6x6 Defender

[munro]

I'm just fishing for thoughts, ideas & opinions at this stage. As soon as finances permit I have this desire to build what could be termed the ultimate tourer, at least in my eyes.

My vision is to start with a Defender 130 dual cab 300tdi. Have the engine replaced with a new balanced & blueprinted (if possible) 4BD1T Isuzu and mated to an Automatic transmission which has a modified valve body to handle towing down hill engine braking. ( I hope that makes sense). Then when that is done to have a 6x6 conversion with an 8 foot tray.

The idea is to be able to either tow an off-road camper-van similar to a Quantam or Conqueror or carry a slide-on camper.

I know where I can get the 6x6 conversion done and the cost but getting information on the engine/transmission has led me to ask here.

So is my ideas a good or bad one?
Are there any advantages in a 6x6?
Is it possible to get a new Isuzu 4BD1T?
Are their any advantages in getting a new or overhauled engine balanced & blueprinted?
Where would I get such a conversion with transmission done and approx cost? I would prefer someone who actually knows & understands Land Rovers.

I am not a mechanic nor a rock hopper, just a budding grey nomad with a head full of ideas at the moment.

Thanks in advance, all ideas, opinions & suggestions welcome.

[Lotz-A-Landies]

There are many and varied 6X6 options out there, some good, some not-so-good and some very poor.

https://www.aulro.com/afvb/images/imported/2011/04/784.jpg
(In the image above it is possible to be driving on only the front axle assembly, the 2nd & 3rd being crossed up without traction and in fact with the weight to the rear no traction on the front axle.)

The issues are that if the 2nd and 3rd axles are spread apart they will scrub the tyres and also if their centres are greater than ?1000mm they need (by law) to be load sharing. Independent coil springs can not load share.

Chassis: The problem with a lot of 6X6 systems is that articulation is limited so in acute ramp over situations the 3rd axle is suspended off the ground, cantilevering the load to the rear of the 2nd axle and the weight of the 3rd axle on the spring mount of the second axle. (Image below)

http://www.foleysv.com/6x6/19.jpg

The best load carrying arrangements are off-set load sharing leaf springs.

Drive: Most 6X6 conversions give you constant 6X4 (drive 1st and 2nd axle, lazy 3rd) with 6X6 only engaged on low ratio or on CDL lock dependant upon system. Very few have a 4th power dividing diff between the 2nd and 3rd axles. Some like the Perentie 6X6 have a separate drive from the transfer box to the 3rd axle. Some of these systems have no high-range capability.

http://t2.gstatic.com/images?q=tbn:ANd9GcRkEA7vKPoJHdwR8l8uMmV8WIKrVkgJA EsURl66AJmmvaKhVWXy&t=1

Other 6X6 have a double pinion diff on the 2nd axle (Image above - very troublesome),

https://www.aulro.com/afvb/images/imported/2012/05/739.jpg

while others have a variety of drives involving a drop box on the prop shaft from the transfer box to 2nd axle (image above) or from the pinion of the 2nd axle. (Image below) These later systems have both high and low ratios.

https://www.aulro.com/afvb/images/imported/2011/04/785.jpg

There is a recent thread on 6X6 in the REMLR section (http://www.aulro.com/afvb/general-chat/123328-6x6-110-pics-info-wanted.html) and another http://www.aulro.com/afvb/general-chat/124406-6x6-drive-suspension.html.

[akelly]

If you need the 3rd axle for load carrying capacity you may want to consider a lazy axle - much simpler than a driven one.

My father has a 6 wheel land cruiser, dual cab tray back. He and Mum are grey nomads (dont tell them that!) and have a slide on camper for big trips. They have been everywhere in the damn thing - a really good tourer. A bastard to drive around town, mainly beacuse the suspension is set up to carry the camper.

Down side is the expense of tyres - the rears scrub out very fast.

YMMV.

Adam

[munro]

Lotz-A-Landies thanks for that. Had a look at the links and seems to be more trouble than it's worth.

akelly, not really interested in a lazy axle setup.

Anyone with info or ideas on the engine/trans swap I am proposing?:angel:

[isuzurover]

Why not just buy a perentie 6x6 then do an auto conversion???

I am unsure why you would need a 6x6 AND a camper trailer???

[Lotz-A-Landies]

I like the idea of an Isuzu 4BD1-T in a 130 (it is what I plan to use in my 150) but would be wary about an auto. You may want to investigate automatics that are fitted to Isuzu NPR of other models that used the 4BD1-T and mate that to the LT230 transfer like some members are doing with Isuzu gearboxes.

