Front Drive Shaft Binding

[cgbexec]

I posted this last week and did not really get a good answer. So now I am going to ask a different question for the same problem, but first I am going to give you the specifications and tell you what I have done so far.

1976 Bronco (V-8)
New NV3550 (5-speed manual) coupled to stock rebuilt transfer case mounted in the stock clock position.
3.5" lift (Bullit Proof) suspension system from Jeff's Bronco Graveyard - this kit comes with the Fabritech extended radius arms.
I ordered a brand new rockwell front drive shaft from JBG and installed it. It binds and will not turn more than 1/8th of a revolution.

1) I removed the brand new rockwell front drive shaft.
2) I used a dremel and removed as much metal as I dare in and around the cartigan joint (double u-joint).
3) I loaded the front end of the frame to drop an additional inch to similate real world running weight. (This is a frame off. The frame has the full weight of the engine, trans, transfer, axels, tires. I am 250lbs and I can climb on the front of the frame and the suspension compresses less than an inch.)

The drive-shaft will now turn about 1/4 of a revolution before binding. I could force it and get it turn without breaking, but any droop or bump would certainly break the driveshaft.

Who would you order a new drive shaft from that can build a drive shaft to work at this angle? This truck will likely see only a little off road duty, but when I do, I don't want any trouble.

 

[doran4x]

What size u-joints are you using? If you are running the 1350 joints that might be your problem.

Tom

 

[cgbexec]

I ordered the shaft from JBG. I purchased the lift from them as well. They are rockwell shafts. I don't know what size u-joints they are using.

Chris B.

 

[cgbexec]

Here are the pictures.

 

[bob_lafrentz]

Hard to say what is going to happen when you get everything put back together. I'd wait till then.

Its that low pinion front differential that is killing you. I have a NV4500 and an Atlas and a low pinion D44. Nothing I could do could resolve the binding issues. With mine, I could spin the drive shaft without any problems on level ground, but a half inch of droop and I was where you are now.

After tons of research, I found only two solutions that did not require me changing the drivetrain around. There were 1) the offset ujoint from Tom woods or 2) a 42-degree CV joint from High Angle Driveline with a toyota u-joint at the diff. #2 is what I went with and I am very happy I did. Very pricey though.

Good luck!

 

[welndmn]

I still say wait until it done with full weight on it.
But Yes add the Tom Woods U-joint to the pinion end will help.
Even going to a 1310 Non-CV shaft will take some bind out of it, and you can run the woods joints in both ends.

 

[cgbexec]

I did not expect to have this much trouble with a 3.5" lift. I don't like the idea of wait and see. If I load the suspension to where it does not bind, then when I un-load the suspension such as you would do off road, then at that point I can break the front drive shaft. I don't think I like that idea. I have contacted High Angle Driveline. Hopefully they can build a shaft that can handle it.

Thanks for the tips.

Sincerely,

 

[73stallion]

sorry to hijack, but how much mod did you have to do to get your J twin sticks to work with your NV3550?

back to your thread, a lot is going to change when you get your body back on. just wait till then and don't be bothered by it right now.

on another note, you may think about waiting until the body and everything is on until you order your driveshafts. i'm willing to bet you're going to bottom out your slip yoke just by installing the body and everything. been there, done that...

 

[cgbexec]

The NV 3550 w/ Twin sticks was not that hard to install. I used a dremel with a cut-off wheel to modify the shift rails per the instructions. The hardest thing was re-drilling the twin stick mounting block for use with the J-shift transfer case. This block is drilled for the T-shift case. I had the proper tap set, so I just had to line everything up just right before I decided where to drill the new hole. I also had to cut down the transmission shift lever at the base where it fastens to the transmission shift shaft. The rear drive shaft stick (inner of the twin sticks) was hitting the transmission shifter when it was in 1st gear. By cutting down the transmission shift lever base about 3/4" it allows the rear drive shaft transfer case shift stick to clear the transmission shifter by about 1/2 of an inch when I shift into 1st gear. The rest of the gears of course move the shifter farther away from the twin sticks. The only other thing is that you have to mount the transfer case in the stock rotation for the twin sticks to work without doing major modifications to the twin sticks. The directions say there are only two clock positions. The adapter ring is drilled for 3 clock positions. The middle position is the stock position. I tried all 3 positions and the only one that would work with the twin sticks was the middle position. I can't wait to drive this thing. The 3 on a tree was unbearable. 1st gear was just too high and 3rd gear was too low. I drove my brothers Jeep Wrangler with this very same transmission and liked it very much. 1st is low enough, but not too low and over-drive should make the highway bearable. I realize that the Jeeps 6 cylinder engine won't be the same as a 330 h.p. small block, but I think I can handle it.

