Checking ird

Hi all, I have a few "issues" with my td4, there is a loudish clunk or bang that sounds to me at the rear of the car, I have lifted the car up and rocked and pulled wheels, all links I can see and the rear diff all seems to be ok, general driving is ok it's only when I had hit a severe bump or pothole or when to car rocks side to side it seems to happen, if I rock the car whilst stationary I can't make it do it however if I rock the rear vcu bearing I can make it knock so will change this first but has anyone any other advice for me to check?
Also I looked under the car when I got home tonight (9 mile drive) the vcu was nice and cool but the front driveshaft was warmish, I followed this up to the ird unit and where to output shaft is was very hot to the touch is this normal?
Thanks.

I'm not sure if that's normal - but I would think so. Heat will radiate to the IRD from the engine plus the IRD has a "cooler" - this isn't so must a cooler as a warmer so that the IRD warms up with the engine.

Maybe check the rear mounts closer, and the VCU bearings in the centre.

Thanks for replys will have a look again tonight.

As above and from a standing start engage HDC. When it starts to roll forward listen for any bangs or grinding. If you hear any STOP! Immediately and take it out of HDC. If not gently put your foot on the accelerator and get it up to 10MPH again listing for bangs or grinding sounds. If you hear any STOP! Immediately and take it out of HDC. This indicates a goosed IRD.
Also do the one wheel up test to check your VCU.Have a look on the forum for all these things

Madmustang said:

As above and from a standing start engage HDC. When it starts to roll forward listen for any bangs or grinding. If you hear any STOP! Immediately and take it out of HDC. If not gently put your foot on the accelerator and get it up to 10MPH again listing for bangs or grinding sounds. If you hear any STOP! Immediately and take it out of HDC. This indicates a goosed IRD.
Also do the one wheel up test to check your VCU.Have a look on the forum for all these things

Click to expand...

What's the reverence of pressing the HDC button?

Nodge68 said:

What's the reverence of pressing the HDC button?

Click to expand...

i'm also interested in that , thought the hdc only controlled the brakes

also ref the vcu , know when i bought mine as a very basic test i done a figure eight in reverse on tickover , so if there was any resistance u would feel it

know of course @Hippo test is the golden rule

Nodge68 said:

What's the reverence of pressing the HDC button?

Click to expand...

You will know if the IRD is goosed by the noise it makes. Loud banging, grinding or squelching crushed metal sounds are not good and are indicative of internal parts failure. But in normal drive its fine. When I was buying my car I test 5 or 6 Freelander’s (All TD4s) Most had props removed. Two had good IRDs because when the HDC was engaged they worked without making any sound. When driving off again they just worked you hardly noticed what was going on. I drove one and tested the HDC and BOOM! Horrible noises the sound of banging could be heard felt rally jerky when the accelerator was pressed and not smooth like it should be, So that was goosed.

gstuart said:

i'm also interested in that , thought the hdc only controlled the brakes

also ref the vcu , know when i bought mine as a very basic test i done a figure eight in reverse on tickover , so if there was any resistance u would feel it

know of course @Hippo test is the golden rule

Click to expand...

It’s does but the IRD or (Big dam gear box as I call it) Takes the weight of the car going downhill, The gearing the fluid and the TC slow the car down to about 6MPH. Pressing the speed pedal disengages it so you can drive normal like on the flat bits when off roading. When you slow down again to go down a steep bit and still have HDC engaged it will take over again.
You would have to read about it to understand it. But my point is it should be smooth if it’s not the IRD has issues only a mechanic or gearbox rebuilder can fix with a rebuild kit or replacing it with a recon or new unit.

I still don't see the relevance of trying the HDC. The HDC system simply activates the brakes. Banging when HDC is active is more indicative of old brake fluid in the system. But depending on ground conditions and speed when the throttled is released, the brakes are applied in different strengths at all four corners. This can lead to snatching at individual wheels. This snatching is was causes quite a bit of noise. It's actually not good to drive faster then HDC minimum speed then lift off the throttle fully. The HDC system tries to slow the vehicle down very rapidly by modulating the brakes.
In my experience. A failing IRD is more likely to make noises under acceleration, when HDC is an standby mode.

