Can You Run Rear Driveshaft With No Cardan/CV Joint?

[bulletpruf]

So, I noticed when I pulled the rear driveshaft from my '72 that it doesn't have the CV/Cardan joint on it. It does have the Cardan joint on the front driveshaft.

Anyway, now that I'm reassembling stuff, removing and reinstalling u joints, etc. I'm trying to figure out what's going on here.

The driveshaft appears to be original. It's maybe 1/2" longer than the shaft that I took out of a '66 6 cylinder Bronco.

Would the original shaft be long enough to work on an unlifted '72 with small tires if there was no Cardan joint installed? It would seem to be several inches shorter than stock, right?

My plan is to purchase a Cardan joint and all new 1310 Spicer u joints and re-install, but wanted to check with the brain trust here first.

Also, is there supposed to be something that prevents the splined end of the shaft from sliding through the splines and whacking the u joint?

Thanks,

Scott

 

[Speedrdr]

I can’t remember having any problem with the rear shaft W/O the cardan joint UNTIL I lifted my 1st EB 3 1/2 inches and swapped in a V8. I grenaded several u-joints and twisted one driveshaft to unusable condition. Went back with a cardan joint in the rear shaft and no more problem.
On the splined end slipping through the U-joint...I think I remember there being a snap ring and groove that prevents slipping. If my memory is flawed, somebody here with more recent experience will know.
Randy

 

[DirtDonk]

Remember that when you're trying to tell someone at the counter what you want (or are searching online even) the word "cardan" is what the u-joints were originally called before we decided to call it a u-joint instead. What you have now are "single cardan" ends on the shaft.
So what you're talking about as the CV joint is a "double-cardan" specifically.

There are a few different sizes too though, so make sure you get the right one for your yoke. And since you don't have one now, you will also need the correct yoke for the double-cardan setup.

Paul

 

[DirtDonk]

Would the original shaft be long enough to work on an unlifted '72 with small tires if there was no Cardan joint installed? It would seem to be several inches shorter than stock, right?

The length of the joints themselves don't really have anything to say about the overall length of a shaft. The total length would include the tube as well, so a single-cardan shaft of the same length as a double-cardan shaft would simply have a longer main tube.
You would have to measure yours end-to-end and see if it matches up, or simply try to install it and see if it fits. Leaving enough of the slip shaft to work in and out without over extending. Like it might have done at some point to push out the grease cap at the lower end.

My plan is to purchase a Cardan joint and all new 1310 Spicer u joints and re-install, but wanted to check with the brain trust here first.

You may have improper angles too. The way to align a double-cardan shaft is completely different from a single-cardan shaft.
With a single cardan your rear pinion must match the angle of the output shaft of the transfer case almost exactly. I think you're limited to approx. 2-3 degrees difference while running, and that's it.
While a double-cardan cares not that the angles match, but needs the lower pinion shaft pointed almost straight up into the centerline of the driveshaft. It's a big point, and if I'm not explaining it clearly you should check out some YouTube videos that show diagrams. Forget what someone is saying and trying to point out while the camera phone is bouncing all over the place and they're trying to move their can of beer out of the shot. Look for some engineering-looking information to highlight the change.

And no, your '72 would not have come with one from the factory under normal circumstances. And certainly would never have had one that was too long or too short, or misaligned. But it could have been put there afterwards by someone who preferred how a single-cardan shaft worked, or simply did not understand the concept of the double-cardan.
If yours was factory made that way, it's the first time after about '70 that I've personally seen one like that. There were quite a few in '66 and '67 that were sent out that way, and a few from '70 for some reason. But all the Ford information has double-cardan setups right from the beginning and nothing else. But we know from several original owners of '66 models that theirs were like that from the factory.
Very strange, but even stranger if your '72 had one originally. More than likely someone changed it out.

It's also not out of line for a dealer to mishandle warranty work back then. I've seen it first hand on a '77 that had a brand new rear end installed under warranty and it was built at the wrong angle. I'm assuming Ford did the welding of the spring perches, and the dealer installed it, but there's no way to know the whole story anymore since the original owner (who still owns it) just drove it that way for the last 40 years and only just fixed it a couple of years ago. Forty years and about 15 rear u-joints later!

