Proper U-joint caps for transfer case

[Tonyduc]

Hello
For my 66, the u-joints I have been finding online for the F & R drive shafts are all 1.063 in cap diameter (1310?). My measurements of all 4 u-joints that are on the vehicle now show that they are all the same.

However, when it comes to the u shaped bolt caps there are 2 sizes. Each end of the drive shaft facing the drive uses a cap that's 1.5" wide, while the each end that is facing the transfer case uses a cap that is about 2" wide.

I think Wildhorses explains this https://www.wildhorses4x4.com/category/Early_Bronco_Driveshafts, but I don't see different sized caps offered ?

Does the wider end on the t-case require a U-joint strap, as opposed to the smaller cap ?
https://www.rockauto.com/en/moreinfo.php?pk=4439052&cc=1434242&jsn=3039&jsn=3039

My Bronco has caps at both ends of each shaft, but I think the PO just bent them wider as needed.

 

[DirtDonk]

Just re-read your post and I'm wondering if the yokes on the t-case are for double-cardans that bolt on (no u-bolts) and you have single joints that take a different yoke.

To be clear though, do your u-joints work at the axle ends and just not the transfer case, or are the discrepancies at both ends?

Paul

 

[Nothing Special]

.... However, when it comes to the u shaped bolt caps there are 2 sizes. Each end of the drive shaft facing the drive uses a cap that's 1.5" wide, while the each end that is facing the transfer case uses a cap that is about 2" wide....

I'm not sure if this is what you are talking about, but the hole spacing for single Cardan joints is different than that for double Cardan joints (assuming the same cap size).

As Paul mentioned above, most Broncos use a double Cardan joint on the transfer case end of both driveshafts and a single Cardan at the axle end. Single Cardan U-joints often (and in vehicles as old as these, always) use a U-bolt over each of the 2 bearing caps that go into the yoke on the axle. These U-bolts need to follow the OD of the bearing caps, so if the bearing caps are 1.063" in diameter the bolt holes will be about 1 3/8" on center and the U-bolts will be about 1.688" across the outside.

Double Cardan joints do not use U-bolts. Instead they just have 4 bolts that go through the yoke on the transfer case and thread into the body of the double Cardan joint. These bolts need to not be right against the bearing caps because there needs to be some material there to give the threads some strength. So these holes are spaced more like 1 5/8" on center (just a guess).

.... My Bronco has caps at both ends of each shaft, but I think the PO just bent them wider as needed.

From what you say here it almost sounds like a previous owner replaced the driveshaft with one that has a single Cardan joint at both ends and found a way to stick it in, even with yokes on the transfer case that are intended for double Cardans. If that's the case you really should get the correct driveshafts (you can't just stick a double Cardan in place of the single Cardan if that's what you have).

To maybe help make it clear, here is a link to a site that has a picture of a driveshaft like a Bronco should have. The double Cardan is in the foreground (you have to look kind of carefully to see the four bolts that are started into the body). The single Cardan is in the back of the picture (there are no U-bolts shown).

If your 'shaft doesn't look like that, but has the style U-joint from the back of that picture at both ends, look at the yokes on your axles and transfer case. The yokes on the axles should have the inside edge of the bolt holes right up against the curve that fits the 1.063" OD bearing cap.

If the yoke on the transfer case looks like this too, then you should have a single Cardan U-joint at that end of the 'shaft as well. But if there's something like 1/8" between the edge of bolt hole and the curve for the bearing cap, then the yoke is for a double Cardan joint and you need one on your driveshaft.

 

[Tonyduc]

Thanks for the help !
Each driveshaft has a single Cardan joint at both ends. I took some measurements, it does seem as Paul suggested that being an early 66, perhaps they were made with single Cardan joint?

I was mistaken in my first post, the U joints are not all the same. The U-joints for both front and rear shafts at the t-case end are about 1.18" diameter, at the drive end 1.062" diameter, all are 3.25" wide. Measuring end to end.

Front shaft has a collapsed length 25.25", running length 26.5" Looks Borg Warner type according to the joint clip style.

Rear shaft has a collapsed length 34", running length 35" Looks like Spicer type according to the joint clip style.

I would prefer to get the double Cardan driveshafts. I'll have to check as suggested if the double Cardan (at the t-case end) in place of the single Cardan would wind up with the same length range. I measure distance from t-case to front drive 25.5" and rear 34.5", end to end.

 

[DirtDonk]

I would prefer to get the double Cardan driveshafts. I'll have to check as suggested if the double Cardan (at the t-case end) in place of the single Cardan would wind up with the same length range.

You can't measure them the same, so it does not matter. The CV section (2 u-joints and the centering ball and yoke) are quite long, so the measurement would be skewed.
But the overall length you're speaking of, while maybe a different inch measurement, is still going to be "stock length" if you have not modified things much.