Fa

Nodge68 said:

I still don't see the relevance of trying the HDC. The HDC system simply activates the brakes. Banging when HDC is active is more indicative of old brake fluid in the system. But depending on ground conditions, the brakes are applied in different strengths at all four corners. This can lead to snatching at individual wheels. This snatching is was causes quite a bit of noise.
In my experience. A failing IRD is more likely to make noises under acceleration, when HDC is an standby mode.

Click to expand...

Far enough

Madmustang said:

You will know if the IRD is goosed by the noise it makes. Loud banging, grinding or squelching crushed metal sounds are not good and are indicative of internal parts failure. But in normal drive its fine. When I was buying my car I test 5 or 6 Freelander’s (All TD4s) Most had props removed. Two had good IRDs because when the HDC was engaged they worked without making any sound. When driving off again they just worked you hardly noticed what was going on. I drove one and tested the HDC and BOOM! Horrible noises the sound of banging could be heard felt rally jerky when the accelerator was pressed and not smooth like it should be, So that was goosed.

Click to expand...

Interesting concept. Not sure I understand how/whether it would work - but I'll keep an open mind on it.

Are you sure it wasn't just the ABS Pump banging away? They're quite noisy critters when they eventually get some work to do!

Madmustang said:

It’s does but the IRD or (Big dam gear box as I call it) Takes the weight of the car going downhill, The gearing the fluid and the TC slow the car down to about 6MPH. Pressing the speed pedal disengages it so you can drive normal like on the flat bits when off roading. When you slow down again to go down a steep bit and still have HDC engaged it will take over again.
You would have to read about it to understand it. But my point is it should be smooth if it’s not the IRD has issues only a mechanic or gearbox rebuilder can fix with a rebuild kit or replacing it with a recon or new unit.

Click to expand...

surely a faulty ird would be noisy regardless if the hdc was on or not

also u mention of testing freelanders with the prop off, which would indicate straight away , of why, faulty ird ,vcu , diff

if the ird is faulty it would be more noticeable when turning

surely the entire transmission system would take the weight of the car

doesn't traction control the prevention of wheels spinning by applying the brakes

when the hdc is activated it controls the abs system

got an open mind , just trying to understand the theory

Ok I tell you what, You all explain to me what you think the IRD is for and what it does?

Madmustang said:

Ok I tell you what, You all explain to me what you think the IRD is for and what it does?

Click to expand...

It is there to cause Freelander owners endless grief, expense and lost skin off knuckles!

Madmustang said:

Ok I tell you what, You all explain to me what you think the IRD is for and what it does?

Click to expand...

If you want an actual technical answer, then you're opening up a right can of worms. Probably not as bigger one as a discussion on the VCU - but just don't quote @Hippo and @wammers or else it will all go tits up.

Madmustang said:

Ok I tell you what, You all explain to me what you think the IRD is for and what it does?

Click to expand...

simply splits power front and rear via the vcu and is in place of a low gear transfer box

As the title says "Checking ird" it doesnt say "Checking VCU" although we have also covered that.

Madmustang said:

Ok I tell you what, You all explain to me what you think the IRD is for and what it does?

Click to expand...

The IRD is simply a box of gears. It's purpose is to take the drive of the gearbox, which is a modified FW drive gearbox and send that power to all four wheels.
The rear wheels are connected to the IRD via a Viscose Coupling (VCU) and rear differential. The problem with this system is its susceptible to damage by various actions. For example, fitting new tyres on the front. This upsets the VCUs equilibrium which makes it start transferring torque to the IRD when it shouldn't. This then overloads the bearings in the unit which results in eventual failure.

gstuart said:

simply splits power front and rear via the vcu and is in place of a low gear transfer box

Click to expand...

Yes and as its title suggests it reduces the gearing or drive on Hill decent, TC is also enaged simply for wheel slip and grip of the tyers but the TC is not whats stopping it running away down hill thats the job of the IRD