*note, info taken from jeep forum*
Common Design
All MJs were built as a full unibody design with the body and frame rails tied/welded together as one piece and cannot be removed, however, the rear is a fully boxed frame with the bed bolted to it, making the bed removable. All MJs have solid axles front and rear. The suspension consists of coils for the front and leaf springs for the rear. All MJs came with disc brakes in the front and drums in the rear.
Also, all MJ's through all years are equipped with a height sensing proportioning valve that is used to change the bias of the brakes if the bed had a load in it.
For those curious to the differences in Cherokee's and Comanche's:
The taillight lenses are different from a Cherokee's, the wheel flares are the same (as a 2dr Cherokee), the front doors off of 4-door XJ's (84-92 at least) are swappable, hoods are swappable from 84-92 models Cherokee's (Cherokee's above 92 used spring-loaded hinges), and all mechanical/electronic parts forward of the firewall ARE identical.
Body
The body comes only in standard cab model with a rear double-top hatch tailgate. Comes in longbed or shortbeds two-tone versions. Long bed versions come with a larger gas tank than the short bed and is located front of the axle. Short bed version was not avaiable in 1986.
Interior: Door panels are removable as stock. Bench seats and bucket seats DO NOT have the same mounting brackets as XJ seats. Gauge cluster is removed by 4 screws. Gauge cluster during 86' have mechanical-powered gauges. On 87-90 gauges, The speedometer uses a cable, but all gauges 91-92 use a computer cable.
Wheelbase:
short bed 2wd=113.1 4wd=112.9 (18 gal tank)
long bed 2wd=119.6 4wd=119.4 (16 gal [longbed, opt shortbed] 23.5 gal [opt longbed; standard from 1989])
Engines
2.5L I4 TBI (fuel injected) - 117 hp @ 5000 rpm, 135 ftlb @ 3500 rpm - used in 86 and updated in 87-90 to 121hp (2.5L became MPI in 91 and was rated for 130hp @ 5250 and 149 ftlb @ 3250)
GM 2.8L V6 - 115 hp @ 4800 rpm, 145 ft lb @ 2400 rpm - used only in 86
Italian VM 2.8L Turbo Diesel - 140 hp, 236 ft lb torque - used in overseas MJs
2.1L 4 cylinder Turbo Diesel - 85 hp, 132 ft lb torque.
4.0L I6 EFI "Power Tech" - 177 hp @ 4750 rpm, 220 ft lb @ 4000 rpm - used 87-90
4.0L I6 MPI "Power Tech HO" (High Output) - 190 hp @ 4750 rpm, 220 ft lb @ 4,000 rpm - used in 91-92
Transmissions
Manual Transmissions
AX4 - 4 speed manual - manufactured by Aisin - used 86-92 with 2.5L I4 and 2.8L V6 engines and 2.8L turbo-diesels
T4 & T5 - 4 & 5 speed manual - manufactured by Borg Warner - used only in 86 with 2.5L I4 and 2.8L V6 engines
BA10/5 - 5 speed manual - manufactured by Peugeot - used only up to 89
AX5 - 5 speed manual - manufactured by Aisin - used with 2.8L V6 and 87+ with 2.5L I4
AX15 - 5 speed manual - manufactured by Aisin - used with 4.0L I6 engines
Automatic Transmissions
Torqueflight 904 - 3 speed automatic - used only in 86 with 2.8L V6 and 2.5L I4 engines and 2.8L turbo-diesels
AW4 - 4 speed automatic, electronically controlled - manufactured by Aisin - used from 87-92 (87-92 models include a Power/Comfort button that adjusts the shift points, also known as a towing package; all transmissions came with the towing package and came with a transmission cooler; 88+ models used Power/Comfort switch for off-roading)
Transfer Cases
The transfer cases used are all chain driven with aluminum housings. NP stands for "New Process" which is the brand, if you will.
NP207 - "Command-Trac" part-time only - 2.61:1 ratio low range - used 86
NP231 - "Command-Trac" part-time only - 2.72:1 ratio low range - shift pattern 2H - 4H - N - 4L - used 87-92
NP228 - "Select-Trac" part-time OR full-time - 2.6:1 ratio low range - used 86
NP242 - "Selec-Trac" part-time OR full-time - 2.72:1 ratio low range - shift pattern 2wd - 4part-time - 4full-time - N - 4LO - used 87-92
Driveshafts
Front Driveshaft - On 86-87 MJs (NP207 t-case) the front shaft is a "GKN" style shaft. On 87-92 MJs (NP231/242 t-case) the front is a "double cardan" two-piece driveshaft with a CV joint at the transfer case end.
Rear Driveshaft - The rear is a one-piece shaft with standard u-joints at both ends. The slip yoke is located on the output shaft of the transfer case. On 86-92 models, the yoke slides in and out of the transfer case and is lubricated by the ATF fluid internally.
Axles
Front Axles
Dana 30 high pinion - reverse cut - 27 spline, 1.16" diameter shafts, 7.13" ring gear - used 86-92 (all axles are vacuum disconnect, and have 5-260x u-joints)
Rear Axles
AMC-20 - 29 Spline, one piece axle shafts, 8.875" Ring Gear; Metric Tonne axle in 86.
Dana 35 non c-clip - 27 spline, 1.18" diameter shafts, 7.58" ring gear, 2.62" axle tube - used 86-89
Dana 35 c-clip - 27 spline, 1.18" diameter shafts, 7.58" ring gear, 2.62" axle tube - used 89-92
Dana 44 non c-clip - 30 spline, 1.31" diameter shafts, 8.5" ring gear, 2.75" axle tube - used 87-89 on some(not all) MJs equipped with towing package.
(note for D44's: All MJ's equipped with the stock D44 come with the Metric Ton Package)
All rear axles are made of a spring under axle design.
Gearing
3.07 - used with 4.0L engine / manual transmission
3.31 - used with 2.5L Fuel Miser option
3.55 - used with 4.0L engine / automatic transmission
4.10 - used with 2.5L engine usually
4.56 - rare but can be found on some older (~ 89 ~) models with 2.5L engine and auto transmission
NOTE:
Cooling Systems
Open style - any normal cooling system used today. Opposite of closed style described below.
Closed style - has no radiator cap and utilizes a pressure bottle. This style cooling system was used in 87-90 MJs.
Airbags
No airbags during Comanche timeline.
Trim Levels
86 - Custom, X, XLS
87 - Base, Pioneer, Chief, Laredo, SporTruck
88 - Base, Pioneer, Chief, Laredo, Eliminator, SporTruck
89 - Base, Pioneer, Chief, Laredo, Eliminator, SporTruck
90 - Base, Pioneer, Chief, Laredo, Eliminator, SporTruck
91 - Base, Laredo, Eliminator, SporTruck
92 - Base, Laredo, Eliminator, SporTruck
Production Numbers
MJ (4x4 only)
SWB/LWB
1986 23,251/xxxxx
1987 6,199/6,685
1988 6,895/9,167
1989 5,354/5,021
1990 3,283/2,129
1991 5,188 (TOTAL)
1992 3,142 (TOTAL)
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