The latest is that Hyundia / Kia in Spain (I think) are producing an aftermarket kit which will allow press button "locking" into 50/50 spilt in both high and low ratio.
The "problem" appears to be that at low revs/power input such as down hill on engine breaking the TOD "may" not be transferring any drive to the front wheels, it certainly "isn't" in high ratio and "may not" be in low ratio (there's all sorts of arguments about that). Anyway, this kit will overcome any potential problem.
In New Zealand they are keeping looking at the problem and I've been promised a kit should they prove successful and be available.
In my experience however it would certainly appear that in Low ratio there is a permanent 50/50 split (that's in my 2005 (2006 in USA) 2.5 CRDi 5 speed auto).
So, if you're doing "traction dependant" off road work in your Sorento, particularly at low power setting, eg down hill, it pays to be in low ratio, though you usually would be anyway !!!!!!
This is NORMAL operation of the TOD. The TOD name is a Borg Warner design also utilized within several Isuzu models (VehiCross, Trooper, Rodeo, Axiom).
The way it works within "Auto" mode is a rear wheel drive until the computer realizes wheel slippage and then it transfers more power to the front in a proportional amount from 0-50% in the front axle. This ONLY is within High range in Auto mode/TOD.
What determines the amount of torque applied to the front axle is:
rear wheel slippage
loss of traction in front
The front differential is open and makes whichever tire has the least resistant get the power. i.e.: a tire lifted off the ground will spin.
The rear differential has a LSD (Limited Slip Differential) or Posi-Traction. It works somewhat as a locker, whichhelps to spin both wheels simultaneously, but that is dependant upon the clutch packs inside the LSD unit and how tight they are. The tighter the better results you will experience.
When switched to Low, this changes the transfer case to low range and thereby a 50-50 split front-rear.
HTH. I have hade extensive experience in playing with the TOD in the Sorento and in the Isuzu in the dirt, mud, snow, rocks, ice, etc.
That pretty much is tech data supporting what I was saying...
The Sorento has been the best snow/ice vehicle I have ever owned. During the blizzard of '03 here in Denver, we were able to drive through 2-2.5' of snow, before I decided to park the Sorento in favor of the lifted Amigo, which handled the 3-4' depths without issue.
So, in a decent, if would make sense that the TOD would not switch any power up front. If you are in a situation where you need the front driving as well, you had better be in 4-Low. The system really isnt that difficult to get accustomed to and once you are, it works great! On the road the TOD is the best of both worlds... rear wheel drive until the front are needed and it transfers power automatically. When off road, 4 low is the answer.
My advice.. practice with it and learn the mannerisms... Good luck!
IMHO, I wouldnt touch the upgrade with a 10' pole...
Yep it's been discussed a lot BUT there's no real answer yet. For what it's worth I would think that the TOD system is great as it works without driver input, ans if the after market kit then allowed you to "set" the torque split to 50/50 and override the automatic system, you'd have all the bases covered. In the meantime I agree completely with whoever said "make sure you're in low ratio when you're on steep downhill, offroad work".
I think the thing that's annoying some people (myself included) is that nobody at Kia pointed out (or maybe even knew !!) that you could end up without 4WD when downhill and perhaps expecting to have that added stability.
So, I'm happy as a little pig in poo with my system but would "like" the added ability to choose a 50/50 split in high ratio for light off-road use.
Axanthas Where do you live in Greece?
I am from Kalamata and i have already mentioned the problem to Kia in Athens but they did not even bother to answer to me.
Anyway i have spoken to the electrician in Kia representative of Kalamata who understood the problem,i arranged to give him all the evidence and he will ask them.
I have already written to www.off-road.gr but only one contacted me.
Are the guy from Thessaloniki who phoned to me?
Please let me know.
Yesterday i tested my sorento CRDI Nov 04. No matter what mode you are (LOW or HI) rear axis engagement occurs only when pedal is pressed.This is for sure,i tested many times ( pull up a front wheel).Of course we must note that we test TOD behaviour under no traction loss situations.
What is shown on the video and the similar experience i had could be a result of the TOD behaviour but also caused by inapropriate tires or bad weight balance.
I don't know.Could someone with off-road experience exlain why sorento would have a different behaviour if it was 50-50 locked (going down with 1st LOW on a muddy road with no acceleration al all)?
