Uh Oh.....is a 1973 Blazer full time 4WD and how do I tell if it isn't....and what do I do if it is?
CK5
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4WD on 1973 K5 is it full time?
- Thread starter Chief Brody
- Start date
If it's an auto, that's the first year for the full time transfer case (NP203).
Nothing to worry about really, it's made to be run in 4WD all the time. It's a less desirable case than some others because its big, heavy, doesn't have a very good low range and can have issues with the chain.
But in normal use it's fairly reliable and nothing to worry about.
Nothing to worry about really, it's made to be run in 4WD all the time. It's a less desirable case than some others because its big, heavy, doesn't have a very good low range and can have issues with the chain.
But in normal use it's fairly reliable and nothing to worry about.
How can I physically tell what it is ...NP203...or what...it has a gear shift on the column and one on the floor....
The t-case shift lever will say 2hi - 2hi-loc - n - 4hi - hi-loc or something like that if its a 203
if that's the case...I am guessing that standard around town driving would be done in 2 hi ? What id thee is a Neutral or 1:1
StevoandaRedK5
1/2 ton status
Stock, a 203 is (From front to back): Hi-Loc, Hi, Neutral, Lo, and Lo-Loc. If it's all factory and has the drive slugs up front, leave it in Hi for the street. I drove mine like that for quite a while til the chain decided to stretch out. Kinda nice to have in wet weather.
Drive slugs?
They are 1 piece hubs , used in place of manual locking hubs on full time cases.
http://www.longfieldsuperaxles.com/products/DANA-60-300M-35-SPLINE-DRIVE-FLANGE-KIT.html
rufusbooth
1/2 ton status
best way to tell is to look at the circular ID tag on the transfer case. This will identify the transfer case. The other thing you can do is post pictures up of the back of the case and we should be able to identify it.
Second thing you need to do is determin if the case has been "converted" to part time. This is a very common practice for a 203.
First question is do you have manual hubs on the front wheels? If you do not have manual hubs (chrome covers with no free/lock knob) It can be safely assumed that you have the full time 203.
Second, if you do have manual hubs the conversion may or may not have been done in the transfer case. the way to check is to set your manual hubs to "free" and then try to move the truck in either the "Lo" or "Hi" position. if the truck does move then the transfer case has been converted. If the truck feels like it is in neutral and will only move when the transfer case is in either "Hi Loc" or "Lo Loc" then someone installed manual hubs and then did not properly convert the transfer case to part time.
Let us know what you find out and then we can tell you some the the "special care and feeding" that the 203 requires depending on if you have the conversion or not.
Cheers,
Rufus
Second thing you need to do is determin if the case has been "converted" to part time. This is a very common practice for a 203.
First question is do you have manual hubs on the front wheels? If you do not have manual hubs (chrome covers with no free/lock knob) It can be safely assumed that you have the full time 203.
Second, if you do have manual hubs the conversion may or may not have been done in the transfer case. the way to check is to set your manual hubs to "free" and then try to move the truck in either the "Lo" or "Hi" position. if the truck does move then the transfer case has been converted. If the truck feels like it is in neutral and will only move when the transfer case is in either "Hi Loc" or "Lo Loc" then someone installed manual hubs and then did not properly convert the transfer case to part time.
Let us know what you find out and then we can tell you some the the "special care and feeding" that the 203 requires depending on if you have the conversion or not.
Cheers,
Rufus
what exactly does the "loc" mean on the tcase? i know my 76 has the 203 cuz my tcase is the same way with the hi loc, hi, n, lo , lo loc. but i have no idea what the differences are
mine has the selectable hubs as well.
mine has the selectable hubs as well.
rufusbooth
1/2 ton status
It totally depends on if the transfer case has actually been converted to part time or if the manual hubs were installed without converting the transfer case.
If the case has been converted.
Hi Loc = 4x4 high range
Hi = 2x4 high range
N = Neutral (of little use other than theft deterant or if you have a PTO)
Low = 2x4 Low range
Low Loc = 4x4 Low range
If the transfer case has NOT been converted and you have manual hubs.
