T case drop

alexgalexg

New member
1998 jeep xj 4.0 automatic part time 4wd
3.5 Rubicon express lift, iro track bar

So I'm paying to work in a shop installing my lift. Its pretty much done and looking good but I only have today left to work in the shop. The angles on the axle dont look TERRIBLE and sadly I wont have time to install the sye I bought.
So here is the plan.
Finish the lift install, drive and check for bad vibes, if I have any I'll install a drop kit just for the winter and install the sye in my driveway next summer since I already have it.
Any recommendations for a drop that fits my lift? Was thinking rusty's. Simple and inexpensive.

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lazyxj

NAXJA Member #1310
NAXJA Member
At 3.5" of lift, it's too high for 97+ XJ transfercase drop to work well.
When you drop the rear, it decreases the rear driveshaft's angles but it increases the front driveshaft angles, leading to front end driveshaft vibes.
When installing a drop, you must also changed the rear axle's angle using tapered shims, to even out the angles.
If you don't have a place to install the SYE, how are you going to install the axle shims?
The rear end needs to be jacked up and the spring's u-bolts loosened enough to install the angle adjustment shims. The same change needs to done with a SYE.
Some adjustment shims require pulling the leaf spring's center bolt.

If you already own an SYE, it's only a few hours work to open the transfercase and do the switch, it can be done without in the car without pulling the case.
Installing a drop will also take time and a place to do it.
 

alexgalexg

New member
At 3.5" of lift, it's too high for 97+ XJ transfercase drop to work well.
When you drop the rear, it decreases the rear driveshaft's angles but it increases the front driveshaft angles, leading to front end driveshaft vibes.
When installing a drop, you must also changed the rear axle's angle using tapered shims, to even out the angles.
If you don't have a place to install the SYE, how are you going to install the axle shims?
The rear end needs to be jacked up and the spring's u-bolts loosened enough to install the angle adjustment shims. The same change needs to done with a SYE.
Some adjustment shims require pulling the leaf spring's center bolt.

If you already own an SYE, it's only a few hours work to open the transfercase and do the switch, it can be done without in the car without pulling the case.
Installing a drop will also take time and a place to do it.
With a sye it takes a few hours assuming I can get the case out without a fight, then I have to wait a week for my custom drive shaft to arrive.
I did not know I'd need to do anything after putting in the t case drop that's why I proposed it so I will see what money is left over from using this space this long. If I can afford it I'll do the sye.

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alexgalexg

New member
I'd like to add the angle didnt look that bad. The JK next to it in the shop had a lift and a worse angle than that with no vibes and that's not nearly as advanced or tough as an xj.
My plan is to drive it and see how the vibes are before installing the sye. If I can put it off for summer I would like to. If not I'll install the sye in my driveway. Just not ideal since its already icy up here

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RCP Phx

New member
With a sye it takes a few hours assuming I can get the case out without a fight, then I have to wait a week for my custom drive shaft to arrive.
I did not know I'd need to do anything after putting in the t case drop that's why I proposed it so I will see what money is left over from using this space this long. If I can afford it I'll do the sye.

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First you said you were buying a sye/driveshaft kit? Second you don't need to remove the t-case from the vehicle.
 

alexgalexg

New member
First you said you were buying a sye/driveshaft kit? Second you don't need to remove the t-case from the vehicle.
Yes but I learned that if I buy the kit together theres a chance I'll still get vibes from the driveshaft. So I'm ordering the shaft after the kit is installed which im finishing up today

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sidewaysstarion

Coffee Drinker
NAXJA Member
Chapter BOD
Yes but I learned that if I buy the kit together theres a chance I'll still get vibes from the driveshaft. So I'm ordering the shaft after the kit is installed which im finishing up today

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You can always toss a stock front driveshaft in the rear after the SYE so you can drive around while you wait for your new driveshaft to arrive.
 

alexgalexg

New member
You can always toss a stock front driveshaft in the rear after the SYE so you can drive around while you wait for your new driveshaft to arrive.
I keep hearing that from people and I almost want to source one just to see how it turns out lol. I'd be curious to see if I got highway vibes not to mention this lift is bigger than 3.5. It "says" it's a 3.5 but I'm thinking more like 5 rear 4.5 front. At least my rough visual.
I should be done with the regular lift today. Only tool i dont have for the sye is the snap ring tool so I'll have to get one of those. Thanks for warning me about the t case drop temp fix thing.


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RCP Phx

New member
Yes but I learned that if I buy the kit together theres a chance I'll still get vibes from the driveshaft. So I'm ordering the shaft after the kit is installed which im finishing up today

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Unless I'm reading that wrong, it's impossible!
 

alexgalexg

New member
Well because it's a generalized fit for any random 3.5 lift. Which as this lift has made clear to me, every 3m5 lift is different by brand. Mine is definitely more than 3.5. I'd probably be fine but I didnt want to chance it. So I bought my sye and am going to measure and order the shaft after it's in

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RCP Phx

New member
Well I can tell you right now that it's going to measure @ 32-1/4" to 32-1/2", which if your using a standard yoke that has a travel of @ 3" will be no issue at all.
 

alexgalexg

New member
Lift is done! Bad vibes especially at high speeds. I'll see about accessing all the t case bolts tomorrow. I really dont want to remove it entirely


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RCP Phx

New member
It's looking good! Are those 31x10.50's on there? Did you remember "Not" to torque the leaf spring and control arm bolts until after you've driven around a few miles?
 

alexgalexg

New member
It's looking good! Are those 31x10.50's on there? Did you remember "Not" to torque the leaf spring and control arm bolts until after you've driven around a few miles?
Thanks! I'm really liking the new look a lot!

Tires are 225/75 radials on 16 inch rims

They are tight but not torqued hard.

Do you know in millimeters what the biggest bolt is I'll need for the transfer case? I know there is one that's over 20 so I have to buy it.

Also rides great! Soft but no body roll I love it! I do here some noise coming from the front drive shaft but the control arms fixed caster so I am not sure if that is indeed what's causing it.

I will also be looking at that thread you posted once I get my sye in

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md21722

NAXJA Member
NAXJA Member
You don't need to remove the case to install a SYE. That is an optional step.

As others have said you can generally use a front shaft, at least temporarily.

I would have a local driveshaft shop make you a shaft rather than buy from someplace online that uses crappy Chinesium parts that won't hold up over time.
 

md21722

NAXJA Member
NAXJA Member
I don't think there are any large bolts in the transfer case. To split the case it's all 13 mm but one on the top is a 12-point 13 mm.
 

md21722

NAXJA Member
NAXJA Member
Use Loctite Gray to seal the case. The cheapest place to buy it is Wal Mart! Just be careful around the oil pump tabs. If you get RTV too close to the tabs of the oil pump, the oil pump will become off center and it will eat up the seal.
 

RCP Phx

New member
Use Loctite Gray to seal the case. The cheapest place to buy it is Wal Mart! Just be careful around the oil pump tabs. If you get RTV too close to the tabs of the oil pump, the oil pump will become off center and it will eat up the seal.
The pump can't get "off-center" since it is splined to the main shaft and runs on a seal surface for the pump seal.

OP, don't forget about the 1-1/8" nuts on the yokes.
 

alexgalexg

New member
The directions advance adaptors supplied are not so good. I dont even know which 4wd selection it wants me to put it in prior to cutting the rod down to an inch. AMD they did not supply directions for reinstalling the front output yoke. Fun

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