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The YJ Guide

174K views 229 replies 152 participants last post by  IVxIV 
#1 · (Edited by Moderator)
Well, I'm making this post to help some of the newcomers understand what they have, and provide a few great resources. This isn't a guide that has my advice, or my opinions...just straight facts about whats in your Jeep.

Engines:

6 Cylinders
4.2 L AMC 258 was used from 1987 to 1991
4.0 L AMC 242 from 1991-1995

4 Cylinders
2.5 L AMC 150

Transmissions:
6 Clyiners

Manual-
Peugeot BA-10 1987-1989
Aisin AX-15 1988-1995

Auto-
TF999 1987-1992 Non lock up
TF999 1992-1995 Electronic Shift
The electronic shift years could be wrong.

4 Cylinders

Manual
Aisin AX-5 1987-1995

Automatic
TF904 1994-1995

Transfer Case
Some YJ's from 1987 came with the NP207, the rest came with the NP231

Towing Capacity:
Frame is rated to pull 2,200 pounds.

Axles
Front
D30

Rear
D35

Differential Gear ratios
6 Cylinders
3.07 or 3.55
From everything I've see, these are the most common. If someone could
throw some more numbers out there with years, that would be great.

4 Cylinders
4.10

AN EXCELLENT RESOURCE FOR INFO, AND ENGINE/TRANNY SWAP INFO:
Novak Jeep Conversions - Home

GEAR RATIO GUIDE:
Jeep Wrangler Gear Ratio Guide

LIFT REVIEWS:
http://www.wranglerforum.com/f8/yj-lift-reviews-25156.html

JEEP PARTS:
Jeep Parts, Jeep Accessories, & Jeep Tops
Jeep Parts, Jeep Accessories & Jeep Soft Tops From The Jeep Parts Experts - Quadratec

HOW DOES MY HEAT WORK?
http://www.wranglerforum.com/f8/yj-heating-system-explained-68618.html

MY CHECK ENGINE LIGHT IS ON. OH CRAP.
http://www.wranglerforum.com/f8/check-engine-light-68329.html

MY STEERING IS GOOFY. WHAT TO DO?
http://www.wranglerforum.com/f8/how-i-tightened-up-my-steering-71025.html

MY SEATS SUCK! WHERE CAN I FIND CHEAP REPLACEMENTS:
http://www.wranglerforum.com/f8/these-seats-bolt-right-in-and-are-cheap-60648-2.html#post796754


There are a few things that could be wrong in here, and if you see anything wrong please say so. Also, if there are some other threads some people would find useful from the past, please put them in a comment!

Hope this helps some people out! :punk:
 
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#63 ·
Rubicon Express, Old Man Emu, and BDS make the best lifts. Spend the money to go with a higher quality lift, because it will pay off in the long run.

Also, lift size doesn't really matter in terms of engine size. The gearing in your differentials is what will make the difference. What rans are you running?
 
#71 ·
Manual trans:

4.2L 258 I-6 and 4.0L I-6's: From 1987-March 9,1989, the standard manual transmission is the light-duty Peugeot BA-10/5 5 speed. On March 10,1989 the assembly line was changed and through the end of the YJ production run, 6-cylinder models received the stronger Aisin-Warner AX-15, 5 speed.
2.5L I-4's: For all years, the only manual transmission is the Aisin-Warner AX-5, 5 speed.
Note: In 1994, the slave cylinder on manual transmissions was moved outside of the transmissions bellhousing to allow for easier replacement.
Automatic trans:

4.2L 258 I-6 and 4.0L I-6's: For all years, the Auto trans is the TF 999 3-speed transmission.
2.5L I-4's: For '94-'95 models, the only automatic transmission offered was the Chrysler TorqueFlite 904 3-speed transmission. Prior to 1994, 4-cylinder models were manual only.

YJ Wrangler - JeepForum.com Community Jeep Wiki
 
#76 ·
Hi Mike, Picked up a 88yj a month ago. 2.5 tbi. It's a project car for my son and I. Had to drag it home and been going through it. New tie rod, drag link, brakes all around, LH ball joints( really fun), new plugs, pcv, rotor , cap, wires and have replaced many vacuum hoses. Still starts rough but settles down when it warms up. Seems low on power and will miss occasionally. Do you have a source for a vacuum schematic as it still seems to run lean. Timing is ok. Any advice on the TBI or other diagnostics that you might recommend?
New to the forum and already I've found great info. I might have to take it in to the shop but( I'm cheap!!) and was hoping to get it figured out.
Thanks,
rob
 
#84 ·
1989 yj roll bar question

I have my jeep in the shop right now. They are installing a new rear seat but are telling me I need to replace my bars as they are to slanted for shoulder harness. Is there any other way to have shoulder belts in the back without changing the look of the jeep. As they want to install square bars. Any help is appreciated !!!!
 
