Ird transfer box

hi all,
No luck with my Freelander, after starting problems then turbo solenoid issues. I had my Freelander in for test, basic stuff & a wobbly hub. All fixed apparently but when I drove & went round a corner started juddering took back to Garage & they said balancing so had that done......

Next day same corner juddered again so thought it must be the hub I’ll limp it to work. All most at work & “crunch”
Thump thump thump bit like a flat tyre. Got out pulled on wheels seemed fine, jacked it up & oil everywhere & noticed there was no Top up plug in the ird see the pinion straight through the hole about 4” from prop..........

What I’d like to know please is
1........can these vibrate out?
2........it was fine when I took the car in drove about 4 miles & now not driveable. Garage just said one of them things?? Is this right
3......... is it definitely a transfer box problem & will a straight swap cure it or could it need more repairs. Engine is still running perfectly just like a crunch when in motion which seems worse on turning.

Thanks in advance for any advice, gutted & not sure best step forward wether to scrap & get a new on or persivere....... she’s a 51reg td4

The IRD had been overloaded, which is why it's failed. The VCU has stiffened, normally caused by mismatched tyres. IRD failure is the result of constant load caused by the tyres/ VCU.

They did change the wheels from 15” to 17” would this have made a difference & front & back tyres were slightly different sizes.

Would these two factors have caused the top up plug to vibrate free?

Do I need to replace ird & wheels?

Thanks

Paul1970 said:

They did change the wheels from 15” to 17” would this have made a difference & front & back tyres were slightly different sizes.

Would these two factors have caused the top up plug to vibrate free?

Do I need to replace ird & wheels?

Thanks

Click to expand...

Changing wheel sizes makes no difference - as they are wrapped in rubber anyway.

However, if the tyres were known to be "slightly different sizes" - in Freelander transmission terms that is a "massive difference"! It will kill the transmission very very quickly.

The fill plug can only vibrate out if it was not tightened up in the first place - ie it was never put back or was only put back finger tight to be tightened fully later but never done.

I'm pretty sure you can't see the pinion through the fill plug - but you will probably see the general (reduction) gearing inside the IRD. When you say oil everywhere - I presume you mean all over the underside of the car rather than on the floor?

To be honest it sounds like the transmission on your car has been well and truely munted by a number of very serious errors. Obviously allowing all the oil to be emptied from the IRD is going to have damaged it. The mismatch in tyres will have damaged both the IRD and VCU and possibly the rear diff also.

Normally when the Freelander transmission fails, you can remove the props and drive it 2WD (either temporarily until problems are fixed or permanently) - however with it having been run without oil in the IRD, its possible that is not an option any more. That would still be my second step in diagnosing what condition the car is in - ie removed props & VCU and see how it drives - if there's any strange noises from the IRD. First step though would be to fill the IRD and put a plug in it!

I filled the ird with oil as the plug was just laid in the tray underneath......

Started the engine which is gone & moved about 20 yards & still the same maybe a touch better.

Is it still worth taking the prop & VCU off, what will this tell me??

Thanks for the input

Taking the prop off will give you an idea whether the IRD is completely destroyed or not.
Unfortunately it quite likely is. They are a bit picky even with oil in them....

You best bet is replace the IRD along with the VCU and 4 identical tyres.

Really hard to know what is going on, but the plugs don't vibrate out. The general anxiety would be regarding the condition of the IRD. Draining the oil (if there is any - and that would be good to establish!) will provide a clue as to the condition of the gears: if it comes out silver, you have a problem!

The VCU condition can be assessed with the "one wheel up test" - and the time should be less than 60 seconds (5kg weight hung off a 1.5m bar). Knocks and bangs can from a variety of sources in the transmission - ranging from major mechanical problems with the IRD or rear diff, through to easier to sort stuff like rear diff mounts and prop bearings.

Keeping your Freelander in good condition it is important to heed Nodge's advice regarding the tyres: they really do need to be the same brand and same size all round, or else transmission wind-up of the AWD system will lead to its premature destruction...

Be careful when buying a 2nd hand IRD. They are often the component that leads a Freelander to end up in a scrap yard - so I would be very wary buying 2nd hand. Usually it is just the components within them that make up the drive to the rear axle that goes and most 'damaged' IRDs will be OK if you just want to run the car FWD - ie remove the props and install a blanking plate instead of the rear pinion on the IRD. Your one may have more serious damage due to running without oil. A recon IRD from a reputable supplier (such as Bell Engineering) is always a more reliable solution, but you may get lucky and find a good 2nd hand one. As said - a good test to see if its any good is to drain the oil from it and see what colour it comes out. If it looks like oil, then you're probably OK but if it comes out looking grey/silvery then that is ground down bearings suspended in the oil. They could of course already have changed the oil and this wouldn't show up.

It is almost never worth buying a 2nd hand VCU, a recon (once again from a reputable supplier such as Bells) is the way to go - and it would be foolish not to get replacement (OEM) support bearings at the same time.

When IRDs go bang - it is a lot of money to fix it with IRD, VCU and tyres all needed. This is why most people just remove the props and replace the IRD's rear pinion with a blanking plate. They are usually fine if you just want a FWD car. You do need to tell your insurance company about the change as well. When mine went bang I bought an IRD rebuild kit (bearings, seals and cooler) for about £175 and had that fitted (which cost more than the kit) and had the crown gear removed from the pinion. So I'm still running all the gear, including props & VCU, but it is only FWD. I did this to avoid the need for certification here in NZ as a modified vehicle. The car has been a very reliable for the 4 years since.