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my SYE alternative

fallacist

NAXJA Forum User
Location
Durango
so I posted this in my chapter forum, and it was met with mixed, but mostly negative/cautions results. Now that I have something empirical to speak to, I figured it should lay it down out here.

I have a 01 XJ w/ a 8.25 in the rear. I have around 4" of lift. A SYE was next on my list, but I was referred to a driveshaft place in CO that makes a double cardan bolt-in rear drive shaft to eliminate the need for a HnT or full SYE install. The guy comes highly recommended, and I've yet to hear anything negative about his work.

I was wary of cutting my output shaft(EVERYTHING goes wrong for me when I do things, I know better...) and I don't prefer tiny parts for a full SYE, so replacement driveshaft seems like a winner.

Most of the guys didn't like the idea of all that unsupported weight on the output shaft, especially since my late model didn't come with an additional cone.

Anyway, here it is:

8RNqol.jpg


Rode SUPER smooth through a full range up to 75MPH. Smooth as its ever driven. I can say that it definitely eliminated vibes, and its beefier too, about another 1.5" in diameter. Pulled the old one out, put this in and done.

Thoughts?
 
sceptical on longevity . but very interested to see how it holds out. hey if it works it works!
 
Good thinking :)

I can't think of one reason why it wouldn't work.

The reason why folks began installing Slip Yoke Eliminators was to... Eliminate the slip yoke, not to avoid using a double Cardin joint in the front.

Will work great unless you over extend the length of the output shaft (usually in droop), then it will fall in the dirt :)

Could be mistaken, but I seem to recall some vehicles coming like that from the factory.

Edit: Do you have specs? Length, yoke type, etc?
 
How much did you spend for it? Did you run into any difficulties installing it? Where is driveshaft place in CO? You've piqued my interest! :)
 
Good thinking :)

I can't think of one reason why it wouldn't work.

The reason why folks began installing Slip Yoke Eliminators was to... Eliminate the slip yoke, not to avoid using a double Cardin joint in the front.

Will work great unless you over extend the length of the output shaft (usually in droop), then it will fall in the dirt :)

Could be mistaken, but I seem to recall some vehicles coming like that from the factory.

Edit: Do you have specs? Length, yoke type, etc?

another advantage of a SYE is shortening the output shaft, and installing a longer drive shaft. this gives you better angles, and its high angles that destroy Ujoints on jeeps that see a lot or road miles.

ive seen this approach once or twice before. as bcmaxx said, im sceptical on longevity. if it cost anywhere near $200, you should have just gotten a real SYE and a junk yard drive shaft.
 
That's a good idea. I'm also very interested in hearing how well it does.

It certainly does not seem "dangerous" to me, as I think you'd feel it right off the bat if u-joints were going out of phase, or allignment as they rotated.

One issue might arise, if the axle was subjected to a grotesque amount of springwrap, thereby causing the main shaft to shift downward enough to cause the rear joint to acheive an extreme angle and possibly causing it to bind.

That would cause the slip yoke to NOT rotate around the TC end, but around the ujoint end, and depending on the size of that rotation could end up causing issues.

This is just off the top of my head...

And again, I think the amount of deflection @ the axle end would have to be fairly pronounced, as it would have to negate the slip in the yoke and the amount of angle the CV joint is able to adjust to.
 
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While the driveshaft may work well right now... how long will the output shaft bearing last with the weight of the driveshaft exerting force on the exposed length.
During droop situations where the driveshaft slider moves outward this can cause excessive force on the output shaft and may cause binding at certain angles....
Only time will tell....
 
i considered doing this sort of thing before i got my sye.. other people have done it and i havent read or heard any negative experiences... time will proove and i dont see why it wouldnt hold up

is the shaft itself any longer than the stock shaft? maybe with around 4 inches of lift you can go 1.5-2 " longer and lessen and/or eliminate any chance of over extending the shaft.
 
So far it's interesting that every reason posted why it may not work is there during normal operation of either the OEM shaft (weight, slip yoke binding), or the SYE configuration (yoke binding under super-outrageous -extreme spring wrap conditions) with either a DS or single u-joint configuration..

VA, I am highly skeptical of your analysis. The output shaft is shortened by only a couple of inches in a H&T config, yet that approach is perfectly fine to 99.9% of the folks here who also use a JY front shaft. As far as u-joint angles, that is the entire reason for going to a double cardin shaft. The DC splits the angles on the TC end. Any remaining angles are dealt with on the axle end. As with any DC driveshaft, the rear pinion to DS angle should be about 1-2 degrees pinion down from straight to account for loading or spring wrap.

I m so impressed that if he provides a list of parts and does a small write up I will post the sucker in the FAQ Forum !
 
So it's just a double cardan slip yoke shaft? How much did it cost?

