SYE on a '98?

I have a 98 xj w/231 tcase. Its got a sealed output. Now from what I understand about an sye is that the general idea is to replace the slip yoke, which if you break a u-joint and pull off the rear axle, you would lose all your fluid. Correct so far? Then that, coupled with a front driveshaft, for example, leads to better driveline angles, fewer vibes, etc.

So my output is sealed, to me that kinda defeats the purpose of adding a sye. If I made the appropriate change to an output flange, would I still be able to run a cv driveshaft and get driveline angle benefits from it without an sye? Is it even possible? Im just toying the idea for the moment, this is just the start of digging deeper and finding a plan.

Thanks

I'm confused. I'm no suspension guru but I've learned a bit while playing with my Jeep. People don't install SYE so that they can pull a DS off and get home after busting a u joint. Might be a side benefit to earlier models. The main objective to a SYE is to be able to run a shorter DS. Whether you can make a front DS work or you have to invest in a CV shaft from RE or Tom Woods is academic. Either way you will get a shorter shaft with a double cardan joint in it. The purpose of the double cardan is that it can work with double the amount of angle in the driveline (so the 2 u joints in it effectively split that angle). This way the last u joint in the shaft (axle end) should be in line with the pinion. Your driveline will be setup entirely different from the way it is now. So...the SYE is used b/c the u joints in the stock driveshaft may not (depending on individual Jeeps) be able to handle the angles that the lift kit will effectively place on them.

Many of the guys on here could probably explain this better and probably even more accurately but I thought I'd try. I hope this helps.

Google search "Driveshaft 101". I can't recall who did it (Tom Woods?) but it is very informative. I'm still dealing with a tiny vibe in mine at 75-80mph. I believe my pinion is still about 2 degrees too high and so I'll be making some adjustments as soon as weather permits.

Wanted to add that if you don't feel like spending the 100 or so IIRC on a RE Hack and Tap SYE you CAN make one of your own. Search on here for home made SYE or just SYE. I believe Yucca has some great stuff on his site (including part numbers) on how to do this. Either way...you're STILL doing a SYE.

From what Ive read from some of the manufactures they usually put it as adding the lift pulls your slip yoke out, if it goes out to far or something breaks, you lose your fluid.

What youve said does make sense though. I know that longer driveshaft tends to have less vibes, ie lwb MJs and a lot of the larger lifted trucks. Yet would I gain the same benifits from installing longer rear control arms and restoring the wheelbase back to stock? I assume a longer rear CA would work the same as longer front CAs.

So the long story short results in buying an sye so you can use a longer cv driveshaft.

I dont have vibes but I want to get rid of my 1" t-case drop.

People put SYE's on for a number of reasons.

I also own a 98', but a Classic.
My reason for considering a SYE is simply to get rid of the external slip yoke which is a mantaince headache. Since I do not have wild angles to worry about I will be using a single cardon shaft with the SYE.

I am running 4" of lift and had angles of 5deg with minimal vibes (hard to tell with MTs) and since I replaced my beat to crap cross member ( The exhaust was actually touching the floor) with a Rustys 1" drop crossmember that has reduced the angles considerably and is now vibration free. Next upgrade is TC armor.

What's this about rear Control Arms? XJ's only have CAs in the front; top and bottom.

Does the rustys 1" drop xmember/skid eat up ground clearance like the 1" drops do?

And if I remember correctly the rear is technically a 4 link, using the leaf springs like bottom CAs and actual control arms for the top. But I could be wrong. Hell, it happens all the time.

EDIT I cant confirm the rear control arms now, I swear I had read that somewhere. Just assume I don't know what Im talking about until I can get outside and check the rear. Maybe Im thinking ZJ?

98XJSport said:

Does the rustys 1" drop xmember/skid eat up ground clearance like the 1" drops do?

And if I remember correctly the rear is technically a 4 link, using the leaf springs like bottom CAs and actual control arms for the top. But I could be wrong. Hell, it happens all the time.

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Interestingly, no. The Rusty's piece is built out of 3/16" steel and they simply lowered the plate the tranmission mount bolts to; resulting in a 1" drop. They even curled the front and rear lips to help it slide over obsticals. The unfortunate thng is that the T-Case sits even with the bottom of the cross member now

Some added armor should help protect the T-Case though.

Rear suspension: It is actually just two leaf springs.
Though the front section of spring acts most of the time more like a CA than spring and locates the rear axle, and much of the spring function is done by the rear; they are not infact CAs. There are no other CA like components in the rear. WJ and ZJ are built with CAs.

Hm cant be an worse than having your stock x-member hanging down an inch and hitting stuff. Im definately gonna hafta look into that. I think cost-wise that will be the best way to go compared to a SYE and new driveshaft.

Yeah I was looking into building a zj a bit back, got my info crossed.

Thanks for the help.

riverfever said:

People don't install SYE so that they can pull a DS off and get home after busting a u joint. Might be a side benefit to earlier models. The main objective to a SYE is to be able to run a shorter DS.

Click to expand...

Actually, the SYE allows you to use a longer driveshaft. This way, the operating angle is reduced slightly and then as you described the CV joint splits that angle between the two joints.

Sealing the rear of the t-case is an added benefit with the 95-older t-cases. There's a seal on the rear of the 96+ but there's also a very long, unsupported tailshaft that is prone to vibrating...so an SYE resolves that part of the problem as well.

Yucca-Man said:

Actually, the SYE allows you to use a longer driveshaft.

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Believe it or not...that is actually what I meant to say. Thanks for clearing that up Yucca. Sorry 98. At least the rest was accurate.

lol believe it or not I read it as longer anyways. The rest made sense for it to be longer instead of shorter as well.