Topic: SYE install questions

[WVUrocks]

Actually, this is my first post on this forum.  I just found this site about a week ago, and I'm loving all the information that is being shared here.

I'm getting ready to start some projects for my '99 TJ.  It's for the most part stock all around.  I'm planning a lift, 33" tires, etc...

I want to install a SYE and new driveshaft to correct for new driveline angles.  My question is, can I install the SYE and new driveshaft prior to installing the lift, or would the lift create the need for a longer driveshaft than the stock setup with the SYE?  Does the length of the driveshaft change enough with a 4-inch lift to require an even longer drive shaft that with the SYE and the Jeep at stock height?

My reasoning for doing this, is that I'm going to have to upgrade my Jeep in stages as money allows.  I can't really install the lift without also buying new tires (well I guess I could, but it would look stupid), and I don't want to use a tranny drop to "band-aid" the driveline angle issue.  I'd rather first spend some money on the SYE and a new driveshaft.  Of course if this wouldn't work, I don't want to have to buy two new driveshafts, hence the reason I'm asking for help.

I'd appreciate anyone's input.  

Thanks, Ben.

[j-freak153]

t-case drop isnt a band aid solution...it is whats necessasry for the 4" lift...itll be cheaper in the short term now than it would be to do the lift, the sye and the driveshaft...id do the lift anyway then the tires then if you were going to go over 4 1/2", id do the sye for sure...mine is going to be put in at the end of the month with the CV and the currie 9"...then i will not need the t-case drop anyway and i'll be taking it out....for even that much more clearance...

[SMC4WD]

I want to install a SYE and new driveshaft to correct for new driveline angles.  My question is, can I install the SYE and new driveshaft prior to installing the lift, or would the lift create the need for a longer driveshaft than the stock setup with the SYE?  Does the length of the driveshaft change enough with a 4-inch lift to require an even longer drive shaft that with the SYE and the Jeep at stock height?

The two reasons for a SYE is to eliminate the slip shaft that comes out of a reat T/C and to extend your driveline length.  Longer driveline has less chance of vibration at extreme angles.

When you do a SYE, you must buy a new rear driveline.  Most people like the dual cardon style, and the 'slip' part is in the middle of the driveshaft, not at a splined end as before.  The SYE allows you to run a rear driveline almost 1.5"-2" longer than the stock one.

To answer your question...  If you do a very small lift (1.5"-2"), that newly purchased driveline will be fine.  But at 3.5"-4+", it will be too short.  You can 'get away' with it, but any extreme extensions might pull the whole this apart.

The guys at Tom Woods are really nice.  You can ask them a little bit more about it.  They may offer a rear driveshaft that has a much longer slip.  They've been doing drivelines for SYE's for many years now.  They've got it down to which lift and which SYE without you having to measure it out anymore.

[WVUrocks]

Thanks for the responses.  It sounds like I'd be better off to hold onto the money (although it will be burning a hole in my pocket) and wait to do the lift and SYE install at the same time.  Thanks again.

[jagular7]

I hope this helps.
I'm running a combo of lift and love it. I've got Rubicon springs for slight lift over the tired 97 4cyl springs. These came from a 6cyl/auto/ac/hardtop 05 Rubicon. Then I added coil spacers to give me additional lift. The springs gave me 1.5" lft and the spacers another 2". I then added adjustable track bars to recenter the diffs under the TJ, lower adjustable front control arms, and upper adjustable rear control arms. To mate this all together, shocks for 4" lift and 2" bump stop risers. All cheap pieces from Ebay. To gain the extra droop up front, I got new JKS sway bar disconnects and added front brake lines for YJs. I added 34's on 7" wide rims to keep the tires tucked under the flares. The lower front to adjust the length as well as rotate during articulating. For the rear, upper adjusts the pinion angle and again helps with the arti.
Click here for some pics. I recently replaced the rear axle with a 8.8 and look closely at the rubber bushings at full droop.
http://s33.photobucket.com/albums/d99/jagular7/Articulating/



To compliment the suspension and to get a taller tire, I've also added a poly body lift. I went with the poly vs blocks is the stock rubber bushings were pretty much cracked and one was slit to the bolt. The block is stiff and without a good base to the frame, there would be a problem. I went poly as its stiffer than rubber, but not as stiff as a block. Sort of a compromise. All this was done over a period of 4 months in stages.
Coils - $40, shocks - $75(new), RE track bars - $260(new), lower front Tera arms - $90(new), upper rear Currie arms - $125, poly body lift - $135(new), bump stop risers - $30, YJ brake lines - $60(new), ACOS/poly spacers - $240(new).
I didn't lower the tranny at all, and did raise the engine 1". I also added a Trailmaster case shifter bracket. This helps with the body lift and removes the crank mechanism off the floor to a tranny bracket. I still haven't done a SYE as I don't need it. I added Currie HD tie rods to help better control the tires and strength for hitting rocks.
Next mod is a 231/D20 doubler setup.


Hope this helps.