ok i am first glad to say that the truck has passed inspection. Thankyou to all of you guys who helped me. Now i finally got a front driveshaft that fits. We got it out of an old Wrangler. the old driveshaft was okay but it had to much vibration to it. We locked the hubs then put it in 4 wheel drive and we started to go. i went a few inches then it felt like i was fighting the car. i gave it more gas and my back wheel went in one direction and the front wheels went in the opposite direction. some how one of the driveshafts is spinning in the wrong direction. did i maybe put the driveshaft on the wrong way or something. when we got out of the car the rear axle was at a pretty high angle and the rear driveshaft was bent at an angle at the yoke on the axle instead of perfectly straight. the axle was already at and angle but this angle was wrong. We put it in 2wheel drive and it corrected itself. My friend thought he saw the rear wheels go in reverse while the front wheels went forward. We never had this problem with the old driveshaft i dont believe. if anyone nows what it is id like to know how to fix it. thanks
joe

 

The drive shaft couldnt do anything like that. take it out of 4wheel but leave the hubs locked and look underneath to see if both driveshafts turn the same way, they should. What kind of t-case do you have?

Dave
http://www.davesmonsterpit.com/dmp31.gif

 

He's right, the driveline can't do that. I'm going to guess that if the front is turning one way and the rear is turning the other way, the parts are wrong. I'm guessing that maybe the TC is wrong for the front end. Ford made a high and low pinion and the high comes in reverse cut, I don't know if that means it rotates the reverse direction, but that sure would explain the problem.

What's the TC and what did it come out of and what is the front end (high/low pinion)?

 

im not sure what tc it is. all i know is that it has a granny gear and the drive shafts do both turn the same way which is clockwise but when i jacked up the front and rotated the tire myself the front driveshaft went counterclockwise. if that helps.

 

im not sure what tc it is but i know it has a granny gear for 1st gear. the driveshafts both turn counter clockwise but when we jacked up the front and turned the wheels my self the driveshaft turned counter clockwise in front while the wheels went forward so it went opposite. this never happened before with the old driveshaft though.

joe

 

Joe, let me make a few assumptions here. Correct me if I am wrong here on any of these.

You just bought an early 70's F100 with a 4-speed transmission. The transfer case does not have a low-range, only 2WD,N,and 4WD. When you got it home you tried out the 4wheel drive and noticed that it vibrated. Are you sure that you were in 4-wheel drive; did you climb any steep hills, or go through any obsticles that you could not do in 2WD to make sure the front end was pulling? It only takes one sticky hub to leave you in 2WD, and on some hubs such as Warn, turning the **** only loads a spring inside--the internal splines may not necessairly be meshed together.

Then you went to a wrecking yard and somehow found that a driveline from an old Wrangler was a match (OAL & U-joint size). You put it on and now the front end wants to go backward when you are in 4WD when you are trying to go forward.

Here is what I think happend, the person who had the truck before you put in a front end from a different vehicle that had a reverse rotation. When he realized what he did, he decided to take the easy way out and sell it. But he had to hide his mistake incase some potential buyer wanted to see if the 4-wheel drive works. He knew there was no "low traction" places in the area to test it, so he did a little work on the hub(s) to keep it from internally engaging when turned by hand.

Look over your old driveline carefully, it could be that the splines are stripped thus allowing the front axle half of the front driveline to rotate in a different direction than the transfer case half. You would not get any engine torque to the front axle, but you would get the noise you were hearing.

 

Its a 1978 f150 4x4. When we bought it it had no front driveshaft. we have not taken it offroad yet. but we did put a driveshaft in but it vibrated to much so we switched it out. We had to put it in 4 wheel drive to backout of the driveway sometimes when it had an engine problem. one of the tires was spinning in the grass so we put it in 4 wheel drive. i would put it in 4 high (4speed transmision, high and low with a granny gear for 1st gear) and then lock both hubs and it would back right out with no problem. the only problem we seem to have then was disengaging 4 wheel drive. we unlocked the hubs then had to drive forward a few feet then put it in 2wd. we then put the new driveshaft on and now have this problem. i dont know if the rear wheels or the front wheels are going the wrong way. today however i jacked up the front and rear driver side and locked the hubs and put it in 4 wheel drive. i could turn the tires so far but i got both to turn the same way when i did it by hand. but then when i lowered it and drove it i got the same problem. The rear axle in this case seems to rotate and ends up at a greater angle than before causesing the driveshaft to almost snap off. A few days ago i had to replace the u-joint to the axle on the rear driveshaft cause the bearings were shot but ever since then i have had this problem. that was before i installed the front driveshaft though. if this helps at all.
joe

 

Maybe your front axle has a different ratio than the rear which could cause some binding. For example maybe your rear has a 3.5:1 and the front has 4.10:1. If you drove the truck like this in gravel you would see the rear spinning like it was pulling something real heavy, and the front would act as if the brakes were applied just enough to cause it to drag a little. From the outside it might appear as if you were "power braking" (one foot on the brake, and one on the gas). On black top, the binding effect could easily give you "axle wrap", especially with light half-ton springs.

You can check for this mismatched ratio by jacking one side of the truck up with the hubs locked, but leave the transfer case in 2WD and main transmission in neutral. Rotate the front tire and record the number of driveline rotations in 10 tire rotations. Adding chalk marks on the tire & driveline will make it easier to see it come around. Do the same with the rear axle, again 10 tire rotations. Then compare the number of front and rear driveline rotations you recorded. I would have to guess that if they are within ½ a rotation of each other after 10 tire rotations, then this is NOT your problem.

BTW are all 4 of your tires approx. the same diameter?

 

When you jack up the front end, don't turn the tires, turn the drive shaft. I'm thinking if it's an open diff (most are) then that might change the direction the shaft turns, however if you turn the shaft, you'll know for sure. You don't even need to jack the truck up, just TC in N then get under and turn the shaft and see which way makes the truck move forward, you'll need to engage the hubs but this will tell you for sure which is which.

Again, the drive line can't change direction, it only transfers power.