Land Rover Free­lander vis­cous cou­pling

This sim­ple swap can lengthen a Free­lander’s life sig­nif­i­cantly.

Car Mechanics (UK) - - Contents -

The Land Rover Free­lander Se­ries 1 doesn’t have the best rep­u­ta­tion for re­li­a­bil­ity, and the four-wheel drive set-up is gen­er­ally con­sid­ered to be weak, cer­tainly com­pared to the sys­tems used on so-called ‘proper’ Land Rovers. As a re­sult, many have been con­verted to two-wheel drive – a process which in­volves re­mov­ing the prop­shaft and, de­pend­ing on the model, mak­ing an elec­tronic fix to trick the anti-lock brak­ing sys­tem (ABS) into think­ing noth­ing has changed.

Some­times you’ll be told the prop­shaft’s been re­moved for econ­omy rea­sons. Don’t be­lieve it – the way in which the Free­lander 4WD sys­tem works means that any ben­e­fit will be mar­ginal at best, as we will see later. The only rea­son any­one re­moves a Free­lander prop­shaft is be­cause some­thing – and usu­ally some­thing ex­pen­sive – has bro­ken.

How it works

The Free­lander’s 4WD sys­tem has no trans­fer box as such, and is best thought of as a con­ven­tional gear­box-besideengine FWD setup with a Rwd-type prop­shaft and axle added be­hind. As usual, drive­shafts run from the gear­box to the front wheels, and the out­put part of the gear­box – con­tain­ing the dif­fer­en­tial – pro­trudes back from the main ’box, so the drive­shaft to the off­side wheel runs be­hind the en­gine.

On the Free­lander, how­ever, this is where an in­ter­me­di­ate re­duc­tion drive (IRD) is bolted to the gear­box. This has two out­puts: one that’s par­al­lel to the in­put for the off­side drive­shaft, the other at 90°, fac­ing rear­wards and con­nected to a prop­shaft that takes drive to a Rwd-type rear axle/dif­fer­en­tial unit. To pro­vide the ‘slip’ needed be­tween

front and rear, and so that the 4WD op­er­ates only when ac­tu­ally needed, the prop­shaft is ac­tu­ally a two-piece unit in­cor­po­rat­ing an oil-filled vis­cous cou­pling unit (VCU) halfway down. When there’s sim­i­lar load on the front and rear axles, the VCU trans­mits lit­tle or no drive and the Free­lander is, to all in­tents and pur­poses, a FWD ve­hi­cle.

That’s why tak­ing off the prop­shaft has al­most no ef­fect on econ­omy – it’s in 2WD mode more of­ten than 4WD any­way. How­ever, if the grip at the back is re­duced or lost – as might hap­pen when driv­ing off-road – the vis­cous cou­pling al­lows the drive to pass, giv­ing 4WD when it’s ac­tu­ally needed. As the con­nec­tion is pro­vided by oil pres­sure rather than a me­chan­i­cal link, the 4WD en­gages and dis­en­gages smoothly, so the rate of en­gage­ment and dis­en­gage­ment, and thus the amount of 4WD ef­fort, are matched to ex­actly what’s needed.

What goes wrong

The draw­back of this sys­tem is that, as with pretty much any­thing that re­lies on oil pres­sure, the Free­lander’s 4WD cou­plings don’t last in­def­i­nitely.

Even­tu­ally, the VCU’S ac­tion will stiffen, be­fore ul­ti­mately seiz­ing com­pletely. With no scope for move­ment be­tween the front and back, ten­sion will build within the sys­tem un­til some­thing breaks. In most cases, it’ll be the IRD/ an­gle drive unit on the front or rear diff, though some­times it can take out the main gear­box. What­ever hap­pens, given the low mar­ket value of most first-gen­er­a­tion Free­landers, a fail­ure of this kind is usu­ally con­sid­ered an un­eco­nom­i­cal re­pair.