If it's locked into a 50/50 split (that IS 4 wheel drive) then all the traction is "shared" by the four wheels, so is the engine braking. Therefore the front wheels as well as the rear will be slowed down by the engine braking so increasing the traction (if they are just "freewheeling" they have no real traction other thanthat provided by the amount of weight holding them down). Otherwise why have 4 wheel drive at all ? if it didn't work this way a 4WD vehicle would be no better off down hill than a 2WD one, do you get the idea ?
Interestingly you say yours tested as needing power on to engage the front wheels, the tests that KiaMech did for me on a 2005 model showed it was engaged at idle in low ratio (he had all four wheels off the ground). Frankly I think this is the whole argument, is it or is it not totally 50/50 in low ratio, if it is there's no problem, if it's not it's potentially dangerous. The thing that the "kit" being talked about would do is ELIMINATE the question and allow absolute 4WD in both High and Low ratios at the press of a button.
As I understand it the TOD system (simply put) outputs a voltage that alters the ratio of rear wheel drive to four wheel drive, at zero volts output it's 100% rear wheel drive only, at 12 volts output it's 50/50 or 100% four wheel drive. I have been told that in low ratio it should be continually outputting 12 v regardless of throttle position and axle speeds, the question is whether this is true or not ?
It would "appear" that the Spanish guys "believe" they have proved it does not continually output 12 volts and that's what the "fix" is to overcome.
Hope that sheds some light, it's not easy to get your head around, but that's the conclusions I've come to.
Derek you are right for everything that you have already written in your post.
If you read the experiment that the spanish did ,putting an oscilloscope(the voltage is not DC 12V,but pulse width modulated) and measuring the output voltage from the TOD Unit then you will see it is not 12 v,even in low mode when not using accelerator.
Anyway we have written a lot ,it is 100% proven that the TOD is not programmed well,that is why Spanish Hyundai accepted the problem and made a manual blockade like the circuit that is designed from people in www.clubterracan.net.
The day before yesterday i went to my local electrician (fixes every kind of car),and he told me that he met once a similar problem in a Ford.
He will manufacture the blockade according to the circuit diagram i gave him and will put it in my Sorento next month.
I am fed up with Kia.
They know the problem but they do nothing.
They were forced in Spain because a lot of Spanish made severe complaints.
What i did is that i pulled one front rear using a jack. With a piece of wood i gradually pressed the pedal. Engine in ACC ON. What i notice is first that TOD behaviour was the same(LOW and HIGH) in terms of engange-disengage the front axis. I couldnt measure the engagement ratio of course. With no or little pressure on the pedal front wheel can be easily turned by hand. Up to a point front wheel was blocked.
That means that in all cases, no acceleration no 4wheel mode.
What i am going to do,waiting for a permanent solution, is to use snow chains in heavy mud and ice conditions.
After several months awaiting , Hyundai-Spain is beginning to install a lock for the TOD transfer case. As probably you know there is a problem with the TOD transfer case in descents with low grip since the torque transfer to the front axle only occur when you put your foot on the accelerator. Unlike the commonly believed, the Low range position does not lock the torque to a 50/50 proportion.
So Spanish users of Terrancan had been talking with Hyundai Spain in order to solve this problem. Fortunately, person in charge of Hyundai has deal this matter in a very professional way and now we have got our manual lock. You can follow this link to see photos oh the lock and the installation process. http://www.clubterracan.net/modules/newbb/..._id=622&forum=2
The bad news is that Hyundai does not recognize the problem outside Spain ….
Many thanks for your most complete information, I believe you've finally provided the answer I've been seeking. It's quite difficult working from Spanish to English etc but I believe I've got the basics now. I intend to confront Kia New Zealand with this and see what the reaction is.
I sent a very "angry" e-mail to KIA GREECE. They answer to me and they asked all the relevant links. I think is a good step. I would like some help from all of you because it could be the beggining of a global solution.
Panayiotis i send you a personal mail to yahoo, please contact me because we must cooperate in this
I agree, "IF" this is absolutely accurate then it's a safety matter and almost warrants a recall in my view. Certainly in New Zealand they are being sold on the basis of being a top line off road 4WD and we are told that the split is 50/50 ALL THE TIME (regardless of throttle settings) in Low ratio.
My only hesitation is the possibility that somebodies "got it wrong" but Hyundia's agreement to fit the "fix kit" seems to eliminate that, it appears that they have accepted there IS a problem.
Frankly that "problem" could be fatal to the unwary and that means (in my opinion) that it MUST be fixed, quickly and on all effected vehicles.