Dukes69
05-30-03, 11:41 PM
Below is a quick and dirty FAQ (frequently asked questions) list with answers. These include some helpful hints, along with some valuable information. This mostly applies to XJ's or the Cherokee, but most will also apply to the cousin of the XJ called the MJ or Comanche. This is not meant to guide people to change, alter or modify any current setups, planned setups, or the way you do things. This is strictly meant to be a list of suggestions that has been gathered by people who feel their experience with these vehicles is enough to warrant posting such information to help out new members of the MJR XJ/MJ forum or any person who is seeking answers to some common questions we run across here on the Forum.
Common Abbreviations
AT = Automatic Transmission OR All-Terrain
MT = Manual Transmission OR Mud-Terrain
TC = Transfer Case OR Torque Converter
SYE= Slip Yoke Eliminator (also called a fixed-yoke conversion or a short shaft kit)
SA = Solid Axle
SFA= Solid Front Axle
SRA= Solid Rear Axle
CA = Control Arm
LCA= Lower Control Arm
UCA= Upper Control Arm
IFS= Independent Front Suspension
IRS= Independant Rear Suspension
SOA= Spring Over Axle
SUA= Spring Under Axle
BPE= Bar Pin Eliminator
DPA= Drop Pitman Arm
ECU= Engine Control Unit
TCU= Transmission Control Unit
TB = Throttle Body
FI = Fuel Injection
MPI= Multi-Port fuel Injection
TPS= Throttle Position Sensor
IAS= Idle Air Stepper motor
CPS= Crankshaft Position Sensor
MAP= Mass Airflow (sensor)
O2 = Oxygen (sensor)
NSS= Neutral Safety Switch (sometimes called Neutral Start Switch)
CCV= Crank Case Vent (?)
PCV= Positive Case Vent (?)
Body (armor, problems, tow points)
Why can't my XJ have a body lift?
XJ's don't have a frame because they are unibody. In essence the body is a cage, which supports it's own weight. This is also why XJ's are so light.
How can I mount tow hooks on the front of my XJ?
In order to safely mount tow hooks on the front of your XJ you'll need either a larger, aftermarket bumper with pre-made tow points OR tow hook brackets. A good link to more info can be found Here.
** Use the proper mounting hardware with brackets that are professionally built, this very important.
What's a nutstrip?
Nutstrips are metal strips with nuts welded to them. They are usually used for mounting rear tow hitches to XJ's.
Why is my hood stuck shut?!
If not properly maintained XJ hood latches can stick shut because the release cable has broken or come loose. Short of cutting the sides of the fenders open, you'll need to crawl underneath and use some creative movement to grab the release cable with some pliers and pull real hard. Do a search, this "accident" has happened before. You can help prevent this by lubricating your hood release latches ever so often with WD40 or some spray-on lithium grease.
(note: it doesn't happen "all the time", don't scare the newbies! LOL!)
Drivelines (Transfer cases, axles, transmissions, gearing, traction, production)
What transmissions came in the XJ?
AX-15: 5 speed manual transmission
AW4: 4 speed automatic transmission
Peugot: manual transmission
What axles came in the XJ?
XJ's all have a Dana 30 axle in the front.
In the rear, the following are options:
Dana 35C without C-clips (1984-1989/1990)
Dana 35C with C-clips (1990/1991-2001)
Chrysler 8.25 (27 spline - 1991-1996, or 29 spline - 1997-2001)
Dana 44 (most common on '87s, also found in some '88's and '89's)
What gear ratios came in XJ axles?
3.07 (usually found with 4.0L and manual tranny)
3.55 (usually found with 4.0L and auto tranny)
3.73 (not common, found in some early/mid 90's XJ's with the tow pkg)
4.10 (usually found in 4-bangers)
What's the difference between a 231 and a 242 transfer case?
The NP231 transfer case (Command-Trac) provides 2hi, neutral, 4hi and 4lo. The NP242 (Selec-Trac) provides 2hi, full time 4 wheel drive, 4hi and 4lo.
