pizzabob

Hello, guys -- I have a '96 4Runner, SR5, V6 3.4L, 4WD, manual transmission. As described in a previous thread, I failed to observe an oil leak which resulted in my transfer locking up. I have gotten about 60-70K miles more out of the old transfer case, but finally the rear output bearing wore to the point that you could wiggle the flange up and down, and the time has come to change it out.

I bought a used transfer and just finished installing it yesterday. (I did a clutch overhaul while I was at it -- why not?) Everything works flawlessly with the new transfer except for one thing.

If you're moving faster than about 2 mph, attempting to shift from H2 to H4 results in a loud grinding noise, about the same as you'd get trying to shift into reverse at 60 mph. It shifts into 4WD perfectly if the vehicle is stationary.

Any idea what might be the problem, maybe something with a synchro mechanism or some such? All my previous 4Runner transfers allowed shifting into 4WD while in motion. They usually recommended slowing to 50 mph or lower. I never had one that required essentially a complete stop to permit such a shift. If I have to, I can live with this, but am wondering what's up.

Thanks kindly!

MudHippy

Umm...you can only shift-on-the-fly into 4WD if you already have the hubs locked or you have ADD(which automatically locks/unlocks the differential/side gear shaft instead). So that the front driveshaft is already spinning at close to the speed of the rear driveshaft when you do. Then the transfer case can easily synchronize the speed of them both.

So if it isn't the hubs, then it's something not functioning with ADD system. Because then the front driveshaft wouldn't be spinning. It's not the transfer case, unless the synchro is gone/the front driveshaft is spinning.

pizzabob

Thanks, MudHippy, that makes sense. Hadn't considered that issue at all.

Now that I think of it, the replacement transfer had a slightly different 4WD switch configuration than my old one. Further, there was an electrical connector near the front drive shaft hookup that was not on my old one -- and nothing is connected to it as a result.

I guess I need to investigate these ball switches and connectors a little bit. I was certainly able to shift into 4WD on the fly before doing the switch.

Sure appreciate the help -- this forum is awesome.

Nelsonmd

Are you sure you got the right transfer case? You need to use the exact same thing you had before; it sounds like you may have gotten the wrong one. Read this to make sure.

http://www.toyota-4runner.org/3rd-ge...tml#post669885

MudHippy

No problem. Glad to help.

Here's the FSM for reference.
http://www.ncttora.com/fsm/1996/96_r...searchable.pdf

DeathCougar

iTrader: (23)

Close, but incorrect.

On vehicles with ADD, the transfer case switches into 4WD before the diff does. This is accomplished via syncros in the TCase. You should be able to put the Tcase into 4x4 regardless of what the front end is doing. If you need proof of this, drive a 4x4 truck with ADD while turning and trying to put it into 4x4. The tcase will go right in, but the front diff (and subsequently the 4WD indicator light) won't immeadietly engage.

Sounds like he put the shifter in backwards, and is trying to engage the low range rail instead of the 4WD rail.

PizzaBob: Try taking your shifter out and spinning it around. This is a very common mistake that people make. It will work just fine until you try to shift it. Try this before messing with your ADD system

MudHippy

I do know how my 88 VF1A works without ADD. I can't shift-on-the-fly unless the hubs are already locked and/or the front driveshaft is spinning at near the same speed of the rear driveshaft. It will act exactly in the manner he described if the hubs aren't locked/both the fr/rr driveshafts aren't spinning at close to the same speed(regardless of how useless doing so would be to begin with). I know my VF1A has a synchro in it too, because I've disassembled it several times now. And it's always behaved liked that, so I believe it's functioning correctly. I also know it only has one, and that's why you have to come to a complete stop when you shift from 4H to 4L(because there's no synchro to handle the difference in input/output shaft speeds associated with it).

I was not aware of how that could be different on any other transfer case. My mind hurts just trying to think about it. Because I understand how standard synchros work.

Here's an analogy: You would get the same grinding and/or not wanting to go in gear from your transmission(which is full of them) if you tried shifting it without disengaging the clutch. Which can be done...BUT the input shaft rpm speed needs to be close to output shaft rpm speed to synchro-mesh gears easily. Because the clutch disengaging is what releases the front input shaft from the crankshaft/flywheel, thus minimizing any resistance to turning it, allowing it's rotational speed to be changed relatively easier. So it's pretty tricky to do without a bunch of grinding and binding trying to find the perfect input shaft rpm for each gear/output shaft speed.

The similarity between them being that the synchro in the t-case is for synchronizing the rotational speeds of the fr/rr driveshafts, instead of the input/output shafts. And it has no clutch. So, if one driveshaft is rotating a certain speed, the other needs to be rotating near to that speed too. Or they won't synchronize easily(or at all).

