I replaced all parts for the cad 4X4. My problem I finally figured out is that I have 15" vac going in to the switch in the transfer case but coming out only have 3" vac. Both sides are the same and it is a brand new switch. Is this normal since going up hill at times it will momentarily come out of 4 wheel drive?

 

This is exactly what mine was doing. I did not want to tear into the T-case so I moved the switch into the cab where the switch is now manually controlled by me.

 

Thanks Seal, thats what I thought I might do.

 

The threads on the switch are a standard bolt thread. I used an all thread nut and I welded a smaller nut to one end that a bolt can thread into. I removed the head of the bolt and replaced it with a ****. I also welded a mounting bracket onto the all thread nut. I mounted it down between my emergency brake handle and the hood release. A piece of advise is to make sure you are not loading the axle or going too fast when you engage it. The engagement does seem harsher than the original arrangement.

 

Seal, I put the vacuum hose from the canister directly to the axle and a gauge in line to test the system. I drop to 10" vacuum from 18" going up hill and the axle coupling still kicks over for a split second which makes a clunk then goes right back into 4 wheel drive. As of right now I don't have a line on the other side. I don't think this would cause the problem. I bought the truck used and it has always had this problem.

 

Sounds like you have a leak in the diaphragm or the housing of the shift motor. Get your hands on a handheld vacuum pump and hook it straight to the right nipple of the vacuum motor and see if it holds vacuum. Most parts hoses lend hand held vacuum pumps.

 

Well, upon alot of further investigation I have found that the transfer switch works fine. Took it out and manually checked it. Found out that the new vacuum lines make a big difference in how much vacuum you get at the axle. New ones were alot lower than the one old one that I had left over. Also found that the rubber plug at the switch was leaking a little on one connector, some teflon tape did the trick. The new hoses look a little bigger on the ID so I will get smaller hoses. At this point not sure if the arm in the transfer case is pushing the button up far enough. I discovered the hose problem and ran out of daylight. Even though the new hoses were tight they would not work. Put on smaller hoses and the transfer swich gives the full 18" of vacuum going up hill but still will get the minor clunk now(only on steeper hill). The splines on the axles look OK so I will live with this small annoyance.

 

I have figured out the answer to my cad problem so I am posting it in case anyone else gets a problem. I removed the front differential cover,drained the oil out of the front axles and found the intermediate axle has a little play (probably worn gears). I took off the fork mounting cover where the 2 vac lines connect and elongated the 4 mounting holes and slid the housing toward the front differential and now I have a very good coupling of the front axles and no more clunking. I could of taken the diaphram out and had another ring groove cut in but thats a pain.