F1technical.net

mx_tifoso wrote:In that case, why not just get a 2WD vehicle and put on some proper tyres? I've done miracles with just rear wheel drive and good all terrain tyres through snow, ice, mud, etc. Especially if said vehicle spends the majority of it's life on-road, 2WD will be more efficient and troublesome over in the long run. Imo.

Actually, the AWD version has a 2.0 TDi unit that provides more torque and power (320N-m and 140ps) as against only 250N-m and 110ps in the FWD version. It also has a 6 speed manual as compared to the FWD's 5-speed. Weird differences. If it was offered in a RWD condiguration, we would ve bought it without even thinking twice. But then it would have to have a longitudinal engine layout, which it has nt, so it is out of question, and we got the AWD variant. Plus, you also get additional features. It's a good deal.
But yeah, having proper of road tyres would ve been better. We got Goodyear Excellence, which are nt exactly AT tyres.

The Haldex unit is a clutch, originally used as a differential brake in FWD rally Saabs. The clutch is engaged by hydraulic pressure generated when there is a speed difference over the clutch. When used in a four wheel drive system the clutch will engage the drive to the normally non driven wheels when the driven wheels spin, causing a speed difference the clutch need to engage.

With the fourth generation the Haldex system got a separate hydraulic pump, making it possible for the clutch to engage whenever its control unit deemed necessary. With the Haldex system, just like many other all wheel drive systems under electronic control, there is no center differential, just the clutch. So when the clutch is engaged it can transfer all availible power to one axle if the other axle loses traction.

aussiegman wrote:

strad wrote:I don't know about the Haldex but the Torsen is great and seamless.

Torsen does have issues with slip where very low to zero load occurs on one drive wheel. During this they act basically as an open diff, sending sending all torque to the one lifted wheel. As such they require a degree of resistance (traction) to work effectively to enable them to see a torque bias across the driven wheels and distribute torque accordingly.

That is where a locked diff, Haldex or plate diff works much better as it does not require both wheel have load (traction) to provide drive. One wheel can have large slip values such as where one is lifted off the road surface into the air or there is on a very low friction surface (ice, mud, water, oil, dirt etc).

There is a hybrid diff from Wavetrac diffs that are a modified Torsen unit which uses a ramped friction surface to overcome the traditional Torsen short comings by engaging when there is a drive substantial differential between the driven wheels.

Glenn, have you tried that wavetrack? It looks good on paper for the stuff we do.

gixxer_drew wrote:Glenn, have you tried that wavetrack? It looks good on paper for the stuff we do.

Sorry for the very late reply Andrew..Work has killed me ATM. Spent more time on planes than the ground ATM!!!

I have driven a few cars with Wavetrac's and they certainly overcome the issue of free wheel drive loss. The power down is smooth however it can sometimes feels a little "slow" which I think is just the delay in the ramps catching up. I found it only really noticeable when there were quick throttle and/or direction changes. Not very often but it was there.

Overall they are really good, much better than a Torsen type diff for track use where you might lift a wheel off a ripple strip or simply through cornering, especially an a FWD or 2WD car.

They also seemed to be a little more like a 1.5 way plate diff under braking but that might have been just my "seat of the pants dyno" perception.

I think that if you were to use one you'd use the optional higher friction surfaces to get it to lock up with a bit more quickly and positively.

Guys, can anyone point a good reference to understand Torsen type T-2/T-2R and T-3 type differential? Thanks.

autogyro wrote:Far to much has been evangelised over four wheeled drive being better off road than two wheeled drive.
In soft sand a two wheeled drive beach buggy with baloon tyres and no transmission locks is far better if the weight can be kept low.