Like I said, that's how mine(non-ADD) works atleast.

My understanding of the ADD system was that:

A) The synchro for the front driveshaft was in the transfer case. And the clutch that engages the front driveshaft is in the axle housing, essentially. Because if you were to activate that ADD clutch mechanism, regardless of putting the transfer case into 4WD, the front driveshaft would spin if the wheels were spinning too.

B) The transfer case 4WD indicator switch is triggered by moving the shifter from 2H to 4H, AND/OR by the action of it shifting fully into/out of 4WD(synchronizing the speeds of the fr/rr driveshafts). And the ADD indicator switch is triggered by the engagement of the ADD clutch mechanism on the axle housing.

C) Both switches need to be closed/switched on before the 4WD indicator light will illuminate.

D) What that means is either one could be switched on first. It doesn't matter as long as they both are eventually.

E) This all must have some deeper meaning then. What am I missing here?

F) AHA! I figured it out!

It boils down to the braking force required by the synchro to synchronize the speeds of the fr/rr driveshafts. And that is due to the fact that the clutch mechanism required to minimize said force is only found on an ADD system.

With ADD, the synchro has to get the front driveshaft spinning up to speed with the rear. And not much else, since the clutch mechanism isn't yet engaged and the "differential" is still "disconnected". No biggie to get just that much turning up to speed in a hurry. There's relatively little turning resistance to overcome.

Without ADD, the synchro has a lot more to deal with. It also has to get the "differential" suddenenly spinning too, since it's always "connected", as well as both CV halfshafts. Not gonna happen without some difficulty, if at all. Why? WAY more turning resistance relatively. The fact that there is no clutch, like there is with ADD, means it's the same thing as if the clutch were always engaged on an ADD system. So it's just like trying to shift the transmission without disengaging the clutch, too much frictional resistance to turning for the synchro to effectively do it's job.

Well..the ADD system finally makes sense to me. Some now I'm happy.

Thanks for pointing me in the right direction there DC! I just couldn't quite grasp the concept until I figured/found out where the clutch was. Sure enough, it's there!

DeathCougar

iTrader: (23)

You are still missing it Mudhippy.

There is no clutch in the transfer case, nor is there one in the diff. ADD systems use chain driven Tcases with syncros. Gear driven cases, such is the case with your 88 VF1A, don't use a syncro like that. If you lock the hubs, you can put your truck into 4WD at any speed. Thats because the front and rear ourput shafts would then be spinning at the same speed. If you don't have your hubs locked, you cannot put your truck (meaning you with the VF1A gear driven case) in 4WD while moving.

On an ADD Chain driven transfer case, that is irrelevant because syncros allow it to go into 4WD while driving. You are however correct about the rolling resistance of the driveline, given that there is almost none. Even if the diff engaged at the same time as the case it wouldn't matter, the key is the system engages the Tcase first, so it can match the front diff input speed to the output speed.

FYI, the 4WD indicator light doesn't come on until the diff locks the ADD collar into place.

MudHippy

Oh I didn't miss anything, I get it. No question in my mind on that. Now I'm questioning whether you fully do though. But that's probably just some minor miscommunication. Let me try and clarify:

1. I have an 88 3VZE with an R150F transmission and a VF1A chain drive transfer case.

2. There is the same single synchro in it, used for the same exact purpose of shifting from 2H to/from 4H, as is in every RF1A or VF1A/VF2A part-time 4WD transfer case. Geared, chain drive, ADD, or not ADD, there's no difference there. You can shift-on-the-fly into/out of 4H ONLY. Why? One synchro ONLY, and it's not used for shifting into 4L! How does this synchro function then? I explained it in simple terms already. But it's kind of a complex notion to digest in total. Try another source for more details.

3. It does matter, BIG TIME, if you try and shift any of these transfer cases from 2H to 4H if the front driveshaft isn't already spinning at nearly the same speed as the rear. When it matters is when you don't have a clutch to "disconnect" the "differential". Yes it's called a clutch. And it's true function justifies it being called such. Again, I have already explained this concept in simple terms too. Maybe somebody else can do a better job. Sorry.

4. Yes, the ADD indicator switch ultimately controls the 4WD indicator lamp. HOWEVER, it's only going to be able do that if you've caused it to happen by shifting the transfer case into 4H and closing/switching on the 4WD indicator switch in the transfer case FIRST! The following wiring diagram proves this to be true. ONLY if the 4WD indicator switch is closed/switched on first, does that complete the ground circuit between the E1(engine ground), it, and the ADD indicator switch. So that when the ADD switch is finally closed/switched on the 4WD indicator lamp can illuminate.

