Alternative to the fluid coupling (VCU)

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Nodge68 said:
I like your fundraising plan. I actually like to way you came up with a working replacement for the VCU too. It obviously took a lot of time, money and skill to come up with. I only have a few concerns about it myself.
First is the gearing issue, so forcing it to be used off road only. An indicator light would be handy. ;)
Second is that I don't think the Freelander is as good to drive as a part time 4WD vehicle.
Third would be the insurance implications.
If some of these can be addressed, then I can see some people wanting a Tegralok for themselves.
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Nodge68,
You are spot on. An indicator light is a glaring omission. ('scuse the pun!) I have a weather-proof switch off an old ride-on that I could configure to activate on anything other than fully disengaged. (safest option). A cleverer person than me would wire it to be failsafe. (suggestions, please).
I don't want to get into too much detail, and be boring, but surely internal gearing would completely satisfy the different axle ratios problem, but only in the "straight ahead" condition. I'm pretty sure the axles rotate at a whole range of relative (to each other) speeds while cornering. It has occurred to me that we all seem to yearn for the FL to have a centre diff so that axle ratios, tyre inflation, different wheel/tyre size/relative wear combinations, cornering, permanent (but silky-smooth) 4-wheel drive all cease to be a problem. If only.............(is there anybody really savvy out there who can re-make the gearbox castings and internals to provide a gearbox output shaft facing towards the rear, so that a centre diff could couple up to that and then send the drive forward into the front axle, and back into the rear axle. maybe with sexy hi-lo too- now there's a real engineering challenge. Chances of it being economic though are slim I think).
Since the FL can't (so far) have a centre diff, the Tegralok is a very, very poor substitute (and therefore not attempted) on dry tarmac. My original feasibility study and design brief was to be able to disconnect the axles while on the road, with all the advantages and disadvantages of that, but be able to select all-drive (albeit with a built-in bias), when needed, with all the advantages and disadvantages of that. As with much in life, I weighed up the pros and cons and came to a decision to go ahead, knowing that some of the consequences would be negative.
I can't discuss insurance in a public forum.
Thanks
 
likimstip said:
Nodge68,
You are spot on. An indicator light is a glaring omission. ('scuse the pun!) I have a weather-proof switch off an old ride-on that I could configure to activate on anything other than fully disengaged. (safest option). A cleverer person than me would wire it to be failsafe. (suggestions, please).
I don't want to get into too much detail, and be boring, but surely internal gearing would completely satisfy the different axle ratios problem, but only in the "straight ahead" condition. I'm pretty sure the axles rotate at a whole range of relative (to each other) speeds while cornering. It has occurred to me that we all seem to yearn for the FL to have a centre diff so that axle ratios, tyre inflation, different wheel/tyre size/relative wear combinations, cornering, permanent (but silky-smooth) 4-wheel drive all cease to be a problem. If only.............(is there anybody really savvy out there who can re-make the gearbox castings and internals to provide a gearbox output shaft facing towards the rear, so that a centre diff could couple up to that and then send the drive forward into the front axle, and back into the rear axle. maybe with sexy hi-lo too- now there's a real engineering challenge. Chances of it being economic though are slim I think).
Since the FL can't (so far) have a centre diff, the Tegralok is a very, very poor substitute (and therefore not attempted) on dry tarmac. My original feasibility study and design brief was to be able to disconnect the axles while on the road, with all the advantages and disadvantages of that, but be able to select all-drive (albeit with a built-in bias), when needed, with all the advantages and disadvantages of that. As with much in life, I weighed up the pros and cons and came to a decision to go ahead, knowing that some of the consequences would be negative.
I can't discuss insurance in a public forum.
Thanks
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You have obviously put in a lot of work and come up with a working front/ rear locker, for which you have my respect.
A few years ago I did look about a drive disconnection system that could be fitted onto a rear hub. This would then allow for drive to be open at the rear, when VCU controlled drive wasn't needed. However I never followed the idea up.
As for the omission of a warning light, how about this as a idea. Simply hook your switch up to the lever so that when lock is engaged, the switch bridges across the HDC master switch. This would then cause the HDC to enter standby mode, flashing the HDC light and automatically engage HDC in first and reverse gear when needed. Simple really;)
 
