Since you now have the shaft off though, I assume it checked out ok and the u-joints and any slip-joints (if applicable) are tight, move freely and smoothly, and otherwise don't act all weird?

Paul

 

Ya, the U joints and slip-joint is new. Now that the drive shaft is off, I will recheck my measurements and see if they are any different than the 7 degrees. As to your question above, Yes, the truck when sitting on the ground is how I took the measurements. Im sure there is an allowable amount to be off, do you know this amount? I can probably shim with tapered spacers , the front axel to change out the angle to match the 90 degrees of the transfer case.

 

If I remember my old teachings (mostly from reading articles in magazines for what that's worth) it was hoped to get them around 2 to 3 degrees from parallel.
This gave a good starting point from which to move (axle wrap mostly) without going too far one way or the other.

But there is also a reasonable operating range for the u-joints as well. So two perfectly parallel yokes that are too far apart (think lifted truck vs stock) for a given shaft length and you run outside of the good operating range for the joint. I believe that was something more along the lines of 9 to 13 degrees. Maybe you can check that aspect too while you're at it with the angle finder.
I believe that the joints had something just over 20 degrees operational angle near to binding. Obviously that's a max, not anywhere near an optimal running range. That's still back down near that 10 degree area, and within 2 to 3 degree offset from each other.

All this is just memory though. I can practically guarantee there's a chart somewhere put out by a driveshaft company, or a youtube video with full descriptions.
Now I've got myself all curious and may just try to hunt one down.

Paul

 

 

When I lifted my '96 Chevy K1500 the blocks that came in the kit had the typical angle cast into them too. In most older trucks, installing them as expected (with the narrow end forward, to tilt the pinion up) worked perfectly. With mine however, it had the opposite effect and simply turning them around so that the thick end was forward was the perfect cure. Luckily I saw the problem before driving it, but that means I never had a chance to experience what exactly it would do.

This was a 6" lift and pretty sure the driveshaft was a single-cardan, single shaft arrangement. Super huge diameter at least partially aluminum thing right from the factory. Not one of the multiple piece setups we deal with a lot on the heavier trucks.

Paul

 

That change in angles at the transfer case is a U joint killer. U-joints change speed twice each revolution, input to output. The greater the angle involved, the greater that cyclical change. The axle end looks pretty mild, looks OK.

Also, how do the small U-joints in the axle ends appear. Some people never service them or give them a shot of grease.

 

Look forward to hearing the report from the shop. The shop I was to take mine to was too busy for me, so it didn't happen yet. It will be a while, since I had foot surgery, not driving for a while. Mine does not have the angled lift blocks. When you get the angles right at the transfer case and the axel, pass them along. It will be interesting to see how far mine is out compared to yours.

 

Interesting that you had to flip the shims the other way. Would have been good to know what they are at now, angle wise.

 

we tried adjusting the angles with no luck. We ended up going with a double cardan drive shaft. Problem solved.

 

As an update, still not 100% sure yet, what the problem is. I did take the truck out for a longer drive a week ago and with it in 2wd and hubs unlocked, I heard that same noise but very faint and could feel a bit of vibration in the transfer case selector. This was also during deceleration, so Im now thinking it may be a bearing in the transfer case all along. Now that the weather is getting better, I will be pulling it off and checking out the transfer case to see the condition of the bearings and such. I needed to change out seals and gaskets anyway.

 

A vibration in the shifter is still often a driveshaft issue. That's how you feel it because that's what's sticking into the cab. But because everything is connected you can feel things through the shifter that are going on elsewhere. A driveline vibration is literally whipping the end of the transfer case around and it's being transmitted into the gears and gearbox and all of it's component parts.
I'm not saying it can't be inside the t-case, but just that a driveshaft vibration is certainly going to be felt most easily in the transfer case shifter.

And your angles are bad/wrong no matter how you look at things. So while you might have issues with other components in the truck, your driveshaft is still a prime suspect.
It's wrong and you have to correct it or all the rest of your diagnosing will be based on potentially false information.
If correcting it means having a double-cardan shaft put together like paulstruck did (and like Ford did on trucks that were too hard to dial in with a single cardan shaft), then that's what it will take.

Paul

 

Paul. I totally understand, but this sound was happening also with the hubs unlocked and the t-case in two wheel drive. This should eliminate all that is happening with the front drive shaft I would think. With the truck having a 6 inch lift, Im hoping to drop it down 2 inches and hope that will solve some of the problems with the angle of the drive shaft. I replaced the front drive shaft with a new one, "two inches longer" but that being a single carton, do you think a double in a stock length from the factory would be long enough with the 4 inch lift vs the 6 inch lift? I may try to see if I can find a good used original length one if possible to try out. You just don't see many pop up for sale.

 

Sorry Cougar, I totally spaced out on the pictures and thought they were of the rear driveshaft. Of course you are correct that with the hubs unlocked, or the shaft removed, any remaining funny vibrations would be from somewhere else.
But my whole mindset is that your issues are with the rear driveshaft anyway. Didn't we see images of that? I'm not seeing them in this thread right now, so maybe I'm thinking of someone else's discussion.

As for stock shafts being long enough for lifts, it's an individual truck thing. Most short wheelbase Early Broncos for instance do not need longer shafts up to 4" lifts, but after that they almost always do in the rear. But the front is hit or miss.
For the longer wheelbase trucks, it depends on the shafts, but I've done many a 4" and 6" lift with no need for longer shafts at either end. While on some it was absolutely necessary.
The only way to tell is to measure your yoke-to-yoke distance with the truck at ride height.

I don't know what the differences were in each case, because even Ford used different design setups on long vs short wheelbase, standard vs super cab, etc.
But aside from the length, even with stock being ok, the angles are still subject to the same laws. If you have a single-cardan setup you must match the front and rear u-joint angles to within a couple of degrees or you will have a vibration. On a double-cardan shaft you can get away with odd angles, but the single joint end still has to point almost straight up into the driveshaft. In other words, all the previously discussed rules still apply.

Obviously the front is only important if you lock the hubs or put it in 4wd. But the rear is critical all the time.
If you have not already, can you post up some pinion and shaft angle images of the rear shaft on your truck?

Thanks for indulging me on my vibration kick!
Sorry about the misunderstanding of which shaft I was looking at before.
Won't happen again... Yeah, right. Not for a day or two maybe!

Good luck.

Paul

 

Thanks Paul, I really appreciate your input. If it's not raining tomorrow, I will drop the drive shaft and take some measurements and post them. I didn't think the rear would be a problem and only thought the front driveshafts got the double cardons.
Until then,
Dennis

 

Lots of the trucks got single-cardan rear shafts because it was easy enough to keep them aligned with a long single shaft like that. But some did get doubles. And some even got singles in the front if I'm not mistaken. But there, with the shorter shaft, I think Ford ended up with more doubles than singles.
Any shaft can be a problem after a lift. No matter how long or how properly aligned it came from the factory, once you make changes you run the risk of running the joints out of their comfort zone.

You don't need to drop the shaft to get measurements for lengths I would say. But it does make getting angles easier I suppose, so probably a good idea.

Paul