Test­ing a VCU prop­erly re­quires spe­cial equip­ment which is gen­er­ally avail­able only to re­con­di­tion­ers. Bell En­gi­neer­ing, one of the lead­ing re­man­u­fac­tur­ers of Free­lander driv­e­train com­po­nents, of­fers a free postal test­ing ser­vice, but even though you can still use the ve­hi­cle in 2WD mode while the prop­shaft is off, it’s hardly prac­ti­cal as a reg­u­lar check.

A ba­sic VCU in­spec­tion can be made by mark­ing each side, tak­ing the car for a brief drive, then see­ing if the two marks are still aligned; if they are, the VCU has prob­a­bly seized. How­ever, while this will iden­tify a fully-seized VCU, it won’t high­light one that’s start­ing to go – ie, if it’s still mov­ing, but less than it should. That’s when you need to know there’s an is­sue. By the time it has seized, it’s likely some dam­age will al­ready have been caused.

Other symp­toms in­clude dif­fi­cult ma­noeu­vring when do­ing tight turns, a feel­ing like brake drag when coast­ing to a stop, clunk­ing and groan­ing sounds when park­ing, and a ten­dency to skid eas­ily on loose sur­faces. Fi­nally, if rais­ing the rear wheels on a jack causes one or both to spin mo­men­tar­ily as they are lifted off the ground, this is a sure sign of built-up ten­sion within the driv­e­train – ten­sion most likely caused by a tight or seized VCU.

Un­for­tu­nately, while these tests can help, none will high­light is­sues un­til there’s al­ready been a chance of dam­age. The best way of avoid­ing prob­lems is to re­gard a 70,000-mile VCU change as part of the rou­tine ser­vice sched­ule.

In­cor­rectly fit­ted parts

Over the past year or so, my part­ner Sarah’s Free­lander has had a bit of his­tory when it comes to driv­e­train faults. It all started when she no­ticed some clonk­ing un­der­neath from the vicin­ity of the VCU. Our lo­cal garage – not a Free­lander spe­cial­ist – di­ag­nosed worn VCU bear­ings and these were re­newed. I sub­se­quently dis­cov­ered they’d fit­ted them the wrong way round and was warned that they might not last the course. About six months later, Sarah re­ported a knock­ing sound from the rear when re­vers­ing around sharp cor­ners, es­pe­cially up a slight in­cline. This is the clas­sic first in­di­ca­tion of a fail­ing IRD. Af­ter con­firm­ing our di­ag­no­sis, a Free­lander sec­ond­hand parts spe­cial­ist in Stafford­shire fit­ted a re­place­ment.

Three months on, a loud noise was ap­par­ent on the over­run and seemed to be com­ing from the near­side front. It sounded like ei­ther the IRD had gone again or that there was a fault in the main gear­box – wor­ry­ing as it’s an auto! Two lo­cal garages were asked to iden­tify where the noise was com­ing from, but nei­ther could give a de­fin­i­tive an­swer.

On rec­om­men­da­tion, we con­tacted a Nor­folk-based Free­lander spe­cial­ist called free­lander­spe­cial­ist.com. It’s run by the hus­band-and-wife team of Sue and Nor­bert, who have ex­ten­sive ex­pe­ri­ence us­ing and re­pair­ing Free­landers in con­di­tions rang­ing from the wilds of Ice­land to the Sa­hara desert, so driv­e­train is­sues are some­thing of a spe­cial­ity.

Nor­bert took our Free­lander for a test­drive. Within 20-30 yards, he was pretty sure the prob­lem had noth­ing to do with ei­ther the gear­box or IRD, but was due to a noisy Vcu/prop­shaft bear­ing.

Back at the work­shop, he re­moved the prop­shaft and spun it to con­firm that one of the bear­ings had failed.

Sarah’s Free­lander was on 115,000 miles, so well over the rec­om­mended 70,000 VCU change in­ter­val. It had been given a doc­u­mented IRD change by a main dealer at 38,000 miles, so even if the VCU had been done at the same time, she was only 3000 un­der the limit. It took lit­tle per­sua­sion to con­vince us to get the VCU changed at the same time. The step-by-step guide shows the key stages of the job.

