Transfer case shifts hard

[sealbee]

Hi, I've posted this at other forums, with no luck, but here goes.
I have a 98 Sportage, 4wd and in order to shift it into 4wd you have to be almost stopped. Once you get it in you can shift in and out easily for a while. After driveing for 20 to 30 minutes in 2wd, you have to almost stop to put it back into 4wd again. I've taken it in to the dealer, 3 times, and they say it's normal. I've changed the gear lube to a synthetic as thin as I can go. I don't believe it's "normal". I've been checking the internet and either it's so normal nobody mentions it, or, it's so unusual, nobody but me has had this problem. Any ideas? Is there an adjustment or something? Do I need a new transfer case?
Thanks in advance!

[LMP]

Do you have the original vacuum hubs or Warn cam operated auto-mechanical?

My suspicion s you have the cam operated autos....and indeed, this "hard shift" would be "consequential" then , but risky practice . Here is why:

With vacuum hubs, the transfer case shifter first synchronizes the Tcase gears, driving shaft, differential and shaft to wheels and when shifter reaches the end of travel, all components are rotating at wheel speed and only then the end switch activates (4x4 sign ) the vacuum solenoid which then applies vacuum to wheel hubs : wheel hubs engage at the end of process once everything ‘s turning and synchronized. That is why engagement « on the fly » is possible and normal.

With cam hubs, the hubs are engaged by the rotation of half shafts : 1/3 of a turn and they « click » in. From stand stil, this is smooth and one can hear hte hubs "click click" within 5 feet. If done as the car is running, the shifter begins being pushed towards 4 wheel drive, and at that time, the shafts and differential are barely turning, so within 1/3 of turn, hubs engage and on a sudden they pick up all the driving train and t-case and bang it to running speed : that is what you call « hard shift » and that is why this must occur only at 0 speed.

Once the cam hubs are engaged by rotation, continuous rotation will keep them ON, even if you shift back to 2wd and this is why to turn the hubs off, you generally have to stop, back-up 1/3 turn.. lets say 4-5 feet – and one can hear them « click-click » OFF.

Similarly, if you shift from 4x4 to 2wd on the fly, the hubs are still engaged so you could generally shift back to 4x4 on the fly… . However, this condition is not stable nor 100% positive and bumps and specially turning sharp turns can change relative wheel to shaft motion and they can disengage when not driven…Bottom line, cam hubs engagement should NEVER be tried « on the fly » as this practice will eventually destroy them.

[sealbee]

Thanks for answering, I'm sure I have vacuum hubs. I bought the car last year with 40k miles and the vacuum hubs were bad so the dealer replaced them with whatever they use now since they no longer make the original parts.

In fact, they leaked and had to be fixed last week. 3 days over warranty....

So what do I need to change so my wife does not have to stop to put it into 4wd? I've owned Fords, Chevy's and Toyota's that will shift on the fly easily at 40mph or less. That what I thought I would get with this car....

[LMP]

Originally Posted by sealbee

...I'm sure I have vacuum hubs...the vacuum hubs were bad so the dealer replaced them with whatever they use now....

so...what you have now is most probably cam hubs..not vacuum....I do not know where they would have got vacuum hubs...and you have to stop...Remove hub cap and take a look and compare to pictures. What you have described totally fits the cam type operation.

THe alternative, if you really NEED to switch on the fly, is to install manuals. Then you lock them ON...and the T_case will make it 4 or 2 WD but the shafts and differential will turn all the time with the mileage penalty. And the drag from front wheels in 2WD when starting cold and road is kind of slippery is a risk to controllability.
Warn manuals: # 60247
http://www.amazon.com/Warn-60247-Sta.../dp/B000CQBM5Y
By the way, I've tried to keep the vacuum as long as I coud because their operation - when they worked - was extremely convenient and seamless. But cold temperature in Canada made them totally unreliable and at the time, KIA would change them for free. SO I got the cam type and got used to manage their operation so they last.

[sealbee]

Thanks for all the help and good info! I'll check into getting the warn hubs and what I've got to do to put them in...