If there is one thing I can speak to confidently about this whole thing, its justifying the price I spent on it. Its more than I wanted to spend at first, but in the long run I'm happy I didn't have to mess with my t-case. It was sold and shipped for $350 minus a local forum discount(frontrange4x4). I realize thats enough to turn a lot of people off, but to me it was worth it. I dont have to cut my output shaft for a HnT, which I was wary of doing(I have REALLY bad luck wrenching on my jeep, nothing has ever been "bolt on" for me), and I don't like the idea of messing with small parts on a full SYE. With this DS, I unbolted the stock one, and swapped this one in. Done in 5 minutes. I work full time during the week, and I'm usually pretty busy on my weekends, so to me time is money. Plus its a beefier shaft, bigger than stock by about 1.5", and I still have my stock DS to bring with me on the trail just in case.

Also the availability of used/spare parts where I live is low, I'm in BFE. We have a junkyard, they wanted something like $65 for a used ZJ tierod. There was no way I was picking up a DS for less than $100. This DS is brand new, so I know its true.


sceptical on longevity . but very interested to see how it holds out. hey if it works it works!

That was the main thing my chapter guys were concerned about. Its nice now, and does the job now, but for how long... guess we'll find out. I'd rather try it this way and find out than never try at all :dunce:

How much did you spend for it? Did you run into any difficulties installing it? Where is driveshaft place in CO? You've piqued my interest! :)

Its Bill's Englewood Driveshaft. The guy comes highly recommended by the FR4x4 guys, and he's done these for some jeeps(and others) on that forum. The only difficulties I had was shearing off the head of 1 u joint bolt that had to be drilled out and retapped. Which in retrospect I'm glad that happened, because I probably wouldn't had thought to get a new strap kit otherwise. Other than that, it was 100% bolt on.

So far it's interesting that every reason posted why it may not work is there during normal operation of either the OEM shaft (weight, slip yoke binding), or the SYE configuration (yoke binding under super-outrageous -extreme spring wrap conditions) with either a DS or single u-joint configuration..

VA, I am highly skeptical of your analysis. The output shaft is shortened by only a couple of inches in a H&T config, yet that approach is perfectly fine to 99.9% of the folks here who also use a JY front shaft. As far as u-joint angles, that is the entire reason for going to a double cardin shaft. The DC splits the angles on the TC end. Any remaining angles are dealt with on the axle end. As with any DC driveshaft, the rear pinion to DS angle should be about 1-2 degrees pinion down from straight to account for loading or spring wrap.

I m so impressed that if he provides a list of parts and does a small write up I will post the sucker in the FAQ Forum !

ha, there's not much to it, but I'm glad that you can appreciate the idea that there is an alternative to a SYE. After hearing all the feedback, it makes me think of people who are skeptical of HnT, when there are plenty of people that do them with no problems. Hopefully I'll have the same success/luck!

1 Driveshaft from Bills Englewood Driveshaft
1 Strap kit from NAPA (~$9)
Grease

This is the first shaft they sent out to me, which was too long because they didn't realize my style T-case had a boot on it, so the measurement was off by about 4". But this gives you an idea of what it looks like compared to stock:

6ZzSCl.jpg
 
VA, I am highly skeptical of your analysis. The output shaft is shortened by only a couple of inches in a H&T config, yet that approach is perfectly fine to 99.9% of the folks here who also use a JY front shaft. As far as u-joint angles, that is the entire reason for going to a double cardin shaft. The DC splits the angles on the TC end. Any remaining angles are dealt with on the axle end. As with any DC driveshaft, the rear pinion to DS angle should be about 1-2 degrees pinion down from straight to account for loading or spring wrap.
ask any woman... a few inches makes a world of difference.

as for the Ujoints, the way you set up a double cardan shaft, and something with a single U joint at the Tcase are different.

exhibit A:
2joint_angle.gif


exhibit B:
cv_angle.gif


i dont know where this double cardan slip joint shaft thing would fall into between these two drawings. but over 4 inches of lift, the U joint at the pinion is still under high angles. i supppose shimming it would help. but with a stock shaft, and "proper geometry" i was eating through U joints. now with a SYE, that is a thing of the past.
 
so, does that mean I need to removed the[supposed] shims that came with my RC leaf pack?


it depends... what does the angle at the pinion look like? now that you have a DC drive shaft there should be no angle at the pinion. (some say it should be a degree or so off to make up for spring wrap) so look at your pinion angle and if it is good and you have no vibes and then leave it alone. if not you need to shim accordingly. i would guess roughly 3 or 4 degrees but you should get an angle finder and do it right.
 
...The output shaft is shortened by only a couple of inches in a H&T config...


Yes, the shaft is only shortened 1-2". But with a SYE there are other changes that reduce the load on the shaft. The yoke is shorter as well. I just measured mine and the stock yoke is 6" from the end to the center of the u joint, while the yoke I use for my HnT is 4", so that's another 2". Then there's the fact that on a sye to yoke is always bottomed out, as opposed to a sy where there needs to be room for travel. Let's say 1.5".

Cut the shaft 1.5", yoke is 2", and travel room is 1.5" for a total of 5" more leverage on the shaft and bearings. On my 99 the distance from the output flange to the ujoint center is 4.5", or about half of the stock setup. That's a huge change.

As many others have said, this is where I'd be concerned with this setup. The concept is fine as long as the tcase can support the load. Which is questionable.
 
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