Help...advice needed

[ninja.turtle007]

We are away from home and what I thought was a brake problem I had fixed has returned. I am now thinking tight VC.

At low speed turning it feels like the brakes are on. This only seems to happen after driving a distance. Is this the symptoms of a tight VC?

I checked all wheels and nothing seems warmer than it should, so it is not a binding brake.

I don't really want to under the van in the wet to remove the prop unless I have to.


Thanks in advance.

[zillertalsyncro]

I think it is a hard VC.

When my VC was really hard it had that symptom in bends. When driving straight there was no such feeling, but all 4 wheels had nearly no difference at the tyre profile.
When I stopped after a bend the car kept standing at the same place for a while, then it did a little "jump" when the VC came out of the hump.

You can try to lift one of the front wheels. If you can't turn it, the VC is hard. Now it's time to remove the prop to keep the gearboxes alive.

Fast driving is hard work for the VC. The temperature gets higher and the VC comes near the hump where it gets hard.
If the VC is hard it has sucked some oil of the gearbox into the VC. This makes it reaching the hump sooner than it should (between 120 and 135°C). The more oil was sucked into the VC the earlier it comes into the hump.

This makes the feeling of the VC "normal" after starting to drive and "hard" after a faster ride.

The earlier it comes into the hump, the higher gets the pressure in the VC. Now the sealings have to work hard and it can happen that they let oil from the VC out in the gearbox - and the VC gets soft.

[futbus]

Better be safe than sorry, sounds very much like the VC has failed or in the process of failing tight, remove the prop should save the rest of the running gear.

[ninja.turtle007]

As I suspected. I'll take it off in the morning.

At least I got the diagnosis right, I must have been listening in class!

How much Is a VC? Around £500 if I remember correctly.

Thanks for the replies, I really appreciate them.

Now for a few more beers.

[toomanytoys]

are all the tyres equal make size and wear and correctly inflated? it all adds up to give the VC a hard time..
You can drop the prop for the meantine to relieve the stress on the VC and rest of the transmission for the mean time....

[PetenAli]

Just to check please folks - does having your decoupler open (i.e. disengaged from the prop) have the same effect as actually removing the propshaft?

Thanks,

Pete

[toomanytoys]

If you have a decoupler, and dissengage it, the drive to the front is removed...

But the prop still goes round as its being driven fron the front diff then...

[PetenAli]

If you have a decoupler, and dissengage it, the drive to the front is removed...

But the prop still goes round as its being driven fron the front diff then...

So if you have a tight VC and have your decoupler open do you still run the risk of bu%%ering up both ends of the transmission?

Ta,

Pete

[toomanytoys]

No, not if the decoupler is dissengaged there is no mechanical connection from rear to front then.. thats why its called a decoupler..

[PetenAli]

No, not if the decoupler is dissengaged there is no mechanical connection from rear to front then.. thats why its called a decoupler..

Thanks - thats what I thought but its good to have it confirmed. Getting Syncro 4wd sussed is a continuing challenge for me!

[ninja.turtle007]

Just got back from a great weekend.

I removed prop Sunday morning with a pretty bad hangover and everything is now okay. Must remember to pack an extra 13mm spanner!!

I checked tyres for uneven wear and the rears are maybe up to 1mm more worn. I checked tyre pressure and all were 30 PSI except OSF which was 26PSI. What are the pressure supposed to be 225/70/16? I thought they would be closer to 40PSI

VC must have been really tight because when I stopped at a motorway services and was on a slight slope it didn't roll. Every minute or so there would be a creek and slight movement. I presume as the VC cooled?

I plugged the ABS back in and it is now working as it should.

From what I have read there is not a definitive way of bench testing the VC. VC's are new to me and I need to be sure before buying an exchange.

[syncropatrick]

My 225/75/16 BFG ATs run at 40psi front and 42psi rear.

[ninja.turtle007]

My 225/75/16 BFG ATs run at 40psi front and 42psi rear.

Thanks, as I wasn't sure I put in 40psi all round.

[ninja.turtle007]

I dropped the oil from the diff last night. It was a little dirty but no unusual smells. The drain plug had a few bits of metal stuck to it.

If the VC at fault wouldn't I expect to oil to be really smelly? Or is this not alway the case?

[axeman]

I dropped the oil from the diff last night. It was a little dirty but no unusual smells. The drain plug had a few bits of metal stuck to it.

If the VC at fault wouldn't I expect to oil to be really smelly? Or is this not alway the case?

only if it has leaked its fluids.

neil