Also, is there supposed to be something that prevents the splined end of the shaft from sliding through the splines and whacking the u joint?

Yes. The length of the shaft.
The dust cap is not going to stop it. And you would not want the shaft coming up against a hard stop anyway. Something else would certainly break.
The length of the shaft and suspension travel are what limits the shaft, because it's hard mounted at both ends.
Your shaft may be too long. Maybe mount it up and show us some pictures.

Paul

 

[DirtDonk]

I forgot to mention that if you decide to stick with the single cardan up at the t-case output, you should verify the size of the existing u-joint/cardan/thingy and match it to what you buy before you leave the store, or click "buy now" on the computer.
Since there won't be any books or computers anywhere from RockAuto to your local mom-n-pop store that show a single joint for your truck in that position, you'll need to verify you get the right one.
It's probably just the same as the rear joint, but you can't assume anything here and need to measure to be accurate.

Then, if sticking with this setup, you will need to make sure the length of the shaft is correct, as already mentioned, as well as making sure that the rear pinion angle is correct.
Short of lowering your t-case crossmember to change the angle, the only viable angle correction is done at the rear leaf spring perches. If needed that is.
If needed, you would either use tapered shims of the proper angle (whatever that turns out to be) or cut and re-weld your spring perches.

It's possible that the person that changed the shaft in the first place has already corrected the angle for that. But as you make changes to the rear end you have to keep re-checking the angles anyway. So it never hurts to check it all now with a good accurate digital angle finder and know what you have so you can make the best decisions moving forward.

Paul

 

[nvrstuk]

I remember my Dad and I talking with some Bronco guys back in '69 or '70 about trying to run non-CV styled rear DS's. They would last for a few months then they'd get another... and these guys only had an inch or two of lift back then. We started talking to them because we didn't have any way to grease the "center ball" in the joint. Not a lot of info on the double carden joint back in '69...

CV's do really allow smooth operation with extreme angles.

 

[bulletpruf]

DirtDonk - thanks for clarifying the terminology.

I do have a few u joints/Cardan joints on the way - Spicer 1310. I'll press these in and put everything together with a single u joint at the transfer case mount (i.e., just like it was when I disassembled it), check the pinion angle, and then post pictures and details.

I did verify that it takes the same joint front and rear on the driveshaft.

Does anyone have a part number for the missing dust cap? I'd like to keep some of the crud out if I can.

Thanks for all the input. I really appreciate it.

Scott

 

[DirtDonk]

I've never found a part number, but obviously they do exist because they still make driveshaft yokes. You might call a local driveshaft shop if you don't turn up anything online.
I do seem to remember a discussion about it oh, maybe ten years ago or so, either here or on broncofix, and someone found a source I think.
I've actually tried putting one back in after it popped out due to too much grease packing inside and could not get it to stay very well. Might take a special technique, or it's a one-time use only kind of thing that has a certain bend in it that gets taken out after it's pressed in.

Just don't pack the cavity full of grease, and make sure the shaft is not too long, and you should be good.

Paul

 

[nvrstuk]

OP- how many miles have you driven with the single joint rear DS?

Don't expect a long life out of a single joint instead of the CV setup. A CV joint, which Broncos had OE (not a double carden)-correction update- IS a double carden but with a centering ball)s designed to allow large variable angles between the t-case output shaft and the rear pinion AND to do it with less vibration. Yes, a single joint at each end will work but since it speeds up and slows down 2x for every revolution it WILL cause vibration and premature wear.

I don't understand why you think or want to use a single joint when they won't last, cause harmonics and will require more maintenance/replacement? Remember, a ujoint being used at appr a 20 deg angle will have it's life shortened by appr 85% over a zero degree application. Safely put, if you double the angle of the ujoints over the 3deg operating angle (angle ujoints are rated at) you 1/2 the life of the ujoint.

