transfer case grind - will not engage on-the-fly

[marmotan]

Hi all. When traveling along at a speed greater than 30 MPH, in 2-wheel drive, the 4x4 shifter (transfer case lever) will grind and chatter violently as I pull back to engage 4-wheel drive. It refuses to engage until I drop below 30 MPH. I just had the fluid changed, with no results. Time for a new t-case? The 4runner has 130,000 miles on it.

 

[Mr. Leary]

Pull it harder and faster. What is happening is the gear to engage the front driveshaft is not catching the chain completely. There is likely nothing wrong with the transfer case. Just give it a little more of a tug and it should engage completely. It would also be a good idea to get in a parking lot and shift it through 2hi, 4hi, and 4lo, just to make sure it is working correctly. If problems persist, change the fluid. There really isn't a whole lot that can go wrong with these transfer cases, they either work or they don't.

 

[marmotan]

Thanks - so you've had this happen to you too? My shift-on-the-fly was working fine earlier in the winter, and now it's protesting - it just happened overnight. The grinding is so loud and the chattering so strong that it's painful to hold onto the shift lever. If you are sure that it won't break anything I suppose I will grab it with both hands and just wrench on it.

 

[theizzardking]

If you are sure that it won't break anything I suppose I will grab it with both hands and just wrench on it.

wrenching on anything like that is never good, you could seriously break something by being like that with it, if the gear teeth aren't meshing right
or not enough fluids, you will break it.

it's best to find out whats going on before you start beating on things.

how does the shifter move when the trans is in neutral not moving?

how about going very slowly?

have you check all related fluids?



honestly i don't know whats wrong with it of the top of my head, but
i can tell you with any mechanical if it's not working smashing it and wrenching on it is not going to fix the problem.
and if it does you have just shortened the life of the equipment by as much as 50%.

 

[theizzardking]

Pull it harder and faster. What is happening is the gear to engage the front driveshaft is not catching the chain completely. There is likely nothing wrong with the transfer case. Just give it a little more of a tug and it should engage completely. It would also be a good idea to get in a parking lot and shift it through 2hi, 4hi, and 4lo, just to make sure it is working correctly. If problems persist, change the fluid. There really isn't a whole lot that can go wrong with these transfer cases, they either work or they don't.

ok so if it's a chain driven trans case then it could be a bad tensioner,
and pulling harder and fast just gives more of a chance to snap the chain if it's not catching at the right place.

seriously "just do it harder and faster" just breaks sh*t,
i will conceded though it maybe time to just roll it till it does break, i just don't like handing out advise that may speed that process along.

just be deliberate with your movements and how you work on things and you should never screw yourself so bad you're SOL.

not being a jerk but am i wrong on this? ever since i was a kid and through training to be an engineer, you learned that a big f*cking mallet doesn't solve everything.

the other advice is good, but please don't just start beating on crap trying to get it to work ACTUALLY FIX IT you know what i'm saying here.....

 

[marmotan]

I hear ya, I'm not too comfortable wrenching on it either. I think Mr. Leary was trying to say that sometimes you need to be quick and powerful with the shifting (in his words, "a little more of a tug"). I've already experimented with different levels of pulling strength, at varying speeds, on a variety of surfaces, etc. It's that magical 30 MPH that I can't exceed when I want to shift into 4-Hi. My mechanic changed out the fluid in all the drivetrain boxes, so I guess the next step is to have him open it up on the bench. I decided to pose the question to the forum first, to see if anyone else had the same problem and possibly a less expensive solution...

 

[theizzardking]

I hear ya, I'm not too comfortable wrenching on it either. I think Mr. Leary was trying to say that sometimes you need to be quick and powerful with the shifting (in his words, "a little more of a tug"). I've already experimented with different levels of pulling strength, at varying speeds, on a variety of surfaces, etc. It's that magical 30 MPH that I can't exceed when I want to shift into 4-Hi. My mechanic changed out the fluid in all the drivetrain boxes, so I guess the next step is to have him open it up on the bench. I decided to pose the question to the forum first, to see if anyone else had the same problem and possibly a less expensive solution...

haha, what about just not shifting at 30 mph? j/k

i've had the same problems on other transfer cases,mostly the np231 and np242, and that was always a either a fluid problem or a ....gear selector tab problem... not sure of the actual part name but it's a little bullet shaped
alum piece that get's pushed into a slot by spring when you move the gear selector, what happens is it gets worn down over time and stops going in all the way and will pop out of gear if worn to badly.

i'd hate to tell you to pull it with out trying a few other things to make sure there is no other possible solution.

 

[Mr. Leary]

I hear ya, I'm not too comfortable wrenching on it either. I think Mr. Leary was trying to say that sometimes you need to be quick and powerful with the shifting (in his words, "a little more of a tug"). I've already experimented with different levels of pulling strength, at varying speeds, on a variety of surfaces, etc. It's that magical 30 MPH that I can't exceed when I want to shift into 4-Hi. My mechanic changed out the fluid in all the drivetrain boxes, so I guess the next step is to have him open it up on the bench. I decided to pose the question to the forum first, to see if anyone else had the same problem and possibly a less expensive solution...