The front shaft will need a new output yoke for the transfer case too because the BW stuff is no longer readily available and everyone sells Spicer stuff.

Here's what we have: https://www.wildhorses4x4.com/category/Early_Bronco_Driveshafts including the three different levels of shaft, the correct Spicer yoke, and other related parts.
You can see that we expect a basic fitment distance of 23.5" for the front and 33.5" for the rear, for stock length replacements. Normally you do not need more than stock length for anything up to and including 3.5" of suspension lift, as long as the pinion angles are still pointed roughly in the right direction.

Are you lifted, or stock height?
More importantly than just "lifted or not lifted" would be how are your pinion angles now?
If Ford did indeed set yours up for single-cardan shafts then they would have modified the axle angles too. And even if a PO did it, they may also have modified the angles.
So your most important angle at the moment is the rear differential pinion.
Looking at it from the side, does it point almost straight up into the centerline of the shaft?

Paul

 

[Tonyduc]

I called Wildhorses, and they have what I need, Spicer type yokes for front and back and stock length shafts.

To get an idea of angle I mentioned that the height floor to yoke center on the rear was 13", and floor to t-case yoke was 23", a rise of 10". That should be stock.

Thanks for the help !

 

[Tonyduc]

Paul

The tire size appears standard. All of the body work and mechanicals are on the truck, 1/2 tank of gas, as far as additional weight I may add roll bar in the future. And for the suspension height, I got 7" front, and 7" for the rear (you mentioned 6" is standard). I did replace all the body mounts with new stock height mounts (originals were stock also). Since in the future I will replace F&R shocks with stock height ones, perhaps that rear measurement being 7" might lower?

I re-measured the distances yoke to yoke again (center of the caps), I got 24 1/4" front, 32 3/4" rear. The Wildhorses link you referred to mentions if you are in between sizes to increase by 1/2" the new shaft. However, if I go beyond the 23 1/2" F and 33 1/2" stock lengths, wouldn't that be kinda shoehorning in the driveshaft ? Would it be better with my measurements to order stock length and have the slider be out 1/2" at resting height? Especially since the truck may settle (and height decrease) with further options and with occupants, etc. ?

 

[DirtDonk]

...as far as additional weight I may add roll bar in the future.

Should not cause any change in height you could notice, so you're good there.

And for the suspension height, I got 7" front, and 7" for the rear (you mentioned 6" is standard).

Yep, and I usually add "approximate" too because that's all it is. It can easily vary by 1/2" in the front, but the rear is also subject to the different GAWR/GVWR ratings for the suspensions. Different rear springs.

Of course, anything could have changed over the years, but if there is no add-a-leaf or block in the rear, and the shocks are not high-pressure gas, I can't account for a full inch discrepancy other than to say "well, it's just that every Bronco is different" again!%)

Since in the future I will replace F&R shocks with stock height ones, perhaps that rear measurement being 7" might lower?

Depends. If the rear ones are jacked up (starting to freeze up for example) or really high-pressure gas, it's possible they're holding it up a bit. I know shocks are not supposed to support weight. They're only supposed to control movement. But I've experienced many times where certain HD shocks will keep the rear end of some vehicles from settling down fully.
Not as likely on a Bronco, but nothing is impossible.

If the spring eye and shackle bushings have ever been replaced, it's possible that during install they were torqued down while the suspension was extended. That will often leave the rear end up a bit.

I re-measured the distances yoke to yoke again (center of the caps), I got 24 1/4" front, 32 3/4" rear. The Wildhorses link you referred to mentions if you are in between sizes to increase by 1/2" the new shaft. However, if I go beyond the 23 1/2" F and 33 1/2" stock lengths, wouldn't that be kinda shoehorning in the driveshaft?

I would not think so. There is some leeway due to the slip-joint in the shaft, and we don't know yet what the difference will be once the new yokes are installed on the transfer case.
With all the other things you've described as being stock height, stock shafts should work even if they don't compute on paper initially.
If they don't then something else is different about your Bronco. Most of us can use stock shafts all the way up to 3.5" of lift.

Would it be better with my measurements to order stock length and have the slider be out 1/2" at resting height? Especially since the truck may settle (and height decrease) with further options and with occupants, etc. ?

Well, half-way is just about what you get normally with a stock length driveshaft. The measurement between the yokes is not the length of the driveshaft, it's just the resting length of the shaft, somewhere near the middle of it's travel.
At least I would call it the "middle" but I never checked if there is a little more travel out, or more in. In fact just looking at them, if anything I'd say they sit a little compressed, rather than extended.

If I understood you correctly? But I still think from all descriptions, stock length shafts are correct for your setup.

Paul