IRD/Gearbox... we made it wrong...

Avocet1 · Dec 1, 2019

Another question, while we're talking about IRDs, if I may?

The backlash between the crownwheel and pinion in mine was excessive when I rebuilt it. I have one steel shim between the pinion housing and the IRD casing:

It's Item 48 in the above diagram. Does anyone know:
(a) if they come in different thicknesses and
(b) if altering the thickness of them is the right way to alter the backlash?
(c) if it ISN'T the right way to adjust backlash, would it work anyway? (I can't think why it wouldn't)!

I can't remember what thickness mine is, but I've bought one from a scrapper and it is 2mm thick. If they're not available in varying thicknesses, I was thinking of drawing it up and getting some laser cut in different thicknesses.

matko · Dec 2, 2019

Hi

I m sorry i didn t read everything until the end, i m quite in a hurry this morning. It s very interesting everything, a little bit complicated for my english to catch all the details.

I have two questions:
1 - It s not possible as said (i don t remember the post) to fix the IRD on the gearbox and then fix the both thing on the motor?

2 - The gearbox command is hydraulic, with a little bottle where it s written not open, not purge... Is it really like that? have to buy the new piece each time you have a problem with the hydraulic? In LR they sell it for 180€

... and i·m looking for an alternative... maybe there are some post about it in the forum?

Thanks a lot, iĺl tell you if we suceed, we go this morning to the place.

Have a nice day!
Mateo

dfossil · Dec 2, 2019

GrumpyGel said:
It was a great series of posts. I think @dfossil did go on to let some air out of tyres to see what the results were, but maybe I just made that up

Avocet1 said:
No, I did see that somewhere in the thread, but he only seems to have done it for his low speed turning tests rather than straight line.

Yes guys I did - not for low speed turning tests - I did a mile having adjusted my tyres to get the same static rolling radius and got this result:-

"Went straight home (after the turning tests) and got my infrared thermometer –
IRD 40C VCU 27C Damper 16C Rear diff 23C"

then

"Dropped rear tires to 20psi – that made my STATIC loaded tire radius
the same front to back - Did 1 mile round the block:-

Straight Front Rear
988 990
-so the rear axle was pushing the rear prop! Circa 0.2% !
Rechecked temperature VCU 28C

then Corrected tire pressure (;-))"

It took a surprising amount of pressure change to achieve that but then it gave that measured 0.2% prop speed difference on my prop revcounters - and knocked up the VCU temperature immediately - hence the rapid pressure correction.
Just sort of endorsed a lot of previous thinking about why the 0.2% hits the sweet spot

Nodge68 · Dec 2, 2019

matko said:
It s not possible as said (i don t remember the post) to fix the IRD on the gearbox and then fix the both thing on the motor?

No. It's not possible.

matko said:
The gearbox command is hydraulic, with a little bottle where it s written not open, not purge... Is it really like that? have to buy the new piece each time you have a problem with the hydraulic? In LR they sell it for 180€ ..

Depends on what engine is fitted.

Avocet1 · Dec 2, 2019

dfossil said:
Yes guys I did - not for low speed turning tests - I did a mile having adjusted my tyres to get the same static rolling radius and got this result:-

"Went straight home (after the turning tests) and got my infrared thermometer –
IRD 40C VCU 27C Damper 16C Rear diff 23C"

then

"Dropped rear tires to 20psi – that made my STATIC loaded tire radius
the same front to back - Did 1 mile round the block:-

Straight Front Rear
988 990
-so the rear axle was pushing the rear prop! Circa 0.2% !
Rechecked temperature VCU 28C

then Corrected tire pressure (;-))"

It took a surprising amount of pressure change to achieve that but then it gave that measured 0.2% prop speed difference on my prop revcounters - and knocked up the VCU temperature immediately - hence the rapid pressure correction.
Just sort of endorsed a lot of previous thinking about why the 0.2% hits the sweet spot

Ah, my mistake, I missed that bit! Many thanks. When you say you dropped the rear tyres to 20 PSi, were the fronts at 30? Also, I'm surprised how cold your IRD was. I don't have an IR thermometer, but my IRD is too hot to keep a hand on for more than a fraction of a second once it's warmed up. 80+ degrees, I'd have thought? Did your front and rear tyres have about the same amount of tread on them and were they the same make / model of tyre at both ends?

dfossil · Dec 3, 2019

Avocet1 said:
Ah, my mistake, I missed that bit! Many thanks. When you say you dropped the rear tyres to 20 PSi, were the fronts at 30? Also, I'm surprised how cold your IRD was. I don't have an IR thermometer, but my IRD is too hot to keep a hand on for more than a fraction of a second once it's warmed up. 80+ degrees, I'd have thought? Did your front and rear tyres have about the same amount of tread on them and were they the same make / model of tyre at both ends?