[munro]

Why not just buy a perentie 6x6 then do an auto conversion???

I am unsure why you would need a 6x6 AND a camper trailer???


The camper trailer is for the wifes comfort. We plan on at least one big lap of the island so the comfort of the van will be appreciated. However, there are other trips that I wish to do and the wife doesn't so me and a mate or two with tent & swags. No trailer on these ones. It's a pain sometimes but happy wife, happy life.

Can you buy perenties? I thought they were military only. Excuse my ignorance. The main reason I was looking at a 6x6 was to get the tray length. I am still debating with the Mrs. about the camper trailer, as the alternative that she would consider is a Northstar slide-on. She insists on internal shower & toilet and no or not much canvas. Of course the 6x6 is not important if we go the camper route and not the slide on. I am just trying to cover all bases of information at this stage.

However, I figure that by buying a vehicle that is around 15 or so years old there is a good chance the motor will need a reco job. So in my mind I figure why not go for something that may be better. The choice if the Isuzu 4BD1T seems to get favourable comments. The Mrs can't drive a manual so auto it must be. Thanks again for all input.

[Nero]

The Army are going to start flogging off their Mogs and Macks soon might be easier and simpler than sinking a heap of money into stretching a 130 to do the job. The 4BD1's have a reputation of extremely long service life and they removable liner motor so are relatively cheap and easy to rebuilt. Other than the motor may run a little smoother I don't think their would be much advantage in a blue print and balance unless you start going for some really big boost numbers.

[isuzurover]

The camper trailer is for the wifes comfort. We plan on at least one big lap of the island so the comfort of the van will be appreciated. However, there are other trips that I wish to do and the wife doesn't so me and a mate or two with tent & swags. No trailer on these ones. It's a pain sometimes but happy wife, happy life.

Can you buy perenties? I thought they were military only. Excuse my ignorance. The main reason I was looking at a 6x6 was to get the tray length. I am still debating with the Mrs. about the camper trailer, as the alternative that she would consider is a Northstar slide-on. She insists on internal shower & toilet and no or not much canvas. Of course the 6x6 is not important if we go the camper route and not the slide on. I am just trying to cover all bases of information at this stage.

However, I figure that by buying a vehicle that is around 15 or so years old there is a good chance the motor will need a reco job. So in my mind I figure why not go for something that may be better. The choice if the Isuzu 4BD1T seems to get favourable comments. The Mrs can't drive a manual so auto it must be. Thanks again for all input.

The 4x4 and 6x6 landies, along with the unimogs, will be sold off by the army starting mid year.

The perentie 6x6 has about a 2.5 tone payload capacity... A unimog has more.

Both could take the world's largest trayon and still have payload to spare...

[PAT303]

IMHO the 6x6's will go for big dollars,same with the mogs so a civvy 4tonner cab over would be a better choice. Pat

[ugu80]

I take it you're meaning a six wheel drive, not a lazy axle.

My only experience with 6wd was early 1970's in the army. We just started replacing the old Studebaker 6wd with Merc Unimog 4wd. The Mercs were more comfortable and civilized but we would still take a Studebaker along to pull the Mercs out of bogs. The Studebaker would still go where the Mercs couldn't because of the 6wd.

[munro]

I take it you're meaning a six wheel drive, not a lazy axle.

My only experience with 6wd was early 1970's in the army. We just started replacing the old Studebaker 6wd with Merc Unimog 4wd. The Mercs were more comfortable and civilized but we would still take a Studebaker along to pull the Mercs out of bogs. The Studebaker would still go where the Mercs couldn't because of the 6wd.


Yes I am talking 6 wheel drive not 4wd with a lazy axle. To fit the slide on camper that I want (Mrs wants) if I go down that path I need an 8foot (2.4m) tray length. With a single rear axle. there would be too much overhang and weight behind the axle. With a lazy or 6x6 that problem does not exist or is of no consequence. However I can see many shortcomings of a lazy axle in an off road situation. I don't want to go there.

There are several companies doing 6x6 conversions all with good & bad points along with just purchasing a Perentie when available. The more I look at this and as tantalizing as it seems, I can see big dollars and probable negatives that may just be not worth it.

But that is why I am here. My intended base vehicle will be a 130 defender, so I am seeking as much knowledge and info on the subject as possible. Also any other suggestions for a silly old bugger like me who wants the ultimate go anywhere gray nomad machine.:D

[Lotz-A-Landies]

The first Perentie 6X6 to come out will likely have high kilometres on them and go for high prices. As more come onto the market the prices may fall depending upon site.