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I live in
Skinny Mike said:
Sounds like a good day out. I wouldn't be able to get down til August, but would like a look at the system.
I'll start saving up for my contribution to the helichopper.
Roughly, where abouts are you?
Mike
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I live in Nottinghamshire, dangerously close to the Lincolnshire border. We are an easy reach from the A1 at Markham Moor. You are the first to show an interest in the redundant VCU, so it can live in my garage until you want it, or decide against it, just say.
The ambicopter came to get me when I was lying busted up and unconscious in a ditch 70m from the point of impact between my Fireblade and a car whose driver "never saw him, officer". But for those guys I wouldn't be buggering about with bits of old iron now. so I owe them big style.
Nodge68 said:
You have obviously put in a lot of work and come up with a working front/ rear locker, for which you have my respect.
As for the omission of a warning light, how about this as a plan. Simply hook your switch up to the lever so that when lock is engaged, the switch bridges across the HDC switch. This would then cause the HDC to enter standby mode, flashing the HDC light and automatically engage HDC in first and reverse gear. Simple really;)
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Kudos. Belting idea. It puts the warning in just the right place, too. I was imagining something lower down on the console, not nearly so visible. Thanks Nodge68. Also, I had already noticed that being able to lock up the drive means the handbrake holds all 4 wheels, not normally an issue, but...............
 
Nodge68 said:
A few years ago I did look about a drive disconnection system that could be fitted onto a rear hub. This would then allow for drive to be open at the rear, when VCU controlled drive wasn't needed.
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I'm sure that would give your VCU a very high wear rate. It would permanently slipping/drapping the rear prop round. I think you'd need to disconnect both ends.
Subaru has an electroincally controlled clutch mechanism to engage the VCU. If you do look doing something - I'd study what Subaru did.
Nodge68 said:
Simply hook your switch up to the lever so that when lock is engaged, the switch bridges across the HDC master switch. This would then cause the HDC to enter standby mode, flashing the HDC light and automatically engage HDC in first and reverse gear when needed. Simple really;)
Click to expand...
This is exactly what you DON'T want to do! If you're losing grip, you'll probably need to power out of it with wheels spinning and mud flying. Turning HDC on will be hammering the breaks trying to bring the wheels down to 5MPH. I'm not sure if HDC deactivates when the Go peddle is pressed, if it does then the brakes won't get thumped when you power out of a sticky situation - but it'll bring your speed down when you don't want it to once you do lift on the throttle.
 
GrumpyGel said:
I'm sure that would give your VCU a very high wear rate. It would permanently slipping/drapping the rear prop round. I think you'd need to disconnect both ends.
Subaru has an electroincally controlled clutch mechanism to engage the VCU. If you do look doing something - I'd study what Subaru did.

This is exactly what you DON'T want to do! If you're losing grip, you'll probably need to power out of it with wheels spinning and mud flying. Turning HDC on will be hammering the breaks trying to bring the wheels down to 5MPH. I'm not sure if HDC deactivates when the Go peddle is pressed, if it does then the brakes won't get thumped when you power out of a sticky situation - but it'll bring your speed down when you don't want it to once you do lift on the throttle.
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Sorry, got to set this straight. You are correct for the setting you describe. For us older, less balls-out folks, just getting out of the grass caravan site after a night's heavy rain without turning the field into marmite and filling the wheel arches with mud, is all we aspire to. The Tegralok, for all its faults, is essentailly a no-drama thing. Everything turning at tickover, and no wheelspin needed.
 
Use of the HDC light though is a pretty clever idea. On my Wabco controller there is a loom of wires going to the dash to control each of the ABS warning lights. You could break into the wire going to the HDC light so that it is either illuminated by the Tegralok or HDC switch.

I don't know if the later Teves units use individual wires or some form of comms to the dash panel electronics.
 
