4 wheel drive - is it?

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How about (and I know this isnt what you wanted to achieve, Ian) putting your system before the VCU so that in 2wd it saves fuel and reduces tyre scrub and in 4wd is the same as originally designed. It wouldnt eliminate the VCU, and the VCU would still be susceptible to failure - but at least the vehicle could then be driven in 2wd mode until the VCU could be fixed. That would reduce the likelyhood of major drivetrain damage, which, I think was your secondary objective, was it not?
 
just reading thro this thread again i notice yu mention "early" freelanders!
Does that mean that "late" freelanders dont have this prob? in which case three q's

what date was the changeover?
how can one tell whether you have different diffs or the same diffs (if yu know wot i mean)?
what are the differences between the diffs?
 
Boxer said:
Ian while i think this would be a great mod . i have a concern that you are still not going to solve the original LR fudge. Namely the front and rear 'axles' will still drive at different speeds , I think this will mean, and I'm only guessing here, with the locker engaged every 100 meters travelled will mean that the rear will be , effectively 5 meters behind the front. I don't know but that seems like a lot of transmission windup to me. The ford that the bits came off would not have had to cope with this as it drives both axles at the same speed.
Click to expand...

Appreciate your thoughts and concerns (the good thing about forums is that all sorts of perspectives can be kicked around quickly all for the ultimate good)
One comment on the diff windup not being addressed--- The "slip" between the front and rear diffs is actually "only" 0.8% ie 80cm in 100 metres, and as I will only be using it on slippery grass and gravel (very specifically no hard capped road work) I fancy that this will be much softer on the rest of the transmission than a fully siezed VCU on the highway.
The point you make about the Ford bits not having had to face that sort of loading in the Raider is a good one. Again I'm pinning my hopes on the (relatively) low windup and the forgiving surfaces on which my Freebie will be used.
If the components turn out to be not strong enough, then its back to the drawing board!

Thanks and Cheers
Ian Hughes
Tassie
 
The Mad Hat Man said:
just reading thro this thread again i notice yu mention "early" freelanders!
Does that mean that "late" freelanders dont have this prob? in which case three q's

what date was the changeover?
how can one tell whether you have different diffs or the same diffs (if yu know wot i mean)?
what are the differences between the diffs?
Click to expand...
Hi Mad Hat Man,
All good points again!
my responses__
Thought about retaining the VCU as you describe, may even try that if the prototype has some problems. Main concern here is space and difficulty of "shoe-horning" something into the space between the IRD and VCU with some rather more serious underbody mods. One of the prototype's pros is that it is essentially bolt on (if you dont include nicking the original Land Rover splines off the old VCu assembly!!)

As far as a change to the relative diff ratios is concerned the answer as far as I'm aware is yes, there was a change around 2001. This was apparently done thru the IRD front drive ratios and (again only as I understand) the front and rear ratios are now the same --ie zero slip at the VCU under normal driving conditions

I asked exactly your questions on other forums about 6 months ago before I got onto landyzone, and got quite a bit of feedback. Some a bit garbled (eg aren't final drive ratio of the rear diff, and crown wheel to pinion ratio one and the same thing??) some quite insightful.
I dont have the part numbers or any other info but I recall on another forum a chap from Greece posting pretty good info on this subject -- will see if I can find it


Cheers
Ian Hughes
 
The Mad Hat Man said:
just reading thro this thread again i notice yu mention "early" freelanders!
Does that mean that "late" freelanders dont have this prob? in which case three q's

what date was the changeover?
how can one tell whether you have different diffs or the same diffs (if yu know wot i mean)?
what are the differences between the diffs?
Click to expand...
had a look back at Landrovernet.com forum and found the thread--
george k from Greece quotes the new IRD part no as TAG000230
i also asked questions about finding out which IRD one had --external markings, actual ratio of front wheels/IRD output pinion to rear prop shaft etc etc but didnt really get anywhere.
For what its worth I jacked up one side of my freebie and found that with a totally siezed VCU, rotating the front wheel 118 revs, caused the rear to rotate 117 revs.. This corresponds pretty well with the 0.8% "overdriven" rear prop shaft figure mentioned on the Rave CD section on the drive shaft/transmission.
The introduction date for the mod may have been later than 2001 (2003/2004??). Also the relative diff ratios were probably just much closer than 0.8% rather than being identical (general info seems to suggest close rather than identical, however a technician at a major Melbourne Dealers suggested identical !!)
These later models have very much less of a drive train problem but some postings suggest it may not have disappeared entirely

All a bit vague I know, but hopefully of some help.

Cheers
Ian Hughes
Tassie
-- this corresponds pretty well with the 0.8%
 
Hi Ian

I think this is great , talking to people all over the planet, i was begining to think that FL owners were not as technically minded as defender bods but i'm wrong.

i was going to do the wheel turning bit this weekend so thanks for that. I was working on a figure of 3% don't know were i got it from 0.8% sounds a lot easier to live with. If LR have reduced or removed the difference they must have sorted the handling out some other way.

Good look with the mod I'll keep checking the forum for progress.
 
The Mad Hat Man said:
Hi guys - I opened up a thread on an engineering site regarding the disconnection of the rear drive and this is the feedback I got. Please read. Basically they are saying that you dont reduce fuel consumption and dont gain any power. This seems to contradictory to what you guys are saying having removed the propshaft. Your (meaningful) comments would be apreciated.

With a dog clutch, you will still be turning almost all the 4WD drive train, it will just be disengaged from the engine, but it will still absorb about the same amount of power. Turning the axles and especially the differential will consume some power. Not having to try to drive both axles at slightly different speeds should save some power.

Freewheeling hubs as used on OEM part time 4WDs saves more as the second diff is not being turned.