DeathCougar

iTrader: (23)

I thought you meant RF1A, which is the gear drive case.

What you are calling a clutch is not a traditional clutch. There isn't any pressure plate, nor is there a disc.

So, in round about terms I suppose we are talking about the same thing.

You can take the front end, axles and all completely out of the equation and you could still shift the tcase into 4wd if the truck has ADD (and the proper Tcase to go with it). Even if the hubs were open or the axles were missing. However, on your truck, which didn't have ADD, you couldn't do that. Try it some time with a vehicle that has ADD. Remove the front driveline, and I bet you could still get it into 4WD at speed without grinding. This ONLY WORKS on vehicles originally equipped with ADD. So it leads us back to the original question, what is the problem here.

Since there were only two options for transfer cases behind autos in 1996, chances are good that he got the correct one. The Limited Tcase is a High-Low selector with a push button 4WD. The shifters are completely different, so that would have been obvious right out of the gate.

Assuming then he has the correct case, that leaves two possibilities. A. Something is busted in the case or B. The shifter is in wrong. Option B is most likely the problem, as with the J-shift pattern cases its very easy to put the shifter in wrong, or out of its keyway.

pizzabob

@NelsonMD -- I think I got the right one -- certainly the vehicle descriptions matched perfectly. The shifting seems to match up with my old one, other than the fact that I now have to stop completely to go from H2 to H4. I will make further inquiries with the seller to be sure. Thanks!

pizzabob

@DeathCougar -- thanks kindly, will check that possibility out for sure.

pizzabob

Had another thought, DeathCougar -- would it change your assessment if I mentioned again that the transfer does shift into the correct gears, as the old one did? The only thing different is that it grinds if I'm moving when shifting from H2 to H4.

Your post seemed to imply that when stopped, with the shifter backwards, the result would be shifting directly from H2 to L4, and that isn't the case. What do you think??

pizzabob

One more thing to ponder -- the transfer I bought:

http://cgi.ebay.com/ebaymotors/ws/eB...m=140562328071

... came from a '98 Tacoma, according to the Ebay listing, but as stated in the listing was supposed to fit my '96 4Runner. It is interesting that the seller says '96 to '98 4Runners only. I did not realize there were significant changes in '99.

DeathCougar

iTrader: (23)

You bought the wrong Tcase.

That case fits 96-98 Manual trans 4Runners only (as stated in that ad). You need one from a 96-98m 4Runner SR5 automatic. There WERE major changes in 1999, the case is about 4 inches longer among other things, but thats irrelevant in this situation since yours is a 1996.

However, you still bought the wrong one. If they won't send you the correct one, call us at Nix99 at 800-782-0682 and I will get you one. Ebay is hit or miss on finding the correct parts. People don't always see the interchange notes either.

DeathCougar

iTrader: (23)

Realistically what likely happened is they sent you a Tcase from a truck with manual hubs. Since vehicles with manual hubs won't go into gear unless the hubs are locked (thus engaging the driveline, since there is no ADD) it explains the grinding. I bet if you manually engaged the ADD actuator to always be on, it would go in and out of 4WD with zero problems (strictly as a testing procedure, you would never want to leave it that way)

pizzabob

Thanks again for reply, DC, but... as stated in the original post, I do have a manual transmission. Did you miss that?? I was as careful as possible to check the description before buying... you're certainly right that Ebay is hit or miss at times...

As to the possibility of installing the shift lever backwards, I wonder if anyone would be kind enuff to post a photo of a 5-speed 4Runner's shifters for me to compare positions to? Like maybe with the tranny in neutral and transfer in H2?? Or perhaps know where I could find such a photo in this forum, or elsewhere??

Thanks to all of you!

Nelsonmd

Well, what makes me think you got the wrong one is this statement here...

What do you mean by "different 4WD switch configuration"? The right transfer case is exactly like your original one. It sure sounds like the new one isn't exactly what you had before.

Don't be too quick to assume you got the right one, it seems to me that all you have to go by right now is the description in the ebay listing, which I think half they guys on here wouldn't trust. If you want to be sure, take some pics of the transfer case so people might be able to confirm if you have the right or wrong one. It would at least put to rest the concerns people here have.

DeathCougar

iTrader: (23)

Ah jeeze, sorry I completely misread the post. I thought you had an auto.

Me and my big mouth

pizzabob

Fellows -- gotta leave town for three days. When I get back I will post some photos of the new vs. old transfer cases, and will also ensure the shift lever is oriented properly.

Thanks again for all your help.