It is likely some of the first ones will have the OH&S rejected side seating bodys. Either way all the Perentie 6X6 have the wide body/wide track configuration which makes them comparable in size to the Ford F250 with less passenger comfort.

[akelly]

The 6x6 perenties are notorious for blowing diffs and clutches if you have any load on them at all. Not sure what sort of trips you are planning, but the LC 6x4 I was refering too has been to the cape and a few other places without problems. If you are concerned about having the middle axle suspended then a winch will soon sort that out!

Not trying to push my opinion on you, but wondering what advantages you see in a 6x6 over a 6x4 for an off road tourer? To me the driven 3rd axle seems like adding complexity for very little gain.

Cheers,

Adam

[munro]

The 6x6 perenties are notorious for blowing diffs and clutches if you have any load on them at all. Not sure what sort of trips you are planning, but the LC 6x4 I was refering too has been to the cape and a few other places without problems. If you are concerned about having the middle axle suspended then a winch will soon sort that out!

Not trying to push my opinion on you, but wondering what advantages you see in a 6x6 over a 6x4 for an off road tourer? To me the driven 3rd axle seems like adding complexity for very little gain.

Cheers,

Adam

Thanks for your input. I don't see any advantage or disadvantage in a 6x6 over a 6x4. I have no experience in either of those axle set-ups. It was an idea I had and that is why I posted here for information, ideas or advice, whether it be good, bad or ugly. My only experience with 6x6 or 6x4 is virtual in what I have seen in the internet. I have read some threads on other forums where posters (experience unknown) have put forward the theory or experience that the rear axle which is the lazy one can leave the middle axle suspended in mid air in some situations. So thinking along that line if the middle axle was suspended in mid air and the rear axle was a driven one then no drama. Yes a winch would probably take care of a situation but I wouldn't want it to be a regular event.

As previously mentioned, I am more interested in the tray length with proper axle support then a 6x6. For my personal purposes, I would rather one vehicle to meet our needs, that is not towing. However if I go down the towing path then a standard 130 dual cab will fit the bill. The wife also insists on 2nd row seating for the occasional hanger on so a single cab which would take the slide-on is not on the cards. There seems to be enough posts in this thread now to suggest to me that I should just pull my head in and forget about a 6x6. As you say in reality a lot of complexity for little real gain.

So I would rather see some more posts here regarding my intended engine conversion. That is where can I get a new or reconditioned 4BD1T with suitable auto conversion done. As long as it is in Australia I really don't care where. Thanks again.

[that_kid]

The perentines will be up for sale soon so maybe keep saving and overhaul one of them? they already have the desired motor then its just he gearbox. If you can get an ex ambulance then the cab is already on the back too!

[wagoo]

Thanks for your input. I don't see any advantage or disadvantage in a 6x6 over a 6x4. I have no experience in either of those axle set-ups. It was an idea I had and that is why I posted here for information, ideas or advice, whether it be good, bad or ugly. My only experience with 6x6 or 6x4 is virtual in what I have seen in the internet. I have read some threads on other forums where posters (experience unknown) have put forward the theory or experience that the rear axle which is the lazy one can leave the middle axle suspended in mid air in some situations. So thinking along that line if the middle axle was suspended in mid air and the rear axle was a driven one then no drama. Yes a winch would probably take care of a situation but I wouldn't want it to be a regular event.

As previously mentioned, I am more interested in the tray length with proper axle support then a 6x6. For my personal purposes, I would rather one vehicle to meet our needs, that is not towing. However if I go down the towing path then a standard 130 dual cab will fit the bill. The wife also insists on 2nd row seating for the occasional hanger on so a single cab which would take the slide-on is not on the cards. There seems to be enough posts in this thread now to suggest to me that I should just pull my head in and forget about a 6x6. As you say in reality a lot of complexity for little real gain.

So I would rather see some more posts here regarding my intended engine conversion. That is where can I get a new or reconditioned 4BD1T with suitable auto conversion done. As long as it is in Australia I really don't care where. Thanks again.


I seriously doubt that the Perentie diffs would give you any problems for your intended use.Anyone who tells you 6x6 has little advantage over 6x4 obviously doesn't have any practical experience of either. They are chalk and cheese offroad, particularly with the relatively limited interaxle articulation that most conversions provide.
Still I think that a camper conversion on a 4x4 Mitsubishi Canter, Isuzu or similar would prove to be just as mobile, more practical, durable and reliable than any LandRover based unit.
wagoo.

