how to tell if transfer case is bad

[gjp]

How do I tell if the transfercase is slipping or going bad. My truck sometimes will rev up to 5500rpm with a loss of power to the wheels. I know the transmission back is good. Has to be the differentals or transfer case. HELP please. Thanks for any input.

ALSO looking will be looking for a good cheap Transfer case for my sy if anything just to have and test.

 

[sly dvl]

Re: how to tell if transfer case is bad

Not likely it's the differentials or the x-fer case. Those things don't slip since they consist of gears & chains, not clutches. Sounds like your transmission to me...

 

['JustDreamin']

Re: how to tell if transfer case is bad

Well, I'd be willing to bet that its not the differentials....You'd know if they're slipping, because they'd make a BUNCH of noise. Trust me, I've broken teeth off of 2 different gear sets in a GM 10 bolt, and they didn't slip, but they made plenty of noise.

The transfer case is unlikely to be the culprit either. As stated earlier, there aren't clutches to slip. There is a chain that drives the front propshaft / differential, and if its slipping, again, you'll know (it'll make a BUNCH of noise too) because it'll be jumping teeth on the sprockets.

The only possible culprit in the transfer case is the viscous coupling. If it completely failed, it might give you that symptom (rev to 5500 while in gear). However, I would expect it to be a complete loss of drive all of the time instead of intermittent, because the typical mode of failure for the VC is usually to lock up all the time (basically making it a 4Hi box instead of an AWD box) and to be completely unlocked at any time would require a loss of a portion of the fluid in the Viscous Coupling and that wouldn't be particularly intermittent.

I'd still suspect the transmission. Stock, these trucks break transmissions with relative ease, but stock transfer cases have gone into the 9's (and I think 8's). It also has components that would fail in just the manor you're describing (ie clutches that activate by hydraulic pressure, and too little pressure = slipping clutches).

Just my thoughts

'JustDreamin'

 

[willyson]

Re: how to tell if transfer case is bad

my transfer case went bad. it road well until 60mph then you could feel the gears grinding, felt like riding on a dirt road.

a loss of power may be the torque converter slipping, i had a loss of power at WOT, it would feel like it was pulling timing.

 

[sy#2921]

Re: how to tell if transfer case is bad

My truck sometimes will rev up to 5500rpm with a loss of power to the wheels.

My truck did the same thing in first gear only. I have since replaced the trans and the TC. I would lean more towards the TC though cause I also noticed at the same time my stall speed was going down. It was suppose to be a 3k stall and was the first year I had the truck but then it slowly slipped down to about 2400. I did the trans as a safeguard since it was one of the famous roadmaster dr. evil's

 

[autoaddictions]

Re: how to tell if transfer case is bad

Must be the converter. I cant believe you hurt the 4l80.

 

[gjp]

Re: how to tell if transfer case is bad

truck did it before and I figured it was the trans. 80E went in and it still does not feel like all the power is hitting the wheels. Yes it feels like timming is being pulled but I am only getting 3-4* of KR at worst without my alky. When the truck hits about 50mph it loses more power, the rpm jump to 5000 and for a second it just revs there, then it feels like something grabs and the rpm drop to 4000 and it takes off again. I will try t get a video of it.

 

[willyson]

Re: how to tell if transfer case is bad

i bet your torque converter is slipping

 

[JSM]

Re: how to tell if transfer case is bad

Bad solenoid or bad connection to them can cause this issue as the trans won't shift correctly.

 

[2fast4u]

Re: how to tell if transfer case is bad

i bet your torque converter is slipping

x2.. after hearing these horror stories, Im gonna ease up on my trans...sheesh :roll:

 

[Flyin Ryan]

Re: how to tell if transfer case is bad

Bad solenoid or bad connection to them can cause this issue as the trans won't shift correctly.

Im going to put my money on this

 

[gjp]

Re: how to tell if transfer case is bad

900$ converter with 1000 miles went bad? no way. 2500 80e with 1000 miles went bad, no way?
has to be something else. truck is faster at 3/4 throttle then wot.

 

[Foot Performance]

Re: how to tell if transfer case is bad

If it did the same thing before and after trans replacement and before was 700 and after was 80e to me that would take care of the trans

I have seen the viscous coupling go bad and it locked up (only when fluid reached operating temp) It just felt like it was in 4wd all the time as far as parking lot driving and stuff.

They may be able to fail the other way possibly? :dunno:

 

[gjp]

Re: how to tell if transfer case is bad

when i turn i feel like its 4wd not awd. like my suburban in 4wd. I can hear and feel a slight thumping. My truck has always done it. thought it was normal? both front shafts are new napa ones.

