slipping in 4hi?

Awhile after I put a 3" lift on it's started sort of slipping when I'm on the freeway in 4, usually at full throttle or close too.

it feels like a transmission slip but a little harder stutter.

is it possible that the t-case linkage could be off and causing it? or the front DS slipping? Or something simpler? I can't think of anything that would cause it.

I have not put a tcase drop in, haven't thought I needed it.

1. what speed are you driving at in 4 HI? it should matter, but unless the road is covered in snow i would see no need for it.

2. is it a part time, or part time and full time case? (np231, and np 242 respectively)

3. how many miles are on it?

4. automatic or manual?

5. what size tires are you running?

your t-case drop wouldn't matter, it will just give you crazy vibrations if not installed.

chances are, if your driving in full time (assuming you have the np 242 case) the differential inside the case could be slipping or broken, try changing the fluid inside the case (same as trans fluid, i believe its ATF, thats what i use). this is the only way the front drive shaft could "slip" as the differential in the case acts like a limited slip for the power between the front and rear wheels (so you can turn without "hopping", which is the same as AWD)

another think it could be if its a manual, is the clutch. there is a lot more stress put on the clutch when in 4wd, same goes for an automatic, you could be overheating the trans. or the trans could be slipping. try changing the trans fluid and put a new filter in the trans and install an after market trans cooler ( a must for bigger tires). the trans could also be on its way out, how does it shift? i know mine slips like crazy when i gas it going about 40 unless its cold and the shift points are all messed up.

give us some more info and we can narrow down the problem a lot easier!

it's a part time. snowy road, say 45mph.
200k or thereabouts
manual
275/65/15

I tend to think the clutch is OK as it's a very short sharp shudder or hiccup, not the engine revving higher like a clutch would.

philip_g said:

it's a part time. snowy road, say 45mph.
200k or thereabouts
manual
275/65/15

I tend to think the clutch is OK as it's a very short sharp shudder or hiccup, not the engine revving higher like a clutch would.

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does the engine rpm stay constant? if so then you might have a problem with the trans or t case. like i said, try changing the fluid in the t case. if you're rolling on 200k with out replacing the clutch more than once, i would consider the clutch as the culprit. my buddy has a camaro and his clutch started doing that. a good way to tell if the clutch is slipping is by "loading" it aka, towing something or pushing something. if engine rpm increases with no noticeable change in speed, then i would replace the clutch. i highly doubt that the t case is the problem since its all chain driven and there isn't a opportunity the trans or the t case to slip unless its the clutch.

rehab said:

i highly doubt that the t case is the problem since its all chain driven and there isn't a opportunity the trans or the t case to slip unless its the clutch.

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over time the chain will stretch and cause it to slip a tooth it is usually noticable by sound or vibration not really a rpm change. seeing as it is a manual there is no slip there besides the clutch the only other thing to slip is the cain in the t-case and seeing as you say it happens only in 4wd i bet thats the culprit. you can replace the chain but it involves a fairly extensive tear down of the t-case and if you can find a reasonably priced low milage case you may be better off with that route. keep in mind that chain stretch is caused by using 4wd primarly when not needed (dry road)

bj-666 said:

over time the chain will stretch and cause it to slip a tooth it is usually noticable by sound or vibration not really a rpm change. seeing as it is a manual there is no slip there besides the clutch the only other thing to slip is the cain in the t-case and seeing as you say it happens only in 4wd i bet thats the culprit. you can replace the chain but it involves a fairly extensive tear down of the t-case and if you can find a reasonably priced low milage case you may be better off with that route. keep in mind that chain stretch is caused by using 4wd primarly when not needed (dry road)

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that sounds about right, but wouldn't there be a loud clunk or grind if its skipping teeth? it sounds probable and it really wouldnt take long to find out, just split the case and look at the chain, if there is slack in it. it could be your culprit since there is a kind of "jerking" when you gas it.

i'm not sure on exactly how to check tension on the chain but i don't beleive you can check it with the case split because the front yoke is held true but the front and rear halfs of the case so if you loose on half of the case you will not accuratly be able to measuer tension. i beleive you can remove the fill or drain plug and maby get a tension that way there must be a similar deflection test similar to checking a fan belt. and yes you will hear a clunk or grinding if it is really stretched. seems to me that if it is jumping at a constant speed you should be able to get it to really jump by hard acceleration in 4wd from a stop.

should have said this previously but start by making sure that your linkage is set correctly. after a t-case drop you should have adjusted it to accomidate the new position of the t-case

bj-666 said:

should have said this previously but start by making sure that your linkage is set correctly. after a t-case drop you should have adjusted it to accomidate the new position of the t-case

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No drop, but haven't touched the linkage since I lifted it. Been too cold to bother with it.
I'll pull the t-case apart this spring when I swap the engine I guess... or just replace it.

Probably right on the chain, there's a firm clunk when it does it.
I run the piss out of the 4wd when it's snowy and it's been snowy a lot this year.

Diffs,driveshafts,and transfer cases cant "slip",they might skip a tooth or break a shaft, but that would never be described as "slipping",thats a major feel you would know when it happens!

RCP Phx said:

Diffs,driveshafts,and transfer cases cant "slip",they might skip a tooth or break a shaft, but that would never be described as "slipping",thats a major feel you would know when it happens!

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the whole part of a differential is the "slip" or unequal torques applied to two different spectrum's, ie: right and left wheel.