GrumpyGel said:
Use of the HDC light though is a pretty clever idea. On my Wabco controller there is a loom of wires going to the dash to control each of the ABS warning lights. You could break into the wire going to the HDC light so that it is either illuminated by the Tegralok or HDC switch.

I don't know if the later Teves units use individual wires or some form of comms to the dash panel electronics.
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Thanks, but do you ever lapse into English! I'm just a simple mining engineer, something you get by starting with an idiot and then kicking his brains out!
 
likimstip said:
Sorry, got to set this straight. You are correct for the setting you describe. For us older, less balls-out folks, just getting out of the grass caravan site after a night's heavy rain without turning the field into marmite and filling the wheel arches with mud, is all we aspire to. The Tegralok, for all its faults, is essentailly a no-drama thing. Everything turning at tickover, and no wheelspin needed.
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Out of interest, have you ever driven a freelander with a fully working vcu ? - it would appear not. - there is no drama or 'marmite' filling the wheel arches. It does what it is supposed to do - and automatically. When in conditions of low traction - low grip / high grip (winter type driving in the UK - engaging the system would be detrimental to the drive train. I still see absolutely no benefit at all, only downsides. The VCU is a superb solution for the freelander.
 
likimstip said:
Sorry, got to set this straight. You are correct for the setting you describe. For us older, less balls-out folks, just getting out of the grass caravan site after a night's heavy rain without turning the field into marmite and filling the wheel arches with mud, is all we aspire to. The Tegralok, for all its faults, is essentailly a no-drama thing. Everything turning at tickover, and no wheelspin needed.
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lol, thanks for implying I'm young - but it would only be in the head - not body :)

Each has their own requirements in 4WD - mine are to be able to drive on the beach for fishing, on river beds for fishing, on icy ski field access roads and steep twisty mountainous tracks - just for the fun of exploring :) Personally, I don't get into "mud flying" situations - but these all require a good amount of power at times and usually keeping a speed above 5MPH - even if I am in first.

From experience you need a locked transmission on the beach and river bed - the D2 relying on TC is a farce - so Tegralok is far superior to that and probably as good as the VCU. On the ski field access roads and tracks though grip is coming and going, so the VCU is far more gentle on the transmission than a locked system.

I can see where you are coming from with the caravan. As you say, you won't cut the field up so much as running 2WD and those wheels spinning out of control. On the road though, trailing a caravan, I'd rather have the safety of a viscous AWD transmission than FWD.
 
GrumpyGel said:
I'm sure that would give your VCU a very high wear rate. It would permanently slipping/drapping the rear prop round. I think you'd need to disconnect both ends.
Subaru has an electroincally controlled clutch mechanism to engage the VCU. If you do look doing something - I'd study what Subaru did.

This is exactly what you DON'T want to do! If you're losing grip, you'll probably need to power out of it with wheels spinning and mud flying. Turning HDC on will be hammering the breaks trying to bring the wheels down to 5MPH. I'm not sure if HDC deactivates when the Go peddle is pressed, if it does then the brakes won't get thumped when you power out of a sticky situation - but it'll bring your speed down when you don't want it to once you do lift on the throttle.
Click to expand...
Sorry GG but I don't agree with the VCU taking a hammering with a disconnected rear hub. All that will happen is it will spin freely without transferring torque across it.
Also HDC is only limits speed to 5Mph if the throttle pedal is at rest. If you want to drive at say 20Mph then pressing the throttle will allow you to drive at 20Mhp. The HDC will only intervene if the vehicle's speed exceeds the throttle position needed for 20Mph or any other speed you fancy within the speed range of first or reverse gear. HDC is in standby for any other gear, so flashes the light. I really can't see using HCD automatically to be a problem. Iirc TC will still control wheel spin, even when HDC is active. LR designed the very well indeed.
 
Nodge68 said:
Sorry GG but I don't agree with the VCU taking a hammering with a disconnected rear hub. All that will happen is it will spin freely without transferring torque across it.
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The reason I say this is because I had a poor VCU - but after 2 years without a crown/pinion gear in the IRD and the back axle/VCU dragging the front prop around - my 1WUT timings were infinite - ie the VCU was completely jammed solid - I could not move it by standing on the bar.
 
