I Installed a Petroworks GRS II t-case in April of 2008.  This last summer after a couple trips I noticed a rumble/grinding sound from the drivetrain so I parked the Samurai until I could get to it.  This week I replaced both rear drive shaft u-joints (one was obviously no good), I inspected rear wheel bearings and rear differential.  Put all back together with Sammy on jackstands, no wheels and accelerated to approx. 40 mph when I heard a loud rumbling / grinding.  I get under and can hear and feel it coming from the t-case.  I disconnect the rear drive shaft and get same results (this is all in 2wd, no front driveshaft movement).  I drain t-case into a clean pan and there is A-Lot of brass colored particles and silver/grey colored particles. 
So after approx. 2.5 years and less than 20K miles, I need to rebuild the t-case??

After first installing this t-case in 4/08, 4wd would not engage.  After spending a good deal of time eliminating all other possible problems I finally sent the t-case back to petroworks (at my shipping expense) and they repaired something in it and sent it back (I dont recall what the exact problem was, I was just excited to finally have a working low range 4wd).  The t-case has always seemed "loose" to me.  When in 4 hi, if I let off the gas and let it coast, in gear, down a small grade or just slow down on flat land, the t-case would make all kinds of awful noise like all the gears were just rattling around inside.  Apply a little gas and all was fine, I just could not coast in gear.  Is that normal??  Not ever having driven a Samurain in 4wd before this t-case I just assumed (hoped) that was normal.

I'm sure its out of warranty so I want to rebuild it myself. 
Are there any good t-case rebuild guides anyone know of?
How involved does this sound?  Do it myself or have a repair shop do it?
Anyone have similar problems and know how to repair?
 

 

I'll give it a shot.  I find it hard to believe that it need rebuiding all ready. 

First hows the u joints in between the t-case and transmission(jack shaft)? I have had issue with those.
All the mounts and arms in good condition and not bent?
Who put the gears in the t-case?  If petroworks did it, I would trust there work.
Do you have the 2WD low conversion that petroworks offered as an option?
Are any of the flanges on the t-case loose?
Any oil leaks?

In my experience a stock Sammy, if you put the car on jack stand and run it up to speed, you will have sounds especially in 5th gear.  there are many places that have a little backlash.  tranny, jackshaft, t-case, rear diveline, rear end, all of which is magnified to some extent by lower gears.
I say all this to rule out as much as you can before you needlessly break down a t-case.

check the jack shaft and let us know.

Thanks for the reply.
I pulled the t-case already (not torn down, just on the bench) so I will check the jack shaft u-joints.
I installed RockyRoad's 'Mega-Mount' mounting system (http://www.rocky-road.com/superbeef.html) when this t-case was new.  Both mounting arms are still just like new, polymounts as well.
Petroworks installed the gears and sent t-case complete, I just sent them a core afterward.
I do have the 2-low option.  I love that by the way, it has come in extremely usefull.
The flange bolts are still crimped and I cannot detect any looseness.
No oil leaks what so ever.  I keep the underside of the Samurai clean so I can detect any leaks early.  I opened the fill plug prior to draining t-case and fluid flowed out indicating it was still full.

As much as I would like an easy/cheap fix such as u-joints (which I will do the other 4 anyway), I cannot dismiss the noticeable amount of brass and metal material that drained out with the fluid.  When up on stands I disconected the rear driveline to remove it as well as the rearend from the equation.  With my hand on the bottom of the t-case, I could clearly feel the clunking from the t-case as opposed to no noticeable feel from the transmission.

I will remove the jack shaft today and report.  If it appears OK, I will install the original t-case from this Sammy and perform same drive test on stands and report.

the test on jack stands may or may not tell you much especially with no load.  thats what I am telling you. there is allot of slop in the trive train and with lower gears.  on your after market mounts and arms, if it is not exacltly right there will be some angles in the jack shaft that will accellerate and decelerate on every revolution, thus causing knocking of the gears because on the no load the gears are bouncing from the coast and load side.

There is only one place in the t-case that has brass.  it is the thrust bearing on the counter shaft.  the gear set inbetween the input shaft and out put.  it is a wear item.  It would take allot before they are gone.  if they were new thee would be some brass for the break in.  Silver silt is normal in any gear box or diff. When you see chunks, thats bad.

If yo do the no load jack stand test put some ebrake on, and then rev up and let off to see where the noise is coming from.

let us know.

The jack shaft joints seemd OK, the rubber on the end caps were intact and they moved on both planes easily by hand.  So I put the stock t-case back in and performed the same test on jack stands.  It was fine in 2wd, no noise and smooth as can be expected, however, in 4wd hi and lo I got the same clunking at speed.  This was done with the rear drive line disconnected. 
The sound was still coming from the t-case. 
So I will connect the rear drive line and use the e-brake.  I will then put the wheels back on and see how does on the road/dirt roads.  Next step then I suppose could be to replace u-joints on jack shaft and see if that changes anything.

Thanks again for the replies, very helpfull.

Did you use the same mounting system for rhe stock tcase to rule that out? Also check you trany and motor mounts...

Yea, i'm using same t-case mounts.  I just got the oem t-case in the sammy and will drive to/from work for the next 4 days until I have time to work on it again.  I will then check the motor & tranny mounts and replace the u-joints on the jack shaft as well as the front driveline.  I will then drive to/from work for a few days with the GRSII installed again and see how it's working after that. 
A quick drive around the neighborhood reminded me that I cannot drive over 40-45mph with stock gearing and 31" tires.  No fun.  Need gears again. 

Speaking of driveshafts, would it be worthwhile to have them balanced, how important is that?

If you still have the issue, you need to rule out your transfer case mounts and arms.  Remember that with the lower gears every thing in front of the t-case is now spinning faster, so vibration would happen at a lower speed. 

I normally don't balance a drive line unless i have a vibration.