SYE questions

[sexjay]

ok so ive been reading all about doing an sye conversion and I really want to do it soon. ive heard of some people using a front drive shaft in the rear..would that actually work? is it long enough for a 4.5 inch lift and how much lift is it good for?? and is a hack and tap sketchy for a daily driver? ive been looking at doing the full output shaft instead of the h&t but I just wanted to hear from some people that may know more than I do :p. thanks! anything will help!!

[Mudderoy]

ok so ive been reading all about doing an sye conversion and I really want to do it soon. ive heard of some people using a front drive shaft in the rear..would that actually work? is it long enough for a 4.5 inch lift and how much lift is it good for?? and is a hack and tap sketchy for a daily driver? ive been looking at doing the full output shaft instead of the h&t but I just wanted to hear from some people that may know more than I do :p. thanks! anything will help!!

I personally recommend the Tom Woods SYE and custom drive shaft. It's about $400 after core refund. I really like the idea of using a front drive shaft on the hack and taps, as it is redundancy. I mean you could trash the rear drive shaft, remove the front, and put it on the back and you can still get home. Of course some people just drive it in 4x4 and do the same. Might be more difficult with a front locker though. ;)

I went with the Tom Woods, because I wanted the short shaft in my transfer case and the custom drive shaft.

Lots of people do the hack and tap and don't have issues. Hack and tap is by far the cheapest route I've seen.

[NW99XJ]

Well it looks like you've got the 231 T-case....which gives you many more options.
But first lets address some of your questions 1 by 1.
YES, a front driveline WILL work in the rear with little to no modifications AFTER the SYE is installed. USUALLY you'll want to grab one from another XJ.... THE ZJ ones will work too, but usually they will have to be modified. That's what I did. It's basically the same drive line, just varies more in length. The XJ front drive lines should be good for lifts up to 5" or so...MAYBE even 6.5"...but would prob depend on how much your rear end can droop.
The Hack and Tap SYE's are not sketchy at all, BUT are a little more finicky to install....well the mod part is the tricky part. Check out my build thread for all that is involved with doing a "H-n-T" SYE. I have ran mine for several years. I DD it for a long time, and have wheeled the living you-know-what out of it. They hold up just fine.
Honestly, the prices have come down to such a fair market value now, that its almost a no-brainier to go with the full replacement kits out there now like the PORC Kit for $169 (http://www.performanceoffroadcenter.com/oscommerce/product_info.php?products_id=8040)
There are several others out there too. Teraflex, Rugged Ridge, ProComp, Advance Adapters, Tom Woods, ALL make great kits too.
Tom woods WOULD be your "One Stop Shop" for this project and most likely is the best you can buy.
Hope this helps, Good Luck!
(be sure to post pics of what you end up going with and some before and after shots too!)

[drakan1908]

I've heard the H&T can cause the rear bearing in the tcase to wear out prematurely from the weight of the CV joint.

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[Mudderoy]

Hack and Tap horror images!

http://img840.imageshack.us/img840/4008/drivelinesye013.jpg

http://i641.photobucket.com/albums/uu137/rcracer951/PIC-0500.jpg

http://www.heyreverb.com/wp-content/blogs.dir/4/files/2010/12/SimmonsArticle.jpg

[NW99XJ]

Hack and Tap horror images!

http://img840.imageshack.us/img840/4008/drivelinesye013.jpg


Yes its true, that there IS the possibility of the drill and/or tap breaking off in the shaft, so I would recommend removing the output shaft from the T-case, and having a machine shop do it.... IF you're left with having to do the H-n-T method. That first pic is a shot of what happened to me. I eventually got a replacement shaft and did the job on a lathe here at work.
Things can go wrong with ANY project on our Jeep, whether its replacing a cracked exhaust manifold and having the bolts snap off in the block, replacing shocks, and the bar pin bolts snap, or doing a SYE install..... Heck you could even screw something up when splitting the T-case or putting it back together...... you could forget a snap ring, or put something together wrong, Murphy's law I think could potentially apply to just about anything here.
Now with that being said, MY particular SYE project is a shining example of what can happen when things go both wrong AND right.