GrumpyGel said:
The reason I say this is because I had a poor VCU - but after 2 years without a crown/pinion gear in the IRD and the back axle/VCU dragging the front prop around - my 1WUT timings were infinite - ie the VCU was completely jammed solid - I could not move it by standing on the bar.
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Ok so you are saying that inactivity can cause a thickening of the fluid. This would tend to suggest that the VCU has a sell by date as such.
My thoughts for a disconnecting hub were more as a temporary thing. So if a spare tyre was used when a 300 Mile motorway journey is needed, added strain on the IRD could be avoided. I just think in those situations, it would be handy to disconnect the rear drive.
 
In those situations, yes I agree there's probably not a lot of trouble that could occur.

The VCU will not be inactive though. The rear prop will 'want' to stay at rest. By 60MPH the front prop will be spinning at about 760RPM and the VCU will drag the rear prop up to this speed - so its not inactive, its spinning (maybe) 20KG up to 760RPM. The VCU's life is spent tackling much greater forces than 20KG, but at much smaller prop speed difference. That's why I brought it up - together with what happened to my VCU in that situation.
 
Cudos for constructing the unit very clever and I'd be interested in seeing how it actually works internally judging by the video and what's been said on i'd say cogs

Just musing out loud and have the following queries,

1) Wouldn't a similar type of type of engagement to that of a Limited slip diff or use of a Torsen Diff remove some of the limitations of this system? ie not permanent AWD? an lsd type engagement would allow for some variations in wheel speed on tarmac within the actual amount of slip a lsd would provide. that method would allow the FL to remain 4x4 when it's needed in line with the original design brief of a interference free 4x4 system eg: the front wheels spun up and the rears would engage and vice versa, essentially a crude haldex system like fitted to the freelander 2 without the electrics.

2) perhaps using the above method would free up the small lever for fitting an actual difflock within the your unit as james mentioned

Now I realise that an lsd/torsen type arrangement could still lead to wind up due depending on the amount of slip the diff allows before transmitting the torque so a whole new kettle of fish :confused:

Maybe it's worth considering for the 'Mark 2' version?:D
 
LUKBENPHI said:
1) Wouldn't a similar type of type of engagement to that of a Limited slip diff or use of a Torsen Diff remove some of the limitations of this system? ie not permanent AWD? an lsd type engagement would allow for some variations in wheel speed on tarmac within the actual amount of slip a lsd would provide. that method would allow the FL to remain 4x4 when it's needed in line with the original design brief of a interference free 4x4 system eg: the front wheels spun up and the rears would engage and vice versa, essentially a crude haldex system like fitted to the freelander 2 without the electrics.
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Aren't you proposing a Viscous Coupling here? That's basically what converts a diff into a limited slip diff, or as in the case of RR a center diff into a limited slip center diff.
 
GrumpyGel said:
Aren't you proposing a Viscous Coupling here? That's basically what converts a diff into a limited slip diff, or as in the case of RR a center diff into a limited slip center diff.
Click to expand...

Essentially a mechanical viscous coupling unit yes,

more than likely the RR centre diff is the torsen type ( dont quote me on that!) , performance road cars have been using them for years its only gets complicated when the japs/germans started adding electronics and clutch packs to them! fitting one of those within the op's contraptions casing would theoretically mechanise what the standard VCU already does and effectivly becomes a mecahnical version of the haldex system fitted to the FL2,

A 2nd hand torsen diff from ebay from a mazda is just over £200 so could make an interesting scrapyard challenge project for the OP

More than likely LR would have looked at the idea originally for the FL and dismissed due to costs and opted for the cheaper vcu which does the same thing

theoretically with an air locker kit you could have a locking central diff also if the two could be made compatible
 
