Vac hubs question

At the meet up and in four wheel drive, I noticed that my back wheels tended to loose grip, but not sure that the front wheels did and since I had new A/T tyres on the rear and part worn A/Ts on the front, it's got me thinking, were the front wheels been driven?

My Gen 3 went in to 4 WD and low range okay, there was a clunk and the lights on the dash all looked okay, so the transfer box and vacuum must be working, but is it possible that the free wheeling hubs were not engaging?  Is this common, everything looks okay, but the hubs don't engage?

I did both Kingpin bearings a few months ago, the hubs looked okay, but I didn't check that the splined collar moved, perhaps they are stuck?  I am certain I put the vac hoses on the right way, I even marked one of them before taking it off.

I am thinking the way to check it is jack up the front end, with the car in gear and 2 WD selected, the front wheels will just rotate, put it in 4 WD and they won't?  Or I could put the car on four axle stands and see what happens in 2 or 4 WD.

I would appreciate your advice?

Ta

Robin

To test: put in 4wd (engine running) and jack up one front wheel. If you can rotate it by hand, there is something wrong with the 4wd system. If it will only rock back and forwards a little, 4wd is working.


The light stays green if the vacuum lines are not leaking, it can't tell if there is a blocked pipe, or if the pipes are swapped over.

wrote:

To test: put in 4wd (engine running) and jack up one front wheel. If you can rotate it by hand, there is something wrong with the 4wd system. If it will only rock back and forwards a little, 4wd is working.


The light stays green if the vacuum lines are not leaking, it can't tell if there is a blocked pipe, or if the pipes are swapped over.
 

That's great, thanks for the help.  I know the 4WD was working last winter, so unless something went wrong when I did the Kingpin bearings it is probably okay, but I will get the jack out tomorrow morning and check the operation of the hubs as you have suggested.

I hadn't thought about a blocked pipe, but that makes sense.

Robin

If you open the door and listen, the hubs go "clickclick" one way, and "clackclack" the other. A single sound means one isn't moving.

If the hubs are locking but the wheel turns by hand in 4wd, most likely a CV joint broken (usually causes notchy or restricted steering in 2wd as well), or could be the diff.

I think there is a "How to" on the 4wd system on here.

The green light comes on steady if there is a vacuum in the "lock the hubs" line when the controller sets them into lock mode- (flashing means a leak) Being Japanese, if there is a vacuum then there is virtual certainty that the hubs moved )

 

Hubs tested and both working correctly, as is the front diff.

I guess the front wheels were slipping as well, but been part worn I didn’t notice when they let go or bit as much as the back.

It was when I was going up hill, so probably more load on the rear as well.

Thanks for the advice.

Robin