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Transfer Case Swap

Discussion in 'Chevy Trucks' started by 3/4tonTodd, Dec 15, 2000.

  1. 3/4tonTodd

    3/4tonTodd Member
    Messages: 63

    I searched older posts and was surprised that I didn't find this mentioned - with the engine and tranny my truck needs, I was considering looking into changing to a part time NP205 transfer case. (I have the NP203 right now.)

    Anyone have any experience with this? If so, let me know the goods and the bads regarding this change.

    Thanks.

    Todd
     
  2. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    For as cheap as 73-87 Chevys are, a donor truck with this setup may be a viable solution to your dilema. They always want an arm and a leg at junkyards for trannys and transfer cases. Look at it as a parts truck. When something on your good truck breaks, just steal it from your donor. Then you have the time to fix it right and then put that part in. You may be better looking for a truck in the Spring, as 4x4 prices in the winter are inflated.

    Good Luck
     
  3. mike reeh

    mike reeh Senior Member
    Messages: 114

    or........

    you could install the part time kit in the np203.. personally, thats what Id do, especially if your 203 is in good shape mechanically. even if it needs a new chain, id buy a chain and the kit..

    else you will need the 205 case, a "stand" for the 205 case that goes between the trans and xfer case, and a 205 (or custom) driveshaft..

    this is coming from someone that prefers the 203 case. you will get other advice from 205 lovers.

    keep us posted..

    mike reeh
     
  4. 3/4tonTodd

    3/4tonTodd Member
    Messages: 63

    Thomas - I had considered the "donor" idea, but I don't have a place to put the extra truck, and the city recently passed an ordinance on having "junk" vehicles on your property. I even know a guy whose dad is getting rid of one, but the guy still hasn't given me any kind of price on the thing.

    Mike - I know VERY little about transfer cases, other than how to tell the 203 and the 205 apart (Thanks go to Chuck's pages for teaching me this!!) and that one is full time and the other is part time. I have an extra question for you - my truck has lockouts on it, but the front driveshaft spins all the time. My guess is that this case does NOT have any modifications to it. But then again, why would someone go to the trouble of putting in lockouts but not the part time kit? Also, what are the consequences of leaving the lockouts in the "free" position even though that front shaft spins all the time?

    Thanks

    Todd
     
  5. mike reeh

    mike reeh Senior Member
    Messages: 114

    Well im not an expert on xfer cases, its just that Ive dealt with a few 203s and 205s..

    Ive seen locking hubs put on a full time truck with no other mods a few times.. the main reasons are probably:

    a) they think it will reduce tire/driveline wear
    b) they think it will improve gas mileage
    c) they think thats all it takes to convert to part time
    d) they already have problems with worn frontend stuff


    in reality it doesnt make a diff. on your gas bill.. I could see it reducing wear on the two front tires, but when I had a full time truck, the tires wore so perfectly and even, it was almost a benefit. I never noticed any harsh handling characteristics.



    let me ask you this: when your hubs are in the FREE position, you have to drive in hi LOC or lo LOC right? (shifter all the way forward or all the way back) If not, then you DO have the part time kit installed. if the hubs are unlocked, and you're just in regular HI or LO range, then the differential in the 203 case thinks you are hanging off the edge of a cliff, or something. in other words, the front end has zero traction, and its giving all power to the front end, and you go nowhere... just like an open differential in a rear end. the tire with the least traction spins every time.

    so...... in order for you to drive, with the hubs unlocked, you have to have the xfer case in LOC mode, which spins the front drive train ANYWAYS.. the only difference is the power stops at the end of the axles, instead of being transfered to the ground.. I dont see the point really. the full time is safer.


    if you DO have the part time kit installed, it is normal for the front end to spin while you're driving.. some more than others.. its just grabbing for whatever reason.. kind of like how if you jack up a car and its in neutral the wheels will still spin while the engine is running.

    well hope i didnt confuse you more than anything.. anyone have anything to add?

    ps- the reason I like the 203 case so much is because 1) Ive seen zero 203s fail under abuse, and at least one 205 fail. Its not an issue of strength.. they are probably the two strongest stock cases you can use. and 2) the 203 shifts so much nicer!! it actually clicks between gears... maybe ive only shifted old worn out 205s or something but its basically a matter of trial and error, and luck when trying to find 4, 4 lo, etc.

    mike reeh
     
  6. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Just a funny tidbit... I had a '76 K10 Silverado Pickup w/o air and with a 3speed on the tree (manual)(very rare) 3.08:1 gears and 32x11.50 BFG's. It was tough to pull out on a hill, so I would shift into 4LO on my 205 transfer case at the traffic light and start in first gear. Then let off the gas and slip her into 2HI, then on to 2nd and 3rd!!! I used it like a granny low until I got the granny low HD 4speed later on.

    I have a 203 in my 75 Suburban and love it for plowing. If it is slightly dry, you dont bind up the driveline on pavement. If the going gets tough, one click into Loc. If it really gets bad, there is lo range, but with 4.11:1's and TH350 and small tires, 4LOW is rarely used.

    I also have Warn Hubs because it used to have the conversion in it, took it out, but left the hubs on.
     
  7. 3/4tonTodd

    3/4tonTodd Member
    Messages: 63

    Mike

    I do NOT have to shift into LOC to drive with the hubs in the FREE position, so I guess this means I have the conversion. (That'll save me a few bucks, I guess, huh?)

    Ok - how about the "clunk" that sounds like U joints? I have all new u joints (except for at the wheels) so I'm thinking this "clunk" might be on the slip yokes (front or back or both). Unless it is something in the transfer case?

    Thanks again!!

    Todd
     
  8. mike reeh

    mike reeh Senior Member
    Messages: 114

    Yep. sounds like the conversion has already been done.. thats a good thing, the way I see it....

    about clunking.. put the trans and transfer case in neutral and then use your hand and move the front driveshaft back and forth while watching the axle u-joints in the front end (near the wheels)

    in my experience, its always those that cause the clunk.. but obviously driveshaft ujoints, transfer case chain, slip yokes, and ring & pinion play can have something to do with it.. I guess you might as well check all those while youre at it?

    mike
     
  9. 3/4tonTodd

    3/4tonTodd Member
    Messages: 63

    Mike

    Ya made me laugh, anyway, but I really don't want to go through and check ALL that stuff!!

    I guess I either check it or live with it, though.

    Thanks!!

    Todd