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likimstip said:
Thanks, true.
(note, off-road comments follow) I ignore the tyre "creep" required to match the ratios difference. I expected it to be tough to detect, and so far it has been. I guess it is smaller than normal tyre creep on grass, but further testing might detect it. More anon.
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As being (as far as I know) the only one to fit revcounters to my props to actually measure prop speeds front and back on my 2005 TD4 I can re-assure likimstip that the 0.2% gearing difference compensates ideally for the extra tire deflection at the front for engine weight - in normal straight line flat road running my props speeds are matched to within 1rpm on tarmac so for offroad use this is not going to be any sort of a problem. Granted a solid prop would load the transmission on road - we all accept that - but this guy has simply put a series land rover transmission into a Freelander and is prepared to accept the less balanced running on tarmac that the Freelander does so bloody well. He can play off road in an identical way as I can in my Lightweight S11A but the fillings won't vibrate out of his teeth on the way to work and he does not need a sports bra either.
If that's your bag offroad and you are prepared to use the Freelander as front wheel drive only on road - then the guy has a well engineered package. Well done.
However my truck which has done 136,000 miles on it's original VCU (judging by the date on the GKN unit fitted - granted it could have been changed with an old stock GKN part) and still can do a one wheel up test of 11 seconds at 8kg and 30 seconds at 5kg - I think it is an expensive mod for a slightly different style of offroad driving. I would prefer to just regularly check and replace as required my VCU (and get the V8 S11A Lightweight animal out on high days and holidays
 
dfossil said:
As being (as far as I know) the only one to fit revcounters to my props to actually measure prop speeds front and back on my 2005 TD4 I can re-assure likimstip that the 0.2% gearing difference compensates ideally for the extra tire deflection at the front for engine weight - in normal straight line flat road running my props speeds are matched to within 1rpm on tarmac so for offroad use this is not going to be any sort of a problem. Granted a solid prop would load the transmission on road - we all accept that - but this guy has simply put a series land rover transmission into a Freelander and is prepared to accept the less balanced running on tarmac that the Freelander does so bloody well. He can play off road in an identical way as I can in my Lightweight S11A but the fillings won't vibrate out of his teeth on the way to work and he does not need a sports bra either.
If that's your bag offroad and you are prepared to use the Freelander as front wheel drive only on road - then the guy has a well engineered package. Well done.
However my truck which has done 136,000 miles on it's original VCU (judging by the date on the GKN unit fitted - granted it could have been changed with an old stock GKN part) and still can do a one wheel up test of 11 seconds at 8kg and 30 seconds at 5kg - I think it is an expensive mod for a slightly different style of offroad driving. I would prefer to just regularly check and replace as required my VCU (and get the V8 S11A Lightweight animal out on high days and holidays
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Thanks, that explains why the Tegralok is so willing to engage at any speed in the straight ahead. I expected it to be reluctant at say 60 mph, but was puzzled when it went straight in, you have answered that.
Does anyone have engineering drawings of the gearbox so that we can all figure out a DIY (but competent and careful) way of introducing a proper centre diff? It would solve most of the problems we are posting on here. Of course those who like the VCU would continue to use them, but variety is what makes this forum so interesting. The FL is a great car, let down by one major flaw - what a pity, it could have been outstanding.
 
dfossil said:
As being (as far as I know) the only one to fit revcounters to my props to actually measure prop speeds front and back on my 2005 TD4 I can re-assure likimstip that the 0.2% gearing difference compensates ideally for the extra tire deflection at the front for engine weight - in normal straight line flat road running my props speeds are matched to within 1rpm on tarmac so for offroad use this is not going to be any sort of a problem. Granted a solid prop would load the transmission on road - we all accept that - but this guy has simply put a series land rover transmission into a Freelander and is prepared to accept the less balanced running on tarmac that the Freelander does so bloody well. He can play off road in an identical way as I can in my Lightweight S11A but the fillings won't vibrate out of his teeth on the way to work and he does not need a sports bra either.
If that's your bag offroad and you are prepared to use the Freelander as front wheel drive only on road - then the guy has a well engineered package. Well done.
Click to expand...
The slight gearing difference between front and rear would help compensate for the extra weight on the front tyres. This would also help explain why the K series Freelander appears to suffer IRD failure more than the TD4s and V6. The latter 2 have an extra 100 to 150 Kgs on the front axle.
 
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