There is some really good explanations out there but there is more IN-correct info cruising around. Why do you think every driveline repair shop that does custom and/or OE work always keep the CV in for 99% of the applications in our market?

Spend a couple extra bucks and run the CV joint.

 

[Yeller]

I've never found a part number, but obviously they do exist because they still make driveshaft yokes. You might call a local driveshaft shop if you don't turn up anything online.
I do seem to remember a discussion about it oh, maybe ten years ago or so, either here or on broncofix, and someone found a source I think.
I've actually tried putting one back in after it popped out due to too much grease packing inside and could not get it to stay very well. Might take a special technique, or it's a one-time use only kind of thing that has a certain bend in it that gets taken out after it's pressed in.

Just don't pack the cavity full of grease, and make sure the shaft is not too long, and you should be good.

Paul

I use fender washers to replace the dust cap. Just get one the right outside diameter and tack weld it in place. My driveshaft shop does stock the dust caps, however I'm not sure they are not just recycling used parts, if one is missing they tack weld another in its place.

 

[TDubya]

My '69 has a rear ds without the cv joint. I had assumed that all Broncos came stock with cv driveshafts, but it sounds like some came from the factory without in the early years. Mine has stock suspension and rarely sees over 55 mph so there has been no issues and I see no reason to change.

 

[jamesroney]

My '69 has a rear ds without the cv joint. I had assumed that all Broncos came stock with cv driveshafts, but it sounds like some came from the factory without in the early years. Mine has stock suspension and rarely sees over 55 mph so there has been no issues and I see no reason to change.

Is it possible for you to measure the pinion angle of your 1969 with single cardan driveshaft?

The transfer case angle in the EB sits right at 5 degrees down. The pinion angle in my 67 with stock springs sits right at 12 degrees up. It would be great if you could measure your pinion tilt to see if it is matched to the 5 degrees, or not.

 

[Lawndart]

My '73 does not have a cardan-joint on the rear shaft.
No lift, 30 inch tires.
It came to me that way, I changed all the u-joints, but I have been running it that way for over 65,000 miles...

 

[DirtDonk]

Curious about the angle too. The two guys I met who were original owners of '66's with a double-cardan front and single-cardan rear had never experienced excessive wear on theirs, but they were still both bone stock too, and not even used on ranches or for any hard work. Just drivers.

Seemed odd to me that it was the rear that got the single, what with the high degree of pinion angle change with the axle-wrap of the leaf springs. While the front was held pretty rigid by the radius arms.

A CV joint, which Broncos had OE (not a double carden)

Was that a typo?
Our CV joints are double-cardan. I guess we should call a shaft with two single u-joints a "double cardan shaft" because it has two cardans, but our joints are still "double-cardan joints" with their two cardans and a centering ball held within a locating yoke.

It's hard to say what they were first called 400 some years ago, but double-cardan and hooke joint were probably bandied about near the same time. With the phrase "constant velocity" maybe coming later with the newer designs? Not sure.
But at least after those initial designs, the actual term "constant-velocity" was the official term for the more modern ball-n-socket types like Rzeppas and the others and ours remained "double cardan" for the old original design.

For ours I only ever heard or read of our system referred to as double-cardan, and all the others referred to as constant velocity.
And the DC term has remained popular in recent times to differentiate between the designs. I don't think anyone called a double-cardan a constant-velocity joint at least in general use for decades until we started doing it here on the forums 10 or more years ago. At least that's when I first started hearing it called that.
Seems like the phrase CV is still seldom used outside of forum discussions when it comes to double-cardan types.

For the history buffs, the single "cardan" as our universal joints were first known, were invented in the 1500's by a guy named Cardano. Again with the clever Italians!
The double-cardan came about as the original first attempt at a true CV joint sometime later when a guy named Hooke (again with those clever English!) put two cardans together offset by 90 degrees and likely called it a "hooke joint" I bet.
Worked very well, but still had it's shortcomings so they kept at it for four or five hundred years after and now we have vehicles with lots of different CV designs in their front axles, Ford Rangers and some Jeeps with CV joints for driveshafts (both ends sometimes!) and all sorts of other mixes of parts.
Even though I also now use "CV" to describe out double-cardan joints to make typing easier, I still prefer to think of the modern designs as CV joints, and ours as double-cardans. Even though they were attempting a CV design with the original DC setup.

