SYE without lift?

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N8N_99xj

NAXJA Forum User
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Location
Curtis Bay, MD
I know, what's the point, right?

Well, I have a limited amount of time to work on my Heep and I'm thinking that if I choose to lift it trying to install a SYE, driveshaft, and lift all in the same day or weekend might be ambitious. so I am wondering if anyone has ever put a SYE on a stock XJ, and if so, will the front DS for an AW4/231 work as the rear DS for the same vehicle, or will it be too long?

I am thinking that I could go ahead and put the SYE in and shim the rear axle in one shot and then drive for a week or so (or if I'm broke, until I have money again) and then install the lift later. Or is this not going to work?

I'm probably going to stick with a very mild lift, but I don't like vibes so I'm pretty certain I'll just go SYE and be done with it.

thanks!
 
Good, thinking ahead!

I would hold off a bit though. Depending on high your "Mild" lift is, you may need to change driveshaft lengths (not as likely), and re-shim the rear end (more likely).

That doesn't mean you can't buy the SYE kit now while you have the funds :)

-Ron
 
I ran 4.5 inches of lift without an sye for a few years, I had a dana35 rear driveshaft with a dana44 and 3.5 springs with 1.5 shackles
 
now that's great feedback. Did you use the AW4/231 front driveshaft for your rear? I've got a turdy-five, so if anything you were cutting it closer than I would be.
 
I have also ran around with an sye on stock suspension. Shimmed the axle when I lifted it, it was a good length at both no lift and 5". No vibrations with either setup.

When installed on a stock suspension the rear slip doesn't move much. In a pinch a 5 speed front shaft is a titch shorter than an auto front shaft if needed as well.
 
Awesome. I picked up a front DS last night so I'll get it cleaned up and new U-joints and then I guess the next order of business is the SYE.
 
factory 4.0/AX15 front shaft is 1.41" shorter than a factory 4.0/AW4 front shaft.

You're going to have some vibes with the SYE because the rear diff pinion will still be angled for a single cardan/single cardan setup while the driveshaft will be double cardan/single cardan. It should work till you put the lift in and figure out what shims you need, though.

Honestly I would go the other way - lift first, SYE second. Break the leafs in and get them settled to their expected height and (if any) pinion angle change, it may change slightly as the leafs break in. Then slap the SYE in and shim the rearend to match and you're good to go.
 
Oh yeah, I know about pinion angles etc... in a former life I built myself a "hot rod" '55 Studebaker coupe, unfortunately the car I started out with had the center driveshaft support crossmember cut out for a bad 289/flightomatic swap, I stuck with that when I swapped in a R1/T10 but I did it neater. Well the later versions of that chassis that used a 1-piece DS apparently used a "broken back" type driveshaft... that caused some head scratching. If you shim it to "normal" configuration the driveshaft will go right into the floorpan the first time you hit the loud pedal hard.

But anyway, yeah, I thought about shimming, i was just assuming that that was part of the SYE install process, even though I didn't explicitly mention it.
 
I think it should be SOP to do an SYE before a lift if you cant add it right after you do the lift. Every set up is different but I got major vibes doing a 2" lift. I would do the SYE, shim it and then plan your lift. I measured and a front DS was too short for me with a 3" lift but again your results may vary. I like my AA sye, btw. No issues at all there.
 
kastein said:
factory 4.0/AX15 front shaft is 1.41" shorter than a factory 4.0/AW4 front shaft.

You're going to have some vibes with the SYE because the rear diff pinion will still be angled for a single cardan/single cardan setup while the driveshaft will be double cardan/single cardan. It should work till you put the lift in and figure out what shims you need, though.

Honestly I would go the other way - lift first, SYE second. Break the leafs in and get them settled to their expected height and (if any) pinion angle change, it may change slightly as the leafs break in. Then slap the SYE in and shim the rearend to match and you're good to go.
Click to expand...

The operating angle of the rear driveshaft on a stock suspension XJ isn't enough to warrant shimming the rear axle IMO. Vibes will be barely pronounced if there are any. Like I said earlier, I did it and it was silky smooth.
 
Always the benifit of being able to remove the rear drive shaft and being able to crawl out with the front axle, big benifit with this SYE.
After a hunting trip off road, I pulled out on a state hwy and accelerated, at 30 miles a hour I busted my rear yoke. Found drive shaft in a dich.
Tow truck home.
 
OK guys I'm sold... now just need to a) get the shaft cleaned up (still have some other parts in the electrolytic tank) and b) cough up for the SYE, u-joints, and possibly some shims...
 
Interesting, I currently have a 3 inch lift with a t-case drop. I am eventually going to go to 4 inches (in a few years). Should I go with a SYE now or later (I only have slight vibes at 55 mph and it dissapears at 57.
 
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