SYE vs. CV

Hi All,
I am looking for opinions or facts that canhelp me understand why it is necessary to do an SYE as opposed to just adding a CV to the drive shaft. A friend of mine said all he did with all of his xj builds he just had a cv built. Supposedly he never had an issue, and I went with him to Moab and ran 4+ trails with him often. Any input would be greatly appreciated.

Are you meaning a cv shaft while still retaing the slip yoke?

cabjeepster said:

Are you meaning a cv shaft while still retaing the slip yoke?

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And, if so, is this related to a rear driveshaft up for auction on eBay?

Yes I am talking about retaining the slip yoke and no this is not in reference to an ad.

I wouldnt do it. Thats alot of weight for the t-case output bearing.

I guess if you feel like putting more money in the XJ to do it right later you could do it. But I would suggest just getting a Advanced Adapters SYE and a Tom Woods rear driveshaft. Then you have piece of mind and a perfect set-up.

POSJ said:

But I would suggest just getting a Advanced Adapters SYE and a Tom Woods rear driveshaft. Then you have piece of mind and a perfect set-up.

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I'll second this. Been running exactly that for four-plus years and no complaints.

Call James @ Adams Driveshaft in Nev. Ive got 4000 miles on one of his shafts for my 242 without a problem. I have stuffed it to the bumpstops with 33s and driven 75 mph on the highway no vibes no leaks from tc seal and has not pulled out at full extension. I think he is looking outside the sye box and has a video on his website to prove they work. Im sorry but the whole hack and tap thing seems crude to me. However assuming that you mentioned sye i guess you have a 231 and not the 242. My .02

cashsxj said:

I think he is looking outside the sye box and has a video on his website to prove they work.

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Thinking outside the box is fine, but throwing the box out before doing so isn't necessarily the best approach.

The thing is that people fixate on the CV joint as the solution without understanding that it's only a component of it. There's a reason why the CV joint is coupled with a two-piece slip-capable driveshaft and fixed-yoke output.

Im sorry but the whole hack and tap thing seems crude to me. However assuming that you mentioned sye i guess you have a 231 and not the 242. My .02

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Oh, for f***'s sake. Not this ignorance again.

Sorry to ruffle your feathers, no need to insult anyone. I am only trying to offer an alternative way of improving on this problem without breaking the bank. The fact that you dismiss the idea of a slip yoke cv tells me you have a higher knowledge on the subject. Please wont you enlighten us?:wierd:

I'll enlighten you because I feel the same was as Casm, and many others.

A H&T is not a hack, crude, or weak way of eliminating the slip yoke on the transfercase.

People will complain about how they think its a weak or inadequate way to do an SYE. The thing is, they have never, nor have the people they initially listen to, ran a H&T. I ran one for 5 years, and on two different cases before I put a 241OR in my Jeep. The second case is on a friend's 5 speed, who beats the ever living crap out of his Jeep. It has never failed. I've never seen anyone actually running one actually have one fail, or even really hearing about them failing.

You cut the output shaft shorter, and slide a flange over it, then drill a hole and tap it to hold the flange in. I know for a fact that not drilling that hole perfectly center will not cause issues or vibrations. I also don't know why people think that this flange, perfectly machines to slide onto your shaft, will automatically fail because of the connotation the name "hack" has.

If you have a 242, and go through Tom Wood's, what do you think his SYE is? It is a H&T, he just puts the shaft on a lathe, and makes it all nice.

Not discounting it for those who have it. I am trying to offer an alternative to a $600+ solution. I have yet to be enlightened as to why the slipyoke cv is inferior, only examples of the h&t and Tom Woods shaft being reliable. IN MY OPINION I am not a fan of h&t, not bashing those who use it. On the contrary, does anyone have any examples of the slipyoke cv shaft being unreliable?

cashsxj said:

Sorry to ruffle your feathers, no need to insult anyone.