What's the difference between a locker and a limited slip?
A Limited Slip Differential, or an LSD, is a traction aid that is most often clutch or gear driven. A simple explanation is that as a wheel starts to slip/spin the LSD detects this and transfers "some" power to the wheel that is not slipping/spinning. LSD's are usually fairly well mannered on the street. A locker, on the other hand, essentially locks an axle together for and allows full power to both wheels. Lockers usually have at least some negative driving characteristics when on the street.
What is Axle wrap?
This is when the rotational force of the tires causes the axle housing to twist or rotate. This rotation forces the springs to bend into an S-shape. When the axle housing rotates far enough, forces cause the tires to loose traction, and jump, or "hop". Once traction is lost, the springs snap back into their original positions.
Engines (cooling, performance, production)
What engines did the XJ come with?
1984 - 1986 - Carbureted 2.5L 4-cylinder or 2.8L GMV6
1987 - 1991 - Fuel Injected 4.0L inline 6cylinder or 2.5L 4cylinder
1992 - 2001 - Fuel Injected 4.0L HO (High Output) inline 6cylinder or 2.5L 4cylinder
Why does my rig overheat?
XJ's are notorious for overheating. From early years until the early 90's they came with a "closed" cooling system. When functioning properly, these systems should perform fine. "Open" systems, on later model XJ's, are just like most typical cooling systems (filler cap on radiator, etc).
Several things can cause overheating…
1) Bad thermostat (it may stick and not allow the engine to cool)
2) Bad electric fan motor or sensor (this should kick on once the vehicle reaches 220 degrees, if it doesn't…it's bad)
3) Bad clutch fan (this is designed to spin on a clutch system, if it fails you will overheat in the city very quick)
4) Bad radiator (plugged or broken fins will cause an XJ to overheat)
5) Plugged coolant passages in the engine block. (typically manifested by highway overheating)
Why won't my Jeep start?
On the 4.0, there are several things known for causing starting problems. The CPS, the TPS, and the NSS. Do a search (http://www.myjeeprocks.com/forums/search.php?s=) on each of those.
Why won't my reverse lights work?
Generally the NSS needs to be removed and cleaned. There is a good write-up on GenXJ.com, and pics at NSS Removal and Cleaning (http://jeepin.com/features/nss)
Why is there oil in my air filter box?
XJ's commonly, over time, build up gunk in the PCV and CCV valves/lines and create pressure which then pushes oil into the air filter. Replace these valves and lines (parts from the dealer) and the problem SHOULD go away. If it doesn't, you may need to clean the inside of the valve cover.
Lifts (tire fitting, backspacing, lift types)
What size tires can I fit on my Jeep?
There is no absolute due to variance in suspensions, but here are some general guidelines…
-- No trimming and no lift, factory wheels
Typically a stock rig can handle 29" tires, MAYBE 30"… 235's metric…
-- No trimming, 15x8" Tech1 w/4.75 backspacing --
With 2" lift = 29 to 30x9.50 tires
With 3" lift = 30x9.50 tires
With 4.5" lift = 31x10.50 tires
-- Minor trimming, 15x8" Tech1 w/4.75 backspacing --
With 2" lift = 30x9.50 tires
With 3" lift = 30x9.50 to 31x10.50 tires
With 4.5" lift = 31x10.50 to 32x11.50 tires
With 6" lift = 33x12.50 tires
In addition to these guidelines, year must be considered. Up to 96 the wheel wells were generally more "open"…97 and later have a tighter front wheel well and are more likely to experience rubbing. Of course, virtually any tire can be fit with enough trimming. Typically most XJ owners don't go much larger than 35" tires, and that's at a minimum of 6" of lift.
If your wheel backspacing is less than 4.75" (such as 3.75") expect to add at least an extra inch of lift.
Also, thinner tires will fit easier as well. (such as 33x10.50's)
What is backspacing?