[akelly]

I seriously doubt that the Perentie diffs would give you any problems for your intended use.Anyone who tells you 6x6 has little advantage over 6x4 obviously doesn't have any practical experience of either. They are chalk and cheese offroad, particularly with the relatively limited interaxle articulation that most conversions provide.
Still I think that a camper conversion on a 4x4 Mitsubishi Canter, Isuzu or similar would prove to be just as mobile, more practical, durable and reliable than any LandRover based unit.
wagoo.

Not wanting to start a whole thing here - and acknowledge that Munro wants to focus on the engine/trans issues - but I have a bit of experience with both (6x6 perenties and the 6x4 LC my father owns) and for carrying a camper on the back in a touring situation I dont see a great advantage in the 6x6, given the added complexity. Most of the 6x6 LRs I have had involvement with would best be described as having drivetrains made of cheese! Except in the case of the highly modified ones.

Cheers,

Adam

[weeds]

The 6x6 perenties are notorious for blowing diffs and clutches if you have any load on them at all. Not sure what sort of trips you are planning, but the LC 6x4 I was refering too has been to the cape and a few other places without problems. If you are concerned about having the middle axle suspended then a winch will soon sort that out!

Not trying to push my opinion on you, but wondering what advantages you see in a 6x6 over a 6x4 for an off road tourer? To me the driven 3rd axle seems like adding complexity for very little gain.

Cheers,

Adam

i have driven many of km's in a GMV '6x6 perentie'..........and my unit had a fleet of IIMV's and i cannot recall diffs or clutches being a problem, keep in mind these are company cars that get abused day in day out

- i spun an intermediate axle being silly getting airborne, engaged centre diff lock and cruised home, LRA even replaced the axle due to being faulty
- seized an intermediate diff when the greasers forgot to refill it after a major service

i would have a four door version today if i could

[THE 109]

Munro,

The 4BD1T is no longer available new to my knowledge but they can be found 2nd hand,all parts are available to rebuild them although depending on its condition can be expensive.
Balancing all my components was under $250.00.

Cheers Eric

[wagoo]

Not wanting to start a whole thing here - and acknowledge that Munro wants to focus on the engine/trans issues - but I have a bit of experience with both (6x6 perenties and the 6x4 LC my father owns) and for carrying a camper on the back in a touring situation I dont see a great advantage in the 6x6, given the added complexity. Most of the 6x6 LRs I have had involvement with would best be described as having drivetrains made of cheese! Except in the case of the highly modified ones.

Cheers,

Adam

The 6x6 conversions you have been involved with Adam were probably British conversions described earlier that employed pinion mounted drop box drive splitters on 'cheesy' Rover diffs. The Perenties employ 2 Salisbury 8HA axle assemblies for the rear bogie which are not known for being weak, and the halfshafts if needed can be uprated to virtually bomb proof 1.5'' 35 spline specification.
I believe Munro mentioned something to the effect that he desired a go anywhere camper. This implies a degree of offroad travel, where a lazy 3rd axle would be a liability on a heavy camper conversion.
Wagoo.

[Lotz-A-Landies]

Wagoo

How would a detroit locker go on a Salisbury 3rd axle?

Diana

[wagoo]

Wagoo

How would a detroit locker go on a Salisbury 3rd axle?

Diana

The Perenties that were sent to Afghanistan were fitted with Detroits in both rear diffs,although some owners of bogie drive heavier trucks with twin Detroits I've dealt with weren't happy with them, complaining of hopping, skipping and banging around corners when unladen.
Wagoo.

[munro]

Munro,

The 4BD1T is no longer available new to my knowledge but they can be found 2nd hand,all parts are available to rebuild them although depending on its condition can be expensive.
Balancing all my components was under $250.00.

Cheers Eric
Thanks. That feedback is helpful. Shame though that a new one is no longer available.

[munro]

The 6x6 conversions you have been involved with Adam were probably British conversions described earlier that employed pinion mounted drop box drive splitters on 'cheesy' Rover diffs. The Perenties employ 2 Salisbury 8HA axle assemblies for the rear bogie which are not known for being weak, and the halfshafts if needed can be uprated to virtually bomb proof 1.5'' 35 spline specification.
I believe Munro mentioned something to the effect that he desired a go anywhere camper. This implies a degree of offroad travel, where a lazy 3rd axle would be a liability on a heavy camper conversion.
Wagoo.

Correct. I desire a go anywhere camper, so good off road ability is what I am after. I am starting off late in life so apart from the lap and the Mrs's Ideas about trips, I still want to do the usual well known trips. I have chosen the Defender because I am led to believe it is the best for off road and not too bad on road as well.

Before I head off and get into too much trouble, I want to make sure I have a reliable vehicle that has more capability than me. Thanks.

