diff locked 4x4

Post by **Mudlark** » 15 Nov 2005, 20:21

If you say your front tyres are lumpy do we take that to mean they scrub and skip in turns ?

If so it may just be that your Viscous Coupling has gone aggressive. Best cure for that is to take out the front/ rear drive shaft and use the van as a 2wd; only needs 8 bolts undoing.

It may be that your saying that your front diff lock is stuck engaged which is a bit more of an issue. Firstly if that is the case you probably wont be able to steer well, if at all ?

Freeing this up is a bit more involved and will require taking the diff lock actuator off and seeing if you can tease the pin out. if not i expect you will have to take the front diff out and take it apart. Get lots of info before you attempt this !

Hopefully your problem is the first one which is easily remedied.

Post by **Diamond Hell** » 15 Nov 2005, 21:31

I'd reckon on a tight VC well before a locked front diff - unless the indicator light on the dash is on. With the front locker in it would be almost undriveable on road.

Are your tyres all evenly worn and inflated to the correct pressures? If not they will cause the same 'binding' sensation as a tight VC as they will MAKE it tighten.

If all else looks OK get that centre prop out quick, before you start popping CVs!

Post by **Mudlark** » 15 Nov 2005, 23:55

Different makes but identical sized tyres ?

If the van drives and steers alright my guess is that your tyres are just knackered and may be THE fault.

A diff-locked front wont drive alright so cant be that; a tight VC works fine until you turn a corner, so if yours dont give you any problems it cant be that either.

Take the van into a tyre shop and show them the tyres and ask them what the cause might be; could be tyres that have just stood in the sun too long breaking up.

Post by **HarryMann** » 16 Nov 2005, 00:23

Ray?

Is it something that someone's said that's making you think the condition of the tyres is to do with the vehicle being 4WD?

Mark's last suggestion is a good one - and if you say what size they are now and your intended use of the van, there's plenty on here that can make good suggestions.

It did sound to me too that it might have been standing for a long time, maybe with a partial flat?

Post by **Diamond Hell** » 16 Nov 2005, 00:45

5* £40 is worth saving your drivetrain for - don't be an idiot and think you can run on un-matched tyres, even if they're the same size, but different brands there could be an appreciable difference in sizes.

If their condition is duff then change them - it's a lot cheaper than a new VC (£400) or a rebuilt gearbox (£800+).

At the end of the day it's your choice, but I know I'd be down to ATS tomorrow buying a set of tyres at the best price I could.

Post by **Aidan** » 16 Nov 2005, 17:38

As Thomas says get the tyres seen to, a syncro NEEDS 4 matched tyres and any vehicle deserves good rubber, it's the only thing keeping you on the road, and the damage a mixed set will do has to be the hardest kick in the wallet.

Post by **HarryMann** » 16 Nov 2005, 22:30

It's important to have the same tyres on all 4 corners - or if not possible, economically or otherwise, tyres that have rolling circumferences as close as possible front to rear axle (seem to remember a figure of about +/- 1.5% but I will be corrected, you can be sure of that!)

Post by **HarryMann** » 17 Nov 2005, 17:17

the vc is solid

It often seems so, esp. at low temps, even when it isn't

Post by **HarryMann** » 17 Nov 2005, 18:23

Ok, it will pull forward on tickover or slightly raised revs when on flat - I think mine would and that's OK. The whole thing is not black and white, its a bit of a black art, as the VC is temperature and rev dependent in its action.

Did you try seeing if something like a 2x4 timber or a kerb would stop it. That's the test - can the engine be kept running without stalling up against such an obstacle - the Derek Drew (on syncro website) article suggests trying this several times, and a pass is if you can do it at least once in say 3 or 4 tries.

So if it either stalls from say 800-1000 rpm or actually climbs over the obstacle repeatedly, when its been warmed up a bit, then that would be a 'tight' failure, but persevere to be sure.

These are not scientific tests, they're subjective, as 'how' tight does it feel on full lock, whether it just scrubs and tightens a bit, or stops the vehicle or skids, hops a wheel.

Sounds like it might be tight (rarely 'solid' as such)