lockers, 4x4, drivetrain issue. help meee!!! - Jeep Wrangler Forum
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Old 07-28-2014, 07:58 AM   #1
JeepJoe22's Avatar
Join Date: Mar 2013
Location: Frazier Park
Posts: 57
Hey all! Just picked up a 1990 yj 4.2 off craigslist and you guessed it! ..there's a couple issues.
When I got it, the guy had the front driveshaft off because "it saved mpgs". Not sure how much truth that holds but regardless, grabbed a couple new u-joints and threw that sucker back in. Instantly noticed a major difference in drivability.
It vibrates a lot more, my top speed has dropped by quite a bit, won't roll in nuetral (if I'm driving and put it in nuetral it will come to a stop almost as if I'm in gear, and it takes quite a hill to make it roll. so it will, but it's noteasy) and feels as though when I turn and shift it's in 4 wheel drive.
I know next to nothing about cars so if you could put everything as simple as possible it would be greatly appreciated.
Here's some other things I picked up on...
My last yj's 4x4 was vaccuum actuated. where the vaccuum was on the last one, on the axel, the new one is sealed up with a plate.
Pretty sure it has rear lockers which I was not informed of on the purchase. (Any way to easily check?) Not sure about the front
The tranny grinds on a couple gears, and on e.v.e.r.y gear when downshifting. Not sure if that makes a difference with the transfer case.
After putting on the driveshaft I now smell my brakes burning.
Any info helps!
Even on the tranny grinding =p
Thanks in advance, forum gas always been super helpful!
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Old 07-28-2014, 11:17 AM   #2
AllMudd's Avatar
Join Date: Apr 2013
Location: SoCal
Posts: 1,538
Cant see then photo to well because this app sucks on Androids. But feom what I can tell it looks good. Sounds like the PO did the solid 1 piece axle shaft swap on the front axle. You are correct they are normaly vaccum actuated. But there is plenty of 1 piece swaps or posi lok (which you dont have because there would be a cable coming out of that plate) best way to check the driveline is lift it and spinn all 4 tires and check all 4 corners just put it in 4wd and hold 1 tire ha e a buddy spin the other side thw oposite direction. If it spins thwn there is no locker (unless its just disengaged). But it kinda sounds like the gearing may be different in the front / rear axles this being the main reason why the PO had the frint DS off. Best way to check and also to do some preventive maintenance, is drop the covers on the axles and count teeth/look for the teeth count or ratio stamp on the ring gear. The trans sounds like its going out. And just to make sure before you do anything go underneath and manually put the tcase in 2wd. Sounds like there has been quite a bit done to this Jeep and maybe the tcase shifter isnt on correctly keeping the tcase in 4wd

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Old 07-28-2014, 01:00 PM   #3
JeepJoe22's Avatar
Join Date: Mar 2013
Location: Frazier Park
Posts: 57
Thank you so much for the quick reply. I'm going to check all that.
I know 4 wheel drive isn't always on because I took it to the off road park bear me to test it. I was in sand and dumped the clutch in 2 wheel and 4 wheel. 2 only the back and 4 they all went. That's what confused me so much. If it was constantly in 4 I'd understand the different but it's not. Makes me think the front dif is spinning the tranny if that's even possible
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Old 07-28-2014, 01:33 PM   #4
reno92's Avatar
Join Date: May 2013
Location: Cardiff By The Sea / Glamis
Posts: 1,166
First thing, pull that front driveshaft till you know the gears front and back match, you'll do major gear damage if you shift into 4X4 and they don't match. It's possible he put a locker in the front, and with the solid front axle your driveshaft will always turn. The vibration may be because your front DS is not balanced, they often are not because they don't normally turn unless in 4X4 with the vacuum engaged. The binding and brake smell may be seperate, it sounds like a front caliper sticking. You may notice smoke coming from it after driving, may just smell it. Jack the front up and see if both tires turn easily, that will point to the stuck caliper. You may want to contact a jeep club by you and see if someone would look over what you have, there are a lot of potential problems, many an easy fix for someone who knows where to look.
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Old 07-28-2014, 01:53 PM   #5
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Join Date: May 2013
Location: Cardiff By The Sea / Glamis
Posts: 1,166
After reading my own post I want to make sure I don't scare a newbie too much. From what you describe, if I were going to guess I would say you have two problems.

First is a sticking brake caliper, easy enough to change out or at least grease up the slides and see if it stops binding.

The second is an out of balance front driveshaft that always turns because of the switch to a solid axle (having the DS always turn will affect MPG's but not by much) The OP probably removed it rather than spend the money to have it balanced.

The grinding may be syncros going out, a bad thing, I'd first change the fluids with some 10/30 weight motor oil and see how it shifts. It may also be a clutch that is not fully disengaging, check the fluid level in your clutch master cylinder.

Like I said it may just be a bunch of little stuff, but it takes someone who knows a little bit about Jeeps to track it down.
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