With hubs in the locked position
Hi Loc = 4x4 High range with center Differential locked (used on limited traction)
Hi = 4x4 High range with center diff open. (Full time 4x4 for use on high traction surfaces)
N = PTO Output
Low = 4x4 Low range with center diff open for high traction surfaces
Low Loc = 4x4 Low range with center diff locked (for low traction surfaces)
With Hubs in free position
Hi Loc = 2x4 High range (Hard on transfer cases)
Hi = Neutral Truck wont move because center diff has not been disabled
N = PTO Output
Low = Neutral Truck wont move because center diff has not been disabled
Low Loc = 2x4 Low range (hard on transfer case)
Hope that helps. you can run the test I suggested above if you want to see if the transfer case has been converted.
One thing to keep in mind is that when a transfer case is converted you should put the case into Hi Loc every 500 miles or so (no need to actually lock the hubs) Run it for about 10 miles then go back to Hi. This lubricated the rear output shaft. when converted these cases can have lubrication issue if they don't see 4x4 every 500 or so miles.
Cheers,
Rufus
If the case has been converted.
Hi Loc = 4x4 high range
Hi = 2x4 high range
N = Neutral (of little use other than theft deterant or if you have a PTO)
Low = 2x4 Low range
Low Loc = 4x4 Low range
If the transfer case has NOT been converted and you have manual hubs.
With hubs in the locked position
Hi Loc = 4x4 High range with center Differential locked (used on limited traction)
Hi = 4x4 High range with center diff open. (Full time 4x4 for use on high traction surfaces)
N = PTO Output
Low = 4x4 Low range with center diff open for high traction surfaces
Low Loc = 4x4 Low range with center diff locked (for low traction surfaces)
With Hubs in free position
Hi Loc = 2x4 High range (Hard on transfer cases)
Hi = Neutral Truck wont move because center diff has not been disabled
N = PTO Output
Low = Neutral Truck wont move because center diff has not been disabled
Low Loc = 2x4 Low range (hard on transfer case)
Hope that helps. you can run the test I suggested above if you want to see if the transfer case has been converted.
One thing to keep in mind is that when a transfer case is converted you should put the case into Hi Loc every 500 miles or so (no need to actually lock the hubs) Run it for about 10 miles then go back to Hi. This lubricated the rear output shaft. when converted these cases can have lubrication issue if they don't see 4x4 every 500 or so miles.
Cheers,
Rufus
StevoandaRedK5
1/2 ton status
So if the tcase isn't converted what makes running the hubs free hard on the tcase?
Thanks a bunch for write up helped a bunch.
Thanks a bunch for write up helped a bunch.
When do you manually lock or unlock the hubs? If I want 2 wheel drive do I just select Hi or Low, or do I need to unlock the hubs and then select Hi or Low?
I'm assuming you mean your T-case is converted. The hubs need to be unlocked for 2 wheel drive. If you expect to need 4 wheel drive you can lock the hubs and run in Hi or Lo, then move to Hi Loc or Lo Loc when you need to. I've never had a converted 203, but I think you need to periodically run a few miles in the loc position to lubricate part of the case.
bridgeguy
Registered Member
That's exactly right, actually. Functionally, when you convert the 203 you are changing the way it works from how it was designed and it does not get adequate lubrication while running in 2WD.
On the 203 I FINALLY got out last night, it didn't have a round tag (someone mentioned that in an earlier post), it was a purty rectangle...under about 1" of who knows how old mud but at least the build date matched up to the '74. The PO apparently had some fun with it as I have yet to have this pig moving under it's own power so I can't take the blame for not cleaning it up.
As for heavy? The 203 and TH350 together are just STOOPID heavy. As this was my first experience with the '74 crossmember, more than a few choice words were used and yes, tools did get airborne with sufficient impetus to make them transverse vast distances. I did successfully find most of them again however.
I am NOT a fan of the 8-bolt crossmember. I hope I never have to deal with that again...especially with the engine out as trying to balance the trans and transfer case on a floor jack while monkeying around with that crossmember just sucked. Really, really sucked.
It was one of the most unweildy things I have ever done...that's why I put it back in with the transmission on the engine and the transaxle on last...it was still very, very difficult...and that crossmember is tough to get on and off...the upper bolts on the frame are only accessible by flat wrenches and stubbies...