I don't think that mounting the body on the frame is going to compress the suspension more than an inch or so at the most. With my 250lbs on the front of the frame compresses the suspension less than an inch. If I climb on behind the motor the compression is less about 1/4 of an inch. The body is going to have its weight spread out over the entire frame. The 23 gallons of fuel in the rear is actually going to uncompress the front suspension to some degree as 23 gallons x 6lbs. per gallon = 138 lbs. hanging behind the rear axel.

 

[NYLES]

I like bobs #2 or some variation of....

 

[73stallion]

good to know, thanks for the pointers. who's twin sticks do you have?

 

[chuck]

At full droop you should not bind the shaft. Changing the pinion end U joint will do nothing for the bind at the t-case end.
Do you have stock motor mounts?
What degree C bushings did you use? Are you sure they are in correct? Could the heads of the long arms be in upside down?With stock arms and a 3.5" lift there should be no driveshaft bind and a longer trans and long arms should be even better so this whole problem comes down to 1 of 2 possible causes 1. you installed something wrong or 2. the arms were made wrong.

 

[welndmn]

Whats the height of the coil?
From top of the coil, to bottom of the coil.
A 3.5 inch spring should be sitting at 15-16 inches.
Suck it down to there and then drop the drive shaft and see what it looks like.

 

[73stallion]

now there's an idea. use a couple of ratchet straps to draw the suspension down to ride height and see what the deal is then.

 

[kontinu]

I had binding on my front driveshaft. I was able to turn it a little then I would feel resistance. I figured since I could turn it by hand that that slight bit of binding wouldn't be a problem. Well I was wrong and broke a u-joint cap. I got a new ujoint and then took it out again and broke the cv collar. The third time I ground out a lot of metal and now it spins freely.
I really didn't offer any help to your problem but I can tell you it WILL break if you drive it.

 

[chuck]

The driveshaft should not bind any with a 3.5" lift, even at full droop. If you can jack the body up until the front wheels clear the floor and the driveshaft binds even a little you will break the cardon joint.

 

[SaddleUp]

This is the second thread where I have seen it suggested to wait until all of the weight is on it to check for binding. That would be fine if it never ever articulates at all. I.E. It would be good for driving straight down the road and nothing else. Simply going around a corner is going to stretch it out. As Chuck mentioned above instead you should stretch it out as far as possible by jacking up the body and letting the suspension droop. Then see if it binds there. If it's binding when any weight at all is on the body (as has been mentioned) then there is no question about it, it is not going to work.

I have seen 2 cases where everything was put together properly where there was no question that it was going to bind no matter what. In these cases Ford originally put regular drivelines in without CV joints. These appear to be rare as most of them had CV's. When this occurs the frontend is tilted back further right from the start because the u-joints need to be parallel instead of pointing the pinion at the t-case. Lifting them increases the angles at both ends and then adding in some extra castor makes it worse as well. I'm not sure if that is the case with this one (Looking at the angle on the frontend it looks like it may be) but if so then the only fix without changing the frontend may be to use a regular driveline without a CV joint. Note: On one of the ones I've seen like this the history of it is known so we know it came from the factory that way.

Keep in mind that when you use a CV the pinion should be pointed straight at the transfer case. (Minus one or two degrees) If it isn't then there will be excessive u-joint wear. Most of us live with a small difference from this since it's on the frontend where we will only use it at slow speeds but the angle on this one is pretty excessive.

 

[bigmuddy]

I had a similar problem when I installed my ZF tranny with the low pin D-44 and cage long arms and had some major binding. The fix is to run 1310 u -joints in a 1330 CV joint. I know a couple of guys that are running this setup in their competition buggies and have yet to blow them up and that is going on a second year of competition. It's a whole lot cheaper than a 42deg shaft, yikes!

Ben

 

[bigmuddy]

I should have added that I purchased mine through wild horses and it works like a champ.

Ben

 

[scsm76]

You said you have long arms, what c-bushings are you running? If you have 7° bushings then you have turned the axle back to much. I'm not sure how much caster is built into the JBG arms, but I would find out. The extra caster in the front end won't hurt anything since Bronco's typically have to little, but when you increase the caster angle you also rotate the pinion down. Many people have switched from standard D44 to HP D44 or cut the knuckles losse and rolled them back to allow a steeper pinion angle and still have good caster, but usually not until 4.5" or greater lifts.