81 k5 build thread

[bhales]

i recently bought a 81 GMC K5 and have a question about some things.

the truck has 1 ton axles, a 350, Np205 Tcase, 6inch sus 3 inch body lift, and a t400 tranny.

when i bought the truck the rear drive shaft was out, and the transmission wouldnt shift. as i was unloading the truck off my trailer i had the gear selector in reverse and hit the gas and the transmission hooked. and i ran into the wall, i put it in drive and it went forward. i turned off the truck and pulled the transmission line to see if the pump was pumping. when i cranked the truck again nothing! the line will spit transmission fluid every now and then. I got underneath the truck and noticed the torque converter had washers between it and the flywheel ive never seen this.
Also the rear drive shaft doesn't have a slip yoke, anyone have any ideas of what to do?

 

[nvrenuf]

I've done the washer thing before on converter bolts. On mine, there was a 1.5"~2" hub at the center of the converter that was bottoming out on the flex plate before the two touched at the bolt bosses. I was told by the tranny builder to put washers between the two to prevent the flex plate from bowing and eventually cracking. I ran this for a long time under a lot of abuse with no problems.

Btw, I have a stock converter out of a running 400 if you want/need it.

 

[nvrenuf]

I forgot - look on the tailshaft of the 205 and see if it has a slip yoke or a bolt on yoke. If the slip yoke is in the tail of the t-case there wont be one in the driveshaft itself.

 

[BulldogK5]

The case probably has a slip yoke built in so no need for one on the driveshaft. You should do a SYE conversion if this is the case and from the sound of what you are running. Although I wouldn't put it too high on the list of mods since you have access to a trailer and could haul it out if need be.

 

[throttleissues]

Oh, the truck is hardly worth fixing, just have it shipped to my house. I'll do you a favor and dispose of it.

 

[bhales]

thanks, John i may need that converter, ill let you know later today.
i have a dumb newbie question what is the SYE conversion?

BTW, that truck won't go back on my trailer any time soon, it almost blew out both axles and all four wheels on the trip home the first time, this truck needs a HD trailer.

 

[nvrenuf]

SYE = slip yoke eliminator (kit). This would be swapping the slip yoke tail housing on the t-case (similar to a car set up) to a bolt on (fixed) yoke that uses a driveshaft with a slip yoke in it.

 

[bhales]

ok, thanks i check it already has a fixed yoke so i need to find a slip yoke driveshaft

 

[nvrenuf]

Ouch, a fixed yoke and a solid d-shaft. Yikes!

 

[bhales]

yea that's why i didn't put it on there, i don't think this truck ever got put back together after the 1 ton swap, the tires still have the little nubbs on the sides. i think he put the 205 and the 1 ton axles in and said to hell with it, or his wife made him sell it.there is to much odd stuff that doesn't make sense

 

[BulldogK5]

yea that's why i didn't put it on there, i don't think this truck ever got put back together after the 1 ton swap, the tires still have the little nubbs on the sides. i think he put the 205 and the 1 ton axles in and said to hell with it, or his wife made him sell it.there is to much odd stuff that doesn't make sense

Welllll, if neither the shaft or the case has a slip on it then the tires will have to take the place of that. Unfortunately for you new tires do not provide enough slippage but older tires that are slightly used and the same size as yours will. Fortunately for you I have such tires and I am willing to trade straight up with you in order to help you out with this problem (I hate to see a brother hurting to go wheeling) and I will even drive to you with said tires so you don't have to be put out.

 

[nvrenuf]

What a guy! Sounds like Ward is coming down to eat again!

 

[BulldogK5]

Sounds like a plan John. Ya'll just have to be there to help load and unload tires.

 

[nvrenuf]

I'm in as long as we keep the work to a minimum, gotta maintain my webwheeler status.

 

[bhales]

wow people on this site are willing to bend over backwards to help out!

 

[nvrenuf]

We're such a giving crowd.

 

[bhales]

hey John what do you want for that t 400 converter? i think im gonna order a driveshaft, by the time i have one cut and balanced here in town it's gonna cost about the same as ordering one.

 

[nvrenuf]

You can have the converter, I have another pidgeon holed in case I ever decide to run that transmission.

Disclaimer: it's a used converter out of a '79 K30 that was running/driving when it was parted out 2 yrs ago but I've never personally run it.

 

[bhales]

interior tear down pics

 

[nvrenuf]

Looks like a peach!

Watch those camper shell clamps on the hardtop, wouldn't want it to pop off like an F16 canopy while wheeling.