transfer case locked in 4x4....sorta??

[ponytail]

ok. i was under the assumption there was 2wd option on the shifter. AWD says it all really. so the front drive shaft and axle will be spinning either way. so, what about the whole clanking problem. assuming loose transfer case chain? is there an adjustment or is it stretched? sounds just like a bad u joint but they are all very tight and sound seams to be coming straight out of t-case. also this may be same problem....when truck is accelerating it pulls smooth but when i let off gas it gains a good vibration. 4wd shifter shakes like crazy. hit gas and goes right away. this could be a sloppy chain as well? my first thought was out of balance drive shaft.......

[OrrieG]

The vibration could be the chain. Under acceleration it is tight, let off the gas and the chain gear and shaft are loose and "fighting" the main shaft through the internal spider gears. I could see how that would cause a vibration. You can check the chain by pulling cover #51 in the diagram below. Be careful when you remove it, there are a bunch of needle bearings that support the chain gear shaft. If I remember right I think you can partially pull it and see the chain. If it has an obvious sag or you can move it up and down easily with a screw driver it needs replaced. Your decision then becomes to fix it and put in a part time kit or go with another model of case. FWIW I rebuilt and converted mine to part time using a shaft kit in 1985 and used the truck as my DD, camping and hunting rig until 2000, putting about 8K miles on it every year. This build I looked at the chain it is still relatively tight.

[cabcorner]

My guess would be that the front drive shaft is causing the vibration.It could be the CV joint ,but i had one where the slip joint got a lot play in it and would vibrate at certain speeds. The clank is probably a combination of chain slack and all of the play in the drivetrain.I would agree pull the cover on the back of the case to see how loose the chain is. Use grease to hold the needle bearings in place for reassembly and remember to refill the case with 10w40 . Gear oil or tranny fluid will damage a 203.I have a parts 203 that the chain is so loose it contacts the chain case. The part time shaft kit that Orrie G refers to is no longer available new . Remember for normal driving you should lock in your hubs and run in the high position. Unlocking the hubs and driving in High lock all the time will eventually damage the internal coupling . I love my 203 but it does get complicated.

[ponytail]

oh yeah...i appreciate the diagram. man there is alot of parts there!

[cabcorner]

Mile marker i believe still offers a part time kit for the 203 but its a wedge kit that replaces the spider gears not the good shaft kit. Super winch made a kit that replaced the spiders with a crown gear,I don't know if its still available. You could install the part time kit with the case in the truck but doubt you could replace the chain without removing it.If you are looking for gas milage now may be the time to invest in a 700R4 -208 combo, Before you invest $300 into a 203. My 86 has a 305-700R4-208 with 3.08 gears and is decent on gas ,around 14MPG. Another option is to look for another 203 as people tend to give them away(around here $50-75)

[OrrieG]

You need to tear the case apart to replace the chain because the main shaft has to be pulled. Mile Marker does list the shaft kit model# 95-92203. Others that have installed it say it is identical to the original Doug Nash DNE2 unit from the 80's. The patent has been through several companies, apparantly MM is the current holder.