I dont know what happened...

[frickenbored]

Well about 2 weeks ago I finally got my 88 k5 blazer moving again after a 6 month sitting period.  I rebuilt a th400 for it after junking a 700r4 and I threw in a mile marker 501 kit into my np203.

So for about two weeks everything works perfect, today however I'm driving the truck around and I put it in reverse, it hesitates, then theres a bang and a jump and it starts to move.  I put it in drive and its fine, I put it in reverse again and the same thing happens.  It feels exactly like a frozen u-joint (both u-joints are brand new) the driveshaft jumps up and the truck jerks in reverse.  I'm about 99% sure something is wrong with the back half of the t-case.

Heres the thing, I have a carrier with welded spyder gears in my rear dif and I have been driving it on pavement, I'm thinking that this caused that torrington bearing in the 501 kit to get trashed, does anyone have any ideas?  I'm going to put my open carrier back in the diff on sunday and open up the back half of the transfer case again.  But if anyone has run into this problem before I like to hear what caused it.

[choptop]

It sounds to me like its low on transmission fluid, at least that's the same thing that happens when any mine get low.

[frickenbored]

my trans is full and the np203 used 75w-90 gear oil.  And I can visibly see the drive shaft jump up.

[74k20]

Oh NO, I feel for you.  Please keep me posted on what you come up with.  I drove my truck about 150 miles in the last 2 days, and still nervous about the t-case due to the MM501 kit just installed.  I actually crawled under and felt the 1 piece tail housing on my 203 and it was quite warm (almost hot).  I'm just hoping it's heat from the rather close exhaust pipe.

I thought we were suppose to use 10w-30 or 10w-40 oil in the np203.  Would the gear oil have been an issue?  Just wondering.

Keep the spirits up.

[beastie_3]

10-30 or 10-40 in 203!

[Captkaos]

Are you sure it was ok before the conversion?   I would definitely remove it and check it out before driving it again.

[frickenbored]

yea it worked perfect before the conversion but I only had the welded carrier in the rear axle for about an hour before I pulled the transfer case and trans, i'm thinking that welded rear end has something to do with it.  My guess so far is that either the rear housing bearing blew up, because I can see the output shaft jump up and down.  

the first problem is that I used a 501 kit in a truck that has an engine that produces 450 hp.  Even if i fix it I'm going to order the shaft kit next month and just elimnate all that stuff in the back half of the case.  I know its not the chain slipping because the chain doesn't move anymore.  Like I said I think its lack of lubrication to that rear bearing and doing 115mph with a welded rear end on a curvy road prob put a lot of unwanted strain on everthing.

As for the oil, I really don't know what to put.  I've read 10w-30, 10w-40, and 30w on the internet.  But in my college manual transmission and transfer case book it says to only use 75w-90 in a 203.  I'm not sure what I'm going to put back in it.

[frickenbored]

If it doesn't rain tomorrow, I'm going to pull everything apart and see whats going on.  Good thing I have a second 203 for spare parts and I kept my open carrier.

[VileZambonie]

Get rid of the welded spiders asap. You're just going to cause more harm then good.

Np203 uses 10w30 or 10w40

[beastie_3]

Get rid of the welded spiders asap. You're just going to cause more harm then good.

Np203 uses 10w30 or 10w40

x2

[frickenbored]

Yea I'm the welded carrier is going tomorrow and I'm going to put my open carrier back in.  The plan was to have this truck for mud bogging only but everything turned out so good that I wanna drive it on the road now too.  So they gotta go.  I still have my money on that rear tail house bearing blowing up.  Right now i'm using straight 30 weight. 

[frickenbored]

ok so now i'm really stumped, the mile marker kit is still looking brand new, I didn't take any bearings out everything looks like its in perfect shape, but it locks up in reverse.  I can turn the output shaft forward but not backwards.  I put the case in neutral and ran the truck in reverse and there was no problems so I know its not the trans.  As soon as I put the t case back in either hi or low it locks up in reverse.  Its gotta be something in the range box portion of the case because the output shaft is out and still brand new, the chain spins in both directions freely.  Anyone encounter this before?

[frickenbored]

alright heres an update, the truck is back together and working fine now.  I'm thinking maybe something got cought in the range box, I lifted the back end up, took out the mile marker kit and output shaft, opened the cover on the side of the range box, started the truck, and put it in reverse.  After it overcame whatever was locking the gears up it started spinning so I ran the truck at 2000rpm in reverse for about 10 minutes.  Then I put everything back together and put my open carrier back in the rear axle.  After I filled the 203 with 10w-30 and replaced the 80w-90 in the axle I drove it down the road in reverse four time.  Everything seems to be fine now. 

I drive it about 10 miles and no problems.  I was also thinking that maybe a bearing in the range box is going bad.

[thirsty]

If it were mine and I had a spare case I would just swap in now. I had good luck in the past with 203's and milemarker kits.

[frickenbored]

My spare case is a parts case, I've taken that one all apart and I keep the parts shelved.  I'm gonna leave it for now, its been fine all day.