Normally I don't get all dictionary and encyclopedia preachy with nvrstuk, because he knows and has built practically everything! But well, there ya go. Had to say something after all...
(hope it wasn't just a typo!);D

Paul

 

[DirtDonk]

My '73 does not have a cardan-joint on the rear shaft.

Have we talked about yours before on the forums? I only remember the early model discussions, but don't remember hearing about a '72 and now your '73 having the single cardan setups. Interesting.
Maybe you can check your angle too, but it's a bet that it's correct due to the fact of your mileage without joint failures.

Just like we know that some '69 and mostly '70 models were delivered with that hybrid Dana 30/44 front axle, it's not out of the realm of possibility that your later model had a single u-joint style shaft I suppose.
You don't happen to know the original owner still by any chance?

Paul

 

[Yeller]

mine doesn't have a CV or double cardan shaft (which ever you want to call it) either, but nothing about it is normal except maybe the glove box door....LOL

 

[TDubya]

Is it possible for you to measure the pinion angle of your 1969 with single cardan driveshaft?

The transfer case angle in the EB sits right at 5 degrees down. The pinion angle in my 67 with stock springs sits right at 12 degrees up. It would be great if you could measure your pinion tilt to see if it is matched to the 5 degrees, or not.

The '69 is at our summer home so I don't have access to measure the rear pinion angle right now. I'll try to remember next time I'm there.

 

[Lawndart]

I measured 15.5 deg.

 

[nvrstuk]

IF you run a single joint at each end the pinion and tcase shafts are supposed to be parallel. The CV style joint is designed to have the pinion facing towards the rear output of the t-case. We have found that 1-2deg below the pinion helps with longevity.

 

[nvrstuk]

Paul- my understanding (I'm wrong all the time) is that a double carden joint does not have a centering ball or pin. At least they don't all the time OR we just call them the wrong thing... Crescent wrench or adjustable wrench...? lol

Double carden joints are used in ag applications a lot and we use them in strg shafts and they don't have a center ball.

I had to look up some reference articles to see how far off I was, but I think the terms are very loosely used in different applications in different industrial applications but I think we're talking about the same part.

If you go on line we will see mis-named CV/double carden examples all over. I checked a couple driveline shops that we all use and they just grouped everything together.


I have to defer to all the guys that know Broncos 100X better than I but I don't see Ford setting up rear end pinion angles differently in the assembly line to be able to properly use a single joint (at each end) drive shaft. Doesn't seem to make much sense.

I think if you didnt buy the Bronco brand new to be able to verify that the rear driveline was a single joint at each end then it would probably be like 99.9% of the Broncos out there and it had been changed out with a previous owner some time in the past 50+ years

I do remember all "hatred" for the CV or double carden style DS back in the day. I think it was from not doing any maintenance on the center ball. I remember going to Harris Ford with my Dad and him asking the Service Manager and then going out to the shop and asking the tech what they used to lube the center and I remember the conversation well... lol but they never lubed them and didn't have an extended pointed grease needle to lube it. This was a dealer!!

My Dad's good friend who built everything for my Dad, a welder by trade, made one with the guts from a metal ball point pen . (ya- he's that good). We always pulled the driveline and held it carefully when using it because obviously it was a bit fragile. My Dad got 186,000 miles out of both the front and rear drivelines (and the 302) although I did upgrade the heads, intake, 4bbl, headers back in 1976 for him. It passed Snohomish County emissions testing every year when they started testing. Didn't burn any oil and like most of us, regretted selling back in 1984 till the day he passed.

It would be very interesting to be able to document with 100% certainty that Ford OE for years was a double carden/CV style rear DS and then sometime down the line made a few that weren't... crazy but hey, we're talking FORD engineering here!! Same guys that put wipers on TOP of the windshield... lol

Here's a pic of a typical double carden joint. At least the way I understand and learned about how they are built and work.