#86 ·
jeep

:punk:
Well, I'm making this post to help some of the newcomers understand what they have, and provide a few great resources. This isn't a guide that has my advice, or my opinions...just straight facts about whats in your Jeep.

Engines:

6 Cylinders
4.2 L AMC 258 was used from 1987 to 1991
4.0 L AMC 242 from 1991-1995

4 Cylinders
2.5 L AMC 150

Transmissions:
6 Clyiners

Manual-
Peugeot BA-10 1987-1989
Aisin AX-15 1988-1995

Auto-
TF999 1987-1992 Non lock up
TF999 1992-1995 Electronic Shift
The electronic shift years could be wrong.

4 Cylinders

Manual
Aisin AX-5 1987-1995

Automatic
TF904 1994-1995

Transfer Case
Some YJ's from 1987 came with the NP207, the rest came with the NP231

Towing Capacity:
Frame is rated to pull 2,200 pounds.

Axles
Front
D30

Rear
D35

Differential Gear ratios
6 Cylinders
3.07 or 3.55
From everything I've see, these are the most common. If someone could
throw some more numbers out there with years, that would be great.

4 Cylinders
4.10

AN EXCELLENT RESOURCE FOR INFO, AND ENGINE/TRANNY SWAP INFO:
Novak Jeep Conversions - Home

GEAR RATIO GUIDE:
Jeep Wrangler Gear Ratio Guide

LIFT REVIEWS:
http://www.wranglerforum.com/f8/yj-lift-reviews-25156.html

JEEP PARTS:
Jeep Parts, Jeep Accessories, & Jeep Tops
Jeep Parts, Jeep Accessories & Jeep Soft Tops From The Jeep Parts Experts - Quadratec

HOW DOES MY HEAT WORK?
http://www.wranglerforum.com/f8/yj-heating-system-explained-68618.html

MY CHECK ENGINE LIGHT IS ON. OH CRAP.
http://www.wranglerforum.com/f8/check-engine-light-68329.html

MY STEERING IS GOOFY. WHAT TO DO?
http://www.wranglerforum.com/f8/how-i-tightened-up-my-steering-71025.html

MY SEATS SUCK! WHERE CAN I FIND CHEAP REPLACEMENTS:
http://www.wranglerforum.com/f8/these-seats-bolt-right-in-and-are-cheap-60648-2.html#post796754


There are a few things that could be wrong in here, and if you see anything wrong please say so. Also, if there are some other threads some people would find useful from the past, please put them in a comment!

Hope this helps some people out! :punk:
i have a 1990 jeep wrangler would not take anything for it.
 
#88 ·
I have a 89 yj with no motor or tranny. I bought a 4.0 that came out of 95. The wiring harness on the 95 had been all hacked up & torn off. What is the best solution to this problem?

Also the tranny I bought is a manual and there was an automatic on the 4.0 before. What all do I need to make the manual work? (I am new to this so any and all help is much appreciated!!)
 
#89 ·
Pretty new to all this forum Stuff. Just got home from afghanistan and went out and bought a toy. I have a 95yj with a 2.5. plans are to put a 4.0 in it. Is there anything you all can provide me with a little guidance on installing this and the problem i may have.or is it even worth it. This is not going to be a big time mudder. just want it to look good while driving down the road. also If i were to put any kind of lift on it. What is the biggest lift kit you would recomend? any help would be great thanks in advance
 
#90 ·
Booker1203 said:
Pretty new to all this forum Stuff. Just got home from afghanistan and went out and bought a toy. I have a 95yj with a 2.5. plans are to put a 4.0 in it. Is there anything you all can provide me with a little guidance on installing this and the problem i may have.or is it even worth it. This is not going to be a big time mudder. just want it to look good while driving down the road. also If i were to put any kind of lift on it. What is the biggest lift kit you would recomend? any help would be great thanks in advance
I wouldn't recommend doing that swap, it can be done but you can swap in a V8 for the same or less price wise, another option is to sell the 2.5 and get one with a 4.0. The 4.0 swap isn't just a motor swap you have to change the tranny and transfer case as well, cut and weld new motor mount brackets, configure a wire harness etc. Just my .02 hope it helps and thanks for your service!
 
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