Same for mud or soft terrain after heavy rain. I was a hunter for several years as my father has been for his whole life, and it was fun to watch some people into their 4x4 getting trapped on the mud while we could pass with our 2wd private car That was with a Citroen BX around 15-18 years ago with that superb hidraulic suspension, while someone got trapped with a Mitsubisi Montero... sorry, Pajero, in Spain it was called Montero as "Pajero" is a coloquial sinonym of masturbator

Weight, or lack of excessive weight to be more specific, can be a lot more useful than 4WD in many circumstances

Now he owns a Suzuki Jimmy wich is far from best off-track 4x4 (no differential lock), but it is light and don´t need it at all so he can go through very difficult terrain both because of the light weight and short wheelbase, wich is also a big plus. Those BIG SUVs are useless for most off-track situations

PhillipM wrote:I regularly take a 2wd car places many can't get in 4wd, just takes the right tyres!

This!

I've taken a FWD compact saloon (1.6D, 110hp) into deep mud and rocky bumps wherein I believe many contemporary SUVs with 20" rims and low ride heights would have rock strikes and probably get bogged down.

The car swung its head like a snake; but I kept my momentum and I was fine.

Car has heavy winter tyres btw.


Sent from my steering wheel

I don't mean 20" rim shod SUV's, I mean Bowlers and the like

Andres125sx wrote: Same for mud or soft terrain after heavy rain. I was a hunter for several years as my father has been for his whole life, and it was fun to watch some people into their 4x4 getting trapped on the mud while we could pass with our 2wd private car That was with a Citroen BX around 15-18 years ago with that superb hidraulic suspension, while someone got trapped with a Mitsubisi Montero... sorry, Pajero, in Spain it was called Montero as "Pajero" is a coloquial sinonym of masturbator

Well if doesn't count if you use BX
Best car I have ever driven!

Andres125sx wrote:

autogyro wrote:Far to much has been evangelised over four wheeled drive being better off road than two wheeled drive.
In soft sand a two wheeled drive beach buggy with baloon tyres and no transmission locks is far better if the weight can be kept low.

Same for mud or soft terrain after heavy rain. I was a hunter for several years as my father has been for his whole life, and it was fun to watch some people into their 4x4 getting trapped on the mud while we could pass with our 2wd private car That was with a Citroen BX around 15-18 years ago with that superb hidraulic suspension, while someone got trapped with a Mitsubisi Montero... sorry, Pajero, in Spain it was called Montero as "Pajero" is a coloquial sinonym of masturbator

Weight, or lack of excessive weight to be more specific, can be a lot more useful than 4WD in many circumstances

Now he owns a Suzuki Jimmy wich is far from best off-track 4x4 (no differential lock), but it is light and don´t need it at all so he can go through very difficult terrain both because of the light weight and short wheelbase, wich is also a big plus. Those BIG SUVs are useless for most off-track situations

Its not a Montero only in Spain. The US calls them that as well. As far as 4×4 vs light weight, my Toyota Tacoma combines to two and will destroy any non 4×4 in deep mud.As others have mentioned off road tires are a huge help.

Pierce89 wrote:

Andres125sx wrote:

autogyro wrote:Far to much has been evangelised over four wheeled drive being better off road than two wheeled drive.
In soft sand a two wheeled drive beach buggy with baloon tyres and no transmission locks is far better if the weight can be kept low.

Same for mud or soft terrain after heavy rain. I was a hunter for several years as my father has been for his whole life, and it was fun to watch some people into their 4x4 getting trapped on the mud while we could pass with our 2wd private car That was with a Citroen BX around 15-18 years ago with that superb hidraulic suspension, while someone got trapped with a Mitsubisi Montero... sorry, Pajero, in Spain it was called Montero as "Pajero" is a coloquial sinonym of masturbator

Weight, or lack of excessive weight to be more specific, can be a lot more useful than 4WD in many circumstances

Now he owns a Suzuki Jimmy wich is far from best off-track 4x4 (no differential lock), but it is light and don´t need it at all so he can go through very difficult terrain both because of the light weight and short wheelbase, wich is also a big plus. Those BIG SUVs are useless for most off-track situations

Its not a Montero only in Spain. The US calls them that as well. As far as 4×4 vs light weight, my Toyota Tacoma combines to two and will destroy any non 4×4 in deep mud.As others have mentioned off road tires are a huge help.

