A question about 94 transfercase issue

[Trapper50cal]

So,

If I know my rig correctly, I have a transfercase with a viscous coupler

I also know that I have installed the CDL and performed the Pin 7 Mod.

The Speedo cable input at the back of the TC is leaking (O-ring issue I think)

The power delivery "slips" a little (doesn't engage as strongly) when going around
turns in slow, town intersection conditions.

Is it fair to assume that as a result of this "slip" and the fact that I know there is a leak, it could be the case that the TC is low on gear oil?

Just looking for some confirmation before I crawl under and check it/replace the o-ring.

Sound reasonable? or idiotic?

both are possible

 

[80t0ylc]

IIRC the viscous coupler has it's own fluid so it's function is independant of transfer case fluid. Your TC level may be low, only way to know is to check it. Don't know how much fluid you're loosing with the o-ring issue, but sounds like it needs to be fixed.

 

[Corbet]

What you doubt my vast knowlede on all things mechanical?

Kidding, consider this a free bump on a problem that would not douplicate its self when I drove it today.

 

[Trapper50cal]

LOL!

just my attempt at self-deprecation while asking for input, assistance and knowledge.

Just trying to be circumspective.

No offense intended Boss.


On a side note: If a viscous coupler has its own fluid, how is it filled? is it a sealed/closed system?

I am pretty sure you are right, Corbet (low gear oil in TC)

As you know, I first thought it was tranny but if it only slips while turning, it has to be part of the All Wheel Drive power delivery decision being made by the Center Diff/TC

That plus it's leaking, that's a pretty good clue, I would guess.

 

[toojayzee]

The power delivery "slips" a little (doesn't engage as strongly) when going around
turns in slow, town intersection conditions.

Is it fair to assume that as a result of this "slip" and the fact that I know there is a leak, it could be the case that the TC is low on gear oil?

Can you describe the feel a little more ? Does it clunk, or chatter at all ?

 

[Trapper50cal]

Nope, it just feels like the tranny is slipping a bit during slow turns, the rpms go up a bit without the associated increase in acceleration/pull. Like if it were low on ATF but it only happens in slow tight turns. The tranny hooks up solid when going from park to drive or reverse, and driving straight...and it is not low on ATF, that's why Corbet thought it was diff based (center diff specifically) as a result of the AWD system making choices about power allocation. If it were doing it in a straight line I would also consider a valve body clog or dirty tranny filter.

 

[toojayzee]

So its different than a slipping transmssion huh...
Im looking in the FSM and it doesnt go into a whole lot of detail about the viscous coupler. The ones ive seen in the past are self contained. Though it looks like this one may be pressure controlled. It calls out a oil pump within the tcase...

 

[Trapper50cal]

Well, the other factor here is that I've been driving a manual FJ60 before this and a manual FJ55 before that...it could be completely normal or at least "not uncommon" and I wouldn't know...I'm gonna replace the o-ring to the speedo connection and check the gear oil in the TC and go from there....maybe flush it and the tranny a couple times too

 

[CJF]

No way is "slipping" due to the transfer case; the TC is geared all the way through.

The VC affects how power is distributed front/rear, but there's no way, failing or otherwise, that it can cause a high rev. tranny slipping situation.

Curtis

 

[Ebag333]

No way is "slipping" due to the transfer case; the TC is geared all the way through.

The VC affects how power is distributed front/rear, but there's no way, failing or otherwise, that it can cause a high rev. tranny slipping situation.

Curtis

What he said.


My first thought was that maybe the torque converter was unlocking. When it unlocks, the RPM goes up a small amount. The TC locks/unlocks depending on load, so I could very much see it unlocking going around corners.

Not sure how slow is the slow you're talking about though....

 

[Corbet]

TC should not be locking in 1st or 2nd gear.

My thought is that the viscous coupler or the rear diff were slipping somehow as JT says it only happens while going around a corner. But like I said it would not do it when I drove it. So I'm just guessing. The trans and or TC should have no clue if the vehicle is cornering or in a straight line

I'm no mechanic, although I did stay ant a Holiday Inn Express last night.

 

[80t0ylc]

I have a '94 also, which it looks to be same year as OP. What I've noticed to be unique about my 80 (compared with other rigs that I've driven), is when it is cold, first 5 -10 minutes or so after start-up when I approach an intersection in my neighborhood and slow down to make a turn, if I have touched the brake pedal, the tranny will downshift in the turn and when I go to hit the skinny pedal to accelerate again, the engine revs temporarily, IMHO more than it needs to. If I keep my foot off the brakes, it maintains the normal rpms through the corner and leaving the intersection. I'm talking speeds of 25 mph or less. Trapper, does this sound like what you're concerned about? Or did I just confuse the issue? I only notice this when the rig is still cold. It may do it all the time. It's just more noticeable to me when I'm leaving my neighborhood - just getting going. - HTH

 

[7schulz]

I would say my 93 does the same thing as the two of you are describing. The VC is a sealed unit no fluid to add but mine is bad and seized up so it's getting tossed soon.

 

[Trapper50cal]

I have a '94 also, which it looks to be same year as OP. What I've noticed to be unique about my 80 (compared with other rigs that I've driven), is when it is cold, first 5 -10 minutes or so after start-up when I approach an intersection in my neighborhood and slow down to make a turn, if I have touched the brake pedal, the tranny will downshift in the turn and when I go to hit the skinny pedal to accelerate again, the engine revs temporarily, IMHO more than it needs to. If I keep my foot off the brakes, it maintains the normal rpms through the corner and leaving the intersection. I'm talking speeds of 25 mph or less. Trapper, does this sound like what you're concerned about? Or did I just confuse the issue? I only notice this when the rig is still cold. It may do it all the time. It's just more noticeable to me when I'm leaving my neighborhood - just getting going. - HTH

This is EXACTLY what is happening

 

[Higgin]

I'm no mechanic, although I did stay ant a Holiday Inn Express last night.

I have no idea what would be wrong, but i just about spit my Dr.pepper on the screen when I read that. LOL.

 

[Trapper50cal]

Yeah, Corbet's a funny guy...

funny lookin, not funny ha-ha

 

[80t0ylc]

This is EXACTLY what is happening

Maybe there's nothing wrong with it then. It's the "personality" of our A442F "bus" transmission, I guess. I've got just under 225K on the clock and am in the middle of a tranny service today. The magnet in the drain plug had very little metal shavings on it and the fluid still has a red tint to it. So I'm curious to see see how it looks when I pull the pan and clean the filter. But the tranny has done fine for the 100K that I've owned it. I've towed some and it's done fine. I'm still amazed on how smooth it shifts on the highway.

 

[Trapper50cal]

Excellent to know....Thanks for the input!

I'm at 206K