Sye vs transfer case drop.

[Muncher]

So i was watching videos on both of these seeing one is needed for a 4.5 inch lift but what one would be better to do?

[89eliminator]

SYE is a way better option if you can afford it.  

[ghetdjc320]

Transfer case drops can cause a lot of other issues like linkage binding and bad driveshaft angles. I’d recommend and SYE from JB Conversions. Best I’ve ever used

[Muncher]

How would i tell what transfer case i have for a sye?

[derf]

21 minutes ago, Muncher said:

How would i tell what transfer case i have for a sye?

Best way is to clean off the round tag on the back of the case.  It will be stamped with something like 231J.

 

Behind the manual transmission in 1987, you'll most likely have the NP231.  It's what would have come from the factory.

 

There's an off chance that someone swapped out the factory case for something else but it's unlikely.

 

[Muncher]

1 minute ago, derf said:

Best way is to clean off the round tag on the back of the case.  It will be stamped with something like 231J.

 

Behind the manual transmission in 1987, you'll most likely have the NP231.  It's what would have come from the factory.

 

There's an off chance that someone swapped out the factory case for something else but it's unlikely.

 

Yeah i don't think its been changed

[89eliminator]

if it goes 2H-4H-N-4L then its a 231

[Sir Sam]

SYE is hands down better. I did a hack n tap on mine since I have a 242 and the SYE kit for the 242 is stupid expensive. 
 

then I ordered a new Tom Woods drive shaft, which came out to like $450. 
 

so SYE is a better way to go, albeit more expensive. But I’m building my truck to get good use out of it, and I don’t want to drive around a half @$$ POS anymore. 

[Pete M]

technically you don't have to do anything.  the stock rear shaft should work fine with a 4.5 lift.   

[ghetdjc320]

1 hour ago, Pete M said:

technically you don't have to do anything.  the stock rear shaft should work fine with a 4.5 lift.   

Yeah very true. No need to run an sye unless you run a higher lift. I ran without an sye for quite some time on 6” soa rear. No driveline vibes or issues. I only went sye because I had to rebuild the t case and wanted a more solid setup.

[Dzimm]

On 8/6/2020 at 1:38 AM, Muncher said:

So i was watching videos on both of these seeing one is needed for a 4.5 inch lift but what one would be better to do?

As mentioned above, 4.5" of lift on a Comanche does NOT require a t-case drop or sye.  I personally have a 4.5" kit on mine and have flexed it out pretty good without dropping the driveshaft and no vibes even on the interstate.  The key on these is pinion angle, worst case you will need some shims for between the axle and leaf spring. 

 

If you really want to do it, get an sye and don't even mess with the t-case drop in this case because if you are going to do it just because you want to, do it right.  Also keep in mind an sye requires a new custom driveshaft, which isn't cheap.  T-case drops are for the budget build and retain the factory DS.

 

Now an XJ is a completely different story, those need an sye or t-case drop at even 3" of lift to correct angles.  I had an XJ at 3" with a t-case drop, just needed some adjustments to the linkages and it was fine.  

[derf]

Yeah, I'd also suggest that you run it as-is with the lift.

 

Tcase drops and SYEs are good ways to solve a vibration.  But if you're not feeling any vibration, no need to change it.

[Pete M]

and on that note, old U-joints don't always like changes in their operating angles, so you might develop minor vibrations that are only cured by installing new joints.