I've heard the H&T can cause the rear bearing in the tcase to wear out prematurely from the weight of the CV joint.
I would think that if this was true, then the same would apply to all the SYE's out there, as the same bearings are used with all kits. The only thing that is replaced or modified is the tail cone, the output shaft, and the rear seal.
Here is a pretty good example of a complete kit....notice there are no bearings that come with the kit.....
http://www.jeepinoutfitters.com/images/hd_sye_combo.jpg

So in this case, I would say you have been misinformed..... is it possible that the bearing IS seeing more weight load? Yes.... but I dont think it would cause premature wear..... It is a 4WD vehicle, so I would like to think that the bearings are designed to handle the stresses of an offroad environment.

[sexjay]

alright guys that was a big help! I think im just gona get the full sye kit with new output shaft and a new drive shaft to make things easier to install. tom woods sounds like a good idea with the one-stop-shop too. and LOL murderoy..those pics look scary!

[sexjay]

well if I removed the shaft I might as well just replace the whole thing

[Mudderoy]

alright guys that was a big help! I think im just gona get the full sye kit with new output shaft and a new drive shaft to make things easier to install. tom woods sounds like a good idea with the one-stop-shop too. and LOL murderoy..those pics look scary!

Well to be clear, I'm giving Josh (North West 99 XJ) a hard time. The short shaft and custom drive shaft was just my selection. I think you'll have less chance of installation issues (however installation is more complex) and less change of failure in the future. Key words are "i think"

[prcjeep]

Is your Jeep Standard or Automatic?

[drakan1908]

This is from Tom Woods site....#2
Hack&Tap Verses Our Modified Stock Shaft

Theirs - vs - Ours

There other conversions out there that leave it up to you to modify your existing out-put shaft by cutting it off, drilling and tapping. This is not something we suggest doing and we believe our modified stock out-put shaft conversions overcome the problems of lesser kits.

We believe the reasons for avoiding the other kits are for sound mechanical reasons. I will outline them for you here.

1. The method of cutting off, drilling and tapping the output shaft of the transfer case while still in the vehicle, is something that I would neither recommend nor attempt myself. We have seen many shafts ruined in this endeavor.

2. After the shaft has been shortened, you will still have a substantial area of unsupported shaft beyond the rear output bearing. I would also consider this to be a problem on a factory original shaft. The result of this is known as "overhung load." The drive shaft which would install against the modified shaft will weigh about 15 pounds while the factory original drive shaft weighs about 9 pounds. This in itself will nearly double the overhung load. We must also consider that under a load, the drive shaft will have a tendency to want to straighten out. This will also increase the overhung load.

3. You should also understand that in order for the new output flange to install on the output shaft, there must be some minor internal clearance between the splined bore of the flange and the splines on the shaft. Because of this clearance, you will then have the potential for minor independent movement between the flange and the shaft. This independent movement, over time (sometimes a very short time) will wear down the splines on the output shaft and enlarge the splines in the bore of the flange. When this happens, it will, because of the looseness between the parts, allow the flange to run eccentric. This will cause a vibration problem with the vehicle. Most people, upon discovering this problem, will re-tighten the retaining bolt. Unless the output shaft has been cut off perfectly square, this will cause the face of the flange to be less than perfectly perpendicular to the centerline of the output shaft. This will usually cause even a more severe vibration problem.

With any of the other conversion kits available, there will be a more substantial shortening of the output shaft, reducing the overhung load. Furthermore on any of the other conversions, the rear output flange or yoke is solidly "sandwiched" between the retaining nut or washer and the rear output bearing. This secure attachment will prevent the wearing of the splines on the mating parts. Thus, preventing the problem as outlined above.





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[sexjay]

Is your Jeep Standard or Automatic?

its an auto