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No ruffled feathers here and I certainly didn't intend that as an insult; I'm just amazed at how much the 'there's no SYE for the 242' mantra gets repeated. This isn't a knock on you by any means, but given that I'm running exactly that on my 242, it's a rather tired misconception.

I am only trying to offer an alternative way of improving on this problem without breaking the bank.

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Sure, and that's fine - and I'd like to mention that the $600 figure you quote seems on the high side. However:

The fact that you dismiss the idea of a slip yoke cv tells me you have a higher knowledge on the subject. Please wont you enlighten us?:wierd:

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OK, I'll do my best.

The whole point of the slip yoke is to take up differences in pinion angle under articulation with a one-piece driveshaft. At stock geometry this works fine, but as you lift the Jeep the driveshaft's range of motion changes and this directly impacts both pinion angle and bind.

Note that SYEs are normally used in conjunction with a two-piece rear shaft; this is in order to move the slip yoke's functionality into the driveshaft. Essentially, the dynamic change in driveshaft length that a two-piece shaft is capable of vs. a one-piece shaft makes up for the bind that a slip yoke or CV joint alone cannot handle at greater shaft angles.

With only a CV joint in a one-piece shaft, bind is somewhat reduced - but as the axle moves vertically, that one-piece driveshaft will remain the same length, pulling the CV joint to the same extent as the U-joint end that it replaced as the slip yoke moves. By nature the CV joint will be able to compensate for some of this horizontal travel in the slip yoke, but not nearly all of it. Pinion angles may be somewhat reduced by nature of the double cardan upstream of them, but across a reduced range of motion compared to a two-piece shaft.

Thank you, I understand that logic completely, you have explained it very well for all of us newbies, as I stated before I am merely trying to offer an alternative albeit not the ultimate alternative, an alternative none the less. I am sorry for the sarcasm.:thumbup:

cashsxj said:

Thank you, I understand that logic completely, you have explained it very well for all of us newbies, as I stated before I am merely trying to offer an alternative albeit not the ultimate alternative, an alternative none the less. I am sorry for the sarcasm.:thumbup:

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No worries, and no offence taken. BTW, you might want to search on it as well - my explanation definitely isn't the gospel truth on the subject, and there's been a lot written on it over the years.

XJ Ranger has an article for it in the FAQ/Writeup section that covers the basics as well.

cashsxj said:

Not discounting it for those who have it. I am trying to offer an alternative to a $600+ solution.

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H&T is $100 from RE, driveshaft nis whatever you get it for. I spent under $400 on mine.

Or if you go with the sye you could check out ironrock offroad
they have a hack and tap kit for 270 and it comes with everything you need
bolts
drill bit
new seal
drive shaft
etc....
its such an awesome deal

Just a couple of points. One is that as the suspension compresses the drive shaft is lengthened or the slip yoke slides out of the housing. As the suspension droops the driveshaft is shortened or the slip yoke slides into the output housing. Not really relevant to this discussion. Second, a properly done hack and tap style fixed yoke is only marginally weaker than a sye with a new shaft. The difference, in my opinion, is negligible. A CV jointed slip yoke setup is just fine as long as there's room for the yoke to slide without coming off of the output shaft or putting a axial load on the output bearing (bottoming out).

jeeperjohn said:

Just a couple of points. One is that as the suspension compresses the drive shaft is lengthened or the slip yoke slides out of the housing. As the suspension droops the driveshaft is shortened or the slip yoke slides into the output housing.

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I think you meant to say that the other way around, compressing the suspension makes the slip yoke slide into the housing, and droop lengthens the driveshaft and makes the yoke slide out of the housing.

jeeperjohn said:

Second, a properly done hack and tap style fixed yoke is only marginally weaker than a sye with a new shaft. The difference, in my opinion, is negligible. A CV jointed slip yoke setup is just fine as long as there's room for the yoke to slide without coming off of the output shaft or putting a axial load on the output bearing (bottoming out).

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I agree