I guess there are too many spanish speakers in the US to use that impolite name

The Tacoma surely is light for its size, but when talking about light weight I was more in the line of this


It will go through terrain no other car will, and cost a fraction of any other 4wd

sosic2121 wrote:

Andres125sx wrote: Same for mud or soft terrain after heavy rain. I was a hunter for several years as my father has been for his whole life, and it was fun to watch some people into their 4x4 getting trapped on the mud while we could pass with our 2wd private car That was with a Citroen BX around 15-18 years ago with that superb hidraulic suspension, while someone got trapped with a Mitsubisi Montero... sorry, Pajero, in Spain it was called Montero as "Pajero" is a coloquial sinonym of masturbator

Well if doesn't count if you use BX
Best car I have ever driven!

I was too young to remember accurately as I was only 16-17 years old and that was first car I drove, only off-track (no driving licence yet), but my father agree with you, he loved it and still miss it

If there was a modern version with that hidraulic suspension he surely would own one, at least if in same price range

Andres125sx wrote:
Now he owns a Suzuki Jimmy wich is far from best off-track 4x4 (no differential lock), but it is light and don´t need it at all so he can go through very difficult terrain both because of the light weight and short wheelbase, wich is also a big plus. Those BIG SUVs are useless for most off-track situations

Those big grown up SUVs/4x4s are actually pretty good off road. Here's one (the hugely under rated Range Rover Sport) towing a Suzuki through muddy gunk after muddy gunk. Suzuki totally incorrectly tyred, of course, but even so it would have struggled on MTs. https://youtu.be/CkVw9OMaCI4

A grown up SUV/4x4 on road tyres is remarkably capable to as seen here: https://youtu.be/2aBsaYpijlo . A Discovery 4 (LR4) doing nicely on road rubber in pretty slick mud. This one has a locking rear diff, as well as centre diff, which helps of course.

The Range Rover Sport and the Discovery have a multi-plate clutch to lock the centre diff (and rear diff where a locker is fitted). All electronically controlled and remarkably effective.

As mentioned elsewhere, all things being equal, the correct tyres for the job are always the most important thing. Even so, I'd love to see evidence that a BX (or other 2WD car) on any tyre would get through the stuff in these videos. [-o<

The great thing about the grown up 4x4s is that you can cover vast distances in total comfort and have real off road ability thrown in. We did a 2200 mile round trip to Spain earlier this year for a couple of days off road fun at the 2016 Land Rover Party. Easy long distances and easy off road ability too in my Range Rover Sport. =D>

Just_a_fan wrote:Even so, I'd love to see evidence that a BX (or other 2WD car) on any tyre would get through the stuff in these videos. [-o<

For the roads of the video you posted weight is not that important, but if you have to go off-road like the situation I was talking about, then weight is crucial. Take a look to the video I posted of the Panda, situation was pretty similar to that part were the Discovery get trapped into the mud. The road had a very very big pool and we all had to go off-road to go around the pool. It was a beautiful meadow with no tracks and no sign of mud. The BX went without noticing, then a Montero came and got trapped into the mud. To me it was mindblowing because I was driving the BX, with 16 years and no experience Ok my father was constantly saying to me what to do, but I guess you can get my feeling, I (a teenager) passed with a BX while a beautiful and off-road esque Montero with a proud owner with many years experience got trapped

On soft terrain traction or even tires are irrelevant, it´s weight what counts, if the car dig into the terrain and the floor stand on it, the rest does not matter, you´ll get trapped. Like that Discovery on the video I linked

Basically there are two basic scenarios for off-road where requirements are completely different, slippery but firm terrain where tires and differential lock are basic, or soft mud/sand where weight is a lot more important than anything else. The video you linked is a route on the first type, while I was refering to the later


The definite weapon, IMHO, would be a Jimmy with differential lock and proper tires. That will go through anything

Andres125sx wrote:The definite weapon, IMHO, would be a Jimmy with differential lock and proper tires. That will go through anything

Or maybe BX 4x4
That car was very light for it's size.
I think most variants were under 1000kg.