Can't remember exactly what pressure the fronts were but would have been to the book or close - treads were within 1mm of each other - matched set of tyres. Temperature? - I never find much rise in temperature normally - for reference I feel the damper lump next to the VCU as that will be picking up the same radiated heat from the exhaust and normally only find a small difference - but then my VCU is a good one - still doing 12 seconds at 1.2M/8Kg on the OWUT.

Listen - if yours is getting that hot double check what your tyres are doing - try this - mark each wheel with a bit of chalk - drive dead straight for about 50m and check again - if your tyres mismatch you can see the difference in rotation - I found that having one Michelin - same size but different type (my spare) - gave a visible difference - and moving it front to back on the car was picked up by my prop revcounters - so there's a quick check on your tyres for you. If your tyres are good I suspect your VCU is getting pretty stiff.

Avocet1 · Dec 3, 2019

dfossil said:
Can't remember exactly what pressure the fronts were but would have been to the book or close - treads were within 1mm of each other - matched set of tyres. Temperature? - I never find much rise in temperature normally - for reference I feel the damper lump next to the VCU as that will be picking up the same radiated heat from the exhaust and normally only find a small difference - but then my VCU is a good one - still doing 12 seconds at 1.2M/8Kg on the OWUT.

Blimey! I tried mine with 5kg @ 1.2m and got 50 seconds, cold, with about 10 degrees ambient temperature. Most seem to reckon that's a bit tight but probably just about towards the top limit of "acceptable". It was a reconditioned one fitted by the previous owner about 12,000 miles ago.

dfossil said:
Listen - if yours is getting that hot double check what your tyres are doing - try this - mark each wheel with a bit of chalk - drive dead straight for about 50m and check again - if your tyres mismatch you can see the difference in rotation - I found that having one Michelin - same size but different type (my spare) - gave a visible difference - and moving it front to back on the car was picked up by my prop revcounters - so there's a quick check on your tyres for you. If your tyres are good I suspect your VCU is getting pretty stiff.

Tyres are a part-worn set of Event ML698 "offroad" tyres. Noisy as hell but came free with the rims that I needed. Rears have about 5.5mm of tread, fronts about 3.5. However, I'd have thought that once everything's up to temperature, the IRD would be pretty hot because of the cooler on the end of it, which will be full of water at the same temperature as the cooling system? At the time I tried touching it, the VCU and damper were about "body temperature". That was after about 5 miles on the motorway (albeit not with those tyres, which were a recent addition).

dfossil · Dec 3, 2019

sorry I misread your "ird too hot to touch" as "VCU" - actually your VCU and Damper at "about body temperature" is similar to mine so not that alarming - apologies
Oh - and my VCU did 28secs at [email protected] then - last week, 10,000 miles on, it did 30sec

Avocet1 · Dec 3, 2019

dfossil said:
sorry I misread your "ird too hot to touch" as "VCU" - actually your VCU and Damper at "about body temperature" is similar to mine so not that alarming - apologies
Oh - and my VCU did 28secs at [email protected] then - last week, 10,000 miles on, it did 30sec

I'm not going to be "casting the first stone" there!

Interesting about your VCU at 5kg. Will have to keep an eye on mine.

matko · Dec 4, 2019

Hi everybody

A message to tell that we suceed to enter the IRD in the gearbox.

We quit another time the gearbox and then we file the tooth of the gearbox and the IRD, 2 hours, swiss work! and it worked!!
Now i can said the freelander is mine, in my house!! tadam!!
What an aventure!
Now i will read all the information about using this 4x4 good.
Have a nice day!!!
Mateo

Alibro · Dec 7, 2019

matko said:
Hi everybody

A message to tell that we suceed to enter the IRD in the gearbox.

We quit another time the gearbox and then we file the tooth of the gearbox and the IRD, 2 hours, swiss work! and it worked!!
Now i can said the freelander is mine, in my house!! tadam!!
What an aventure!
Now i will read all the information about using this 4x4 good.
Have a nice day!!!
Mateo

Sometimes when you work on the clutch the master can fail. It did on me.
If this happens do not buy a cheap aftermarket master as they are crap.
Good luck with it.

IRD/Gearbox... we made it wrong...

Avocet1

Well-Known Member

matko

Member

dfossil

Well-Known Member

Nodge68

Well-Known Member

Avocet1

Well-Known Member

dfossil

Well-Known Member

Avocet1

Well-Known Member

dfossil

Well-Known Member

Avocet1

Well-Known Member

matko

Member

Alibro

Well-Known Member

Similar threads