Locking the front hubs

[bobjtls]

This is a follow up question to an earlier one. The answers previosly provided have brought more questions to my mind. Caveat, I am a newbie D22 Navara owner and know little about 4Wd'ing

1. What does locking the front hubs actually do? Lock the front wheels to what?
2. A previous answer indicated I can go into 4L with unlocked front hubs for pulling a boat trailer. So,
- what happens if I run locked hubs in 2wd mode? Why might I have to do this or what problems may it cause?
- when might I have to run with free hubs in 4H/4L mode?
- how long could I run in 4H/4L mode with free hubs?
3. If the answer, as I suspect, to 1 is, lock them to the front dif, and if I run on tarmac in 4wd mode causes diff windup, is locking the front wheels functionaly similar to diff lockers, at least for the front diff?
4. I have read that the D22 4Wd is an occasional 4WD system. Does this mean I can not run all day in 4WD mode on dirt? If not then what is the sweet spot in hours?

If someone knows of a web page describing this type of 4Wd system, could they let me know as I would like to know more.

Bobj

 

[jaymac90210]

This is a follow up question to an earlier one. The answers previosly provided have brought more questions to my mind. Caveat, I am a newbie D22 Navara owner and know little about 4Wd'ing

1. What does locking the front hubs actually do? Lock the front wheels to what?
2. A previous answer indicated I can go into 4L with unlocked front hubs for pulling a boat trailer. So,
- what happens if I run locked hubs in 2wd mode? Why might I have to do this or what problems may it cause?
- when might I have to run with free hubs in 4H/4L mode?
- how long could I run in 4H/4L mode with free hubs?
3. If the answer, as I suspect, to 1 is, lock them to the front dif, and if I run on tarmac in 4wd mode causes diff windup, is locking the front wheels functionaly similar to diff lockers, at least for the front diff?
4. I have read that the D22 4Wd is an occasional 4WD system. Does this mean I can not run all day in 4WD mode on dirt? If not then what is the sweet spot in hours?

If someone knows of a web page describing this type of 4Wd system, could they let me know as I would like to know more.

Bobj

Google about it mate, or look on the patrol forum or 4x4 earths forum

 

[scooba_285]

ill give this one a crack, locking the hubs is when you want to use 4wd, it locks the hubs into the cv's which the diffs turn,providing drive to the front wheels, if you dont lock them in and use 4wd it will drive the front diff and cv's but no power will reach the front wheels, you can have the hubs locked in when in 2wd but its really only for when u think your going to have to engage 4wd down the track, part time 4wd means its 2wd until u want to use 4wd, full time 4wd is like a Subaru's all wheel drive system (its always 4wd), theres no limit to how much you can use 4wd, the hub locks and diff lock are completely different, dont ever use 4wd with out the diffs locked in and dont use 4wd on tarmac or really hard surfaces unless u really have too, i think i covered it all

also having the hubs locked in in 2wd is recommended if you dont use 4wd very often, i think the owners manual says do it once a month but dont go over 80kph, its to get the front diff oil turning over

 

[bods]

Basically it's called a part time 4wd system. In very short terms that means to actually use 4wd you have to lock the front hubs. Think of the rear diff, you put the transmission in gear, this drives the driveshaft, which drives the diff, which drives the wheels.

On the front, as you have indicated in your post, locking the hubs locks the front wheels to the diff, which is then turned over by the driveshaft when you put the transfer case in 4wd. This is not the same as having a diff locker, the difference being, if it's an "open centre" diff, as they are in the front of d22's, when you lose traction one wheel will spin, resulting in you not moving anywhere. What a diff locker does is makes both wheels spin at the same speed whether they have traction or not. The result of this on the front wheels when in 4wd is the steering will be heavier and return to centre easier.

Yes, as you have said, driving in 4wd with the hubs locked on hard surfaces will cause transmission wind up. What 4wd does is makes the front and rear driveshafts spin at the same speed. This means when you try and turn a corner the front and rear diffs will try and spin at different speeds, obviously this isn't good for the transfer case chain which will stretch and may even break if it is done often.

As for using 4wd for long periods, that's fine. It's only called part time because when the hubs are unlocked and the transfer case is in 2wd the front driveshaft and diff aren't turning over. That's why Nissan recommend locking the hubs for approx 16km every month if you don't use 4wd very often. This is to make sure the oil is splashed around the gears and seals to stop them drying out.

As for why you'd want to use low range with the hubs unlocked, if you need to manoeuvre a trailer at low speed, instead of riding the clutch you can stick the transfer case in low range and use the lower gearing to move slowly without having to keep riding the clutch. I wouldn't recommend running like this for a long distance though and if you go by Nissan's recommendation you shouldn't do it at all, but it is OK for small amounts at a time.

Hopefully that helps a bit.

 

[bobjtls]

Thanks for your reply bods, that makes things clearer. I have also found http://www.4x4abc.com/4WD101/hubs.html. This is a simple understandable explanation of what locking the hubs does.

I am learning more and more every day and feel more comfortable 4wd'ing

Thanks to all

Bobj