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Interchangeable parts question

N

Noslo_2

NAXJA Forum User
Location
Western Washington
My xj is a 1990 manual, with a sye kit 3.55 gears lockers front and rear. My question is if I buy a stock auto will everything change over or do I need to buy. New sye kit? Everything on my jeep is solid but I kinda want an auto and I have some wiring issues that might be easier to to fix by just just buying a stock jeep and changing everything over.
 
depending on the years... the auto to manual swap can be quite labor intensive. im not familiar with how the auto trans communicates with the PCM, or if there is a difference in CPS between transmissions.

IMO, the easiest way to swap to an auto is to find a clean rig with the desired trans and swapping over your lift components. autos are far more common than the manual variant. this is obviously assuming that your not emotionally attached to your current unibody.
 
Ya that would be what I would would do is buy one with an auto and changer over my lift components but I don't know if my sye kit from my manual would work in the auto trans
 
Noslo_2 said:
Ya that would be what I would would do is buy one with an auto and changer over my lift components but I don't know if my sye kit from my manual would work in the auto trans
Click to expand...

The SYE adapter, doesn't care what transmission you have as it is connected to the transfer case. There might be a difference in drive-shaft length though
 
Right i knew it was transfer case not sure why I said tranny. So all may have to change is the driveline length then? Now what year can I go up to 96? Will my 3.55 gears work in the auto just fine? If I swap both front and rear complete axles I have now?
 
its easier (in my opinion) to just swap the whole tcase instead of taking it apart and removing the SYE. everything will bolt in and swap over, the driveshaft length will more than likely be a moot point. it will be slower... stick XJs came with 3.07s, autos 3.55s. so to get the car back to the "same" gearing you had in the auto, you'd want 4.10s, but i'd (and everyone else here) would recommend 4.56s.
 
XJLI said:
its easier (in my opinion) to just swap the whole tcase instead of taking it apart and removing the SYE. everything will bolt in and swap over, the driveshaft length will more than likely be a moot point. it will be slower... stick XJs came with 3.07s, autos 3.55s. so to get the car back to the "same" gearing you had in the auto, you'd want 4.10s, but i'd (and everyone else here) would recommend 4.56s.
Click to expand...

no hes going from a manual to an auto(why, im not sure) so his gearing will actually improve a tad. 3.55 still sucks though, depending on lift and tires. im running 31s with 4.10s, im gonna go 33s....well see, but new gears may be in the future.

and OP. swapping the tcase over may or may not work. 1990 had the ax-15 manual which had a 23 spline output, but autos of that year were a mix. mid 1990 year they went from 21 spline to 23 spline. take the tcase off, count the spines on the auto. if it is 23 then just swap the tcase, if it is 21 then the sye will swap to another tcase(providing it is a 231, if the auto came with a 242 then you need a hack and tap).
 
biztyke said:
no hes going from a manual to an auto(why, im not sure) so his gearing will actually improve a tad. 3.55 still sucks though, depending on lift and tires. im running 31s with 4.10s, im gonna go 33s....well see, but new gears may be in the future.
Click to expand...

huh? 3.07s are stock on a manual, and he's currently running 3.55s... on a manual. so he is geared up. he's going back to stock with an auto.
 
With an auto it's easier to roll into the throttle when climbing hills if you need to instead of riding the clutch gas and brake at the same time. And I will make sure the auto I buy has a 231 in it and not a 242. The gears that are in it came in it. With a Chrysler 8.25 with Yukon shafts and a Detroit locker and the front with a lockrite and a sye kit and $400 driveline and and dam near new km2's only paid $1500 and it runs good just have a few electrical issues.
 
XJLI said:
huh? 3.07s are stock on a manual, and he's currently running 3.55s... on a manual. so he is geared up. he's going back to stock with an auto.
Click to expand...

There is really no "stock" gear ratio. Each dealer could select what ever axle ratio they wanted. There were many XJ's that came with 4.56's.
 
XJLI said:
huh? 3.07s are stock on a manual, and he's currently running 3.55s... on a manual. so he is geared up. he's going back to stock with an auto.
Click to expand...


my bad. missed the part about him running 3.55s already with a manual....assumed he was running the normal 3.07s.
 
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