Sorry if I was a little vague. thelizzardking is correct. To clarify, do not yank on it with both hands, nor should you kick, punch, or speak meanly to it! I have just found that with mine, it takes a little more persuasion when you are moving than it does when you are not (i.e. neutral vs under stress in drive). If you are pulling the lever slowly, it will bounce off because it is not catching. When I took one apart a while back, there was not a clear "place" for it to catch the chain. It should be able to engage anywhere in its rotation, hence shift otf, because the whole assembly catches, not just one part.

There should be nothing magical about 30mph. There is something magical about 50mph or so... don't shift into 4hi when you are driving fast for risk of damage to the drivetrain (as per the owner's manual).

Inspect for leaks. As always, unlubricated parts can cause big problems.

Make sure you can engage the transfer case in all positions while in neutral. While driving slowly try 4hi (not 4lo), and then try it again with a faster flick at speed. The fact that you are hearing the grinding noise means that it is trying to engage.

Personally, I try not to shift while moving when it is avoidable, partly because of the uncomfortable noise it can make if it doesn't engage. I don't think what you are experiencing is anything new. Mine has done the same thing, and my transfer case still shows few signs of wear at 186k on the ticker.

 

[brian2sun]

Don't know if this will help, but it can't hurt. Mine won't shift into 4HI if I'm on the gas at all. It will grind like crazy if I try, but the second I let off the gas and let it coast it'll go in no problem and then the 4x4 light won't come on until I start giving it gas again (or roll about 500 ft). Mine has always done this ever since I bought it in '01 and my '95 2nd gen did it before that.

And to get it back in 2WD, I can move the shifter from 4HI to 2HI while on the gas, but the 4x4 light will stay on until I let off the gas and coast for a few feet.

 

[Mr. Leary]

Don't know if this will help, but it can't hurt. Mine won't shift into 4HI if I'm on the gas at all. It will grind like crazy if I try, but the second I let off the gas and let it coast it'll go in no problem and then the 4x4 light won't come on until I start giving it gas again (or roll about 500 ft). Mine has always done this ever since I bought it in '01 and my '95 2nd gen did it before that.

And to get it back in 2WD, I can move the shifter from 4HI to 2HI while on the gas, but the 4x4 light will stay on until I let off the gas and coast for a few feet.

Forgot that one :iagree:... you should not be shifting while accelerating... your front drivetrain is being pulled along by the rotation of the wheels. when you let off the gas, so is your rear. Assuming you don't have drastically larger tires or different gearing in the front or rear, things should mesh up nicely because everything will be rotating at the same speed. When you shift, there will be a split second window when things can get out of sync, and hitting the gas can exacerbate this problem.

 

[Mr. Leary]

haha, what about just not shifting at 30 mph? j/k

(I know, right?)

 

[marmotan]

hmm, good thoughts - so what i'm hearing is that it is OK to be in (tranny) gear during a shift into 4HI, but it is NOT OK to be accelerating. would it help to to shift the tranny into N and then engage 4HI?

 

[Mr. Leary]

hmm, good thoughts - so what i'm hearing is that it is OK to be in (tranny) gear during a shift into 4HI, but it is NOT OK to be accelerating. would it help to to shift the tranny into N and then engage 4HI?

If I have to shift while moving, I do this, but shifting into N does not mean that everything will not be spinning, just that it is not being pushed by the engine. Can't hurt anything. Give it a try.

 

[Pikeman]

With my experience the only time I have to shift into N is going from 4Hi-4Lo and less then 5mph. while the manual says it is possible to travel up to 50mph in 4 hi I am not sure why you would want to shift into 4wd at that speed or even 30mph. If the road conditions are loose enough to merit 4wd then it is also not safe to be traveling at a high rate of speed. See Brian2Suns rant about flat landers driving to fast for the conditions screwing up the mtn roads. Sorry but that is my 2 cents.

 

[marmotan]

thanks Pikeman, but i'm not offroading at high speed. i commute on I-90 in Montana, where during the winter the road surface is frequently snowy/icy one minute and dry the next. hence the necessity of shifting in and out of 4HI frequently while doing 50-60 MPH. do you have any t-case advice you could share?

 

[Pikeman]

OK you asked if shifting into Neutral would help and I replied with the only time you should have to shift into N would be to go into 4 Lo (some advice). Now on my way home from work I went ahead and tried shifting in and out of 4wd at various speeds since it was straightline even though good traction. 30 mph no issues, 40mph was good but 50mph no go. So my other bit of advice for your T-case is that it was not filled completely and a low fluid condition can cause the problem. I hope that is the extent of the problem and that it is not a shaft bearing which is another possibility. Best of luck with finding a solution.

 

[Mr. Leary]

thanks Pikeman, but i'm not offroading at high speed. i commute on I-90 in Montana, where during the winter the road surface is frequently snowy/icy one minute and dry the next. hence the necessity of shifting in and out of 4HI frequently while doing 50-60 MPH. do you have any t-case advice you could share?

If you are going 50-60mph, I don't think you should be putting it in 4wd at all.

 

[Azh0059]

Did this every got result?