Grinding Transfer Case

[gt1009]

I was leaving my friends house today in four wheel drive when suddenly a strange and loud grinding came from somewhere underneath my 4wd selecter lever. I really have no idea what is wrong and any help from you guys would be greatly appreciated. One more thing, the street is a one lane, curvy, hilly road completely covered in snow and ice. I think that this noise started when I accidentely locked up the brakes. Now, I can't get it into four wheel drive. When I move the selector to 4 wheel high, the light doesn't come on. However, it still feels like it is in 4wd, as I couldn't spin the wheels when I tried to do a little test to see if it was just my light bulb now.

 

[acetomatoco]

linkage tends to hop out of gear sometime in the shifter...sounds like you were not in the detent and it was just grinding away.... regarding the light, does it come on in 4wd low,....? I would imagine all the vibration from the grinding just messed up the switch in the linkage... Do you have your hubs engaged? ACE

 

[jumpmasterjim]

I'm having a small problem eith one of mine too. When I hit the brakes hard in 2wd it pops out of gear. I have to shift into 4 low to reengae it. I'm gonna get my spare rebuilt then swap it out. It seems that most people overlook checking the level and changing the fluid.

 

[CCATLETT1984]

all these issues stem from GM's choice to use aluminium shift forks with nylon wear pads (so they would be quiet) instead of steel. the parts are cheap, but you have to tear down the case to get to them.

 

[gt1009]

Well,
The 4wd worked again today, so I think that I'm just gonna take it easy on the brakes. It seems like when I locked up the wheels wile going about 20 the noise started. I think that just messed it up and I'll just not stop hard if I can avoid it.

 

[Milkman357]

One day wheel drive goes GRGRGRGRG

I think My Transfer case might be doing what's talked about here.

One day ok.
Then next not....grgrgr (Grinding noise like gears arnt going in)
After it did this I played with it a little. It would go in gear for a few seconds Mayby 5 seconds. Then grinding starts again.... So the fork problem does sound plausible....

Can I get steel, instead of aluminium....?

Where do I find the parts? Chevy dealer?

 

[Cucvnut]

the best bet is to junk the 208( the nylon bushings suck ) and get a 205 you can twin stick it so you have have low in the front and high in the rear for wheeling. plus it uses metal rods not alum. people say the 208 has a better low gear but you can re gear a 205 it has gears not chains... or you might need to replace your T case mount with a new one. to help ot from poping out of 4wd.

 

[Cucvnut]

new process gear made the t case not chevy you can check with novac adapters for parts here is a link Parts for Transfer Cases - Novak Conversions they dont show the 208 but they have parts for it jsut email them

 

[dstang97]

If it just grinds going into 4 hi or low its because there not syncronised. Mine will go into 4 hi fine but hates going into or out of 4 lo. I have to shut off my truck and move the shifter. I have to do it on my 205 and 208 TC's

 

[4bogginchevys]

The 208 in my 84 1008 will not allow me to go into 4 hi when moving...I have to stop everytime, although no issues with 4 low other than some "gear noise". I have thought alot about changing the case to a 205 or even 203 but never will because of moving/changing the cross member, adapter, both drivelines, aswell as various lever changes and all the unforseen mods that always seem to appear when you try to swap the stuff. For these reasons, and because I want to keep it as military stock as possible, when the 208 finally gives up I will just swap it with another and be done in about 2 hours.

BTW, my guess would be a loose chain/lac of oil problem...and the rear brakes may need adjustment/replacement so that they engage more and take some stress off of that chain

 

[12vctd]

Most common problems in a np208 case are avoidable. First the shift is body mounted, this can cause alot of engage ment poping out of gear problems, as the busings to the body, motor, trans and transfer case wear. You can usually adjust for some of it, but only so much. If your having shifter poping out of gear issues then I would suggest inspecting your drive line bushings at a min. second problem alot run into is the rear oil pump/slinger burns up when there is a lack of fluid, this can lead to needing a rebuild. This mainly comes from leaks at the slip yoke going without repair. The 208 case is a decent case but I too prefer the n-205. But I would suggest anyone having issues with grinding after engagement or poping out of gear to look at your drivetrain bushings and replace if needed then adjust the linkage. It should solve most issues.

 

[4bogginchevys]

i'm not sure about the 205, but I know your suppost to run 4wd atleast with hubs unlocked, once a week or so to keep everything oiled in a chain case

 

[Milkman357]

Hmm

I thought I read not to run it in 4Wh drive with the hubs in free...

Not sure why...

 

[Cucvnut]

no you should not run it with the hubs open.

 

[Milkman357]

Adjusted linkage

I did adjust the linkage. It seemed out of alignment. Had high hopes. Still same problem.

Goes in 4wheel.....for a short time. Then seems to pop out....rgrggrgrgrgr.

SO now I'm mulling what to do....I guess I'll price the shops first, what will it cost for rebuilding mine....

If too much $$$$ Maybe I'll try replacing the part first, and see how that goes.

 

[12vctd]

how are your rubber mounts for the transfer case and trans, as well as body mounts?

 

[Milkman357]

Bushings...

Everything looks ok. They are there....not crumbling. They are 25 years old I'm sure.

I Can see the bushings being an issue if your using truck hard / or climbing in out of a ditch or something.

On straight and level ground, not going fast, I would be surprised that the bushings, or body movement are the culprits.

Transfer case is coming off. I gotta learn how todo it sooner or later.

Rebuild shop won't will to give me a price without me bringing in the vehicle first. I would just about bet money it's the problem stated here.

Novak had 2 "forks" both shipped to me sounded like under $65.

 

[12vctd]

There is a detent spring and ball inside the case. These have also been known to cause issues. I have taken some pics as soon as they upload I will post. I personally have rebuilt more np-208's than I ever cared to mess with. But I can say that they are a very simple case to rebuild. I always first suggest the most common issues to people when I diagnose problems over the net. As I cannot be with the vehicle to recomend. Theres more flex ina drivetrain on level flat road than one would think, especially under takeoff conditions and when the bushings are worn. Gimme just a few mins and I can post some pics of a 208 apart and give a few suggestions on areas to check.

 

[Milkman357]

I adjusted

I adjusted the selector linkage, out side the transfer case, still same problem.

I havn't opened up transfer case yet....

I might as well start the learning process..

 

[12vctd]

ok here are some pics of inside the 208, I tried to take pics of areas that would cause the issues you are describing. I have only seen 1 bent mode fork in a np208, and I think it was simply because the 208 shift linkage (outside) just really isn't strong enough to gain the leverage to bend the mode forks, or the shift rail. Not to say its not possible, just not a common occurance from my experience. I would suspect either the ball on the range selector, a broken shift rail spring or worn syncro's. also very possible that the plastic area that the mode fork on the annulus gear rides on is bad. Sorry for low quality pics, but I haven't gotten around to getting a new camera. Pic 4 shows the area on the annulus gear that is worn.