The word viscious means "liquid slipping" does it not. Truck had 95k when I bought it. who knows what the past owner could have done. if there was not enough fluid in it before who knows. The 700r had a 3k build and 2k miles on it before it blew up? if that was done wrong who knows.
To me its worth it to pay 3-400$ for another case just to see. If anyone has one for sale. I can pull the T case very fast now because I had to unweld the crossmember when I did the 80e conversion.

 

[George Blake]

Re: how to tell if transfer case is bad

Contact five2drive. He may be able to get you one and he's not too far from you. His torque converter isn't slipping. I've got the identical setup to Gary's and I can vouch that the 3 disc PI is NOT bad. His truck did this before. He swapped the entire transmission, converter and front and rear driveshafts. All that's lift mechanically is the front and rear diffs and the transfer case. Now, something to consider. As far as the control end of it: The way I set up the controller harness for the TCI controller guys is this:
You connect the two originl wires that fed the stock 700r4 together. This completes the circuit from the ecm back to the ecm as well as providing a signal from the ALDL "F" terminal. The TCI controller has command over speed that the TCC locks up. As long as the ECM is commanding TCC lockup, the relay will be closed because the F terminal will have 12 volts to it. See what's happening? The stock ecm closes the relay. The relay then allows the TCI to control TCC lockup. If you step on the brake, the power is broken at the ALDL "F" terminal and the relay opens. TCC unlocks. If the ecm for any reason disengages TCC, then the F terminal will lose 12 volts, the relay will open and you will lose lockup ability until the ecm commands it again. If there is an open anywhere in that circuit, a problem with the ecm, or the brake switch, you will go in and out of lockup because you are losing the signal to the relay to close it. If that's the case. This will manifest as an rpm flare and then TCC will lock back up and it will come back down. A PI 3 disc is a completely different animal than a regular single disc converter. If I have my project truck up and running still when Homecoming comes around this spring, I will have it there and give some rides. There is NO frigging doubt when it locks up and when it's released. It ain't gonna slip:tup:

 

[Foot Performance]

Re: how to tell if transfer case is bad

when i turn i feel like its 4wd not awd. like my suburban in 4wd. I can hear and feel a slight thumping. My truck has always done it. thought it was normal? both front shafts are new napa ones.

The word viscious means "liquid slipping" does it not. Truck had 95k when I bought it. who knows what the past owner could have done. if there was not enough fluid in it before who knows. The 700r had a 3k build and 2k miles on it before it blew up? if that was done wrong who knows.
To me its worth it to pay 3-400$ for another case just to see. If anyone has one for sale. I can pull the T case very fast now because I had to unweld the crossmember when I did the 80e conversion.

I can see monday if I can get a new coupler from gm (doubtfull)

but is should not feel like a 4WD when pulling into parking spaces that is what the couplier is for. hopefully you have found you problem :tup:

 

[gjp]

Re: how to tell if transfer case is bad

I can see monday if I can get a new coupler from gm (doubtfull)

but is should not feel like a 4WD when pulling into parking spaces that is what the couplier is for. hopefully you have found you problem :tup:

Thanks. What T cases fit our trucks. I would guess the bravada's??? So I can look for one at a local pick and pull.

 

[alwayscode390]

Re: how to tell if transfer case is bad

my transfer case went bad. it road well until 60mph then you could feel the gears grinding, felt like riding on a dirt road.
.

This is what my truck is doing. At first , I heard popping and clanking on the drivers side. I have been driving it off and on like that ( stupidly but I needed it in the snow ) ... and now the popping is gone , but the truck feels like I am driving it on gravel ... and SOUNDS like I am in a lifted truck with SUPER KNOBBY tires on a rough paved road. Its mainly on the drivers side. It gets better at 60+ or accelleration , but almost shakes the truck loose if I let off the gas and allow it to gradually slow on its own.

How much are transfer cases? What other damage could I have done from driving it so long ... axles/gears/ tranny (seems fine , but I am not familiar with what connects to the t-case).

Good Luck Gary ..... ---

 

[fivetodrive]

Re: how to tell if transfer case is bad

With the syclone it is a bit harder to find. You need to look for a 1991 or earlier astro van at the local u-pull-it. I have only seen one 1991 bravada in the last 3 years of junkyarding... They are a lot harder to find than the 92 and up bravadas...

I have one but they are pretty expensive to ship. They get shipped at the 50+ pound weight. (around $50)

Let me know if you cant find one...

 

[willyson]

Re: how to tell if transfer case is bad

if you can find one used they go for ~4-500, new double it