[Lotz-A-Landies]

The Perenties that were sent to Afghanistan were fitted with Detroits in both rear diffs,although some owners of bogie drive heavier trucks with twin Detroits I've dealt with weren't happy with them, complaining of hopping, skipping and banging around corners when unladen.
Wagoo.Thanks Wagoo

Good to know the Perenties have them. I would think the detroit in the 3rd wouldn't be a real problem when it's running lazy most of the time. If I fit anything to the 2nd axle it will likely be an air locker or maxidrive if I can get one.

Diana

[wagoo]

Thanks Wagoo

Good to know the Perenties have them. I would think the detroit in the 3rd wouldn't be a real problem when it's running lazy most of the time. If I fit anything to the 2nd axle it will likely be an air locker or maxidrive if I can get one.

Diana

Do you presently own a Perentie or civilian 6x6 Diana? The 3 civilian examples I've worked on, and a few of the army ones I've looked at all had relatively new rear axle double cardan propshafts at quite low 40-60,000KMs.Not sure why LandRover chose to mount the centre bearing on the chassis rather than on the forward rear axle as was commonly done on Studes, GMCs etc, but that is one modification I would consider to reduce angles and to eliminate the double cardan joint.
Wagoo.

[Lotz-A-Landies]

Wagoo

Yes I do have a 6X6, "Ikea" because it is currently flat packed. It was taken apart to repaint the chassis and never re-assembled before the PO died.

It is a UK built unit, from an apparent fleet contract of similar vehicles. The interesting part it has a Rover Group ID plate showing all three axles and it has a JLR service and warranty history, so I am assuming it is a Land Rover Special Vehicles factory build.

The 6x6 design is the coil spring type with the drop box over the 2nd diff pinion as shown in various pics, but the third axle is Salisbury. I have also been promised a Detroit/Salisbury from the 4BD1/LT85 donor.

Diana

[wagoo]

Wagoo

Yes I do have a 6X6, "Ikea" because it is currently flat packed. It was taken apart to repaint the chassis and never re-assembled before the PO died.

It is a UK built unit, from an apparent fleet contract of similar vehicles. The interesting part it has a Rover Group ID plate showing all three axles and it has a JLR service and warranty history, so I am assuming it is a Land Rover Special Vehicles factory build.

The 6x6 design is the coil spring type with the drop box over the 2nd diff pinion as shown in various pics, but the third axle is Salisbury. I have also been promised a Detroit/Salisbury from the 4BD1/LT85 donor.

Diana

There is nothing wrong with the drop box splitter concept, providing it employs gears not morse chain.I used homebuilt pinion mounted drop boxes on both rear diffs on my own 6x6 without problems way back in the day.
The rearmost 4.7:1 Rover diff would blow fairly frequently though. Never broke a diff on the forward rear axle. I later removed the axle tubes from a Salisbury, machined back on a lathe the pinion snout and welded a bolt flange to it to accept a drop box. Due to the extra bulk of the Salisbury, my original drop box, which contained a series intermediate gear and 2 high range gearwheels was too short, so I fabricated a new case that I was going to use 3 large diameter gears from LT95 intermediate gears meshed together. never got around to finishing that project due to subsequent domestic responsibilities:(. If Ashcrofts new super duper crownwheel and pinion sets were available back then, the original Rover diff setup would have been much more successful because my vehicle was compact and relatively light, being built for extreme crosscountry performance as opposed to a heavy load carrier.
Wagoo.

[akelly]

The 6x6 conversions you have been involved with Adam were probably British conversions...

No. I know what a perentie is and have clocked a fair few k's in them, most of the variants. If you load them up, they break - particularly on the bitumen during hill starts. I'm happy for you to disagree - its a free world!

If you go this way I would definitely go for an auto if you can make it work - the clutch is a major weakness on the perenties.

Have fun!

[isuzurover]

No. I know what a perentie is and have clocked a fair few k's in them, most of the variants. If you load them up, they break - particularly on the bitumen during hill starts. I'm happy for you to disagree - its a free world!

If you go this way I would definitely go for an auto if you can make it work - the clutch is a major weakness on the perenties.

Have fun!

:angel:

What "breaks" exactly...???

The weak point in a perentie 6x6 (rear) axle is the 1.24" 24 spline halfshafts. Which can easily be upgraded to 1.5" 35 spline.

The front ring and pinion was also a weak point during the trials until they made a special upgraded version.

If you are breaking a perentie 6x6 drivetrain doing hill starts on bitumen then I would question your driving skills.

[Lotz-A-Landies]

No mod hat here, but I think this is touching on too personal!

Diana