need some wisdom

76gmc

76gmc

Active Member
Joined
Aug 30, 2009
Location
K-vegas
Ok let me start from the begining here, i bought a 1976 gmc k15,350,turbo 350,np203, dana 44's..about a month or so after i bought it it started making a grinding sound and then the front of the truck would almost start hopping off the ground.. so i asked a guy at galloways 4x4 center and he says the np203 could be my problem because it is a full time 4x4 t/c. he also said that i would have to take the t/c apart and pull some kind of gears out and replace them with something..my question is do i have any other options? would an np205 solve the problem??help me please!!!
 
203s have a better low range than the 205 but I don't like chains in my TCs. The 205 is gear driven and stronger IMO. The 203s are bulky, long and a pain. Depends on if you're willing to give up a little low range for a hassle free TC.
 
is the 205 a better case or would they be about the same as far as power? how much trouble is it to install the part time convo kits? is it worth it to do so vs. buying a 205?
 
lower gearing = "more power"

the 203 has a lower final ratio than the 205 so you will feel a difference in "power"

the 205 is a stronger unit. which means more power can be sent through it and is less likely to break (like your current tcase is).

"better" depends on your point of view.
 
i deffinately dont want to loose my low end power but is it a very significant difference or just a slight one? and do u guys think my transfer case is to blame?? has anyone ever had any similar problems?
 
The 203 is a strong case. It is cast iron just like the 205 but is chain driven. The chain is the weak link but how hard are you going to be on it?. 203's can be found for cheap. The 205 has a low range of 1.96 to 1 compared to the 2.0 to 1 of the 203 so not much differance. If you get a part time kit get the one that replaces the rear shaft http://www.wheelindixie.com/forums/showthread.php?t=7968. I hear that if you replace just the gears in the tail shaft that it could cause oiling problems for the chain.

the easiest thing to do is replace the auto hubs in favor of some manual locking ones. Don't go cheap here. Get the Warn Premium's.
 
I put a part time kit in my 203. Did it under the truck. Engaged 4 wheel drive for about a 1/2 mile every fill up to lube rear bearing. Never had a problem in 5 years. Hammmered it best I could, but I only have stock 350/350 in front.
 
well see ive already got manual lock out hubs on the truck but even when the hubs are unlocked if the front drive shaft is in when u first start its fine but about 100 yards after u take off it feels like the front end of my truck is going to jump off the ground...but when the shaft is not in theres no noise or grinding..no jumping missing nothing..only when the shaft is in...ive checked my ring and pinion and all that is good so im guessing it has to be the t/c..right?
 
A unmolested 203 is made to be full time four wheel drive. No hubs manual or auto. The selector would have you choose high or low range and locked and unlocked. Inside tc is a differential that allows different speeds between front and rear driveshafts. If your tc is stock the front drive is going to spin all the time. If you unlock hubs the front drive shaft will spin faster than the rear unless there is a load on front. I think there is a problem with the front drive shaft, it doesn't like spinning real fast with out a load. Try locking hubs, in the unlock position(normal driving) everything should be fine, in the lock position(off road) steering should be affected because tc diff is locked out.
 
like i said when the drive shaft is connected it makes a gring sound and jumps...weather its locked in or not thats wat i dont understand..but ifthe shaft is out theres nothing no noise or anything..
 
It sounds like the tc is to blame.... not allowing for the different d-shaft speeds. It also sounds like your hubs aren't unlocking. The grinding , jumping and bucking is coming from the driveline binding up with all 4 turning.


Matt
 
have you checked the ujoints? failing ujoints can make it sound and feel like it is about to explode. if they are not bad remove the front driveshaft and see if the problem is gone. the springs in the hubs may have failed causing the grinding noise.
 
Make sure front and rear diffs have the same gear ratio.
 
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