The distance from the inner edge of the wheel to the hub mount pad. Note: Sometimes the distance from the outer edge of the wheel to the hub mount pad is referred erroneously to as offset. BE CAREFUL!
What is wheel offset?
OFFSET - The distance from the centerline to the hub mount pad (where the wheel attaches to the hub). POSITIVE OFFSET - The hub-mounting surface is toward the front or wheel side of the wheel. NEGATIVE OFFSET - The hub mounting surface is toward the back or brake side of the wheels centerline.
Vibes (wheel shimmy, vibes, SYE's, death wobble)
What's a SYE?
A slip yoke eliminator replaces the slip style yoke that came on almost all XJ's with a fixed yoke and (usually) a CV style drive shaft with a slip built in. This reduces driveline vibes common with lifted XJ's and steep driveline angles.
Will I get vibes after my lift? (Do I need an SYE?)
This is not a cut and dry question/answer. The safest answer is: wait and see. Prepare ahead of time, have enough money saved to buy a slip yoke eliminator in case you end up needing it. Of course it's always ideal to get one, but sometimes people can't afford it. That being said, here are the options:
Typically, if you are over 3 inches of lift, you'll need an SYE. Now, that's just typical, not absolute. That is especially true for 1996 and newer XJ's because they have a longer output shaft. This puts more stress on the components and creates more vibes.
Other options are transfer case drop kits and long travel slip yokes. These typically are more of a "band-aid" than a fix and can sometimes cause more problems in the long run.
What is death wobble?
You'll know it if you experience it. Death wobble is when your jeep suddenly, and violently, begins to shake back and forth. It often comes after hitting a bump, and USUALLY at higher speeds. It is truly frightening. This is not to be confused with tire shimmy, where the steering wheel gets a shake in it at certain speeds.
What causes Death Wobble?
Death wobble is typically caused by
A) Out of balance tires or out of round wheels.
B) Loose track bar.
C) Worn front-end joints. (tie rod ends, track bar, ball joints, etc)
D) Bad alignment.
E) Bad caster angle.
F) Bad steering stabilizer.
There are kits out there to correct the effects of high lifts, but usually it comes down to checking those 6 things.
What causes tire shimmy?
Tire shimmy is typically caused by unbalanced tires or out of round wheels. If it gets bad enough it's possible for it to deteriorate into death wobble.
What is and causes bump steer?
Bump-steer is the result of poor (and sometimes unavoidable) suspension geometry. The reaction is described as the vehicle steering off the intended track, on it's own (without driver input), when encountering a bump. Sometimes it is described by a driver as the vehicle needing constant direction correction whenever driving over a bump, "I hold the steering wheel straight but the vehicle steers to the right every time I hit a bump." The cause is the axle tilt, due to the tire hitting a bump, changing the length between the axle draglink mount on a spindle and the pitman arm on the steering box. During a compression bump this length is reduced and the spindle must rotate (steer) to accommodate the draglink length.
Generic information
How do I post pictures on the forum?
How to Post Pictures!! (http://www.myjeeprocks.com/forums/misc.php?s=&action=bbcode#imgcode)
Common Forum Abbreviations and lingo
BTT = Back To Top (used when one feels the need to bump a thread to
the top of the main page)
BTW = By The Way
LOL = Laughing Out Loud
ROFL = Rolling On the Floor Laughing
LMAO = Laughing My A$$ Off
ROFLMAO= ROFL + LMAO
IIRC = If I Recall Correctly
IME = In My Experience
IMO = In My Opinion
IMHO = In My Honest (Humble) Opinion
AFAIK = As Far As I Know
AFAICS = As Far As I Can See
WB = Welcome Back
TY = Thank You
TIA = Thanks In Advance
OTOH = On The Other Hand
WTF = What The?