When Audi introduced the Quattro they claimed that the reduced drag from the wheels more or less compensated for the increased drivetrain loss, so the fuel consumption was not hit by the AWD.

If the intention is to save fuel then the /maximum/ benefit would be of the same order as the difference between a 2wd and 4wd version of the same vehicle.

The six-speed model meanwhile is rated at 12.2 litres/100km for RWD and 12.8 litres/100km for AWD.

However, the AWD weighs 90 kg more, from 1995 for the 2wd, and I suspect that about half that fuel saving is due to the weight change.

My guess then is that you would save a maximum of 0.3 litres/100 km, and if we believe Audi it will be less than that. At today's fuel costs in the UK (taking a wild stab) that is 0.6p/mile for which you have to install this thing and risk blowing up your transmission. That's 60 pounds a year.
Click to expand...
mad hat Man,
Just took the time to read all of the posts on your enquiry to the engineering site. I had originally only read the post included by you, but having read the rest of the thread I am more than somewhat bemused.
As a professional Chemical Engineer,(with a bit of mechanical aptitude), I can only observe that if thats their attitude and the way mechanical/automotive engineers treat the occasional innocent interested interloper, its not surprising that some of their presumed brethen managed to engineer the piece of wonderment that is the early Freelander drive train!!

What a bunch of underinformed insightless snot gobblers they seem to be.
My advice is, -- dont bother with them, and certainly don't feel compelled to apologize for asking questions or (apparently) disclosing sufficient info early enough>
Cheers
Ian Hughes
Ps hope none of them read this!!!!!
 
lol - i thought groveling was a small price to pay for some (possibly) valid info. its only words - but yes I agree - not very friendly were they?
 
Just like to echo those views on the automotive industry and its tendancy to use the money spending customer as guinea pigs for their creations. I'm not an engineer but i am a very logical sort of guy (ask my wife!) and while a VC is an established of providing 4x4 drive , the mis-matching of axle speeds to cure another problem was just lazy. Shouldn't grumble too much as it probably saved the company and what would we buy if it didn't exist? Yes you've got it, old Landrovers!! The alternative doesn't bear thinking about for me.
I've just driven the FL back from Anglesey in a rain storm and four wheel drive is brilliant. Still got that clunk from the front end though.............
 
The Mad Hat Man said:
spose we cud pm them - but maybe they are too busy :D
Click to expand...


I thought I saw aussielander on earlier? Yep maybe they have scrapped the spline method and gone for the dog clutch approach.

Its just I placed prop back on and not a whiff of snow, it would so handy having a button or manual means to disconnect prop. In fact weather is so mild and sunny I might get the roof down in my other car or take the hard top off the FL.
 
If you live on the wirral you spoke too soon there. Woke this morning to two inches of the crisp white stuff. An I had an appointment in Snowdonia today. Set out with high hopes and the camera, crossed the border to beautiful sunny weather and not a whiff of snow!!!!

I was also wondering if Ian ( Terra Australis) had progressed his design.
 
Hi All from deep and darkest tasmania.
After giving my mech eng man what I thought was a decent break over the Xmas/New Year period, contacted him yesterday to see if he had finished my 2wd/4wd selector unit!!
Not surprisingly he hadn't, but surprisingly ( and more than disappointingly) hadn't really progressed since Oct/Nov!!!.
He expressed concern that the small but finite (0.8% = 1turn in 120) difference between the front and rear diffs would lead to such diff wind up, that even on slippery surfaces, the selector unit, once engaged, would be virtually impossible to disengage and lead to such transmission loadings that gear teeth would snap etc. He said he didnt want to be responsible for rooting the drive train altogether!!!! Thanked for his concerns but am still keen on pursuing something along these lines.
I was aware of the potential of course but had reasoned (see earlier postings) that it would be no worse than a totally seized viscous coupling especially as it would be only used on slippery surfaces.

Will attempt to persude hime to build the unit anyway, (pay him a bit more maybe) and absolve him from any resposibility for consequential damage to the rest of the drive train. (either that or quit the Freelander for a Volvo XC90 V8 -after I've checked what sort of @#$#@ing drive train they have!!!!)

Cheers
Ian Hughes
Tassie
 
Thanks Ian for the update anyway, looks like it is a manual removal of the prop for the time being.

Have you considered a new rear diff? from 2001 onwards the ratio is the same in front and rear, therefore no slip and possibly a means to go down the dog clutch route
 
I wud say that if yu is paying him to make something you have designed - it aint his responsibility anyway. Just ell him - "yu is being paid - just get on wiv it!"

thanks for the feedback, Ian - let us know how it is going.
 
LR1796 said:
Thanks Ian for the update anyway, looks like it is a manual removal of the prop for the time being.

Have you considered a new rear diff? from 2001 onwards the ratio is the same in front and rear, therefore no slip and possibly a means to go down the dog clutch route
Click to expand...
Re diff ratios -- have mused over it -- however I am sure I have seen somewhere in an earlier life (last year maybe on another site) that LR achieved the effect of minimising the difference between front and rear diff ratios, by altering the effective front diff ratio in the IRD !!!! From my simple old chem eng perspective would have thought it much simpler to just change the crown wheel/pinion set in the rear diff.
Re dog clutch - I guess I would see the sleeve/spline set I have as similar to a dog clutch but with a few more teeth and consequently more opportunities per rev of slip to engage smoothly.
May revisit the prospect of physically fitting my unit (if it ever gets built) in series with a serviceable VCU -- might end up the best of both worlds as there will always be some drive train wind up even if the front and rear diff ratios are identical!!

Will stay in touch
Cheers
Ian Hughes
Tassie
 
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