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T-Case Drop VS. SYE

8

89BlackXJ

NAXJA Forum User
Location
California
I have ordered a Rusty's 4.5 lift and it comes with a t-case drop.....i will be using the jeep mainly as a DD with moderate weekend wheeling. Will the t-case drop stop most of my driveline vibes and prevent the driveline from slipping out of my transfer case....or is a SYE absolutely necessary?
 
spend the extra bit of money, get the SYE kit and a new cv driveshaft and be done and never worry. my 2 cents.
 
hey i have a 6" of lift and a dropped sye and i wasnt feeling anydriveline vibes but just recently i smashed down on my crossmember and there was vibes. yeah its ok if you dont have vibes but when you do have vibes and keep it like that its bad and its extremely annoying like you have no idea it sucks. im thinkin bout the tom woods sye conversion that comes with the cv for 370 good price considering re's sye is like 250 and cv is 300 to 350.
 
Every XJ will react differently, and some years are said to be more prone to vibrate than others. Try the drop first, but make sure your angles are set correctly. Without a CV the angles for each u-joint should cancel each other out. If you have 7 degrees down at the t-case, you will need 7 degrees up at the pinion. Even then it may still vibrate. You could try a longer yoke at the t-case, or have your shaft lengthened and rebalenced, but why spend the $$$ on that when you can get a Hack and Tap SYE.

I went straight for an Advance Adapters HD SYE and CV driveshaft when I did mine. It is an upgrade in strength over the stock slip-yoke design and you can remove the rear drive line without spilling ATF out of your t-case (good on the trail). If you are on a budget you can run a front shaft in the rear, or hit the junkyards in search for a CV shaft the right length. Just make sure the joints and yokes will match up.

Greg
 
I've always considered a T case drop like a band-aid... It'll get you buy, and possibly get the job done, but why take a chance... The price of SYE's makes it an easy choice too...

-Will
 
When I did my Rusty's 4.5, I just installed the 1" t-case drop, and while vibes were minimal, I didn't like having the drop on there because it's basically a band-aid. Plus under deceleration, the rear driveshaft would bind up and make a grinding sound. So I ordered an sye and used a stock front driveshaft and couldn't be happier with my decison. Sye cost me 200 bucks, and I picked up the driveshaft at the wrecking yard for 35 bucks. I've never heard about anybody breaking a stock front ds when using it in the rear, and I've wheeled mine hard and it's been perfect for me so far. HTH
 
which front drive shaft would be better? longer is better im assuming. one form a aw4, a ax-15, or nv3500?
 
MontanaXJ said:
Every XJ will react differently, and some years are said to be more prone to vibrate than others. Try the drop first, but make sure your angles are set correctly. Without a CV the angles for each u-joint should cancel each other out. If you have 7 degrees down at the t-case, you will need 7 degrees up at the pinion. Even then it may still vibrate. You could try a longer yoke at the t-case, or have your shaft lengthened and rebalenced, but why spend the $$$ on that when you can get a Hack and Tap SYE.
Greg
Click to expand...

Sorry to HiJack... I've heard about the fact that the angles need to be the same to cancel each other out (at pinion and tcase), but I had never heard that was only with a stock (non CV) shaft.... How are you supposed to set angles with a CV shaft? Thanks!
 
89BlackXJ said:
I have ordered a Rusty's 4.5 lift and it comes with a t-case drop.....i will be using the jeep mainly as a DD with moderate weekend wheeling. Will the t-case drop stop most of my driveline vibes and prevent the driveline from slipping out of my transfer case....or is a SYE absolutely necessary?
Click to expand...


I ran my 87 with a 4.5" and 1" t-case drop for about a year with zero vibes. Ran the Rubicon as well as a few other difficult trails that way. I lifted to 6" in the rear and kept the 1" t-case drop and SYE for a few months, i started to notice vibe, but only dead on 35 and 70 mph. I did do an sye/cv then..

i guess what i'm trying to say is try it and see what happens. Odd's are you'll be fine. Newer (96+) xj's are a different story, over about 3" it becomes necessary - their tranfercase has a different yoke setup.
 
TC drops are WORTHLESS IMO...did a 4.5 RE lift on my XJ...didnt install the drop. Drove it around the block and it vibrated somethin feirce....installed the TC drop and it vibrated just as bad and created something else to get hung up on.

Do yourself a HUGE favor and go with an SYE.

With 4.5(gonna be more like 6) inches, you WILL get vibes without an SYE...how bad you get them is impossible to say.
 
kristoffers said:
Sorry to HiJack... I've heard about the fact that the angles need to be the same to cancel each other out (at pinion and tcase), but I had never heard that was only with a stock (non CV) shaft.... How are you supposed to set angles with a CV shaft? Thanks!
Click to expand...

This is a wonderfully informative write up. Check it out. It should explain everything pretty thoroughly.

http://www.4xshaft.com/driveline101.html

As far as the TC drop or SYE. I used the band-aid for about 8 months before going with a SYE and CV shaft. I wish I had done it sooner. You might not think you have many vibes...but they are there. I only have a 3" lift on my 96 and it felt like poop.
 
Jeffro600 said:
TC drops are WORTHLESS IMO...did a 4.5 RE lift on my XJ...didnt install the drop. Drove it around the block and it vibrated somethin feirce....installed the TC drop and it vibrated just as bad and created something else to get hung up on.

Do yourself a HUGE favor and go with an SYE.

With 4.5(gonna be more like 6) inches, you WILL get vibes without an SYE...how bad you get them is impossible to say.
Click to expand...


Now your starting to sound like me, with all the definates. I thought cockiness was my role, but I guess I can share.

Not everyone gets vibes at 4.5 or 6 " without an SYE, it has a lot to with the year of the jeep and what rear end you have (the dana 35 has a small pinion and leaves you with a better angle, for example). He's on an 89, so he'll probably be ok.
 
ttu.or said:
which front drive shaft would be better? longer is better im assuming. one form a aw4, a ax-15, or nv3500?
Click to expand...

If memory serves me correctly, the donor has to have an AW-4, and you also have to have an auto to make it work without lengthening it. Also, its a bonus if you have the 8.25 in the rear beacuse its pinion is longer and therefore closer to the t-case. It dosen't matter if the doner vehicle has the 231 or the 242 case. The shaft is the same.
 
kristoffers said:
Sorry to HiJack... I've heard about the fact that the angles need to be the same to cancel each other out (at pinion and tcase), but I had never heard that was only with a stock (non CV) shaft.... How are you supposed to set angles with a CV shaft? Thanks!
Click to expand...
When running a CV shaft the pinion should be pointed up towards the t-case output to put the pinion inline with the drive shaft. Most say about 2 degrees down at the pinion is good to account for axle wrap in a leaf sprung vehicle. If you had links in the back you would make it zero.

Why? A CV drive shaft is made up of 3 u-joints. The actual CV part consists of 2 joints that already cancel each other out, leaving you with 1 joint that needs to be as straight as possible so that it will not vibrate.

Greg
 
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