POS = Piece Of
SOL = Sorry out of Luck
FWIW = For What It's Worth
HTH = Hope That Helps
BRB = Be Right Back
BBFN = Bye Bye For Now
TTFN = Ta Ta For Now
TTYL = Talk To You Later
IOW = In Other Words
BTA = But Then Again
FYI = For Your Information
This was barrowed from Dave (Phatxj) over on JU, all of this is his, none is mine.
Common Abbreviations
AT = Automatic Transmission OR All-Terrain
MT = Manual Transmission OR Mud-Terrain
TC = Transfer Case OR Torque Converter
SYE= Slip Yoke Eliminator (also called a fixed-yoke conversion or a short shaft kit)
SA = Solid Axle
SFA= Solid Front Axle
SRA= Solid Rear Axle
CA = Control Arm
LCA= Lower Control Arm
UCA= Upper Control Arm
IFS= Independent Front Suspension
IRS= Independant Rear Suspension
SOA= Spring Over Axle
SUA= Spring Under Axle
BPE= Bar Pin Eliminator
DPA= Drop Pitman Arm
ECU= Engine Control Unit
TCU= Transmission Control Unit
TB = Throttle Body
FI = Fuel Injection
MPI= Multi-Port fuel Injection
TPS= Throttle Position Sensor
IAS= Idle Air Stepper motor
CPS= Crankshaft Position Sensor
MAP= Mass Airflow (sensor)
O2 = Oxygen (sensor)
NSS= Neutral Safety Switch (sometimes called Neutral Start Switch)
CCV= Crank Case Vent (?)
PCV= Positive Case Vent (?)
Body (armor, problems, tow points)
Why can't my XJ have a body lift?
XJ's don't have a frame because they are unibody. In essence the body is a cage, which supports it's own weight. This is also why XJ's are so light.
How can I mount tow hooks on the front of my XJ?
In order to safely mount tow hooks on the front of your XJ you'll need either a larger, aftermarket bumper with pre-made tow points OR tow hook brackets. A good link to more info can be found Here.
** Use the proper mounting hardware with brackets that are professionally built, this very important.
What's a nutstrip?
Nutstrips are metal strips with nuts welded to them. They are usually used for mounting rear tow hitches to XJ's.
Why is my hood stuck shut?!
If not properly maintained XJ hood latches can stick shut because the release cable has broken or come loose. Short of cutting the sides of the fenders open, you'll need to crawl underneath and use some creative movement to grab the release cable with some pliers and pull real hard. Do a search, this "accident" has happened before. You can help prevent this by lubricating your hood release latches ever so often with WD40 or some spray-on lithium grease.
(note: it doesn't happen "all the time", don't scare the newbies! LOL!)
Drivelines (Transfer cases, axles, transmissions, gearing, traction, production)
What transmissions came in the XJ?
AX-15: 5 speed manual transmission
AW4: 4 speed automatic transmission
Peugot: manual transmission
What axles came in the XJ?
XJ's all have a Dana 30 axle in the front.
In the rear, the following are options:
Dana 35C without C-clips (1984-1989/1990)
Dana 35C with C-clips (1990/1991-2001)
Chrysler 8.25 (27 spline - 1991-1996, or 29 spline - 1997-2001)
Dana 44 (most common on '87s, also found in some '88's and '89's)
What gear ratios came in XJ axles?
3.07 (usually found with 4.0L and manual tranny)
3.55 (usually found with 4.0L and auto tranny)
3.73 (not common, found in some early/mid 90's XJ's with the tow pkg)
4.10 (usually found in 4-bangers)
What's the difference between a 231 and a 242 transfer case?
The NP231 transfer case (Command-Trac) provides 2hi, neutral, 4hi and 4lo. The NP242 (Selec-Trac) provides 2hi, full time 4 wheel drive, 4hi and 4lo.
What's the difference between a locker and a limited slip?
