears spins is maybe true on a test-rig, with split second timing, but in reality even on tarmac the tyre surface is always slipping* so the front is always working - to some extent.

* which is why its possible for a good 4x4 roadcar to have claimed better economy under some road conditions.

Post by **toomanytoys** » 06 Feb 2008, 12:21

easy way to see is leave the rear lock off and pull the front on over some slippery stuff.. if it stops and no wheelspin at the front then the vc is open... sounds a lot like it is though...

Oh.. and you dont realy want to be resting it on the centre bars.. they dont really like all that weight on them...

Continual problems... well thats the norm for a used 15 year old syncro really... once all sorted will go another 10 years..