Tyres 'distorted'?

Unless the tyre was completely wrongly load rated, then - nope - that's a duff tyre.

Freelanders aren't that heavy.

Adrian put finger to keyboard:

Agreed.

I've had two or three distorted tyres and AFAIK in each case it was the steel belt that was broken. Wouldn't expect this to happen for years though.

The guarantee should cover it, unless they're claiming that it was damaged by kerbing or summat.

How can any tyre, or indeed any other component, not be guaranteed for the vehicle it's been designed to fit to? That doesn't even make logical sense never mind legal sense.

Halfords told me that the tread always detaches from the 6 month old Austin Metro metric runflat tyres they sold and that it was quite OK, just a visual defect. I asked them to put that in writing, they decided it might be best to give me two new tyres.

Rover alloy wheels always have been particularly delicate.

I asked the garage owner today about this (he is off work with a broken leg) He confirmed that it is not a faulty tyre, but, the viscous coupling on the propshaft that was damaging the tyre (I was told the propshaft was faulty at the time by the mechanic). Apparently, the viscous coupling seizes, so when on full lock, or during tight turns, the wheels try to rotate at different rates, causing extra twisting force, generally, to the rear tyres. If done enough, it twists the tyre out of shape slightly, which is what has happened to mine.

If it carries on, it can mean damage to either the gearbox/transfer or rear diffs, so luckily was spotted in time.

Ta

by an odd co-incidence last week a freelander came in that needed its second, rear diff front mount, in a year. The cause is the viscous coupling becoming locked . 600 quid for a new one plus fitting. The owner is looking for another vehicle.

Would that be this problem?

"The LandRover Freelander is essentially a front wheel drive car with a transverse engine and gearbox. Drive is also taken, via a viscous coupling, to the rear wheels. The rear differential ratio is slightly taller than the front (3.214:1 v. 3.188:1 with the petrol engine) so that some torque is always going through the rear wheels, even in the absence of any wheel slip at the front." So that the viscous coupling overheats and seizes?

The LR dealer said it happens because the vehicles are not used enough off road ! Apparently the trick is (for most people) to remove the whole propshaft and leave it as FWD only. The giveaway as to it failing is the clicking noises it makes once it seizes, followed by the rapidly disintegrating rear diff mounts which were not designed to cope with a locked centre diff on tarmac.

Bell Engineering are the people to go to. £200 for a re-con unit. Add on £50ish for the new support bearings, and it isnt so bad to replace. Tell him to be aware of people advertising cheap re-con'd viscious units, there are loads of tales on LR forums about dodgy sellers, Bell Eng. are recommended by all.

I will pass that on, thank you.

A VLSD has to slip a bit initially to shear the viscous fluid which then stiffens up a lot and locks the diff. Once in shear under load it stays locked until the shear load is removed, then it becomes runny again. They got the ratios a little bit wrong so it locks far to much and too hard which destroys everything else as well.

It don't have a centre "diff", it has a viscous coupling. It's either free, when the front wheels aren't slipping and the rear wheels run at about the same speed as the front. Or locked - when the front has started slipping and the drive needs sharing around a bit more.

The rear diff will still have to diff between the 2 axles and on tight turns will still lock both axles together though viscous coupling. One test for VLSD is to jack the car at driven end(s) and turn a wheel, if it has a LSD the other wheel turns the same way (and whole pumpkin turns so the input turns too), an open diff it goes backwards (and input remains stationary as only the pinions in the pumpkin revolve).

Here we go.

The power flow though IRD

0.828 : 1 in from engine, drives lay gear 1.762 : 1 to front wheels diff from lay gear 0.553 : 1 to back wheels from lay gear

So front overall ratio is 0.828 x 1.762 = 1.467 (IRD ratio) Rear diff 3.214 Rear wheels overall ratio = 0.828 x 0.553 x 3.214 = 1.471 Just a bit longer than the front so it's trying to drive the rear wheels a bit slower (0.86%). That puts the centre coupling fluid in shear and makes it stiffen up.

With a 3.188 rear diff. Rear wheels overall ratio = 0.828 x 0.553 x 3.188 = 1.459 Just 0.055% out.

What buggers viscous diffs is big differences in speed with loads that exceed the locking torque so they slip while the fluid is still stiff. Having worn out tyres on one end and new on the other will do it. LR getting the IRD ratios wrong does it no good. Having it brake tested on a 2 wheel MOT roller brake tester will do it - should fit the accelerometer and go road test it.

I arrived at a MOT station one day to find the git ragging one rear wheel as fast as the brake tester could run it, while holding the other on the brake. Partly it was my fault not telling him it had a VLSD, having to do a road test would have really pissed him off. But on finding the LSD sticker on the diff he purposely set to, to F''k it. The car was a bit rusty and he didn't like the bits falling off on him and in his eyes and me having it welded back together year after year. After that when doing 3 point turns or parking I could hear the viscous plates grinding on each other. Shss, Shss, Shss. Still locked well enough to leave two black stripes. He lost the £400 a year trade he had from me in new tyres.

Having a "supercar" spec rear diff oil cooler and 0.6L extra oil capacity extended diff cover with deep fins didn't help. The oil pump doesn't run until the gear box mounted speed sender is doing 20mph and with only one wheel running it would have to been going 40mph before it triggered that.

Next car on the rollers was an Audi Quattro. Like he didn't know they have Viscous coupled 4wd and shouldn't be tested on rollers.

Now MOT is fully computerised some cars have a warning that brakes need a road test come up on the screen.

When I scrapped it I should have taken it back one last time, with a welded diff. Something would have had to give, would have really f''''d him as it jumped sideways off the rollers or buggered his tester by snapping a chain or belt.