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Old 03-05-2017, 10:48 PM   #1
adis
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N203 Slop

i took the TC out of my K20 to rebuild the trans. im debating on rebuilding the 203 since it's out and i have no idea what shape it's in. all i know is that it's got a part-time kit in it, other than that, i've only put about 100 miles on the truck since i bought it and that was in rwd. so, the first thing im looking at before i tear into it is the slop between the shafts. between the input and rear output shafts it seems pretty tight - about 5* of play. between the input and front output shafts there is a lot more - like 28* of play (a little more than 1/16 of a turn. ) does this seem excessive? if i need to replace the chain, i'd consider a 205 swap. but if this is an acceptable amount of play, then i'll go ahead with the rebuild. any thoughts/advice is appreciated. - mark
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Old 03-06-2017, 12:08 AM   #2
sweetk30
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Re: N203 Slop

if planning a 205 swap what trans now ?

if th350 then your fine 203 AND 205 use same tail shaft in trans .

if th400 there each specific to 203 OR 205 OR others.

so before reman on trans make sure you know what t-case you want to run .

I don't rebuild whole 203 cases . just the range box units then bolt them to a doubler kit and 205 in the back .
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Old 03-06-2017, 09:43 AM   #3
adis
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Re: N203 Slop

thanks for the reply, Sweetk30. i dont really want to swap in a 205. optimally, id prefer to just inspect the 203 find that it's in good shape, replace seals/gaskets and put it back in. i only mention a swap because of the cost to repair the 203 if it needs a new chain or new hard parts. i'd think seriously about the swap if i must do repairs that would cost more than the cost of a rebuild kit with bearings. the truck's just a crappy work truck, but i want it to be reliable. ive already rebuilt the t350 - including mods - so it's staying.
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Old 03-06-2017, 02:31 PM   #4
andyh1956
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Re: N203 Slop

Be aware that you can shorten that chain without even taking the TC totally apart & it will NEVER slip again!
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Old 03-06-2017, 11:35 PM   #5
adis
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Re: N203 Slop

Andy, i did not know that you could shorten a stretched chain - do you have any (web) links for that procedure? (no pun intended). i guess my next question is how much play should there be with a serviceable chain? also, what are other causes of slop in the case - such as worn sliding clutch gear or differential carrier teeth? does the range box ever produce slop - its all gears, right? the play between my shafts is the same in both high and low, so i presume thats not the problem. how about the part-time kit locking tabs, do they wear out? also, how much does endplay result in sloppiness? i cant imagine a few 100ths of an inch of endplay causing more than 25* of slop between the input and front output shafts. again, thanks for any insight.- mark
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Old 03-07-2017, 01:15 AM   #6
bilfman
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Re: N203 Slop

Remember 203 use light oil like 10-30w. Do not use gear oil. Also some cheap insurance when converted to part time is use some pipe to extend the filler hole up another couple inches, gets more oil in the case to keep the rear splash lubed when not engaged.
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Old 03-07-2017, 10:58 AM   #7
B. W.
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Re: N203 Slop

Andy is "yankin' your chain!" (pun intended) If you remove a link (difficult on a hy-vo chain) your chain will be too short to re-install.
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Old 03-08-2017, 02:20 PM   #8
andyh1956
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Re: N203 Slop

Quote:
Originally Posted by B. W. View Post
Andy is "yankin' your chain!" (pun intended) If you remove a link (difficult on a hy-vo chain) your chain will be too short to re-install.
That's partially true. You only remove "Half" a link.
Tutorial- 1st remover the front output assy & the rear support for same. The chain will be hanging down. Next grind of two of the brads (Next to each other) that hold the links together & push them out & that link assy will fall out. It will come out in a bunch of pieces, Next take the outside links & shorten them in half. When you re assemble the chain you are only gonna use half of what came out. Re-insert the brads (I think only one brad is used now that I think about it) that hold the links together & you apply a little brass on the ends to keep it from coming apart. When re-assembling you will need some stout line up bars to pull the output & rear support back into their respective bores, it aint easy.
Now, this procedure won't work on a chain that's in good condition, it REALLY has to be wore out & slipping all the time to use this. I can assure you I'm not yanking your chain (Pun Inteneded???)
Back when NP203s were as common as np241s are now this was a regular weekend deal for trucks, but that HAS been a long time ago!

PS- adis a problem for you using this tutorial is that you have a DN kit in your case & the chain is not used unless in 4wd. So you can't really tell how much stretch your chain has unless you go back to full time 4wd & see. But you never forget the NP203 chain pop sound!
Your 03 has a differential in it just like in the front & rear axles, it's just turned sideways 90 degrees. It "Differentiates" between the front & rear axle. Just like the third diff in an 18 wheeler set of drive thru tandems work (Called the Power Divider) The DN kits had a, for lack of better terms looked like some diff spider gears all welded together that replaced the 203 spiders in the diff. They wouldn't rotate & the kit did away with the full time feature & let you select a "Lock" position for 4wd, can't remember if the 2wd mode was the old neutral or what now. That big housing on the output of you 03 is where the diff is located. Sorry if all this is confusing, I'm not a good orator...

Last edited by andyh1956; 03-08-2017 at 02:40 PM.
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Old 03-08-2017, 02:32 PM   #9
B. W.
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Re: N203 Slop

Never heard of that! Learn something new every day! I still think I'd just replace the chain though.
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Old 03-08-2017, 02:42 PM   #10
andyh1956
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Re: N203 Slop

Quote:
Originally Posted by B. W. View Post
Never heard of that! Learn something new every day! I still think I'd just replace the chain though.
Oh I think I would too now.
You learn how to do stuff like this from being POOR!
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Old 03-09-2017, 09:44 PM   #11
adis
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Re: N203 Slop

Andy, thanks for the insight - its great to learn things from people who are willing to share their experience. i think you've hit the nail on the head - i think im going to have to put the TC back in and drive around in 4wd for a while to get a feel for what shape the chain is in. but i am NOT looking forward to having to drop that thing again...
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