Apart from need­ing to press the new bear­ings onto the VCU with a hy­draulic press, it’s all straight­for­ward DIY stuff. You don’t even need to jack up the Free­lander for ac­cess – a cou­ple of planks un­der the wheels on one side is the most you’ll need.

Ex­pect to pay around £250 for a good qual­ity ex­change VCU, plus around £60 each for the bear­ings – GKN or gen­uine Land Rover parts are rec­om­mended – so you’re look­ing at £350-£400, plus an hour or two of not-too-ar­du­ous labour. But it’s only once ev­ery 70,000 miles and the al­ter­na­tive is much worse. And if our ex­pe­ri­ence is any­thing to go by, you’ll find that be­cause the front and rear are once again work­ing in per­fect har­mony, the new VCU sharp­ens the car’s han­dling and cor­ner­ing.

This is the rear axle/dif­fer­en­tial unit with the prop­shaft re­moved. It’s mounted on rub­ber bushes, one of which can be seen to the left of the drive flange. These de­te­ri­o­rate with use, but VCU prob­lems shorten their life dra­mat­i­cally. Re­newal is a bit fid­dly, but gen­er­ally straight­for­ward.

This is the Land Rover Free­lander’s IRD unit on a work­bench. The left-hand side at­taches to the gear­box out­put, the off­side drive­shaft goes into the right-hand side and the flange at the top con­nects to a two-piece prop­shaft which goes to the back. A failed VCU usu­ally takes this out as well.

The VCU and prop­shafts off the car. The shafts are at­tached by four bolts and a flange at the front and rear, while the VCU is held by four bolts into cap­tive nuts in the floor­pan. Front and rear shafts each run through a press-on bear­ing, which are re­newed with the VCU. There are poor-qual­ity re­place­ments around, so use GKN or Land Rover branded items.

This is the ex­change VCU. New ones are avail­able, but a re­con­di­tioned unit from a rep­utable sup­plier is fine. Do not try to cut cor­ners with a sec­ond­hand VCU – even if you’re re­in­stat­ing a pre­vi­ously-re­moved prop­shaft – as these are lim­ited-life com­po­nents which, if not func­tion­ing cor­rectly, can cause very ex­pen­sive dam­age.

As you can’t see very much of the shaft and VCU be­ing sep­a­rated with a span­ner in place, this shows the im­me­di­ate af­ter­math of dis­man­tling. The slot­ted plate (on the right) holds the shaft onto the VCU – slacken the bolt and this can be re­moved, al­low­ing the shaft to come off af­ter a bit of per­sua­sion.

You will need a ring span­ner (19mm) to at­tach the front and rear prop­shafts to the VCU as there isn’t re­ally room for a socket, and space is too tight for an open-en­der. Again, note the use of white grease – it can be a strug­gle if the prop­shaft and VCU splines rust to­gether.

The bear­ings need to be pressed onto the VCU and must be re­newed with it as they’re vir­tu­ally im­pos­si­ble to re­move in one piece once fit­ted. They also have to go on the cor­rect way round, with the wider side fac­ing out­wards as shown. The se­cur­ing bolt is moved over and screwed into the re­place­ment VCU. Note also the white grease on the prop­shaft splines.

These are the rear dif­fer­en­tial bushes (ar­rowed). As with most, ours had been weak­ened by the VCU prob­lem, but it’s not too se­vere. New bushes will be needed, but with the cause of the VCU prob­lem now fixed, re­plac­ing them can wait a while un­til there’s time.

White grease is needed on the flange con­nec­tions, too. There’s no need to mark the dif­fer­en­tial or ICU and prop­shaft flanges to en­sure they’re the same way round on re­assem­bly as you’re re­new­ing the big bit in the mid­dle any­way, and the bear­ings pre­vent bal­ance is­sues af­fect­ing any­thing.

The new VCU and bear­ings are bolted in place. With this done, the noise was gone. What we weren’t ex­pect­ing was that cor­ner­ing and han­dling now felt a good bit tighter and more pre­cise. Be­fore the change we had no idea that per­for­mance had ta­pered off by so much.

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