A Limited Slip Differential, or an LSD, is a traction aid that is most often clutch or gear driven. A simple explanation is that as a wheel starts to slip/spin the LSD detects this and transfers "some" power to the wheel that is not slipping/spinning. LSD's are usually fairly well mannered on the street. A locker, on the other hand, essentially locks an axle together for and allows full power to both wheels. Lockers usually have at least some negative driving characteristics when on the street.
What is Axle wrap?
This is when the rotational force of the tires causes the axle housing to twist or rotate. This rotation forces the springs to bend into an S-shape. When the axle housing rotates far enough, forces cause the tires to loose traction, and jump, or "hop". Once traction is lost, the springs snap back into their original positions.
Engines (cooling, performance, production)
What engines did the XJ come with?
1984 - 1986 - Carbureted 2.5L 4-cylinder or 2.8L GMV6
1987 - 1991 - Fuel Injected 4.0L inline 6cylinder or 2.5L 4cylinder
1992 - 2001 - Fuel Injected 4.0L HO (High Output) inline 6cylinder or 2.5L 4cylinder
Why does my rig overheat?
XJ's are notorious for overheating. From early years until the early 90's they came with a "closed" cooling system. When functioning properly, these systems should perform fine. "Open" systems, on later model XJ's, are just like most typical cooling systems (filler cap on radiator, etc).
Several things can cause overheating…
1) Bad thermostat (it may stick and not allow the engine to cool)
2) Bad electric fan motor or sensor (this should kick on once the vehicle reaches 220 degrees, if it doesn't…it's bad)
3) Bad clutch fan (this is designed to spin on a clutch system, if it fails you will overheat in the city very quick)
4) Bad radiator (plugged or broken fins will cause an XJ to overheat)
5) Plugged coolant passages in the engine block. (typically manifested by highway overheating)
Why won't my Jeep start?
On the 4.0, there are several things known for causing starting problems. The CPS, the TPS, and the NSS. Do a search (http://www.myjeeprocks.com/forums/search.php?s=) on each of those.
Why won't my reverse lights work?
Generally the NSS needs to be removed and cleaned. There is a good write-up on GenXJ.com, and pics at NSS Removal and Cleaning (http://jeepin.com/features/nss)
Why is there oil in my air filter box?
XJ's commonly, over time, build up gunk in the PCV and CCV valves/lines and create pressure which then pushes oil into the air filter. Replace these valves and lines (parts from the dealer) and the problem SHOULD go away. If it doesn't, you may need to clean the inside of the valve cover.
Lifts (tire fitting, backspacing, lift types)
What size tires can I fit on my Jeep?
There is no absolute due to variance in suspensions, but here are some general guidelines…
-- No trimming and no lift, factory wheels
Typically a stock rig can handle 29" tires, MAYBE 30"… 235's metric…
-- No trimming, 15x8" Tech1 w/4.75 backspacing --
With 2" lift = 29 to 30x9.50 tires
With 3" lift = 30x9.50 tires
With 4.5" lift = 31x10.50 tires
-- Minor trimming, 15x8" Tech1 w/4.75 backspacing --
With 2" lift = 30x9.50 tires
With 3" lift = 30x9.50 to 31x10.50 tires
With 4.5" lift = 31x10.50 to 32x11.50 tires
With 6" lift = 33x12.50 tires
In addition to these guidelines, year must be considered. Up to 96 the wheel wells were generally more "open"…97 and later have a tighter front wheel well and are more likely to experience rubbing. Of course, virtually any tire can be fit with enough trimming. Typically most XJ owners don't go much larger than 35" tires, and that's at a minimum of 6" of lift.
If your wheel backspacing is less than 4.75" (such as 3.75") expect to add at least an extra inch of lift.
Also, thinner tires will fit easier as well. (such as 33x10.50's)
What is backspacing?
The distance from the inner edge of the wheel to the hub mount pad. Note: Sometimes the distance from the outer edge of the wheel to the hub mount pad is referred erroneously to as offset. BE CAREFUL!
What is wheel offset?
