Thread: Perentie drive line 6x6 & 6x4

Originally Posted by 101 Ron

I might add the rear axles drive set up was not designed for the Perentie.
The set up was developed for the Forward control military 101 landrover.
The 101 Landrover was designed from the start for a power driven trailer and why the same transfer case is set up the way it is.
The 101 Landrover has a completely different winch, but the drive for it is taken via gears from the bottom of the transfer case.

Knew the history of where the rear axle drive setup originated, though powered trailers are bit of fun off road.

Originally Posted by Jackofalltrades

Whats best way to check vacuum cylinders are working properly?

Also thankyou you for answers, no real info on the web or other threads

No worries, apart from the dash lights coming on when they lock, the only other way to check is jack up a wheel and see if it is locked or not.

Originally Posted by Bearman

The rear axle drive unit gear is driven off the low range gear on the intermediate shaft which is in contact with the centre diff gear. This drive unit is selectable by a vacuum cylinder the same as the centre diff lock and actuated when you lock the centre diff. The rear output unit bolts onto the rear cover plate where a PTO would normally sit. The Perenties have a bottom PTO for the winch that is part of the cover plate that bolts onto the sump of the transfer and is driven by a chain that comes off the transfer input gear on the rear of the gearbox mainshaft. So the rear axle is only DRIVEN when you lock the centre diff but unless you have free wheeling hubs it will still turn or "windmill" all the time regardless of whether the actuator is locked or not. Hope that explains it!! I have free wheeling hubs on the rear axle of mine and changed the vacuum locker lines around a bit and added an extra switch so I can lock the centre diff without locking the rear axle drive unit. Reason I did this is so that I can lock the centre diff on the move and not damage my rear axle drive unit as it will not be turning with the freewheelers disengaged.

Hello Brian

I read this with interest as I have Free Wheeling Hubs (AVM) also. You say you wanted to be able to engage the Centre Diff without damaging the rear axle drive. I have been engaging and dis-engaging mine (only at low speed). Is this not o.k to do? Also since installing my Free Wheeling Hubs I have wondered if it was o.k. to do the same with the Hubs in 4x2 (dis-engaged)? I did this in Low Range once and the High/Low Selector jumped out several times. I figured maybe no load on the Rear Axle caused this?

On a different note, I have removed my Hubs temporarily as the axles were leaking a lot of oil. I have found replacement inner seals (RTC5992) at LR Spares in the U.K. which are very expensive so I hope they do the job. I have been told, to replace these seals the Diff Crown Wheel etc has to be removed to gain access to the seal. Is this right?

A few people have said that I should be concerned that if the Free Wheeling Hubs allowed the oil to leak that water will get in. Is this a serious problem or just a matter of regular maintenance?

Thanks again for your time.

Regards

Guy

If you have the free wheel hubs disengaged, and engage the centre diff lock (and hence the rear - rear axle drive) while moving, the dog in the transfer case is trying to engage a moving part with a stationary part. Depending on the speed you are going, this may result in anything from minor wear and a bit of noise to catastrophic transfer case failure, but is never a good idea.

Originally Posted by GMDMD53

Hello Brian

I read this with interest as I have Free Wheeling Hubs (AVM) also. You say you wanted to be able to engage the Centre Diff without damaging the rear axle drive. I have been engaging and dis-engaging mine (only at low speed). Is this not o.k to do? Also since installing my Free Wheeling Hubs I have wondered if it was o.k. to do the same with the Hubs in 4x2 (dis-engaged)? I did this in Low Range once and the High/Low Selector jumped out several times. I figured maybe no load on the Rear Axle caused this?

On a different note, I have removed my Hubs temporarily as the axles were leaking a lot of oil. I have found replacement inner seals (RTC5992) at LR Spares in the U.K. which are very expensive so I hope they do the job. I have been told, to replace these seals the Diff Crown Wheel etc has to be removed to gain access to the seal. Is this right?

A few people have said that I should be concerned that if the Free Wheeling Hubs allowed the oil to leak that water will get in. Is this a serious problem or just a matter of regular maintenance?

Thanks again for your time.

Regards

Guy

G'day Guy, John pretty much explained it. But just to make sure you know what is happening. WITHOUT freewheeling hubs the rear axle driveshaft is turning at the same speed as the other driveshafts as the rear axle wheels are turning the diff which turns the driveshaft so when you engage the centre diff lock the rear axle drive unit vacuum cylinder engages the sliding dog clutch and the transfer case then DRIVES the rear axle instead of it windmilling. WITH freewheeling hubs fitted and in the 4X2 position, the rear driveshaft and diff is stationary. If you engage the centre diff lock while moving the sliding dog clutch will try to engage to a stationary driveshaft while it itself is spinning - you can imagine what damage could result from this. No problem if you stop and then engage it. That is the reason why I added a second vacuum switch. Now I can lock the centre diff on the move without trying to lock the rear axle drive unit. When I have the freewheelers engaged I can have 6X4 or 6X6 by locking/unlocking the second vacuum switch. To replace those seals you are talking about you DO have to remove the diff centre or crownwheel carrier. The reason the rear diff has these seals and not the intermediate shaft is because of the tilt angle of the rear diff - it has to be tilted for the drive shaft to go over the intermediate axle and consequently the oil level has to be higher to ensure an oil supply to the front pinion bearing. Without the seals there would be not enough oil reaching that bearing and it could possibly seize. Last time I had my rear axle engaged I also noticed some oil coming from the breather on the rear diff but after checking it out I have decided that reason this is happening is because the rear diff cover I have fitted (aftermarket HD one) has the breather in a different spot to the original cover and the crownwheel is actually feeding an oil supply straight into the breather when it is turning. Just have to move it a bit to one side and that should fix it. I am also contemplating drilling an extra couple of holes into the axle housings between the diff centre and the hubs and adding an extra couple of breathers there as well as I have found that when I have the hubs engaged my freewheelers leak on the seal where you turn it to engage, presumably from pressure buildup. With regards to the jumping out of gear, it is very unlikely that this is caused by the freewheelere, most likely by wear on the intermediate shaft gear engaging dogs. Hope this helps...........Brian