OFFSET - The distance from the centerline to the hub mount pad (where the wheel attaches to the hub). POSITIVE OFFSET - The hub-mounting surface is toward the front or wheel side of the wheel. NEGATIVE OFFSET - The hub mounting surface is toward the back or brake side of the wheels centerline.
Vibes (wheel shimmy, vibes, SYE's, death wobble)
What's a SYE?
A slip yoke eliminator replaces the slip style yoke that came on almost all XJ's with a fixed yoke and (usually) a CV style drive shaft with a slip built in. This reduces driveline vibes common with lifted XJ's and steep driveline angles.
Will I get vibes after my lift? (Do I need an SYE?)
This is not a cut and dry question/answer. The safest answer is: wait and see. Prepare ahead of time, have enough money saved to buy a slip yoke eliminator in case you end up needing it. Of course it's always ideal to get one, but sometimes people can't afford it. That being said, here are the options:
Typically, if you are over 3 inches of lift, you'll need an SYE. Now, that's just typical, not absolute. That is especially true for 1996 and newer XJ's because they have a longer output shaft. This puts more stress on the components and creates more vibes.
Other options are transfer case drop kits and long travel slip yokes. These typically are more of a "band-aid" than a fix and can sometimes cause more problems in the long run.
What is death wobble?
You'll know it if you experience it. Death wobble is when your jeep suddenly, and violently, begins to shake back and forth. It often comes after hitting a bump, and USUALLY at higher speeds. It is truly frightening. This is not to be confused with tire shimmy, where the steering wheel gets a shake in it at certain speeds.
What causes Death Wobble?
Death wobble is typically caused by
A) Out of balance tires or out of round wheels.
B) Loose track bar.
C) Worn front-end joints. (tie rod ends, track bar, ball joints, etc)
D) Bad alignment.
E) Bad caster angle.
F) Bad steering stabilizer.
There are kits out there to correct the effects of high lifts, but usually it comes down to checking those 6 things.
What causes tire shimmy?
Tire shimmy is typically caused by unbalanced tires or out of round wheels. If it gets bad enough it's possible for it to deteriorate into death wobble.
What is and causes bump steer?
Bump-steer is the result of poor (and sometimes unavoidable) suspension geometry. The reaction is described as the vehicle steering off the intended track, on it's own (without driver input), when encountering a bump. Sometimes it is described by a driver as the vehicle needing constant direction correction whenever driving over a bump, "I hold the steering wheel straight but the vehicle steers to the right every time I hit a bump." The cause is the axle tilt, due to the tire hitting a bump, changing the length between the axle draglink mount on a spindle and the pitman arm on the steering box. During a compression bump this length is reduced and the spindle must rotate (steer) to accommodate the draglink length.
Generic information
How do I post pictures on the forum?
How to Post Pictures!! (http://www.myjeeprocks.com/forums/misc.php?s=&action=bbcode#imgcode)
Common Forum Abbreviations and lingo
BTT = Back To Top (used when one feels the need to bump a thread to
the top of the main page)
BTW = By The Way
LOL = Laughing Out Loud
ROFL = Rolling On the Floor Laughing
LMAO = Laughing My A$$ Off
ROFLMAO= ROFL + LMAO
IIRC = If I Recall Correctly
IME = In My Experience
IMO = In My Opinion
IMHO = In My Honest (Humble) Opinion
AFAIK = As Far As I Know
AFAICS = As Far As I Can See
WB = Welcome Back
TY = Thank You
TIA = Thanks In Advance
OTOH = On The Other Hand
WTF = What The?
POS = Piece Of
SOL = Sorry out of Luck
FWIW = For What It's Worth
HTH = Hope That Helps
BRB = Be Right Back
BBFN = Bye Bye For Now
TTFN = Ta Ta For Now
TTYL = Talk To You Later
IOW = In Other Words
BTA = But Then Again
FYI = For Your Information
This was barrowed from Dave (Phatxj) over on JU, all of this is his, none is mine.